Help: New Clutch...Still Slippen..

[super_usdm]

Hey Guys,

Im new to the forum, but Ive been lurking and searching around here since February when I picked up my 1993 T-leg 5MT. A few months ago my clutch started slipping really bad. I purchased a new Exedy 02-03 wrx clutch and flywheel and installed both about a month ago. Installation went well, the clutch doesnt shudder and engagement is smooth. The problem is that under WOT the clutch starts to slip just a little bit on hot days.

Before I installed the new clutch, the engagement point was wayyy off the floor... like, foot practically off the clutch high. I fighure this would go away after the new clutch was installed. BTW: I removed the clutch dampener during the clutch installation (Hydro clutch). With the new clutch installed, I readjusted the clutch pedal so the engagement point would be closer to the floor, but when I did this the first 2 inches or so of pedal were complete freeplay. I assumed that when I bled the clutch that this play would go away... It didnt. I re-adjusted the pedal at the floor to soak up the freeplay but the engagement point of the clutch is still way off the floor just like before.

It feels like the clutch isnt engaging completely because the engagement point is so high. Has anyone had similar issues to this? I have already adjusted the floor adjustment many times... to the point where the pushrod isnt even touching the master cylinder piston. Anybody know if there is a pushrod adjustment on the slave cylinder?

Any input is appreciated.

-Jason

[BoostedSubie]

Did you just replace the clutch disc or did you do the disc, pressure plate, throwout bearing, and pilot bearing? Is the shifter stiff trying to put it into gears, like the clutch isn't disengaging all the way?

[BoostedSubie]

I would also have a buddy depress the clutch pedal while you watch the slave cylinder to see if its working properlly.

[super_usdm]

Everything you mentioned was replaced with new. I bled the clutch right after the install and the slave appears to be working properly from what I can tell... The car shifts into all gears with no problems.

[Alphius]

If it doesn't slip under full boost, go with it.

I have a brand new Exedy WRX clutch and a brand new flywheel in mine (plus a new master and slave cylinder) and the engagement point is way up near the top as well. No slip at 18psi, so it's good by me.

[super_usdm]

Right now the car is running approx 13lbs. It begins to slip just before I reaches max boost. What did you replace the master and slave with? I'm womdering if I need to replace the master cylinder with a wrx one to solve my problem.

[BoostedSubie]

My buddy Matt replaced his clutch/lw flywheel recently with a wrx setup and when he puts it into gear it doesn't go in as smooth as it should. I was wondering if the wrx slave has a longer rod or something. We bled his slave and he replaced the gear oil in the tranny with Subaru stuff, it made shifting smoother but imo still not as smooth as it should be. It doesn't slip or anything, he's running 17lbs of boost, and has even spiked to 23lbs with no slip. I have't personally drove his car so don't know where it engages on the pedal. I have a cable clutch with a excedy stage 2 clutch and have no problem going through the gears. I wondered if swapping to the wrx slave would help his shift smoother.

[super_usdm]

I was wondering if the wrx slave has a longer rod or something.

I wonder the same thing. But it also makes me think that there could be an adjustment on the slave pushrod. Perhaps by spinning it?? If my logic is correct, I need my slave cylinder pushrod to be just a tad shorter in length. Im seriously considering grinding down the end just a little bit.

That is wierd. It sounds like your buddy is having the exact opposite problem I am having. I wonder if his clutch engagement is super close to the floor...

[kimokalihi]

There's no adjustment on the pushrod. It just flops around in there when you take the slave cylinder off. You can pull it right out. There is however a small adjustment I believe by loosening the bolts and sliding it forward or back. It's probably just your pedal adjustment. Are you going by the factory specs for the pedal freeplay?

I have the turbo legacy Exedy clutch kit in my car running 15 lbs of boost on my EJ20G swap and it holds fine and the clutch pedal feel and height is the best I've ever felt in any car.

[super_usdm]

Ill try loosening the bolts on the slave to see if I can push it back a little. You are referring to the bolts that connect the slave to the trans correct?

