Lets Talk ATV Differentials

[drivetrainUW-Platt]

I'm looking for something to replace the fat torsen diff, thinking that the Honda Foremann/Rubicon front cam and pawl Suretrac is the way to go. The steel inner case that holds the actual gears looks like it would work out pretty good untouched except for gettin oil to stay in it somehow.
Those that have run this (Kettering, Monash ect...) please chime in and give us some info on how it worked/didnt work and any pictures would be great
thanks

[drivetrainUW-Platt]

I'm looking for something to replace the fat torsen diff, thinking that the Honda Foremann/Rubicon front cam and pawl Suretrac is the way to go. The steel inner case that holds the actual gears looks like it would work out pretty good untouched except for gettin oil to stay in it somehow.
Those that have run this (Kettering, Monash ect...) please chime in and give us some info on how it worked/didnt work and any pictures would be great
thanks

[JerryLH3]

We'll be using the same diff that was used in our 2005 car. It's a cam and pawl from a Honda ATV, and it made for a compact drivetrain. At least one of the judges liked it.

[Jarrod]

works pretty much the same as torsen from what i understand, but it opens up quite a bit after a bit of driving (carroll smith talks about this in one of his books). We simply put some silicon in the holes in the back, and run a lip seal against the cv joint shafts on a little sleeve that goes around the diff bearing surface. The sleeve is also required as it is designed for a 29mm ID bearing (??) so we sleeve it up to a common size. Wollongong made their own casing, which was quite a bit neater than our setup. I believe the newer diffs have the crownwhell integral with the case, and you need to cut it off somehow, but the cases we have were bolt on crownwheels.

[jack]

how much to the honda diffs cost?

[drivetrainUW-Platt]

I recall one team talking about having to cut the gear off for there 05 car, not much a lathe couldn't do. Any pictures of your setups?

heres some info I found:
http://www.vincie.org/Suretrac_Test.pdf
from:
http://forums.atvconnection.com/messageview.cfm/catid/8/threadid/460560.cfm

[drivetrainUW-Platt]

http://i22.photobucket.com/albums/b309/duwem/FSAE-A20200320167.jpg

Monash's I believe

[Jarrod]

yep, thats ours, in 2003. From wollongongs website if i recall?
Our website is currently down, some administration thing. There will be pics on there when we get it back up.

[Faterooski]

I think I remember the University of Guelph using some sort of Suzuki ATV diff for their awd setup. I also remember vaguely them saying that the diff and the splined shafts they wanted to used luckily mated right up. Sheer luck I guess. Anyone have any more details on what they used?

[Rob Battiston]

Guelph uses a Suzuki ATV front diff, from the Vinson 500...

[drivetrainUW-Platt]

like every part on the car, I need this diff yesterday, anyone have one laying around they want to get rid of or know of a good source I can get/buy one from?

[formula_geek]

I believe the Honda diff. was about $500. You should be able to order it from any Honda dealer that carries ATVs. We used the CVs from the Honda as well, was fairly expensive as we had to buy the complete assembly (including the shafts that we were throwing away) as well.

I'll see if I can dig up the particulars on the diff (what years & models it was available, etc).

Travis Slagle
Kettering University FSAE Alumni

[Ryan McCauley]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by drivetrainUW-Platt:
from:
http://forums.atvconnection.com/messageview.cfm/catid/8/threadid/460560.cfm </div></BLOCKQUOTE>
Mike, That link right there was one of our team members asking about the Forman/Rubicon diff. We are going to be running it this year, so were going through the same thing you are right now. We ordered it a week ago off of ebay for $260 shipped...Ours is off of a 2005 Honda TRX 350 FM. We also found THIS (http://www.servicehonda.com/parts.php?partnumber=41400-HN5-M40+&getpart=1) website that sells them for $482. Hope that helps you out some...Sorry I can't help you out more with the setup.

[drivetrainUW-Platt]

so what exact year am I looking for, I beleve its a Formann/Rubicon 2000 or newer? which ones have the ring gear welded on and which dont? Going be shopping around in the next few days and would like as much info before I make a purchase and start calling junkyards.

[mtg]

Once upon a time in a galaxy far, far away, UMR used a Honda Cam & Pawl based diff.

It was about the size of a can of tuna, weighed about the same, and worked about as well as a can of tuna.
The good points are the ability of different torque bias ratio on accel and decel, as well as being light. But, it ratchets and you can feel it when you're driving. There's nothing like hauling into a hairpin and waiting for the diff to ratchet so you can get some yaw going on.

[jsmooz]

We use a Rubicon diff. It's actually the front diff. Call you're local Honda ATV dealer for prices. I want to say that with a slight discount we gets our for ~$300. I'm not the guy that purchases them tho so I might be wrong.

[Chris Allbee]

For those of you that have used this diff or something similar, can you comment on how it performs against the T-1 torsens? or how it feels to the driver? do you even notice the difference in the diff?

[drivetrainUW-Platt]

Gona be lookin around in the next few days to buy one, unless someone has one they want to sell or knows a good source to get in contact with

[Ryan McCauley]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by drivetrainUW-Platt:
so what exact year am I looking for, I beleve its a Formann/Rubicon 2000 or newer? which ones have the ring gear welded on and which dont? Going be shopping around in the next few days and would like as much info before I make a purchase and start calling junkyards. </div></BLOCKQUOTE>
You can get them on the 2004-up Foreman/Rubicon TRX 350 FM. I'm not sure which ones have a welded ring gear.

[drivetrainUW-Platt]

I was quoted $160 for each half shaft and a few hunderd for the diff new, around 800 total for all new parts, if anyone was wondering...definitely dont wana go the new route but its not ungodly expensive compared to the torsen and custom shafts/cvs.

[CMURacing - Prometheus]

just to compare, for those of you that don't have costs of these lying around:

torsen: $360, toyoda-koki (new)
driveshafts: $1000, rockford constant velocity; $1800 complete, taylor racing

so you're spending $800 for the equivalent parts. that's cost report (and real) money I'd KILL for (it'd let me buy some nice ohlins shocks)

[Andycostin]

We used a Polaris LSD diff last year, with a custom casing, and will be using the same this year. Performs well, and looks trick to boot. Haven't got any pics, and drivetrain leader isn't around atm. But will see if I can get some pics up soon. Pricing was around $US700 (i think)

[johnnySV]

what kind of modification is necessary to change the input from 'perpindicular drive-shaft style' to 'concentric sprocket drive'

[mtg]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by johnnySV:
what kind of modification is necessary to change the input from 'perpindicular drive-shaft style' to 'concentric sprocket drive' </div></BLOCKQUOTE>

Ditch the stock housing and gear drive, make a new housing with a sprocket that attaches to it.

So, basically you end up only using the internals of the ATV diff.

Andy, what kind of diff was in the Polaris?

[johnnySV]

so the dif will function if the original input circuit is eliminated? will the sprocket end up being directly connected to one side of the driveline (one axel), thus the potential for the system would be that other side of the dif is purely reactive? (other axel) is there anoth thread that better describes this concept? (search function returns a lot of disussion but i am struggling to understand the fundamentals - thank you)

[Colin]

the diff in the polaris has a viscous coupling that pushes against a series of clutch packs, pretty neat and very easy to adjust lockout, all you have to do is shim the clutch pack. And we've had zero problems with wear of the clutch pack, heaps better than the suburu viscous diff we used to use, we'd go through two of those in a season.

[mtg]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by johnnySV:
so the dif will function if the original input circuit is eliminated? </div></BLOCKQUOTE>

Usually, the input torque of a diff is applied to the pinion shaft, which in turn applies torque to each side gear. So, it doesn't matter how you apply the torque to the housing.

Think of it this way: ring gears (driven by perpendicular shaft) usually bolt onto the housing. Remove ring gear, bolt on a sprocket in its place. Voila, chain drive. You can't do this in reality because the housings usually have large holes in them, and its good to have oil in a differential. But, its a way to imagine changing the input torque method.

Race Car Vehicle Dynamics has a pretty good section on diffs in it.

[Underthefloor]

Are there atv clutch pack differentials available? Any info about this would be greatly appreciated.

