how do you look at their products? and how much? since these guys are from australia, they probably have direct comparison to cars equipped with ayc... what do people think of it?

 

Very good post, what about front diff's, anyone go to an aftermarket front diff in the TC? Any difference noticed?

 

From what rally drivers tell me, it's a must in every race car for sure. I'm getting one for my 9 and I'll tell you my feelings about it in a while.

It should improve how the front of the car turns a whole lot though.

 

The front diff is already a torsion style LSD in the front on the IX.

I thought the only benefit of a quaife or other torsion diff in the front was added strength?

 

That was my understanding as well

 

Has anyone tried out an aftermarket front diff to replace the front oem unit with a different setup like a 2 way for the front? Oem is 1 way iirc, for the front so just curious. Should we just stick a 1 way for the front diff?

 

The thing about the front diff is you want it open under decel. If its providing any lock up it will just encourage understeer. Look at the 2004 STi... Hopeless turn in from what Ive seen/felt. Under power they work pretty good though.

$/gain, There would be much better places to look IMHO.

 

Torsion diffs aren't really "1-way" or "2-way" since they don't have a clutch/cam lock mechanism.

I had a clutch pack front diff in my old GS-T. Worked great...for drag racing. Made the front end wash out HORRIBLY under any kind of condition with the steering wheel turned.

I couldn't imagine a clutch pack front being good for anything but high speed road racing.

 

BTW, going to have Shepherd do my rear diff for the RS. We've never looked into this, it's obvious how to make it MUCH better than stock but to do a full build like he offers it requires machining.

 

Anybody know if Shep is doing an 8-plate setup or is he actually getting in there and machining it out to fit more discs? I thought he said 8-disc when I got it done, but I could be wrong.

The more I look into this now, the more I see there likely are some differences between what Shep does and what TRE does.

 

I spoke with John.

The 8 disc rear diff service includes:

The mods to the diff. New axle and pinion seals, new pinion nut and setting up the proper clearance on the ring/pinion. That is $150.

The 12 disc rear diff service includes:

All of the above with more machine work and additional clutches being added to the rear diff.

That is $350.

Just got more information from John.

His advise on which one of these to get is this:

The 8 disc is good for nearly everyone and the 12 disc is recommend for drag cars or serious track cars. I'm assuming by serious track car he is referring to one with large sticky tires.

 

I'd think AutoX guys would be included in the 12 as well

 

I got the 12 plate version from TRE...

You're going to want the 12 plate Dave

 

Track or autocross, whatever, cars with a lot a traction is what John relayed to me. I'll probably never have more than a 255 street tire on my car. After, if, this car runs 8's, the drag racing is more or less done with the car.

 

That is most definitely not true. (1, 1.5, 2 way only describes the relative lockup in accel and decel and has nothing to do with the method of torque biasing) Torsen type 2 units apply their friction through the end faces of the gears, where they meet the case. One end of the gears is the friction surface for accel, and the other end of the gears is the friction surface for decel. Making the surface finish smoother, or adding needle bearings to these interface surfaces, would reduce the locking effect at the same input torque (as compared to OE). Making the surface finish rougher, or possibly machining away part of the gear end surface (to increase unit frictional loading) would increase the locking effect as compared to OE. Since there are different surfaces for accel and decel, you could make a 1.5 way or 1 way if you wanted (stock Torsens should act like a 2 way).

It would depend if it was a Eaton-style clutch diff where springs provide static preload which never changes and is the only method of torque biasing, or a Salisbury/ZF-style where separate angled ramps for accel and decel allow the diff's own input/output torque balance to adjust the lockup. Salisburys can be made to have very very little lockup on decel with 90 degree ramps (the decel ramp is vertical - I guess that makes it a wall, not a ramp...) BMW road race cars love these diffs.

Matt