Well I believe I have discovered my shifting problems in my car but I want to first, double check with others to see if this sounds right. And secondly, figure out how to cure the problem.

At first the car wouldnt disengage too well with my old clutch. I adjusted it WAY out and it started disengaging properly.... sooner or later it went bad again and I could not adjust it any farther. Yes it was bled well. I replaced the clutch because my first one I destroyed anyways. The car shifted again well. First time at the track with high boost, it started to not want to shift at 8.5-9k. Now it is really bad again... I push the clutch all the way in and I have to jam the hell out of it to get it in gear (Yes terrible for the synchros). Once it is in gear it pulls the car slightly forward. When I slowly release the clutch it barely grabs more until about halfway out then it grabs like it should. Again, yes it is bled well... I have rebled it plenty of times.

The slave cylinder is inside the tranny now assembled as part of the throw-out bearing. If that was leaking there would be fluid inside the tranny and I would be losing fluid. This is not the case. There is no air in the lines so my only other idea would be the master cylinder is leaking. Does this sound correct?

Lastly, if it is the master cylinder.... does anyone know where I could get a rebuild kit for it? Or use one from a different car or something? Mitsu wants like $200 for a new one which I am obviously not gonna buy. I am assuming one of the rubber seals is the culprit and I know i could find one of them at Napa but the other one I assume is a 1 way o-ring... can these be bought at a local store anywhere?

Has anyone else had problems with the master cylinder going south? Were your symtoms the same? Anyways, any help would be greatly appreciated.

 

Well I took the clutch master cylinder off... its fine. Now i dont know what the problem is.. guess the trannies coming out again

 

I doubt the clutch master is bad, but who knows. My friend, bite the bullet and get an OEM, I highly doubt that there is a rebuild kit for an Evo clutch master cylinder. On the other hand I have seen and personally experienced improperly bled lines. Usually the culprit is the reservoir and the line that feeds the clutch master. From what you describe it sounds like you have tranny concerns. By the way it is not uncommon to have difficulty shifting at 9k rpms.

 

The bulk of the problem is I have pulled the tranny at least 10 times so far for various reasons. Now I need to again. The master cylinder is perfect, I pulled it all apart and there is nothing wrong with it. The lines were bled properly, the clutch shifted fine for over a month. First day beating on it, the clutch started to disengage worse and worse until it got to the point it is at now. I have no idea on what is wrong with it now... I am guessing I bent the pressure plate spring fingers but Im not sure. Im gonna put the master back on the car, rebleed it and see what happens. Maybe I will be fortunate and the only problem was a bad bleed in the start and heating the fluid up enough caused it to bubble a little more but I really doubt it.

The transmission is a race built tranny. The clutch is a twin disc with a hydraulic throw out bearing/slave cylinder. All lines are ss briaded. If the master cylinder is fine and it is bled properly there is nothing left except for stuff inside the tranny.... which means it comes off again

 

Also, I checked all the trans bolts to ensure it was not coming loose from the block and they are all solid tight. Same with the pressure plate bolts to the flywheel. Nice and tight on those as well. I am starting to think the problem is one of the discs is dragging and not releasing fully... I guess I will hopefully know for sure soon.

 

what kind of clutch are you using??

 

Quartermaster Twin-Disc with a hydaulic release bearing (No slave cylinder or the bs throw out bearing). It seems the problem is most likely either a warped disc(s) or the splines on the friction discs are getting rounded off. Apparently this is not an uncommon problem with twin discs. I cant even get the tranny seperated from the block now

 

Put a slight amount of high temp anitseize on the input shaft and clutch disc splines next time. It's pretty common for the outer disc to not slide freely on the input shaft if you just slide it on with no prep work.

 

So it would seem I wish I would have been armed with this knowledge previously... oh well.

The good news is it seems everyone is standing behind thier products so it will get fixed shortly. Maybe then I can finally run the car and see what it can do.

 

Yeah I've been there, done that. I think almost everyone has a problem on their first twin disc install. If you double check the splines on the second disc you'll be fine though.

 

It is actually my third install with a twin-disc. The problem is supposedly the friction hubs are not that tough a metal compared to the input shaft. When I really hit it hard (I dont lift to shift when I can get away with it) the friction hubs are wearing out. They get far enough torn up where they will get stuck binded up on the input shaft.

Thats what I hear at least from the manufacturer. We will find out soon enough. I really think A tilton would have been the choice but I am amazed at how well they are taking care of me with this problem so we will see how it ends.

 

It is usually torsional vibration that wears out splines on the disc, not torque. The torsional vibrations are like an impact hammer that just keeps beating on things. Since you don't have springs in the disc center, there is nothing to dampen the vibrations out except the weigh of the assembly which of course is very light.

 

I believe the problem may be with the QM hydraulic release bearing. If they used one of the "standard" HRBs, the piston area is too large. The stock 5/8" bore master cylinder probably isn't providing enough fluid volume to the HRB to compensate for plate warpage. It would probably work fine when the clutch is new/non-warped. When the plates warp, the diaphragm spring must travel further to disenage the clutch.

Tilton's clutch packages include a hydraulic release bearing with a reduced piston area so that it would work with the stock 5/8" master cylinder.

 

Now that sounds pretty interesting. The only thing that makes me not think this is that big a problem is because I can get the clutch to release at only about 10% pedal travel and still have 90% more to push.. it just never completely releases it. That combined with the fact that the tranny is now stuck to the block

I will know for sure in a day or two. They are inspecting everything for me and yanking out the tranny and everything. I just want to actually run the car once and make one clean pass.

 

Makes sense to me. The question is why do they use such a weak metal hub for these discs? Is it so when they do fail they dont destroy input shafts or what? Thats the only thing I dont really understand.