[drivetrainUW-Platt]

well, the deal I had fell through on the one differential assembly I was going to pick up, so I'm still looking, the junkyards dont seem to have anything as new as I'm looking for.

[Ben Beacock]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by drivetrainUW-Platt:
well, the deal I had fell through on the one differential assembly I was going to pick up, so I'm still looking, the junkyards dont seem to have anything as new as I'm looking for. </div></BLOCKQUOTE>

If you can get sponsorship from an atv shop, the cost on a Suzuki Vinson 500 front diff unit is only about CAN$800. Retail was almost double that. IIRC the ring gear/diff assembly was a bit less than that. (can't get the ring gear or diff separately, but they bolt together)

[CMURacing - Prometheus]

if you're looking to shave weight from your diff, why don't you make a new housing to replace the cast iron piece the torsen comes with? quite a few teams have done this, from what i recall...

[drivetrainUW-Platt]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by CMURacing - Prometheus:
if you're looking to shave weight from your diff, why don't you make a new housing to replace the cast iron piece the torsen comes with? quite a few teams have done this, from what i recall... </div></BLOCKQUOTE>
did that last year, few things I didnt like about how it turned out that would basically result in a completely new part if I wanted to change them so I figured why not start out with something smaller/more compact. I would love to do the longitudional engine but I dont see that happeneing this year.

[Bowtie Man]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Are there atv clutch pack differentials available? Any info about this would be greatly appreciated. </div></BLOCKQUOTE>

We'll be running a posi style clutch pack differential out of what i believe was a Honda TRX 350 or something like that, it's an older Honda 4x4 atv. without a ring gear it weighs just a shade over 5 lbs. I guess you'll all see how it works out for us in May

Luc

[drivetrainUW-Platt]

What other atv diffs are you guys running? Specific models and years would be helpful. I still like the Forman's stock steel housing just for pure simplicity, not really sure how the cam and pawl differentiating action will work out for our car thou....

[drivetrainUW-Platt]

A new Honda TRX350 diff and front axles are in the mail, should see them this weekend, what modifications can I expect to do to this part?
so far I have:
&gt;machine down the bearing surfaces to accept a common size.

&gt;Incorperate some sort of knife seals for the axles.

&gt;Drain/fill plug.

Thats all I can think of for now, any other things I'm overlooking? What are you guys doing to strengthen the stock steel housing?

[Bowtie Man]

Mike,
you wouldn't happen to have the spline info for those axles. I'm assuming they're the same as the ones for the diff we got donated to us. As far as strengthening I'm not sure yet. We'll be running an aluminum case around it and using the 6 bolt holes from the ring gear to transfer the torque. I'm thinking we may put the bolts in triple shear but a little bit of analysis and testing will tell us whether that overkill or not. I'm hoping the case is strong enough for what we're going to put into it.

Luc

[drivetrainUW-Platt]

I do not have the spline data, but I would think any respectable driveline manufacturing plant would have the proper tools to measure them. I plan on just running the inner stock cast iron housing and sealin it up, why build an aluminum housing around something that is already there, just more parts to wear out and become loose and more room for leaks to occur....

[Jarrod]

be wary of aluminium, as the drive force is transferred to side of the the pawls through the drive faces in the case, and the pawls are sliding back and forth while the diff is working, not and ideal situation for aluminium. The steel parts do exhibit noticable wear over time. We have constant issues with the sprocket/case bolts loosening up, so triple shear may be a good option.

[Bowtie Man]

By the sounds of it, the diff you're using is a newer version of the one we're using. I don't have any pictures but ours is a posi style being open with clutch packs on either side. The aluminum will be solely a cover and will not be taking load it's just there to seal up the unit

[Conor]

I don't want to kick a dead horse on this one, but I've been shopping around for atv differentials and I found a rather perplexing issue. I noticed that the front diff offered on all the the Honda 4x4 atvs is, aesthitically, completely the same. Except for the fact that the 650cc differential is roughly $500 more than the 500cc differential (I was comparing the TRX500FE with the TRX650FGA). Knowing this, I used the OEM parts finder from a local dealer www.mmcycle.com (http://www.mmcycle.com) (oem parts finder is in the left menu) and did a comparison of all the components in the differential assembly. After writing down all the part numbers, all the inner workings of the differential were the same and the only thing differing between units was the ring gear which would be replaced with a sprocket anyways. For the sake of saving $500 dollars, I'm inclinded to say that I should go with the 500cc differential and call it good. The only thing I'm concerned about is the fact that our engine is 600cc. So, what I would like to know is how did your teams fair after using the front diff designed for a 350cc engine? Any ideas on why these units would be so similiar yet so different in price?

[Bowtie Man]

The Diff managed fine, our drivers are complaining of understeer possibly caused by the clutches locking too tightly or binding in some way. So this weekend I'll likely pull it apart and see what the deal is. However be aware that with the older posi type the halfshafts are small in diameter and if proper heat treating isn't done on the spline, you'll twist them off on an accel run in no time. We were running custom made 4140 unequal length halfshafts and the short one twisted off with under 2 hours of testing. I'm not sure whether or not it was in the annealed state when it was put in but it didn't last long at all. We then got a couple more made and heat treated and never had a problem since. After I pull it apart I'll let you know what the insides are like after about 6 hours of running or so.

Luc

[drivetrainUW-Platt]

same here with the Honda, made it thru endurance on a little oil leak and was ice cold after the 20 laps so I doubt theres any wear, will have it apart in the following weeks

[murpia]

This thread is a little confusing to me right now.

Can a helpful somebody list the various ATV diffs and their operating principles? I think the Honda diff mentioned is a variation on the cam and pawl principle, but which diffs are plate types?

Regards, Ian

[ach1]

I guess I am unaware of any of the honda diffs with a welded ring gear. Some of the newer diffs have speed sensors on them, which just adds a little to the cost if you need it.
www.servicehonda.com (http://www.servicehonda.com) has almost all the schemeatics for the atv's and you can see what style (clutch pack or cam & pawl). Since this thread is about getting more ATV parts into a Formula car, I've got to tell all what I know.
Don't buy the interals separate. Huge savings on buying the whole diff assembly and throwing out the case if you don't want it.


TRX350FE 41400-HN5-670 = $334.30 3.769 Interal reduction C&P
TRX500FA 41400-HN2-000 = $334.63 3.231 Interal reduction C&P

If you want to pay more for the cluch pack diff, look for the
TRX300FW HC5/HM5 3.80 interal reduction
TRX400FW HM7 3.154 interal reduction
TRX450S HN0 3.154 interal reduction


James
UofM-Dearborn

[LU-Bolton]

Hey everyone, there seems to be a lot of confusion in this thread. In '06 our team ran the Honda Rubicon front differential, it was a cam and pawl type. We bought the entire assembly... diff, diff case with sensors and bearings, etc. etc. The whole assembly cost $420 through a Honda dealer and we basically threw everything we didn't need on the shelf. That specific diff has a cast ring gear going longitudinally on the car. So we simply milled the ring gear off on a rotary table mill, and used the existing bolts that keep the two halves of the diff together to bolt on a sprocket. The sprocket mated right up to the face that we had just machined the ring gear off of. Then we just made a spacer/brake hat on the other side of the diff which spaced the rotor off of the diff to where we could fit a caliper on. Again, we used existing diff bolts to mount the rotor and brake hat. Tolerances were tight, but we made it all work rather well. Also, we had no problems with diff sealing with the rotary shaft seals that we used(stock parts). We also took the diff apart yesterday to clean it up and examine it. There were metal bits in the diff oil, nothing to be afraid of though. All of the internal pieces are wear parts, you can also read more about this in one of Carrol Smith's books about cam and pawl's, Prepare to Win I think. There have been no noticeable problems so far with this setup, now we just have to do more tuning. Hope this helps guys.
http://community.webshots.com/photo/550746290/2498205900083135628rfmodK
http://community.webshots.com/photo/550326333/2089175520083135628DQBSdw

Aaron Cassebeer
2007 Lehigh Team Leader

[Conor]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by ach1:
I guess I am unaware of any of the honda diffs with a welded ring gear. Some of the newer diffs have speed sensors on them, which just adds a little to the cost if you need it.
www.servicehonda.com (http://www.servicehonda.com) has almost all the schemeatics for the atv's and you can see what style (clutch pack or cam & pawl). Since this thread is about getting more ATV parts into a Formula car, I've got to tell all what I know.
Don't buy the interals separate. Huge savings on buying the whole diff assembly and throwing out the case if you don't want it.


