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-   -   Spinning front, inside tire. (https://www.evolutionm.net/forums/motor-sports/749083-spinning-front-inside-tire.html)

kaj Jun 3, 2018 01:56 PM

Spinning front, inside tire??
 
** 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!

MinusPrevious Jun 3, 2018 02:22 PM

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?

:beer:

Ayoustin Jun 3, 2018 02:47 PM

I would make sure nothing has shifted in the alignment.

I thought (correct me if I'm wrong) the OE front lsd was a torsen style and if that's the case you may be lifting the front inside side causing it to act like an open diff. See if anyone has photos of you mid corner.

Maybe consider some adjustable endlinks and brackets for your sway bars to tune them.

Also that tire change is playing a role. The 71s may have had enough grip to keep it from spinning before.

I'm not well versed on the acd stuff as my car is an 04 but it is stupid how well the front of my car bites with a wavetrac up front. Maybe your driver mod is necessitating a better front diff. (You may be going a fair bit faster than you used to)

griceiv Jun 4, 2018 03:24 AM

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.

Bee-Raddd Jun 4, 2018 04:14 AM

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.

Dallas J Jun 4, 2018 08:32 AM


Originally Posted by griceiv (Post 11824485)
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.

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.

griceiv Jun 4, 2018 10:55 AM


Originally Posted by Dallas J (Post 11824511)
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.

Dallas J Jun 4, 2018 12:55 PM

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.

kaj Jun 4, 2018 02:31 PM


Originally Posted by MinusPrevious (Post 11824422)
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?

:beer:

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


Originally Posted by ayoustin (Post 11824427)
Maybe consider some adjustable endlinks and brackets for your sway bars to tune them.

Also that tire change is playing a role. The 71s may have had enough grip to keep it from spinning before.
(You may be going a fair bit faster than you used to)

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.


Originally Posted by griceiv (Post 11824485)
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.

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.


Originally Posted by bee-raddd (Post 11824487)
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.

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.


Originally Posted by Dallas J (Post 11824511)
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.

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. {thumbup}

kaj Jun 4, 2018 02:41 PM

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:

kaj Jun 4, 2018 03:21 PM

https://cimg3.ibsrv.net/gimg/www.evo...273b224495.jpg

griceiv Jun 4, 2018 03:27 PM


Originally Posted by Dallas J (Post 11824573)
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.

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.

kaj Jun 4, 2018 03:36 PM


Originally Posted by griceiv (Post 11824605)
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?

Bee-Raddd Jun 5, 2018 08:59 AM

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.

griceiv Jun 5, 2018 12:56 PM


Originally Posted by kaj
What should the measurement be?

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.


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