** edit: turns out my rear diff is toast.

**edit again: Turns out to be user error (still stumped on how). Rear diff is NOT toast. I'll post up details ASAP!

 

Jason

What spring rates?
You noted SB's are unchanged. Does that mean stock?

If you are on the stock bars, wonder if body roll is causing an unloading of the inside tire?

 

 

Seems unlikely that you're spinning inside fronts. It takes big time grip or a really bad setup to do that. More likely that the rear diff preload has decreased and you are spinning inside rear tires.

 

Hey Kaj i posted about this a month or 2 ago.

Got lots of good info on the thread i made. have a read through. what spring rates and stuff are u running?

I actually found dropping the rear end made a big difference to this. which is counter to every textbook in existance haha. but it did help.

Have you tried changing what setting you have the ACD on.

 

Have you guys seen finite life of the TRE 12plate? Wondering if mine has been getting weak.. May send it to Jon this winter just to get refreshed after 6-7years since last rebuild.

 

all clutch type diffs wear out. if the preload gets down near 45 ft-lbs we start to have inside rear wheel spin problems.

 

Havent ever tried checking my preload. Can you do it in the car just holding one wheel and applying torque to the axle nut? Trying to decide if youd need all 4 wheels up or just measure the side opposite of the ring gear.

 

9k front, 10k rear. Robispec 25mm RSB. This setup worked fine before, I so honestly didn't think to list it.

I have an adjustable end link front and rear. Both set to zero preload. I can't imagine the tire would really make that much difference. I used to get power oversteer just by looking at the pedal. I haven't been driving much.. definitely not faster, though I wish that were true LOL.

I was thinking about this last night since it clicked "hey.. I'm no longer getting oversteer under acceleration". My Weir unit has very little use, so I didn't consider that being a problem. If it is, I'll go back to the stock, re-stacked. I'll be seriously disappointed if this rear diff gave up the ghost with only a couple thousand miles.

I only have 13mm rake. I don't think I want to drop the rear any more. My current setup used to work perfect. To be honest, I have tried other settings and don't remember them making any difference.

After thinking last night and reading this thread, I'm leaning that way. I should be seeing power oversteer, especially on these little tires. I used to be able to control the car with throttle alone. Now it acts like a FWD car.
Maybe I'll swap my OEM diff plates back in and see how that works. I only have a couple thousand miles on this Weir kit. I'll be quite disappointed if it's the problem.

Thanks for the posts, by the way, guys.

 

Turns out I was stupid and threw away my OEM clutchpack (It DID have 130k miles on it). Where can I get a replacement? I can't seem to find just the plates, anywhere.

**edit: here are the measurements from the FSM. I did not do this with the Weir plates. I didn't think it were necessary, since there is no way to make adjustments. Also, I see the OEM plates with different part numbers for different thicknesses. I have no way of knowing which I need.. so guess I'd need to buy an extra 4-8 plates just in case? That sucks. Or buy a set, measure, do the math, order accordingly. That's a lot of down time.

The site is not letting me attach to my edited post, so I'll add below:

 

 

disconnect the drive shaft from the rear diff then, yes, apply torque to the axle nut with one wheel held still (like by jacking the car up on one side only). a beam style torque wrench makes it easy. if you don't disconnect the drive shaft you'll get really high torque values because you'll engage the ramps (depending on which way you twist), but that isn't measuring preload.

 

What should the measurement be?

 

you need to get somebody to watch from outside the car and determine if its the front or rear wheels that pick up. evos are known to pick up the inside rear. ive never heard of the inside front picking up tho.

And when i said lower the rear i meant go negative rake. sounds stupid. but it worked for me. i was recommended it by a WTAC open class top 5 car owner. Owns fastest time attack car here in NZ and i was like get outta town ur crazy n he was like na honestly try it and boom the rear inside wheel pick up almost disapeared.

 

I'm not sure there is a single answer, many variables to account for. I get concerned below 45 ft-lbs, but some diffs don't get that much preload even when new. Certainly if you measure something like 10 ft-lbs you want to rebuild.