TRX350FE 41400-HN5-670 = $334.30 3.769 Interal reduction C&P
TRX500FA 41400-HN2-000 = $334.63 3.231 Interal reduction C&P

If you want to pay more for the cluch pack diff, look for the
TRX300FW HC5/HM5 3.80 interal reduction
TRX400FW HM7 3.154 interal reduction
TRX450S HN0 3.154 interal reduction


James
UofM-Dearborn </div></BLOCKQUOTE>

James,

I'm a little confused as to where you got the part number for the diff for the 500FA. I'm using the oem parts finder from a local dealer and it shows that the diff assembly part # is 42400-HP0-A01. Please help me out on this one because the part number I found is much cheaper http://fsae.com/groupee_common/emoticons/icon_smile.gif. Thanks.

[drivetrainUW-Platt]

Ours had the one piece housing/ring gear. We had it ground, not machined, off since it is bloody hardl. When I looked at the parts breakdown of the front assembly it showed the gear as a separate piece, but when I got the parts it was all one, maybe they just stopped have 2 parts. Either way the 1 piece is a lot beefier when the bolts that hold the 2 piece housing together are, so if you can machine it off its a better setup in my mind. I wasnt aware that Leheigh was running this model as well...good to know that more ppl are using it.

Anyone played around with different thickness inernal spacer washers yet? It comes with a 1.5mm one stock I believe and we put a 1.4mm in becuase we hadn't broke it in before comp. and we were chirping tires around corners. They offer like 1.3-1.6mm or something along those lines from the dealership for a buck a piece.

[Underthefloor]

All three design finalists at west ran Salisbury diffs.

We ran an open diff and it worked well. There was some inside wheel spin. No problems in acceleration. It works much better than the torsen for our car.

[Conor]

Salisbury diff? Haven't heard of that one. Can you give me some more info? I have two free open diffs at work that an engineer got for me. One differential is from a golf cart and the other is from either a John Deere gator or the front of a Jeep. Can't remember which. The bigger one will undoubtedly do the job, and I was seriously contemplating trying to use the golf cart diff.. It's only 5 or 6 pounds. I still think it's probably best to go with a limited slip, but maybe a free open diff would be good enough...

[LU-Bolton]

The Salisbusry differential is simply another name for a clutch pack type differential. They were mentioned earlier on in this thread, and can be found in some ATV front diffs. The nice thing about them is that the bias ratio can be varied for both acceleration and braking.

Aaron Cassebeer
2007 Lehigh Team Leader

[jdstuff]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by LU-Bolton:
The Salisbusry differential is simply another name for a clutch pack type differential. They were mentioned earlier on in this thread, and can be found in some ATV front diffs. The nice thing about them is that the bias ratio can be varied for both acceleration and braking.

Aaron Cassebeer
2007 Lehigh Team Leader </div></BLOCKQUOTE>

A salisbury is a clutch diff, but a clutch diff is not neccessarily a salisbury. As Aaron stated, the percent lock-up for accleration and off-throttle response can be independently tuned. This is accomplished through a set of ramps. A traditional LSD will have 2 element gears, which ride on a fixed shaft. The salisbury will have 3-4 elements, and are allowed to "float" on the ramps. It works a little something like this:

The ramps mesh with the outer diff housing, either through several keyways or splines. As the housing is turned, torque is transmitted through the ramps, to the element gears. Since the ramps are in angular contact with the elements, an axial force is generated forcing the ramps outward against the friction plates. You can tune the amount of lockup in the diff by varying these ramp angles.....less angle = more axial force, more angle = less axial force....and varying the type and/or number of friction plates. There are simple (BMW) and complex (Hewland Powerflow) versions of this diff, but they all pretty much operate on this basic principle. Here's a model of the small-case BMW salisbury that has been behind their 4-bangers since the 80's.

http://gozips.uakron.edu/%7Ejdstuff/salisbury_guts3.jpg

http://gozips.uakron.edu/%7Ejdstuff/salisbury_guts_expld3.jpg

Hope this helps. It's a pretty freakin cool diff, and IMO one of the best choices out there for racing because of it's versatility.

[jwales]

Does anyone know the gear ratio's for any more of the differentials, obviously as much specific model information as possible would be appreciated.

[Bowtie Man]

jwales,
are you talking about Torque Bias Ratios??

[jwales]

no, I'm talking about the actual gear reductions for the ring and pinions. I'm looking to run straigt back to the diff with universal joints, no chain and sprocket.

I'd especially love to know for sure the ratio for a 2000 yamaha timberwolf, either for the rear axle for the front diff.

[Conor]

sounds rather complicated and heavy...

[absolutepressure]

JD, I'm not seeing the ramps in that thing.

Duwe, what a gay forum topic name "Lets Talk ATV Differentials," OK GIRLFRIEND, LETShttp://fsae.com/groupee_common/emoticons/icon_smile.gif

[drivetrainUW-Platt]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by absolutepressure:
JD, I'm not seeing the ramps in that thing.

Duwe, what a gay forum topic name "Lets Talk ATV Differentials," OK GIRLFRIEND, LETShttp://fsae.com/groupee_common/emoticons/icon_smile.gif </div></BLOCKQUOTE>

Seeing that there are 3 pages of relevant posts and yours is the only nonrelevant, maybe your are the one who shows the most gayness.....

[Alan]

http://img144.imageshack.us/img144/1359/diffla1.png

[jdstuff]

Thanks Alan.

The ramps picture above are 45x45 and from a BMW street car...so both 45 degrees for braking AND acceleration.

Here's a 30x80 ramp from a Hewland Powerflow racing diff. You'll notice the difference from the BMW in that there are only 3 element gears, and they get rid of the shafts and capture the elements directly (less weight!).
http://gozips.uakron.edu/~jdstuff/hewland1.jpg http://gozips.uakron.edu/~jdstuff/hewland2.jpg

Also, perhaps this high-quality MS Paint image will help to clarify things a bit.... =)
http://gozips.uakron.edu/~jdstuff/ramp.jpg

[absolutepressure]

Thanks alan, jd for answering my RELEVANT question. That is a pretty sweet set up now that you clarified it for me. However, has there ever been a case of the shafts, under an extreme force, being rammed past the ramps and into the seam? Thus permanently locking them, or splitting the housing? Say if someone did a drive to reverse in an auto for example? Could that be why the racing one has a much bigger radius right off the gear as opposed to a skinny shaft?

Duwe, nice try turing the gay comment around (I don't think they're buying it though)

You know I'm just fuckin witcha, right?

[jdstuff]

Well, I obviously can't speak for that NEVER happening....but I would guess it highly unlikely. The two ramps don't really spread that far apart for something like that to happen. And if there was a huge input force, load reversal, or something of the sort, I would guess that the element & side gears would be the first thing to go.

[absolutepressure]

Gotcha

[drivetrainUW-Platt]

Who is going to run an ATV diff this year? Our Honda made it through endurance at comp, but that was behind a very underpowered pig of an untuned engine...

[Hanster]

I have tried contacting Honda to get specs for Rubicon differential, but I have just not been able to find anyone that can help me. Hopefully some of you guys that have run these diffs in the past can help me out:

1) How much torque can they safely handle?
2) Is the 2003 differential capable of as much torque as the new models? (The 2003 model is more convenient for us since the ring gear bolts on seperately, which is where we will bolt on our own sprocket)
3) Have you ever experienced excessive wear or failure with the diff?
4) How is the differential lubricated (oil, grease)?
5) What handling characteristics does the diff promote?


Thanks,
Spencer
BYU Racing

[Conor]

If anyone has answers to Hanster's questions, I too would be very interested. Our team is planning on using a honda diff with a 600cc engine. I'm not sure if anyone has run a honda diff with this large of an engine yet, but I would definetely be very interested in how it held up. The diff is designed for a 500cc 4x4 atv so I don't have a doubt that it will be able to withstand the abuse we can give it. Also, does anyone have a complete listing of what models and years are the cam and pawl limited slip diff and what models are the clutch pack style?