I didnt look into factory specs for the pedal adjustment. I had the pedal adjusted so that the pushrod wasnt even touching the master cylinder and the clutch still slipped. If all else fails Ill be getting out the dremel I would imagine that shaving off a couple mm's should do the trick.

[kimokalihi]

Shaving a couple mm's off of what exactly? I was referring to the slave, correct.

[super_usdm]

Off the slave pushrod. Probably the end that sticks into the slave, rather than the end that pushes the shifter fork. The way I see it, I can always adjust the pedal adjustment to push the fork more if need-be.

Do you think this is a bad idea?

[kimokalihi]

I wouldn't do it on my car just because I think you have a problem elsewhere. I don't think it should be slipping, you're not making much power and you're using OEM parts so something is not adjusted right. I too removed my clutch damper so we have essentially the same exact setup except I have a brand new master and slave.

[super_usdm]

What would not be adjusted correctly? I already set up the pedal so the master cylinder would allow for the fullest clutch engagement possible...

Did you go with OEM Legacy master/slave cylinders or WRX? If in fact I need to replace one or both of those pieces I figure I might as well try to fix the current system first. Althouth I havent looked at the backside of the pushrod yet so I dont really know what I would be working with.

[kimokalihi]

Just oem subaru legacy parts. I dont know whats wrong it just doesnt seem like it should be slipping. I think the wrx and turbo legacy oem spec clutches are the same.

[Alphius]

I have OEM Legacy master and slave I believe. The Turbo Legacy clutch disc is 2-3mm smaller in diameter than the WRX disk. The WRX disk will work on a T-Leg flywheel, that's what I'm running right now.

One thing I am noticing you are saying is that you "set up the pedal so the master cylinder would allow for the fullest clutch engagement possible" which is not actually what you want. You do not need to push the clutch fork more, in fact what you are doing is still pushing it a little bit when the clutch is all the way out, which is creating slip under boost.

Also, shaving a mm or two off the slave cylinder would not fix your problem. The hydraulic system (which is self-adjusting except for pedal freeplay) would simply take that slack out and you would be right where you are already.

You need to adjust the clutch pedal U-bolt so that there is about 1.5" of free play in the pedal and master before you actually start disengaging the clutch. You also will want to make sure you still have the return spring installed on the clutch fork.

[kimokalihi]

That sounds right.

[super_usdm]

You need to adjust the clutch pedal U-bolt so that there is about 1.5" of free play in the pedal and master before you actually start disengaging the clutch. You also will want to make sure you still have the return spring installed on the clutch fork.

I had the clutch pedal adjusted this way and re-bled the clutch and there was no difference. I just got done looking at the slave and shifter fork. I was under the impression the the shifter fork was being held in a slight "disengaged" position by the slave, and that that was the root cause of my problem. I see what you are saying now about the self adjusting system because when I pushed the shifter fork towards the cab of the car, it went freely. So it basically looks like the clutch IS fully engaged, its just not grabbing.

At this point I can only attribute the slippage to 3 different possibilities.
1. I didnt clean the clutch and fw surfaces well enough when I installed the clutch (used brake cleaner)
2. Its new and just needs to break in a little more
3. Im crazy and the clutch isnt really slipping.

Thanks for all the good info and helping me to understand these cars a little better. Im just going to drive it around some more to see if the problem goes away.

[Legacy777]

Just a couple things to note when adjust the clutch pedal push rod and where it sits in the bracket. The clutch master cylinder has a certain point where it allows fluid pressure in the slave to bleed off into the MC resevoir. If you depress the clutch just a little bit, that "bleed back" goes away. So if you had the clutch pedal or the rod adjusted too tightly, you will leave pressure on the system, and the slave cylinder will not fully disengage. This will act like riding the clutch and will prematurely wear the clutch.

I'm not saying that this is your problem, but it could be.

