'salisbury' atv differentials

[jimbo_diff]

Hello ladies and gentlemen,

This year i was bestowed the differential as my path of labor/love so I have been looking into a clutch type differential off either a Honda foreman, or Polaris. Problem is that this year we are also running a turbo charged 600cc honda engine(hopefully putting out 80ft-lbs). Anyone with experience on how much power they can actually take? I much rather stick to the torsen unit than have sleepless nights an endurance failure.
Also weights for either? I know the torsen is at 8lbs and you can get the cam and pawl internals for about 2lbs.

I am planning on running the Salisbury internals and using either titanium or aluminum for the housing and endplate

Any knowhow will be extremely helpful.
Thanks

[jimbo_diff]

Hello ladies and gentlemen,

This year i was bestowed the differential as my path of labor/love so I have been looking into a clutch type differential off either a Honda foreman, or Polaris. Problem is that this year we are also running a turbo charged 600cc honda engine(hopefully putting out 80ft-lbs). Anyone with experience on how much power they can actually take? I much rather stick to the torsen unit than have sleepless nights an endurance failure.
Also weights for either? I know the torsen is at 8lbs and you can get the cam and pawl internals for about 2lbs.

I am planning on running the Salisbury internals and using either titanium or aluminum for the housing and endplate

Any knowhow will be extremely helpful.
Thanks

[Kirk Feldkamp]

To answer your first question:
http://fsae.com/eve/forums/a/tpc/f/125607348/m/72110779141

[flavorPacket]

There is no tire that can handle 80 lb-ft. have fun with that.

[mtg]

Also, a clutch pack diff is not the same thing as a Salisbury.

[billywight]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">This year i was bestowed the differential as my path of labor/love so I have been looking into a clutch type differential off either a Honda foreman, or Polaris. Problem is that this year we are also running a turbo charged 600cc honda engine(hopefully putting out 80ft-lbs). Anyone with experience on how much power they can actually take? I much rather stick to the torsen unit than have sleepless nights an endurance failure.
Also weights for either? I know the torsen is at 8lbs and you can get the cam and pawl internals for about 2lbs. </div></BLOCKQUOTE>

You're not going to make 80 Ft*lbs without a LOT of boost, and that would be impractical due to the restrictor. A realistic torque value would be 50 ft*lbs for forced induction (55 if you're really good).

If you end up going for it, aluminum or magnesium will be fine for the housing, just use some sort of inserts (steel or Ti) for the ramps to run on (transfering the torque from the housing to the ramps). A Ti housing would be a nightmare to manufacture and end up heavier and much more expensive than the Al one.

Also, look into different types of diffs so you have a good understanding of the pro's and Con's of each type. Decide on what type of diff would be best for your team first, then work out where you get it from and how to make the housing.

[Pete M]

Since when do tyres see engine torque? It all depends on your gearing and final drive. If the increased torque means you can avoid dropping to a lower gear in some corners, you'll save time skipping the up shift.

Having said that, 80 ft.lbs would make yours one of the highest torque SAE engines built thus far. That's pretty ballsy considering it's your first year with a turbo (or did i misunderstand you?). We presently make 72-74 ft.lbs, but as billy mentioned, it takes a pretty decent amount of boost to do that, and you can only make that boost in the lower rev range due to the restrictor. Plus, we're definitely in the region where the engine could be considered "stressed", i wouldn't be surprised if you got some fun stuff to yield.

[flavorPacket]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Pete M:
Since when do tyres see engine torque? It all depends on your gearing and final drive. </div></BLOCKQUOTE>

OK, you got me. I was assuming a typical turbo final drive.

[jdstuff]

If you do, in fact, want to run a salisbury and not just a clutch diff, I might suggest looking at early 90's BMW differentials. They had several different diff options, but the lower powered 3-series had the smallest salisbury differentials. You can also buy them used at about the same price a "university special" will run you. Take out the guts, add your own housing, and perhaps make some of your own ramps.....and you will have a highly tunable diff for FSAE.


http://forum.planetisuzoo.com/albums/album22/DSCF0071.jpg


http://forum.planetisuzoo.com/albums/album22/DSCF0086.jpg

[Pete M]

Off topic, but what's a typical turbo final drive? Serious question, i'm curious.

[jimbo_diff]

Thanks for the feedback guys, Im still new to my part and your comments are defiantly helping me sort out some of my confusion. We are using a 4.18 to 1 final drive ratio for our 08 car and right now our engine is putting out 65ft-lbs on the dyno so 80 ft-lbs for next year does seem to optimistic. Looking at the options for a light diff I like how the clutch style lsd functions but weight is going to be my deciding factor on which to choose. Any knowledge on the different weights for the units I mentioned or any that I havent would be extremly helpful

Thanks again

[mtg]

http://fsae.com/eve/forums/a/tpc/f/125607348/m/35510440821/p/1

Read that thread also, there's lots of info.

[flavorPacket]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Pete M:
Off topic, but what's a typical turbo final drive? Serious question, i'm curious. </div></BLOCKQUOTE>

We've tested that a bit, so I won't give away an actual number, but for us, with an F4i and roughly 60 lb-ft, under 4ish was best.

Running a 3.7 in accel in one gear is always fun...

[Poe]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">You're not going to make 80 Ft*lbs without a LOT of boost, and that would be impractical due to the restrictor. A realistic torque value would be 50 ft*lbs for forced induction (55 if you're really good) </div></BLOCKQUOTE>
Last year we made around 73 ft-lbs, right on par for what PeteM said his team was making. Our two teams must be gods on your scale http://fsae.com/groupee_common/emoticons/icon_wink.gif

I'm sure we aren't the only ones making that much torque either...

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Running a 3.7 in accel in one gear is always fun... </div></BLOCKQUOTE>
Definitely the most fun I've had in the FSAE car. The best we managed last year without traction control or launch control was 3.9, but that was good enough to win acceleration at Detroit last spring.

[flavorPacket]

We were plagued by clutch problems at Detroit, but if you were at the Goodyear shootout then you saw what we can do.

[Poe]

I graduated in May, so I was unable to travel to goodyear in the fall...

[flavorPacket]

Shame. You guys did really well considering the BC failure on the trip up.

For what it's worth, we use a salisbury. it's light, it works, it doesn't break that often.

[Chuckster]

OK you Salibury users-especially those using car type versions-what do you do about oil flow thru the suckers when you "can" them tightly for chain drive?


I've looked at various aftemarket ones like Cusco for hot hondas and they brag about having better oil flow thru the unit thru axial oriented holes in both sides next to the bearings.

Now, that looks difficult to run bearing blocks with sealed bearing and have any clearance for oil flow around in a can or housing.