[Parker]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by drivetrainUW-Platt:
Who is going to run an ATV diff this year? Our Honda made it through endurance at comp, but that was behind a very underpowered pig of an untuned engine... </div></BLOCKQUOTE>

We will be using the front diff from a Polaris Xplorer 450. We haven't actually pulled it apart yet, but I understand that it is a clutch pack style. nice and lightweight too.

[absolutepressure]

Duwe, what was the hardness on that diff? Wasn't it off the scale? Didn't the machinist have a hard time finding something hard enough to cut it? I don't know hardness levels, but think that if it's off the scales, it'll handle anything you can throw at it.

[drivetrainUW-Platt]

yes, it was very hard, If I recall it was 69 on rockwell C scale???
We havent had ours apart since competition, but after endruance it was ice cold so I assume there wasnt much done to it internally.
We had the one that didnt have the removable ring gear, I actually ordered the one with it removable, and I think they stopped making that part and give you the all one piece one now. It did look beefier then the removable though as far as the bolt flanges go.
I have heard of people having the diff force apart where the two section come together, so extra beef is good there.

[Conor]

Duwe, what size engine did you guys run(maximum torque output at the diff and overall hp)?

[drivetrainUW-Platt]

Honda F2..with a piss poor tune making dick for power...so I have no clue if it will hold up to a decently tuned engine

And along these lines....
Never twin turbocharge a '70s stationwagon with semi truck turbos. Someone could die from the explosion.

http://www.1320video.com/gallery/dwmonday/DSC05899
http://www.1320video.com/gallery/dwmonday/DSC05896
I belive it has a new I-5 outa a GM Colorado
101mm turbo.... Was in Hot Rod drag week...

[VFR750R]

I've seen the 6 cylinder out of the trailblazer(same engine plus a cylinder) in a rail drag car at a NHRA national event. Making something over 500hp NA, and I heard from a guy at work there's another guy with the same motor turbo'd. They race in Comp Eliminator, sub 8 sec quarters.

[rjwoods77]

http://www.hotrod.com/eventcoverage/113_0505_2005_pump_...esults/photo_18.html (http://www.hotrod.com/eventcoverage/113_0505_2005_pump_gas_drags_results/photo_18.html)

turbo 4200. runs pretty fast.

[rjwoods77]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Rob Woods:
http://www.hotrod.com/eventcoverage/113_0505_2005_pump_...esults/photo_18.html (http://www.hotrod.com/eventcoverage/113_0505_2005_pump_gas_drags_results/photo_18.html)

turbo 4200. runs pretty fast. </div></BLOCKQUOTE>

I just looked at that wagon with the turbo engine. That is the same car that is in that video I have a link of. It is a 4200 I6 engine with a t76 I believe I found as the turbo. As far as a twin turbo I dont think that this is the case. He finished it like 3 days fo before the comp and had a horrible tune on it. Still broke nines though.

[absolutepressure]

Wow, what a coincidence. I wasn't refering to that car. If there was only one kind of stationwagon in the 70's, I guess I'm wrong on the year. But my Dad told me a story of when he was in high school down in Florida of two hics (yes, I guess they were actually hics in every sence of the word) that did just that. They took two semi turbos that they had lying around the farm, made their own manifolds and put them on a V6 stationwagon engine.

He said that they were feeling all cool one day, revving up their engine after school, but one time one of the guys really revved it. It turns out that the turbos never really had a chance to spool up before, but this time they did, and boy did they spool up.

The heads blew clean off of the engine, splitting the intake manifold in half, blew the hood off of the car, and pushed the fenders out. You know what he said their reaction was? Hehehe, oh well, I guess we'll take the truck back. They didn't think twice about the heads that flew towards the people on the sidewalk.

[Conor]

Did anybody FEA the stock Honda diff to get an idea of how much the housing can take? I plan on running one in which I constrain the bearing mounting surfaces and apply a load reflective of the torque from the sprocket at the bolt holes which hold the two halves of the housing together. The more I think about it, I'm getting a little worried that the ATV diff won't be able to handle the abuse of our 600cc engine, even though crocket rocket engines don't produce that much torque. I'm also concerned about how fast the internals will wear, but most people said theirs held up alright through enduro. Did anybody cut and weld the stock axles from the front of the Honda ATV? I was thinking of running taylors with this diff, but damn its pricey.

[JerryLH3]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Conor:
Did anybody cut and weld the stock axles from the front of the Honda ATV? I was thinking of running taylors with this diff, but damn its pricey. </div></BLOCKQUOTE>

We did. The axles were cut, prepped and lengthened using a technique NTN suggested to us. They (knock on wood) have not failed yet.

We liked the compactness of the Honda diff the past two years, but this year will try something else out.

[Conor]

Jerry,

Can you give me some more information on the technique? I understand each team has its secrets, but any information would be incredibly helpful. Also, is it possible to mount dual inboard brakes to the CV housings of the ATV axles? Thanks for the help!

[Parker]

So what is the general concensus about these ATV diffs? is the clutch type or cam/pawl type preferred?? does one or the other generally weigh less? I know that the clutch pack type can be adjusted pretty easily, but are they less reliable?

[Conor]

How many teams are running a center diff versus unequal diamater axles? What's your reasoning?

[JerryLH3]

I assume you meant unequal length axles? I think it's probably split as to what teams do. Read these threads for some more info:

http://fsae.com/eve/forums/a/tpc/f/125607348/m/26910051431/p/1

http://fsae.com/eve/forums/a/tpc/f/125607348/m/23610821821?r=23610821821

Conor, I'm working on getting those pictures for you. It's been a hectic week, I guess they all are, really.

[repeatoffender]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Conor:
If anyone has answers to Hanster's questions, I too would be very interested. Our team is planning on using a honda diff with a 600cc engine. I'm not sure if anyone has run a honda diff with this large of an engine yet, but I would definetely be very interested in how it held up. The diff is designed for a 500cc 4x4 atv so I don't have a doubt that it will be able to withstand the abuse we can give it. Also, does anyone have a complete listing of what models and years are the cam and pawl limited slip diff and what models are the clutch pack style? </div></BLOCKQUOTE>

I remember seeing wollongong's turbo 600 running one at california.

[jdstuff]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by JerryLH3:
I assume you meant unequal length axles? </div></BLOCKQUOTE>

Well, if they're unequal length they had darn better be unequal diameter too!

[Conor]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by JerryLH3:
I assume you meant unequal length axles? I think it's probably split as to what teams do. Read these threads for some more info:

http://fsae.com/eve/forums/a/tpc/f/125607348/m/26910051431/p/1

http://fsae.com/eve/forums/a/tpc/f/125607348/m/23610821821?r=23610821821

Conor, I'm working on getting those pictures for you. It's been a hectic week, I guess they all are, really. </div></BLOCKQUOTE>

Jerry, those pictures will be more than appreciated. Take your time, I understand how life can get. Don't let me be a bother. Also, I did say center diff. Our team WILL be running a center diff. I would love to indulge, but we've come up with a rather clever solution for acheiving this that you'll have to wait until competition to see. From what I know, I don't think any team has tried what we're doing. I could be wrong though... Either way, anybody else going to give it a shot?

[JerryLH3]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by jdstuff:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by JerryLH3:
I assume you meant unequal length axles? </div></BLOCKQUOTE>

Well, if they're unequal length they had darn better be unequal diameter too! </div></BLOCKQUOTE>

Indeed, I'll claim brain fade as Conor and I had previously been talking about unequal length axles.

[Mick]

To all who have used the Honda diff in the past, how is the adjustability? It looks to be just a variable width washer, is that the case or have I been mislead?

[mtg]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Mick:
To all who have used the Honda diff in the past, how is the adjustability? It looks to be just a variable width washer, is that the case or have I been mislead? </div></BLOCKQUOTE>

The Honda clutch pack diff can be adjusted by changing preload on the friction discs. It makes a noticeable difference on car behavior, but the friction discs wear out quick enough where you have to keep adjusting the shims to hold the preload constant- in '04 we used that diff and the friction discs were almost worn out by the time we got to competition.

