Torsen's from Audi or Miata?? whats the diff? =)

[Christopher Chow]

Hello, Having no hands on experience with independant rear drivetrain setups is tough. We are currently having a #$%@ time deciding on where to get a Torsen unit from. What are the differences between the Miata unit and the Audi Torsen? Which unit will be easier to source the splines from? What splines fit? Being a first year team, we would like to save time by having a large number of these drivetrain parts come out of cars or atvs without having to cut and paste too much.

Thanks for any insights.

[Christopher Chow]

Hello, Having no hands on experience with independant rear drivetrain setups is tough. We are currently having a #$%@ time deciding on where to get a Torsen unit from. What are the differences between the Miata unit and the Audi Torsen? Which unit will be easier to source the splines from? What splines fit? Being a first year team, we would like to save time by having a large number of these drivetrain parts come out of cars or atvs without having to cut and paste too much.

Thanks for any insights.

[Denny Trimble]

You can buy a torsen for about $350, directly from zexel. Follow This Link. (http://www.torsen.com/fsae/fsaefaqframes.htm)

You can take the spline spec to your nearest friendly gear shop and ask for sponsorship - we did.

I don't know anything about the torsen that lives in a miata, but it might be (gasp) larger than the one we typically use, which is in the center location and before the ring gear reductions. It still handles about 5X the torque of an FSAE final drive, but I'd imagine the miata final drive diff is larger. Just a hunch though.

[Vector006]

Alot of people are going with the Honda Rubicon (sp?). Here, you dont have to worry about getting shafts splined, just buy the atv halfshafts.
If you do want to use a torsen, there are several places that sell blank spline shafts that you cut and weld to CVs of your choice. Google search should answer all your questions.

[MikeWaggoner at UW]

What kind of diff is the rubicon? I found a picture and it looks strange.

http://www.off-road.com/atv/rubicon/images/rubicon_127_sm.jpg

[Christopher Chow]

Hmm, We are interested in using parts from a Rincon. Is that Rubicon diff open? or limited slip?

[MikeWaggoner at UW]

It's a torque sensing LSD (according to Honda), but I can't cearly see the mechanism.

[Greg]

That looks like a cam and powl differential.

Were there a bunch of small steel pieces in there as well?

I believe that Carroll Smith talks about them a bit in Prepare to Win, and Engineer to Win.

[ben]

Monash run one as well. To me it is closer to the AP Suretrac in detail design rather than the ZF cam and pawl Smith describes in his books. I think they both operate on the same priciple though.

Ben

[Alan]

Here is a diagram of a Suretrac out of some Subaru Literature.
http://img62.exs.cx/img62/996/suretrac.jpg

[Flash]

We are using a type 2 torsen from a MX5, I believe most of the Audis use a type 1. We went for the type 2 due to the attractiveness of the single axis machining, however have found that it may be more of a problem than an advantage.

The element gears are located using a semi-circular bore as a bearing surface for the blunt ends of the gear teeth. This makes a full aluminium housing far less feasible than for the type 1, although not necessarily impossible.

We have ended up removing as much steel from the MX5 unit as we can, and sleeving it with an ali casing to seal it. Far from the best solution, but quick and reliable.

We haven't run this yet, so can't report on the performance. Would be interested in hearing if anyone has made an entire housing for a type 2? We looked at surface treatments, hard anodizing etc., but steel teeth on an ali surface seems to be a potential problem.

Matt

[Pavan Dendi]

We have run type 2 torsens out of Miatas for about 4 years now. The machining is a little bit of a pain due to the amount of material that needs to be removed from a piece of billet, but it works. We do not treat the aluminum in anyway, although past diff cases have been cut out of 2024. The most recent car used regular 6061 without any problems.

[Kyle Jeffries]

does anyone happen to have any more information on the rubicon diff? TBR? technical drawings? spline data? a ballpark weight?

Also, is there any way of changing the TBR without changing the internals completely?

Thanks.

[The guru of guru's]

the best diff is a spool diff!!!!!

[K.Sampson]

We used the Rubicon internals with our own housing in 2002 and 2003.

Cam and Pawl Differntial (http://wwwcgi.umr.edu/cgi-bin/cgiwrap/formula/imagefolio2.2/imageFolio.cgi?direct=Old_Cars/2003-26/Differential)

The assembly in the pictures weighs 6 lbs. Internals alone weigh 1.38 lbs. The housing pictured is titanium with a titanium nitride coating. The coating didn't do much as you can see from the Damage picture.

If you have any specific questions just ask.

[MikeWaggoner at UW]

How much runtime did you get out of it?

-Mike Waggoner

[fsae_alum]

We used one from a Miata in 02. Cost was $60. Good thing was that we were able to use the bearings, seals, clips, and stub axles from the Miata too. Yeah!!!! Not a bad deal. Little bulky, but it worked just fine and we knew it wasn't going to break!

[K.Sampson]

The titanium diff pictured has been in service since April 2002.

[Steve Chalmers]

I have a specific quaetion:
Assuming a team want to purchase saya Torsen diff, is there considerable gains to be had in manufacturing your own diff housing from scratch? How much work is involved (FEA and more I would imagine) and do you have any Do's and Donts you can grace me with.

Cheers