Drove Cars Today

[Daves]

We took our '02 and '03 cars to a track today to get the new team members used to driving them. Only about 7 of our team members (out of 20) accepted the opportunity.

First we unloaded both cars from the trailer. Yes, they both fit on a single trailer, and this was not our usual formula trailer. The '02 car's nose was hanging off the back because the car is long enough for a 6'-6" person to drive.

After unloading the cars and scratching up the paint a bit as usual, we got both cars out on the track. Our team leader was driving the '03 car, but he only took one lap around the track (in first gear of an F4i) because the electric solenoids were not strong enough to change gears. Fortunately, our '02 car performed flawlessly for quite a while, giving all of us a chance to drive it and take some great photos. This is our rookie car which is shown on our website. After all of us drove it, one of our team members tried dropping the clutch at high rpm, which tore our differential housing from the diff. sprocket.

Good times.

Speaking of differentials, what options are available? We've been using Zexel Torsens for the past 2 years, but our team leaders are leaning towards a Taylor this year. Is it true that a Taylor diff. costs $2200 and that it comes with its own housing? In the photo below, WWU's diff. is shown. What kind of diff. is it? Travis or James, how reliable is that design?

http://dot.etec.wwu.edu/fsae/images/Gears%20in%20new%20differential%20housing_JPG.jpg

http://www.letu.edu/formula

[This message was edited by dave_s on September 21, 2003 at 12:39 AM.]

[Daves]

We took our '02 and '03 cars to a track today to get the new team members used to driving them. Only about 7 of our team members (out of 20) accepted the opportunity.

First we unloaded both cars from the trailer. Yes, they both fit on a single trailer, and this was not our usual formula trailer. The '02 car's nose was hanging off the back because the car is long enough for a 6'-6" person to drive.

After unloading the cars and scratching up the paint a bit as usual, we got both cars out on the track. Our team leader was driving the '03 car, but he only took one lap around the track (in first gear of an F4i) because the electric solenoids were not strong enough to change gears. Fortunately, our '02 car performed flawlessly for quite a while, giving all of us a chance to drive it and take some great photos. This is our rookie car which is shown on our website. After all of us drove it, one of our team members tried dropping the clutch at high rpm, which tore our differential housing from the diff. sprocket.

Good times.

Speaking of differentials, what options are available? We've been using Zexel Torsens for the past 2 years, but our team leaders are leaning towards a Taylor this year. Is it true that a Taylor diff. costs $2200 and that it comes with its own housing? In the photo below, WWU's diff. is shown. What kind of diff. is it? Travis or James, how reliable is that design?

http://dot.etec.wwu.edu/fsae/images/Gears%20in%20new%20differential%20housing_JPG.jpg

http://www.letu.edu/formula

[This message was edited by dave_s on September 21, 2003 at 12:39 AM.]

[Brent Howard]

that Looks like a torsen diff...same type as most teams use...i'm kind of interedted in the al body though..seems like a great idea to me. Only thing i would worry about it the bearing surfaces.

brent

www.ucalgary.ca/fsae (http://www.ucalgary.ca/fsae)

[Charlie]

That is the old style Torsen University special (bolted together). The new style is the 1 piece case, and is the only one Torsen sells anymore (since 2000? I think).

We made an AL housing too, in fact it is fairly common now among the top teams. We did it mainly because it is easier to package.

None of our thrust surfaces are Al though, I would be interested to see if WWU has had any issues with that.

-Charlie Ping
Auburn University FSAE (http://eng.auburn.edu/organizations/SAE/AUFSAE)
5th Overall Detroit 2003
? Overall Aussie 2003. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[GIJoeCam]

LTU used the torsen for their 99, 2000, and '01 cars. For all of those, they built an aluminum carrier. We have had reliability issues with all of them, from cracking fingers to aluminum shafings from the wear surfaces.

For '02, we used the 1-piece design shaved down and lightened significantly. We have had ZERO reliability issues with it in two and a half summers of driving it. We built a custom AL housing to encase it and drive it, but it was all the stock inners.

'03 used a modified Quaife diff. Much smaller, but had some unique challenges regarding the brake mounts on the rear end due to the adjustment they designed for the chain tension.