Then there's the cam & pawl Honda diff, which was on another couple older UMR cars. In theory, they work great- a tuna can sized diff with seperate torque bias ratios for on throttle and off throttle. But the ratcheting upsets the car in tight turns, which really sucks.

[Conor]

mtg,

I'm not saying you're wrong in any way, but I believe you're the only one to describe this "ratcheting" behavior. Do you think this is attributed to soley having a worn out diff or other factors? What kind of diff did you switch to? I can't imagine any other choices being as good as the Honda diff when price, ease of installation, avialability of parts, size, and weight are all considered.

[JerryLH3]

Well, we used the cam and pawl diff the past two years. We loved the lightweight and compactness. We did not always love its behavior. For competition, I believe it was assembled wrong, thus there was no differentiation. It was also worn out pretty good once we finally took it apart. After replacing virtually all of the internals, it did begin to differentiate. However, it still seems to lock and unlock while in the corner.

[mtg]

If you understand how a cam & pawl diff works, it should not be surprising that it ratchets. As a cam & pawl diff wears out, the ratcheting reduces, not increases. And, apparently USF found the same thing.

The Honda clutch pack diff is very convenient to use, but there is a major tradeoff with performance- the torque bias ratio is barely more than 1. Be aware of that.

[drivetrainUW-Platt]

You can get different shims to load the spring washer that holds the cams from slipping. They offer different sizes in 1/10 mm thicknesses...I have never felt any ratcheting when I was driving the car......

[Conor]

So would you guys recommend the cam and pawl diff or the clutch pack diff? Are their external dimensions fairly similiar? Also, I'm new to all this differential stuff, so could you be a good sport and shed some light on the torque bias ratio I should be concerned with?

[Lusardi]

Is the clutch pack diff from the honda atvs a salisbury diff. Also which atvs have the clutch pack differentials or where else could I find a suitable salisbury differential? In general, would the clutch pack from the hondas be lighter than a torsen.

thanks

[mtg]

After using both the Honda cam & pawl and clutch pack, I'd recommend the clutch pack for these reasons:

- It is smooth and predictable for the drivers
- By adjusting the friction disc preload, the handling can be changed noticeably

Although when you get to design, when a design judge asks why you used a certain diff, if you say "because mtg posted it on the forums"....

As far as not noticing ratchet action with a cam & pawl, there are two explanations for that:

1. The driver is not sensitive enough to notice it
2. The diff is transferring very low amounts of torque across the rear axle

If it's not transferring much torque across the axle, what's the point of a limited slip diff?

jdstuff put a very good explanation of the difference between clutch pack and salisbury diffs on here recently, so refer to that.

As for pictures of the Honda diffs applied to an FSAE car, see below:

Cam & Pawl (http://wwwcgi.umr.edu/cgi-bin/cgiwrap/formula/imagefolio2.3/imageFolio.cgi?direct=Old_Cars/2003-26/Differential)

Clutch Pack (http://wwwcgi.umr.edu/cgi-bin/cgiwrap/formula/imagefolio2.3/imageFolio.cgi?direct=Old_Cars/2001-14/Differential)

Torque bias ratio is the ratio of different torques applied to each wheel across an axle. An open diff has a TBR of 1 because both wheels always get the same torque. The Torsen is 3 or 5 or something- meaning "the wheel with the grip gets 3 - 5 times more torque than the wheel that slips". I put it in quotes because it sounds like marketing hype, but is a pretty good explanation. The torque transferred is a function of the input torque.
A clutch pack diff has a TBR of approximately 1, but there is a static frictional torque before it lets loose, then becomes a "speed based" diff where torque is transferred across the axle as a function of speed differential between each wheel, instead of input torque.

[Conor]

Matt, those pictures were very helpful. It looks as if you made a custom housing for both the cam and pawl and the salisbury. Is this correct? From what I understood, the diff was essentially ready to use and didn't need but minor sealing.

One last thing; I did a little research using ach1's post and found the diff from a Honda TRX 500FA model #42400-HP0-A01. It should be a salisbury, but the picture, however, shows a cam and pawl diff. The price is also half that of the cam and pawl diff. Has anyone used this specific model because now I'm very confused.

[Underthefloor]

I've heard that the cam and pawl diffs are nice because they are about the size of a can of tuna but unfortunatly, they work about as well as a can of tuna.

There is a great paper on clutch pack diffs that I mentioned before. 'Development of a Limited Slip Differential' by Hass and Manwaring

It gives equations for how preload and clutches effect the TBR.

In my opinion, a high preload on a clutch pack diff is the worst way to get tbr on a racecar. You basicly have a very high tbr at low loading and a lower tbr at high loading. The amount of torque trasfered due to the preload remains constant regardless of the input torque. You get all of the bad charecteristics of open and LS diffs. You get an anti yaw moment when entering and at the apex of a corner(low loading/high tbr) and then potential wheel spin on corner exit(high loading/low tbr).

Preloading makes sense on street cars and atvs where you might encounter siutations where one tire has almost no grip(ice, mud, ect)and needs to be able to transfer just a little bit of torque to get past the hazzard. As far as I can speculate, preload is bad for formula SAE cars.

[Mick]

OSU

If the cam and pawl diff is junk and a preloaded clutch pack diff is just as bad how else would you suggest getting a varialble limited slip? The salisbury style looks great but I am having a tough time finding one that is as light as I would like.

[jdstuff]

Mick,

If you're serious about the salisbury then build your own! You're right in that there aren't any apparent "light" salisbury options on the market (at least, none that I've found yet)....but if you sit down and look at the basic principal of the thing you'll realize they really aren't that complex. Cannibilize what you need out of production parts (like friction disks, etc)...you could even convert a small ATV clutch diff into a proper salisbury. Look at the ramps from the BMW diff, they're dirt simple...and I'm willing to bet that with a bit of design you could even make them out of aluminum for FSAE use. 80% of it would all be basic lathe work, with a few simple mill setups to finish.

And to further comment on what Underthefloor said about preload, I agree completely. In MOST open-wheel, road track configured cars (and especially FSAE) a lot of preload would be no good. You probably want something on the order of INCH-POUNDS....possible even negative preload , or air gap (where the internals would actually rattle around a touch).

Best of luck,

[mtg]

Most of time you want some preload, otherwise you can not apply any torque to the rear wheels if one of them has no vertical load on it -which can definitely happen on an FSAE car in the middle of a corner. If you have to wait for the inside rear to set back down to get on the throttle, it can cost you down the straight.

High preload does make it about impossible to turn though, unless you set the car up like a kart (essentially like a spool).

[ach1]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by mtg:
After using both the Honda cam & pawl and clutch pack, I'd recommend the clutch pack for these reasons:


As for pictures of the Honda diffs applied to an FSAE car, see below:
. </div></BLOCKQUOTE>

Did you run that diff dry? I've never seen one worn out like that. I've also never noticed a ratcheting effect with the cam and pawl diff and I've been using them in Baja cars since 2001 and Formula cars for 2 years. They are a lot cheaper than the clutch pack diffs too.

[mtg]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by ach1:
Did you run that diff dry? I've never seen one worn out like that. I've also never noticed a ratcheting effect with the cam and pawl diff and I've been using them in Baja cars since 2001 and Formula cars for 2 years. They are a lot cheaper than the clutch pack diffs too. </div></BLOCKQUOTE>

I don't remember, but it had just been in hard use for several years and had a somewhat "experimental" housing. It got converted to a spool after that. Talk about a beast to drive- a car with a spool that wasn't designed for it.

[Mick]

ach

How much fluid are you running that diff in? I know the Torsen has to be about 1/2 submerged and a standard ring gear should only be under fluid of about an inch, give or take given on dimensions.

Also, is everyone running a sproket or has anybody converted over to a right angle drive incorporating a ring and pinion?

[drivetrainUW-Platt]

all the ones discussed here, the ring gear was removed and a sprocket bolted up in its place. Some teams have run them in the stock form and shaft driven them. This is on cars with longitudional mounted engines. There was Guelph with the awd and then that japaneese team with the baby blue powdercoated frame, very small and quick car.

