Ok so I bought a exedy twin h.d. a few weeks ago used, but in near new shape with 700 miles and the discs reading .396 and no warping or hot spots on the p.p., flywheel or floater plate.

The clutch has been holding great on the street. The car put down 533hp 380 somthing tq a week or two ago on a dyno jet and has been holding great.

Fast forward to last night at the track. First pass out the clutch was slipping pretty damn bad in third and fourth so I let out. Thought maybe it was to hot from the 70 mile trip then stright into the lanes so I let it cool down. Tried again about a hour later and it still slipped in third and fourth. Let it cool down again and just tried a 3-4 pull on the track and it held fine and didnt slip.
At this point it seemed like it only slips if I launch the car and bang through the gears. If it matters this is with 1.7 60fts. Also I noticed the clutch adjust changed a good bit, went from normal to grabbing really high.

I then let the car sit for about 2 hours, fiddled with the adjustmen and bled the line a bit. Ran the car and it seemed to hold great, ****ty 1.8 60ft and went 11.5 at 125. After the run I noticed the clutch adjustment changed once again! Started to drive home and it start to release way to high. Pulled over adjusted it again and it was fine the entire way home.

Im really stumped on what could be going on here. This clutch is rated for more torque then im making and a buddy of mine has one and is going 10.7-10.8 all day on radials with no issues. One thing that is weird is the car starts to creep with the pedal about 1/8 off the floor and it doesnt start to really grab hard untill like 1/2-3/4 of the way up.

Any input is greatly appriated.

*what I have done since last night.*
-Bled the system again.
-Removed the restrictor in the slave
-Adjusted the clutch.

-On a side note im far from new to the car scene, im a mechanic for a living, just new to a twin disc. Im not sure if the floater may have gotten warped or something small im over looking.

 

Do you have a fork stopper? This happened to me and wound up needing adjusting

 

Yeah I made one up The adjustment may be a issue because my pedal feels different then my buddys. His feels stiffer and has some more free play at the top. But I doubt it because you can still push the slave in when your not pressing the clutch so there is free play in the system.

 

was that the first time you launch it since you put it in?

 

Its most likely the stopper then. Back it off and it should fix it. Since you adjusted the pedal you might have to adjust that back to where it was. The stopper needs to be adjusted as the clutch wears out.

 

I have launched the car 5-10 times on the street before going to the track. It spins mostly on the street. The track it was hooking pretty well.


I have free play between the fork and the stopper so thats not the issue either.

 

Anyone think it could have been due to the restrictor being in the slave still when I went to the track? I may try a new master cylinder but hate doing things that arent needed.

 

I hardly doubt it's the master
cylinder.

 

Hi I have just done a search on this when I saw this. I have the exact same problem with my twin disc HD.

I broke in the clutch properly and made adjustments but the same thing happens eventually. If I am in fourth around 3rd gear and floor it, it will slip just before 4,000 rpm and then catch itself later.

I've only got 1,700 miles on this clutch and my mods are only an exhaust, a boost controller, and a tune. There's no way this should be happening so soon.

After I broke in the clutch I did 2 hard launch and it held really good, 2 days later its slipping. I also have the fork stopper and the extended slave cylinder rod.

Any one else ever had this problem and may know a fix to this?

 

Not sure if you read my reply before but make sure the fork stopper is backed away from the fork. It needs to be adjusted as the clutch wears out.

 

Ok I'll try that thanks.

 

Curious, does the evo have the same clutch bleed valve in the master cylinder that a 2g has? Since your pedal is changing a bunch, Im wondering if you are experiencing clutch pump-up.

If the clutch is adjusted so the MC rod doesnt come out enough then the pressure doesnt bleed out of the clutch line and keeps it loaded. After a few pumps it will tend to pump itself up and keep a load in the line. That will keep pressure on the clutch and may be enough to cause slipping.

Again, Im not sure if the evo is the same as a 2g in this regard but its a pretty common issue for DSMs. Hard to explain in words, but check out this video.

http://www.jackstransmissions.com/pages/tech-articles (its the "Proper clutch adjustment" vid)

 

Just looked under his Evo section and it has the same video, so I would double check this. Once the clutch is adjusted to max travel there should be no reason to have to adjust it. It will give the most separation between disc and flywheel, and also make sure you don't have pump-up issues.

 

I had a dsm before the evo, if you read my second post it states I have free play in the slave thus eliminating the pump up theory. But thank you for the idea. To the other owner with slip probelms, mine does not up from a el pull. Only when I drag race the clutch the other night did I notice it sloping. I did several roll pulls after with no problem.

 

To Dallas J,

Thanks for that video, it was really informative. My mechanic was the one making all of the adjustment and after watching the video I adjusted the pedal myself as shown. It was very close to how it was supposed to be but the problem was the fork stopper, it was backed out all the way to the point that it was preventing the fork from moving back freely. I backed it off until there was a little space in between, tightened it and now its holding good. Thanks.

To mxguy1286,

I spoke to a friend of mine who is using the same clutch and is making about the same power as yours, although his car is a honda civic, and he told me he experienced a similar issue when it slipped only when drag racing, he never found out what it was.

The weird thing is that he says it doesn't do it anymore. He raced an night with less boost for less power and it held good, the next day he turn the power back up and from that day it never slipped again.

Hope you get your problem solved soon cause I know its not a good feeling.