-Joe

2002 LTU FSAE Co-Leader
2002 LTU FSAE Brake System Engineer
Inaugural 2002 Road and Track FSAE Triathalon Champions!

[Luke Rains]

"None of our thrust surfaces are Al though, I would be interested to see if WWU has had any issues with that"

What do you use instead of Al?
How is attached to the Al
Do you have any pictures or advice?

We are going to try this for the first time this year so any recomendations would be appreciated

[Travis Garrison]

Thrust surfaces...Yah we didn't think al would be so hot as a bearing surface, we have some water jetted stainless steel plates that go on either side of the worm gears...plates with two holes for the worm gear pins that go on the sides of the "fingers"...

Reliability is probably going to be an issue with ours...we do have a carbon fiber case that is a very tight fit with the "fingers", so hopefully the diff won't flex too much, but we'll see when we run it...

Travis Garrison
WWU FSAE

[Charlie]

We had a similar design with cast iron plates. Ours is a 1 piece design that eliminates the 'finger flexing fatigue' problem. http://fsae.com/groupee_common/emoticons/icon_wink.gif

-Charlie Ping
Auburn University FSAE (http://eng.auburn.edu/organizations/SAE/AUFSAE)
5th Overall Detroit 2003
? Overall Aussie 2003. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Arron]

There is mention of the fingers flexing when adopting to use a custom built aluminium housing.

Does anyone actually have any figures on the loads the planet gears apply to the housing through their spindles and the sides of these gears for a given sprocket torque???

Would appreciate any such information http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Robert]

The two piece diff never made it on the car. Here is a pic of the one piece diff that is going on our next car (the housing weighs about 1.7 pounds) and a pic of what is on last years car.
We have had no diff failures to date and it has seen some hard thrashing.
However I am convinced that more weight can still be removed.
http://dot.etec.wwu.edu/fsae/HostedPics/Viking38/Diff/
http://dot.etec.wwu.edu/fsae/HostedPics/Viking35/Diff%20without%20cover.JPG

[Travis Garrison]

Put that back!

-Travis Garrison
(WWU Alum)

[Robert]

Lets try this again, I hope this image shows up.

http://dot.etec.wwu.edu/fsae/HostedPics/Viking38/Diff/V38%20Diff.bmp

[Travis Garrison]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Arron:
There is mention of the fingers flexing when adopting to use a custom built aluminium housing.

Does anyone actually have any figures on the loads the planet gears apply to the housing through their spindles and the sides of these gears for a given sprocket torque???

Would appreciate any such information http://fsae.com/groupee_common/emoticons/icon_smile.gif </div></BLOCKQUOTE>

Arron...look at the angles of the gear teeth and work from there...

http://www.torsen.com/fsae/fsaefaqframes.htm

Robert, you guys should double check your factor of safety on that diff...the pocketing seems extreme, and the sharp corners can't be good for the life of the part...

-Travis Garrison

[Disco]

Robert,

The current torsen uses pressed pins to lock in the pins that hold in the element gears, which is fine for a cast housing.

In your picture you seem to show a similar design. The problem is if you every need take the diff apart, you'll destroy your very nice (and very expensive) aluminium housing by hacking into it.

I would also find a way to locate the washers up against the aluminium housing face. You'll find the thrust forces under accel and deccel will soon eat into your housing and destroy your tolerances, and your TBR with it. You'll know when it happens cause you'll find you'll excessively spin inside wheel under power on corner exit.

Good luck.

Steve
RMIT Alumni

[James Waltman]

Travis,
That picture of your diff is an old one. As long as I'm still here nobody gets to take anything off of our car.

The CAD drawing was Justin's initial concept. We know that it needs some big changes but the redesign is on the back burner right now.

Steve,
The washers are held in place by the worm gear pins. Are you saying that the washers need to get bolted to the housing or something so that they can't ever slide on the pins? We haven't had any problems yet with our diff from last year but maybe we need to take it apart and inspect it.

[Travis Garrison]

James,

I figured it wasn't actually getting canabilized, I just wanted to give Robert a hard time. I suppose the humor doesn't translate well without emoticons...

Disco,

Are you sure about that? The UW diff is essentially the same design (less the pockets) and after quite a few hours of ruthlesss driving it's showing no signs of wear. Do you have pictures of one of your diffs doing that? Becuase I would like to see what we have to look forward to.