[ach1]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Mick:
ach

How much fluid are you running that diff in? I know the Torsen has to be about 1/2 submerged and a standard ring gear should only be under fluid of about an inch, give or take given on dimensions.

Also, is everyone running a sproket or has anybody converted over to a right angle drive incorporating a ring and pinion? </div></BLOCKQUOTE>

The fluid level is almost half way up the ring gear, which is close to a pint of 80W90. I imagine you would have lots of problems running a cam and pawl dry.

[Damon]

Hi guys,

I'm not exactly well up to speed with all the ins and outs of diffs so I'll try not to sound like a complete prat and pretend I know all!

The Honda diffs are very nice and compact units and these were considered, however Birmingham back in 2004 decided to go with the Yamaha Grizzly LSD. The reason was that the powertrain guy didn't think that the little Honda diffs would last. We stripped the grizzly down to the bare essentials and machined our own aluminium housing. Our transmission guy did some extensive rig testing with different pre-loads on the clutch pads and came up with his preffered settings. Below is a link to a pic of our rear end.
UBRacing rear 2005 (http://ubracing.markdooley.com/cars/05pics/7.jpg)
As far as I was aware it worked pretty well and we had no dramas with having to continually adjust the pre-load.

Has anyone else used any of the Yamaha ATV diffs?

[Conor]

How intensive is it to design and machine a custom housing for an ATV diff, especially when you don't have the best of machining capabilities?

[mtg]

The Honda clutch pack diff is plenty strong as long as there's enough oil in it.

As far as adjusting preload, it's like valve clearances in the engine- if you never adjust them, you'll never notice a loss in power. But friction discs in a clutch pack diff do wear out, and the springrate of the belleville washers that provide the preload is pretty high, so a small amount of displacement (ie wear) changes the preload noticeably. I'd recommend checking the preload everytime you drive if you're using a clutch pack diff. As the preload changes, the handling of the car changes, and if you don't know the preload is changing, you'll be scratching your head as to why the car keeps turning in faster and faster everytime you drive it.

As far as machining a housing- the pictures I posted were complex machining jobs that were done by a sponsor who machined titanium medical replacement joints. I'm sure if you're only option was a manual mill and lathe, you could do it simpler (the teeth for the friction discs to engage on would be a challenge, though).

[Conor]

I hate to keep bringing up old conversations, and anyone can criticize me if they deem it suitable, but I'm going to summarize everything I've put together on the ATV diffs and get a little feed back. Here we go:

First off, I've decided to run a cam and pawl style. Even though Carroll Smith says cam and pawls don't work worth the damn, his opinions are based on extensive seasons of racing and wear issues that occur. Let's not kid ourselves, our cars don't see a very extensive run time in one given season. Therefore, wear can be accepted within financial reasoning. My basis is this; a slisbury style (which Carroll Smith favors) from an ATV runs about $500-$600. Not to mention, the units is very large, cumbersome, and will definetely need a custom housing if your team plans on centering without extensive other hardware. Using Carroll Smith's argument that cam and pawls work great when they're new, I figured at most, I'd replace the internals once a year. If this is the case, I can buy a brand new differential for $118 and replace it once in the same year for another $118, giving me a grand total of $236 dollars if I even need to replace it(many teams reported that their diffs didn't wear too much). So for less than half the price, I can get a diff with good performance, weighs much less, is much less cumbersome, and is much easier to mount to our car (no custom housing needed to center it). The only thing I have to worry about is tearing it apart a little more often than a salisbury, but hey, I like racing because I like to get my hands dirty. The cam and pawl I've decided to order is model # 42400-hn0-671 and it costs $118 at servicehonda.com. I chose this because it's cheap, small, and the spider gear is bolt on and doesn't need to be machined off. I would like to know, for my reference, and everyone else's, what model # did your team use, what modifications did you have to make to it, how much does it weigh, and how much did it cos? I would like to compose an extensive list of options. Hopefully this will answer a lot of questions people have about these ATV diffs(sorry the only brand I covered was Honda but there are more obviously). God knows I had quite a hard time figuring it all out when I first started, so hopefully this is a good contribution for anyone in the same boat. Thanks in advance to those who take the time and contribute information on their diffs to help everyone out.

[Underthefloor]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Mick:
OSU

If the cam and pawl diff is junk and a preloaded clutch pack diff is just as bad how else would you suggest getting a varialble limited slip? The salisbury style looks great but I am having a tough time finding one that is as light as I would like. </div></BLOCKQUOTE>

With a non salisbury type clutch pack diff, you can adjust the tbr by arranging the clutches in different ways. Half of the clutches are connected to the side gears and half are connected to the housing. You can set up the clutches so that every other clutch is connected to the side gear and the housing. This gives you the the largest number of friction interfaces. You can stack all of the simmilar clutches together and end up with just one friction interface which is an open diff. You can also have any combination in between. Preload is not the only way to adjust tbr.

If I could do it all again I would probably build a custom Salisbury diff.

[Parker]

I was wondering if anyone might be able to tell what sort of differential this might be from the picture.
http://parts.polarisind.com/images/9920009%5C9920009d03.gif

[Conor]

Beats me. Let me know when you find out though, I'm very curious now.

[mtg]

It looks like two one-way clutches to me. Part number 7 attaches to each CV/axle, and when you hit the throttle, torque is transmitted from part 10 to both part 7's.

[Parker]

That's what I'm thinking. Polaris has such nice prices for our team that Im thinking of just buying one to see exactly what it is.

[Conor]

What's the pricing?

[Parker]

Just an update guys. I found out that it is an electronically locking differential. Polaris no longer makes any limited slip differentials.

Another question I had. I know some teams are using the ATV axles, and I would assume bearings as well. Would anybody know the ID and/or OD for any of the Honda bearings?

Thanks,
Parker

[Conor]

We just got our axles in so I'll let you know once I measure them. Otherwise, you can find the bearings on the OEM parts finder. The part description will list the dimensions of the bearing.

[Parker]

ok, well we finally got our differential in. This is part number 42400-hn0-671 from honda; its one of the cam/pawl differential assemblies. This one has a bolt on ring gear, which makes fitting a sprocket relatively easy. Many people have expressed concern over sealing the unit to retain fluid, as well as machining a new housing out of aluminum. from what I can tell, neither will be very challenging. anyway, on to the pictures...

http://img119.imageshack.us/img119/1606/dsc2339sv5.jpg
http://img182.imageshack.us/img182/5079/dsc2341gm1.jpg
from what I can tell, the only thing keeping this from being sealed normally are these six holes...
http://img175.imageshack.us/img175/4571/dsc2342sq9.jpg

For reference, it is sitting on a 14inch wide box, and the diameter of the ring gear is around 5.5inches.

[Bill Kunst]

Okay, quick question of the day.

If you had the electronic, and I am not sure what method of "locking" they use, could you use a controller to cycle the diff for different situations? Lets say that as steering increases, differential tbr decreases. This could be used with a air system as well. Stated diffently, could you have a tbr on-the-fly adjustable differential that didn't cost a lot? Or are these differentials to aggressive in lockup?

[Parker]

Bill,
The diagram of the Polaris part that I posted is the one with the locker. But either way, I am sure it would depend on how fast the locker mechanizm engaged. If it engaged rather quickly, or could be modified to engage quickly, I don't see any reason that a PWM type engagement couldnt be had. It might end up being less...umm...rachety than the cam/pawls, but not as smooth as a torsen or clutch pack, with the big advantage of being able to control the TBR.

[drivetrainUW-Platt]

Parker, thats the one we ran, I just JB Welded up those holes. They ended up cutting the ring gear off with a die grinder and then machining the remaining surface to make it flat. Its a hard little pecker. We also made some press on "bearing extenders" to step it up to a comon size bearing and allow us to put axle seals in those pieces. That also gave us clearance for the chain to ride. The drive gear was bolted up using those existing 6 holes that hold the housing together.

If you look at UMR's pictures, their housing ate it bad, I dont think aluminum would hold up worth a damn. The stock housing itsnt that heavy and its set up nicly to seal.

