For reference, this is for an Evo 9 with 350awhp/312ft-lbs torque.

This was only a minor issue previously as I had just first noticed it about a week ago and it got significantly worse after doing a few drags with the car.

The rpms will climb to redline when WOT at the torqueiest part of the powerband without the car going faster. In the higher, less torquee rpms, this does not seem to be an issue when stomping WOT. During this, I can also feel the rear wheels spinning in the lower gears but in the higher gears (4th, 5th) I don't notice the wheel spin as much. I never notice the front wheels spinning during this.


Really, this comes down to a few things it could possibly be:

1. Clutch: only ~6k miles, Competition Twin Disk installed by English Racing. Probably the strongest part of my drivetrain.
2. Center Differential
3. Front Differential
4. Broken front axle
5. Crappy Tires (still doubt they would spin in 4th gear going 80+)

Is there a good way to go about troubleshooting these to pinpoint the exact failure? I was thinking I could get it up on a lift and put it into gear and see if the front wheels spin with the rear wheels.

 

Sounds like your clutch. Did you break it in right? Does it matter if it's hot or cold?

 

It was chucked on the dyno after install then it was driven ~300 miles which included sitting through stop and go traffic for ~2 hours before it was launched for the first time. Also, this issue will happen whether the clutch is cold or hot.

 

I agree, your clutch is toast.

What makes you think your rear tires are spinning? IMO you're not making enough power to be having that kind of issue. What tires and what size?

 

265/35/18 Nitto NT555. I can feel them spinning and sometimes with a little hop.

I guess I should get a hold of English Racing and see what type of warranty there is on the clutch.

 

I emailed exedy about throwing my twin HD on the dyno right after it's installed and one of the tech people couldn't advise more against it. He gave the usual 500mi break-in procedure, not going above 4k on shifts, etc. Could be them protecting thier butt, I'm deciding on a base tune since I'm getting a motor put in at the same time and the exedy recommended break in. Some people will say if it's done on the dyno it's okay but I prefer to go with the manufacturer's recommendation.

 

Sounds like a clutch man. You won't be spinning 265's making 350whp unless its wet or you're in gravel.

Call up Adam @ MAPerformance and order your Quartermaster 8 leg 7.25" twin

 

You are truly going to be the devil to my wallet...

 

Hey...just tryin to save you money in the long run

 

Any reason this clutch wore out so quickly?

Will the Quartermaster last longer? 5 months, 6k miles and 30 launches does not seem worth the clutch + install cost. My car is nowhere near capable of pushing the limits of this Competition clutch and the whole reason I got it was so that it wouldn't start slipping after a few launches.

 

probably because you didn't break it in properly. I did the exact same thing as you to a SPEC clutch back in the day. Now I wait the full recommended perior before abusing the clutch...and even then I take it easy.

 

Well not much of a break in on this style clutch that I know of. Stop and go traffic wares these clutches pretty bad 7-10k is tops for milage from most of the 7.25 clutches I see. Comp,qm,tilton etc..

The comp rebuild is pretty cheap though. Will have to check with Aaron on pricing for sure.

This is why my car has a hdss and I just deal with the high rpm lock out.


The reson for these clutches is taking the heat of a launch and letting you power shift well at high rpm.

 

My exedy stage two, three puck thick facing cerametallic clutch is on its last leg, never dragged or dropped it. Its seen the road course at PR twice, and the go-kart track once. I do drive hard, but Im smart about clutch use. Put it in at about 70k, im at 93 now. Ive continually adjusted @ the pedal as described elsewhere on this site, its good for a couple days, then goes right back out to near full pedal travel to hook up. Sigh. Not looking forward to changing this clutch again. Took me four 8 hour days last time, maybe I can cut it down to two days this time. PS, def getting a lightweight flywheel this time. Not sure on the clutch yet though. Fricking pressure plate diaphrams cant handle traffic for beans. No more DD for this thing I think.

 

Try making the 1-2 shift at 8500RPMS when you're making 500+whp after doing a small burnout and then cutting a 1.5 60'

Your 2nd gear synchro will cry.

 

Update from the far future!

So I finally got around to pulling the clutch. The clutch literally failed as I pulled into my parent's place after driving for a couple hours on the highway in third gear.

The clutch after the rebuild does not feel nearly as grabby as the old one. It is quite soft driving around town and hard shifting feels more bouncy than locking up and making the rear diff clunk. The engine and tranny mounts are all bolted on tight so it is not that (Blox engine mount). It also does not have the "seal bark" on engagement anymore.

I had to adjust the clutch pedal out a bit more than before the rebuild and there is still a bit of play on the top for the engagement (~0.50"). I tried to adjust it at the allen head bolt on the bracket Competition Clutch provides for the pull to push conversion but it was not budging (If it even can budge). I put very little axle grease on the input shaft when reassembling so I am not sure what would be causing this clutch to be a lot less "harsh." I would doubt that it is from the flywheel being a few mils thinner without the pressure plate bolt locations being milled down to match as the old clutch was still "grabby" on the get-go despite slipping a lot.

Anyway,

The new plate thicknesses are:

Transmission side disk: 0.252" average measurement
Engine side disk: 0.251" average measurement
Middle floater plate: 0.189" average measurement
Top floater plate: 0.183" average measurement


The thicknesses of the plates pulled out were:
Transmission side disk: 0.235" average measurement
Engine side disk: 0.231" average measurement
Middle floater plate: 0.169" average measurement
Top floater plate: 0.178" average measurement


So, the wear on these plates are as follows:
Transmission side disk: 17mils
Engine side disk: 20mils
Middle floater plate: 20mils
Top floater plate: 5mils

I had the flywheel resurfaced at 5mils when rebuilding the clutch. It looks like next time I can get away with resurfacing the top floater plate and reusing it as it wore very little. It could be possible to resurface the middle floater plate and reuse it but it would require milling down pressure plate bolt locations proportionally which I will probably do next time anyway (20mils and then shim the TOB the same).

On to the pictures:




Toasted.


Oh Yay!...Not for resale... I must be unique...


Toasted as well.


Any insight into why my clutch is not "grabbing" like it used to would be appreciated.