Torque Bias Ratio Testing

[albrewe]

Does anybody have any ideas how to physically test the torque bias ratio of the torsen differential? Also, what are some ways of modifying the TBR?

Andy

[albrewe]

Does anybody have any ideas how to physically test the torque bias ratio of the torsen differential? Also, what are some ways of modifying the TBR?

Andy

[LukeT]

Torsen says that you can drop the weight of the oil to increase your TBR some. I also called them, and talked with Rick, and he suggested changing some of the washers so there will be a higher coefficient of friction between the washers.

-Luke Thompson
Vandals Racing 2003-04
University of Idaho

[Ryan Schoffer]

you need to design some apparatus that will measure the torque input, and the output thru one shaft with the others torque output limited

Vehicle electronics leader

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

[John McCarthy]

Albrewe,

Firstly, my knowledge of torsen dofferentials is not what I would call extensive, so perhaps the following suggestion is not applicable.

However, in my (fairly limited) experience in setting up 4wd Turbo rally cars, occasionally we test the torque in each (Front and Rear) diff by jacking one side of the car so the wheel is lifted off the ground. By using a torque wrench on the centre nut and adjusting it so it clicks just as the wheel starts to rotate, you can get a pretty accurate measurement of how much the diff is "torqued up".

Perhaps if you did a similar thing with your torsen by clamping one side in a bench vice you could achieve what you are after.

If anyone else has an opinion on the above I'd be interested in hearing it.

Technical Manager,
QUT Motorsport.
www.qutmotorsport.com (http://www.qutmotorsport.com)

[Ryan Schoffer]

maybe if you did this:

jack both rear wheels off the ground with the tranny in gear
put a torque wrench on each centre nut
set one to 50 ft-lbs, secure it
see how many ft-lbs you can torque the other wheel to (in the same direction) until the 50ft-lb set wrench 'breaks'

if its 150 ft-lbs, then your TBR is 3:1

Vehicle electronics leader

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

[jack]

drive your car, if the inside wheel spins, you need more tbr.

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

[awhittle]

Wrap a cable a couple of wraps around the left tire and hang a 100 pound weight to it. Do the same thing on the right tire with say 50 weight on it. Try to turn the ring gear on the dif and see if both weights raise. Now remove a few pounds from the 50 lbs side and retest. The less on the light side is better. This ranges from about 2.5 - 6.0 to one depending on design and gear preload. Look at the Torsen T2, T2R and T2 that is used in the Ford FX4 Pickup truck. These are different in design than the FSAE unit but the principles are the same. All preload and gear angles.

I think the motion has to be applied thru the ring gear to get a fair test.

Hope this helps

Andy

[This message was edited by awhittle on February 25, 2004 at 07:54 AM.]

[Hsoj]

Thanx, jack. I think your opinion is worth "jack".

I like using the torque wrench on either one or both wheels, Andy. Sounds like we can get a pretty fairly accurate measurement that way. Does anyone know how to MODIFY the TBR, though? Thanx.

Hsoj

[Ryan Schoffer]

you need to take the diff apart and get different thickness friction washers for it - the thicker the washer packs, the higher the TBR will be

Vehicle electronics leader

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