[Bill Kunst]

Parker,
I realize that the ratcheting of pulsing a locker is bad, but my question would be to examine the ability to change the tbr while driving. I have no good reason to suggest this, as I have already graduated, but I thought that it would be sweet.

[Parker]

maybe something like an adjustable center differential from a Subaru STi?

That is part of our "skunkworks" section. aka, the "wedonthaveenoughtimeormoneyrightnow" section of the club. http://fsae.com/groupee_common/emoticons/icon_wink.gif

[Conor]

Parker,

Will you be machining down the bearing surfaces or using an extension as described by Mike?

[Parker]

as of now, we do not have any such plans. we planned to use the stock bearings from the Honda differential. We have a sponsorship from a local honda dealer so that we can get them relatively easily.

[Conor]

Parker,

Just a word to the wise, the stock Honda bearings are not a sealed type. Infact, it's almost impossible to find a 29mm ID sealed bearing. You can always step down a size to a 28 and do some machining on your housing or make some press on spacers. Just some suggestions...

[Francois]

I wonder if any team hae already use a viscous differential type in a FSAE car?? I would like to use a Bombardier renagade front diff.

[Parker]

Anybody know what material these axles are usually made of? we dont have the time/money for an analysis and need to know whether we will be able to adjust the length of the honda units or just have our own made.

[Conor]

Parker,

Run a file across the axle and you'll see that they're pretty soft(ours were). We never figuered out exactly what the axles were made of, but we knew for sure they were too soft. We bought some 4340 bar stock and turned our own axles. We used a lathe to adjust each diameter (unequal lengths means different diameters) and then we used sand paper to get a mirror polish and make sure there wasn't any lathe marks left for cracks to propogate. It's not very hard to do. In fact, I'm doing the final sanding tonight and dropping them off at a company who's cutting the splines for us later this week. Finding a place to do the custom splines will be your biggest challenge. Let me know if you need any help...

[denn]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Conor:
Just a word to the wise, the stock Honda bearings are not a sealed type. Infact, it's almost impossible to find a 29mm ID sealed bearing. You can always step down a size to a 28 and do some machining on your housing or make some press on spacers. Just some suggestions... </div></BLOCKQUOTE>

Agreed, a sealed 28x52x11 makes a suitable substitute. We've had luck with the 60/28-2RS1 from KML. Cheers.

[grams]

Has anyone ever tried the idea of using two one way clutches for the differential. That would allow the outer wheel to free spin around a corner. However would that mean there would be no torque to the outer wheel?

[drivetrainUW-Platt]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by grams:
Has anyone ever tried the idea of using two one way clutches for the differential. That would allow the outer wheel to free spin around a corner. However would that mean there would be no torque to the outer wheel? </div></BLOCKQUOTE>

That would be an on off locking though, which would mean anytime the car is not going straight, 1 wheel would get 100% of the engines torque...way to think out of the box though!

[Fyhr]

I don't know if you've already sorted your problems out parker.

On our honda diff we sealed the holed with liquid metal save one, which we tapped to allow for lubrication. Oil may still find it's way out through the grooves in the driveshaft holes, we're using and OEM seal fitted into our press fit bearing spacers.

Standard shafts seem a bit short for FS use?

[mtg]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by grams:
Has anyone ever tried the idea of using two one way clutches for the differential. That would allow the outer wheel to free spin around a corner. However would that mean there would be no torque to the outer wheel? </div></BLOCKQUOTE>

You would have to overcome the problems of engine torque catching up with a "free wheeling" tire.

If you were going down a straight full throttle, chopped the throttle for a kink, and jumped back to full throttle, you'd have a pretty serious kick when the engine spooled up and caught up with the wheels. It's not impossible to overcome, but definitely a downfall. The best I've thought of would be a crazy soft cush drive (much softer than a motorcycle and a clutch in a car). Maybe you could fix the problem via engine calibration and basically make the engine have terrible throttle response while it is unloaded.

[drivetrainUW-Platt]

FYHER, could you give some inside on what seals and what your add on bushings look like. The bushings we addded ended up being pretty thin walled so the seals are very small as well, and started to leak after competition as the car sat. I am not 100% sure they are even the right ID for the stub shafts going into the diff. I wish I could have made them longer, but the CV joint and length of the stubb shaft limited this. Making them bigger diameter would allow for a better seal, but also multiplies the size of the bearings.

[Conor]

Have you guys tried rotary shaft seals? We ordered some for our stub shafts and machined a small pocket on the diff bracket for them to sit in. They're very cheap and very easily found at mcmaster.com. I don't know if they will work yet or not because we haven't tested, but if they do, it will be the easiest solution I've seen yet.

[Fyhr]

Mike, we are using a seal that is 7mm wide, 22mm ID, 32mm OD, i don't have a picture at the moment but its a standard unit out of some catalog costing 7 dollars or so. The bushing is basically a cylinder with a small flange for axial placement of the bearing, and press fit holes for the diff and seal on the inside. We are using a single row deep groove ball bearing with 35mm ID. It is quite a large bearing but as you said, going with a small bearing makes the bushing very thin walled.

[drivetrainUW-Platt]

Isn't it cute? (from the 06 car)

http://i22.photobucket.com/albums/b309/duwem/DrivetrainSmall.jpg

[kbuckert]

We used this differential on our 2007 car, it worked awesome for accel and the autocross & endurance events. however, you should know that under acceleration, it acts as a locked differential creating a solid axle. our skid pad times were horrible because the car kept pushing around the course.

I do not suggest going with this unless you design the suspension correctly &gt;&gt;pick up the inside tire during the skid pad! this seems like a weird way to do it, but go-karts are designed with a similar set-up. other than the skid pads, it worked awesome.

Kris Buckert
2007 Bradley University FSAE Captain

[drivetrainUW-Platt]

Did you try reducing the thickness of the shimms to allow more "ratching"? I havent had enough drive time to play around with this.

Why wouldnt you want it to be locked under acceleration, thats how a limited slip should work??

[begreer]

We ran the honda diff, and skidpad was our best event. 12th place. but the suspension was setup to unload the inside rear tire.

[Fyhr]

Right, back from comp in England.

I do believe the type of seals we used are typical rotary shaft seals, they do seal very well and i've yet to see any leaks.

With the standard shims though it is difficult for it to slip, the team was always complaining about turning too tight in the pits. On track it should be fine with setting the rear dropstops for inner rear lift. Though i'd love some discussion on how thick shims you've tried and reflection on what might be suitable. I'll try to experiment some with it aswell when we get back out on the track.

[Ehrin]

Does anybody know what type of Limited Slip differential the Suzuki Vinson 500 front diff is?

[mtg]

bump

[BMH]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by drivetrainUW-Platt:
Isn't it cute? (from the 06 car)

http://i22.photobucket.com/albums/b309/duwem/DrivetrainSmall.jpg </div></BLOCKQUOTE>

What differential is this and what was the approximate weight?

If my assumptions are correct from the past few pages and all, I assume that it is the cam and Pawl type honda differential?? If so, what modifications did you have to make to it?

[BMH]

Does anyone have the spline profile for the Honda Cam and Pawl Differential?

[Conor]

Your assumptions are correct. That is a cam and pawl limited slip out of an atv (most likely a Honda Rubricon). Not many mods needed other than machining off the ring gear and maybe a little material around the case if you want to spend the time. The spline profile is a standard metric spline. I assume you're looking to get some axles made so I would suggest ordering one of the cv/axle assemblies, pulling out the inner axle, and giving the spline to whoever is going to be machining your new axles. That will also allow you to reuse the CV assembly.

[BMH]

Do you have a CAD drawing of the spline profile? If not, do you know the spline count?

[Conor]

I did at one time, but not anymore. Like I said, if you want to use that diff, order an axle/cv assembly and pull the shaft out. Any place that does splining will be able to get the pattern by counting the splines and doing a pin to pin measurement.

[Ian_N]

After reading through this topic, I did look into these as a possible alternative to our current differential setup since it's my job this year to work on the transmission.

Question is: Has anyone actually found a maximum torque rating for this differential at all? Or have people just assumed it'll be ok?