I'm using a turbo legacy MC & slave cylinder with a WRX clutch setup without any issues. I also did get rid of the clutch damper. Have you tried bleeding the clutch again? Once you've engaged the clutch a few times, try pushing the rod on the slave cylinder back into the slave cylinder. This will help push air bubbles back into the MC.

[Alphius]

A poorly bled clutch will not cause a partial engagement problem. Period. All it could possibly do is prevent full clutch disengagement. Yes, too tight on the adjustment rod will cause a continuous "ride" of the clutch, which is why you need to leave 1-2" of pedal free play on the MC adjustment. That is the only part of the hydraulic clutch system that could cause a partial disengagement while driving. It sounds like you are good on this adjustment now, so we can rule that out. I made that mistake (and had the exact same issue) when I bled my clutch and adjusted it a couple months ago when I put the WRX disc/PP in, and did experience slipping above 15psi. With a proper freeplay adjusted into the pedal, my problem went away.

super_usdm,
Your 3 scenarios are indeed accurate as to why it may be slipping. Questions:
1. Did you re-surface the flywheel (or even scuff it up with a scotch-brite pad)? was it heat spotted or glazed (shiny) at all? If it was glazed badly, a couple thousand miles of minimal slippage should fix it up right as rain.
2. How many miles on it since the clutch job? Did you notice a bit of slippage right off the bat or has it slowly gotten worse?
3. How would you describe the slippage? Does it flare for a second then return to normal RPM/acceleration immediately? Or does it just slip higher and higher as long as you're building full boost?

[super_usdm]

Have you tried bleeding the clutch again? Once you've engaged the clutch a few times, try pushing the rod on the slave cylinder back into the slave cylinder. This will help push air bubbles back into the MC.

I've bled the clutch twice since the installation. Once (first) while there was zero freeplay on the clutch and once (second) where there was about 2 inches of freeplay. Currently I have it adjusted back to only have about 1/2 inch of freeplay. I did push on the shifter fork with my thumb and it went back freely (pushing the rod back into the slave at the same time). So, Ive ruled out the possibility of the MC not letting the clutch engage all the way. I still have the IC off so Ill push the rod back in the slave before I put it back together.

super_usdm,
Your 3 scenarios are indeed accurate as to why it may be slipping. Questions:
1. Did you re-surface the flywheel (or even scuff it up with a scotch-brite pad)? was it heat spotted or glazed (shiny) at all? If it was glazed badly, a couple thousand miles of minimal slippage should fix it up right as rain.
2. How many miles on it since the clutch job? Did you notice a bit of slippage right off the bat or has it slowly gotten worse?
3. How would you describe the slippage? Does it flare for a second then return to normal RPM/acceleration immediately? Or does it just slip higher and higher as long as you're building full boost?

1. The FW is brand new. All I did was clean the surface with brake cleaner 3-4 times before installation.
2. The clutch has < 50 miles on it. The slipping has remained the same since installation as far as I can tell. It only slips when its hot outside (~90 degrees or more) . I set up my FCD the other night while it was cooler outside and the clutch did not slip.
3. The first one. Flares up and then catches again. Nothing like before I replaced the clutch.

[Alphius]

Tip: Avoid full boost until you have at least 500 miles on the clutch. It might work better then. I ran the first 500 at 13psi before I cranked it up, and I avoided full boost or launches/shifts with boost. I only used the 13 to pass on the highway in one gear.

Now the clutch holds 18psi and can spin all 4 tires from a dead stop clutch drop launch with boost.

[super_usdm]

Thanks for all the info. I'll keep off high boost for the next few tanks. I'll try to remember to report back in a month or so to let you know if it went away.

[super_usdm]

Hey guys,

Thanks for all your advice before. Just wanted to post an update on my situation. The clutch still slips but it feels like it is getting better. First and second gear don't slip at all.. I can even chirp all 4 off the line. The car still slips occasionally in 4th and 5th. If I punch it on the freeway in 5th gear for example, right around 5 psi the clutch slips and the rpms shoot up.

It's not too bad. Ive learned to drive it without having it slip. all I can say is "you win some, you lose some". Thanks again.

Jason