How much drive train assembly weight?

[Han sungsoon]

I have finished assumed drawing and calculated the Differencial Housing and LSD assembly weight(except CV joint and axle ) It is about 8Kg .
Could you let me know the other teams'
its weight for me?

Nice to meet you!
Good work!

[jack]

6.5lbs (2.9kg) for our complete diff--no cv's. it has the old style uni special gears, and aluminum housing with a carbon cover. we designed and manufactured the housing here at WWU. hopefully i can have a picture tomarrow for ya.

on another note, when we made our new diff, we kept the tollerances as accurate as possible. when turning the diff in your hands, it has much less resistance than it did in the stock (audi) housing. after measuring the (brand new) stock housing i found it to actually be outside the tollerances i got from torsen. has anyone else noticed this???

jack @ WWU
http://www.etec.wwu.edu/

[jack]

here are some pics. this is a new generation of the old diff, which was basically a copy of the original housing.
--and yes it is possible to time!



http://dot.etec.wwu.edu/fsae/SharedPictures/Diff/Diff%20with%20cover.JPG http://dot.etec.wwu.edu/fsae/SharedPictures/Diff/Diff%20without%20cover.JPG

jack @ WWU
http://www.etec.wwu.edu/

[James Waltman]

The new design (above) is all one piece and the gears ride on steel plates. Jack designed it and Travis machined it. They both did a great job.


This is our old diff design. It had some problems with tolerances.
http://dot.etec.wwu.edu/fsae/images/Gears%20in%20new%20differential%20housing_JPG.jpg


Another thread with some talk about diffs. (http://fsae.com/eve/forums?a=tpc&s=763607348&f=125607348&m=9116035234)

James Waltman
http://dot.etec.wwu.edu/fsae/
Vehicle Research Institute at
Western Washington University

[karter]

if you are going to the trouble to make a new housing, why use 3 sets of gears, 2 should be plenty and if balance isn't an issue, use 1 set!

[Charlie]

Interesting Idea. Not sure how you'd time it though, aren't the gears cut to be 120 deg apart? Hmm

-Charlie Ping

I just need enough to tide me over until I need more.

[Denny Trimble]

From the Torsen FSAE FAQ: (http://www.torsen.com/fsae/fsaefaqframes.htm)

24. Can I build the differential with only two of the element gear pairs?

This is not recommended. Attempting to build the differential with only two pairs of element gears, arranged 180 degrees apart, will create timing errors in the gearing. In a vehicle such as a Formula SAE car, the differential may actually survive for a while as such, since the cars are lightweight and have only small torque outputs. Assembly with the gearing 180 degrees apart is very difficult to "time" and without correct timing, the unit will eventually fail (refer to question 14).

University of Washington Formula SAE ('98, '99, '03, '04)

[karter]

oops, didn't realize there is a timing issue, sorta like timing a roadranger truck trans .....

[jack]

im still curious what other people's diff's weigh? i really dont think you can get an ounce lighter than 6.5lbs, i would be impressed if another team got that light.

jack @ WWU
http://www.etec.wwu.edu/

[LukeT]

How about over a pound lighter jack? The Torsen that I made this year weighs in at 5.15 pounds, however that's with wires in place of the roll pins. It includes the thrust washers we made to protect the housing from wear, all gears, and the journal pins. I'm not including the weight of the bushings used to help stabilize the spindles, the oil seals, oil sleeve, bearings, etc... On Monday I will try to get a complete weight, with the seals and bushings included...

-Luke Thompson
Vandals Racing 2003-04
University of Idaho

[Travis Garrison]

Wow...thats impresive. I would love to see a picture, if you don't mind sharing that is...

Did you get rid of the massive sprocket adapter that ours uses? Maybe mount the sprocket up on the wide part of the diff?

Travis Garrison
WWU FSAE

[ReadySetGo]

Hey James, nice CNC job there but watch out for the 3 threaded holes for the cap. thats where we sheared ours and had to spend all night in one of the michigan university shop fixing it.

We basically had the same set up, except we had helicoils instead of bare aluminum. If it works for you please let us know. We'd love to figure out why ours sheared so easily.

Thanks
-Omar

-Omar Barker
Vice President
CSU, Sacramento
Hornet Racing Development

[Han sungsoon]

I would like to know LSD,housing,oil,sprocket,disk assembly weight.
Just dynamic system..
Could you let me know the other teams' weight?

[jack]

omar, i think you are talking about the first generation diff (3rd pic), and the three bolts that hold the cap on. ours didnt sheer because we never actually tested the diff, we couldnt get it to time right, because the tolerances were to far out. we thought that those bolts would be a problem so we designed the second gen diff (1st, 2nd pics) as one piece. the cap on this diff is much less structural. hopefully by the end of the week we will test the new diff to its full extent.

han, the weight of the diff with oil (probably too much), cv's all seals+bearings and carriers (peices that mount it to the car) is 12lbs.

jack @ WWU
http://www.etec.wwu.edu/

[LukeT]

jack, are you guys venting your diff? In the past we have had trouble with the pressure building up and forcing the oil through the seals, so this year our machinist came up with a way we can vent...

-Luke Thompson
Vandals Racing 2003-04
University of Idaho

[Pat]

LukeT, we have had the same problem in the past and also came up with a way to vent the diff. Since then, it stop overheating and leaking. One advise in case you havent done it already. I don't know how you guy are venting the housing but if it is similar to ours, I would suggest putting the vent on the sprocket side since a small drop still come out once in a while

Pat
Montréal Poly

[LukeT]

We are also venting on the sprocket side for that very reason, plus it will make filling it a bit easier. Filling it will be fun, I'll have to use a syringe to inject oil into the 1/4" hole in the oil sleeve. http://fsae.com/groupee_common/emoticons/icon_razz.gif

-Luke Thompson
Vandals Racing 2003-04
University of Idaho

[Travis Garrison]

LukeT, So are you going to post any pictures? http://fsae.com/groupee_common/emoticons/icon_smile.gif I really would like to know how you got it so light...

Travis Garrison
WWU FSAE