Would be nice to know what it was as so far i've had zero luck in finding any technical information on it, having calculated the max torque we can put down from the tyres (Cheers Pat for that FSG talk!)

Would be nice to know what it was though we're not looking at this at the moment since we've found something we feel is a major improvement over our previous setup from last year.... But don't ask as i'm not giving the game away on that one till next year at FS UK http://fsae.com/groupee_common/emoticons/icon_wink.gif http://fsae.com/groupee_common/emoticons/icon_biggrin.gif

[murpia]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Ian_N:
Question is: Has anyone actually found a maximum torque rating for this differential at all? Or have people just assumed it'll be ok? </div></BLOCKQUOTE>
There is a 3rd option: instead of relying on manufacturers spec's, or luck, why not measure & analyse one and decide for yourself?

Regards, Ian

[Conor]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by murpia:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Ian_N:
Question is: Has anyone actually found a maximum torque rating for this differential at all? Or have people just assumed it'll be ok? </div></BLOCKQUOTE>
There is a 3rd option: instead of relying on manufacturers spec's, or luck, why not measure & analyse one and decide for yourself?

Regards, Ian </div></BLOCKQUOTE>

Or you could even look at the stock model at which you're borrowing the differntial from and analyze its torque production and make some interpretations... There's lots of ways to skin that cat...

[jdstuff]

I can't believe that this thread is still going strong 4 years later.

New guys, good job....way to use the search function!

[Nick.Jayjock]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">New guys, good job....way to use the search function! </div></BLOCKQUOTE>

I tell anyone on our team to search this thread right off the bat when they want to know something about the Honda Diff we plan on using. Very useful thread no matter the age.

[Leafy]

I understand that this site would rather an old thread be brought back up rather than a new thread made and I've read through this whole thread multiple times for my teams search for a diff. We know we want a clutch type, that is for sure, and we need a small one to mount in our own case (We're going to be running a gearbox differential setup rather than a chain drive). The one that I've found from this thread that's most reasonably priced is from the Honda TRX400FW 1996 (and thereabouts). To me it looks like a clutch type in the factory service manual exploded view and there are clutches on the parts list for it as well, I just want to be sure before I outlay the $500 for this since thats ~10% of our budget for this part of the school year (its next year's car).

Here's the link to a site with the best picture and part number listings that I found, not the best price though. TRX400FW Front Diff (http://www.cheapcycleparts.com/model_years/761-honda-1996-fourtrax-foreman-TRX400FW/assemblies/11567)

[Some Guy]

It apears to be a clutch type to me, it certainly isnt a cam and pawl. That said there are much cheaper ones out there if it doesnt need to be a clutch type.

[Conor]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Some Guy:
It apears to be a clutch type to me, it certainly isnt a cam and pawl. That said there are much cheaper ones out there if it doesnt need to be a clutch type. </div></BLOCKQUOTE>

That looks like a clutch type to me as well. It's been awhile since I've dug into FSAE differentials, but I would say the biggest indicator is the multiple "Disks", or friction plates. $500 does seem pricey and why are you going after a 1996 model? We used, I believe, a 2005 Honda Rubicon cam and powel setup. I think we were able to get both rear axels, including inboard and outboard CVs, for $500 or less. A lot of people criticize the cam and powel, but I thought it worked fine, especially because we had such a limited number of hours on it (performance degrades as a product of wear for a cam and pawl - its true inherent flaw). Regardless, you can probably find a clutch pack in a much newer model. I wouldn't be surprised if it cost less as well.

[rjwoods77]

I had a question for those of you who had experience with ATV diffs. I am looking to see out which one(s):

1) Are bolt on ring or can be modified to bolt on to a diff.

2) Are a spiral bevel instead of a straight bevel.

3) Are not made of a cheap powdered metal.

The closest thing I have found to this are out of a BMW or Moto Guzzi motorcycle.

[Adambomb]

We used a Honda cam and pawl for one year, and one year only. It was the later model one with the cast-in ring gear. Pretty sure it was spiral bevel as well. As I recall the older models had bolt-on ring gears. It was certainly not a cheap powdered-metal one; machining off the ring gear was a huge pain!!! It was also only like $140.

Because of the integral ring gear it would be attractive for a transaxle, although I was not happy with its torque biasing properties. It felt like an off-road locker; sort of like a spool only much less predictable. In action it didn't bias torque so much as just lock the rear wheels together as soon as power was applied. Felt terrible on a true FSAE course with super tight turns.

[Adambomb]

As for applications, it was a front diff for a Honda Rincon or Rubicon if I remember correctly, something in the vicinity of 500-700 cc, around 2005 vintage. Exploded diagrams from Bike Bandit were helpful.

[RANeff]

I would be careful with the honda clutch type. It is extremely weak, as in its torque bias just isnt sufficient for FSAE.

The cam and pawl has a much better torque bias ratio, but does have its downfalls as well. However, Adambombs sounds like it certainly had something wrong, either too much preload or the pawls installed wrong. The main problem with the c/p diff is the racheting effect they have at very low speeds.

[rjwoods77]

I am just asking about the ring and pinion and not the differential and housing.

[mech5496]

Bump! Take a look here (http://www.fsae.com/forums/showthread.php?7276-Differential-For-Longitudinally-Mounted-Aprilia-SXV-550), you might be interested!

[xander18]

I'm just gonna keep tagging onto this thread. I've read it through a few times now and there's lots of good information here, might as well keep compiling.

Our team has been running a cam and pawl Honda ATV diff (42400-HN0-671) in a custom aluminum casing for years now. This year I'm switching to a custom salisbury-type derived from ATV internals, as has been suggested before.

I have two questions: some say the Honda clutch pack diffs are really weak and won't hold up, some say they're fine. I'll only be using the gears and clutch packs and it sounds like others have run them. Any reliability issues? I plan on doing some in depth analysis on strength but without having one it's hard to do any analysis on the gear teeth. And I'd like to save the $250 if it'll definitely break.

Second questions: a Honda diff is my first choice because we have drawers of axle drivers built to match the splines on the cam and pawl, which is a 20-spline shaft. I would like to find a clutch pack that will allow back compatibility. Does anyone know if any of the Honda clutch pack ATV diffs have the same spline? I'm looking at the 42400-HM7-610 from the 1995-2001 TRX400 and the 1998-2001 TRX450 or the 42400-HC5-020 from the 1988-2000 TRX300, what are the differences between these? What spline count do they have?

Last note here, this is a bit more general, anyone looked into golf cart differentials? I figure they'll mostly be too weak for an FSAE car. How about side-by-sides?

[xander18]

So, anyone run the HM7 Honda diff?

Edit: I just called Honda Powersport about this and they had no information for me on splines.

[AxelRipper]

We upgraded from the HN0 to the newer version of that diff a few years ago. I don't remember part number, but I think it was a little bit lighter, though you had to machine the ring gear off of it (get some good tooling you can toss afterwards). Never looked at the HM7, but I'd guess for Honda's sake they ran the same splines on them as with the newer cam and pawl diffs.

ATV diffs, like the Torsen Uni-special diffs, are a dying breed it seems. Taylor has finally caught up with the weight of the Honda packages, but hard to beat $250 vs $3000.

[xander18]

AxelRipper (appropriate name), we're currently running the HN0. The HC5 has smaller splines, 24 I believe, but I think the only difference between the HC5 and HM7 is the spline count. Some helpful person on a Honda Foreman forum took at a look at his diff and believes it has 20 splines (http://www.hondaforeman.com/128-foreman-450/112529-how-many-splines-do-front-halfshafts-trx400-450-have.html).

The cost is a driving factor here. With plentiful machining and material sponsors the only investment in the ATV diff over the Taylor is my own engineering time and this is tons of fun!

[AxelRipper]

Well how do you do your splines? We bought used axles cheap off ebay, popped the CV's apart, machined them down so it was just the spline, then welded an adapter plate to them to run Taylor tripods.

[xander18]

We machine the splines ourselves. It's a single piece spline and tripod. We've made them out of ridiculously strong alloys or just 4340 with a heat treat.

[xander18]

Update: the HM7 differential has the same splines as the HN0 cam and pawl, 20 splines.