Also, I seriously doubt they are going to press the little retaining pins into the diff. Last year we used 10-32 screws to retain the pins, and it looks to me like they are doing the same on the new one.

-Travis Garrison

[Disco]

James/Travis,
I'm refering to the washers in the axial direction of the differential (concentric with the side gears). These thrust in the axial direction, eventually wearing out the housing. The friction forces in the diff translate to your TBR, if the tolerance gets erroded, so does your TBR. I've written a conference paper on design of torsen diff housing, if you like I can send it to you both??

Regards
Steve

[James Waltman]

So if we look at the CAD image above you are talking about where the red gears meet up with the ends of the housing. I thought those already had washers (see the very top picture). To be honest, I don't know that much about the Torsen.

I'm sure that I can speak for Travis on this one: we would love to see your paper. You can send it to the email addresses in our respective profiles.
Thanks

[Disco]

James,

That is correct, the gears/washers in red. Yes there is washers, but they are originally located in the cast housing. Under power (or braking) there is an axial load due to the invex gearing, this causes the side gears and associated washers (8 in total) to thrust themselves into the housing.

This is not specifically spoken about in the paper as if was something discovered post testing (good thing we made two!).

I'll email paper.

regards
Steve

[Travis R]

Why are you guys still using the T1? The housing for the T2 is so much easier to make. We haven't broken one... ever as far as I know.

[Mechanicaldan]

http://sae.stuorg.iastate.edu/albums/Final-Drive/diff_1.sized.jpg

[Travis Garrison]

Disco,

I thought you were refering to the planet gears and their washers. Sorry for the confusion.

The torsen we got (T1 actually out of an Audi) had needle bearings between axial washers...so it went al housing -&gt; washer-&gt; thrust/needle bearing -&gt; washer -&gt; sun gear.

Edit: I didn't think wear was going to be an issue becuase of the needle bearings but it hasn't been driven long enough to prove that one...the UW diff based on the newer univeristy special gear set (which I definetly can't take credit for) has the washers locked down solidly

Thanks for that paper. Looks like some good work, you're going to be in Detriot right? I think the paper is worth a beer http://fsae.com/groupee_common/emoticons/icon_smile.gif

-Travis Garrison

[Underthefloor]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Disco:
James/Travis,
I've written a conference paper on design of torsen diff housing, if you like I can send it to you both??

Regards
Steve </div></BLOCKQUOTE>

Could you send me a copy also?

Danj@engr.orst.edu

[Disco]

John, paper sent via email.

Travis, Won't be in detroit, I'm an alumni member and won't be making the trip. I think one of the other guys from RMIT would certainly take the beer on my behalf! Rotor, Drum....any takers??

Cheers
Steve

[Jetser]

Steve,

could you send me a copy also:
powertrain@dutracing.nl

I've designed our diff this year, but never thought about the wear those side gear washers cause. Mayby I should check the diff of our 04 car.

The new housing weights only 550 grams though http://fsae.com/groupee_common/emoticons/icon_cool.gif ,to bad the weight of the gears is about 3 times that.

Grtz Rob

[John Hunt]

Steve,
I would really appreciate a copy of the paper. My e-mail is jchunt123@gmail.com
Thanks,
John

[kwancho]

Ditto here. kwancho@stanford.edu. Thanks a bunch!

[Matt Gignac]

I guess I'm jumping on the bandwagon

matt.gignac(the at goes here)gmail.com

Matt Gignac
McGill Racing Team

[Daves]

I would also appreciate a copy of your report:

Dstotera@gmail.com

[RickyRacer]

Bandwagon looks like it is getting full. I hope there is room for one more.
rtorres@csulb.edu

Thanks in advance.
Ricky
Long Beach State

[Broderick]

I'd like a copy too. This sure is a happenin' bandwagon.

rbroderi@eden.rutgers.edu

Ryan B.

[Disco]

Gees, I didn't think it would be this popular, should have started a business!!

Instead, you guys can buy beers for the RMIT team heading over for FSAE this year.

Email apaper out just then Good luck to all competing!

Cheers
Steve

[BMH]

Old, old thread and all, but does anyone have a copy of the paper that was mentioned within the last few posts of the thread? I am currently working on designing a housing for the Torsen diff and would like to learn a little more.

Thanks!