Sticky clutch after heavy braking

[BSOD2600]

Lately I've noticed that right after heaving braking, when I depress the clutch, it's sticky. It doesn't feel 'normal' and some times slowly comes back to the normal position. Some times, it'll stick to the floor. Under normal driving, the clutch pedal never is a problem.

I've already bleed it a few months ago and still has plenty of fluid. New clutch slave cylinder and OEM spring back in Aug 2007.

Anyone experience this type of thing before?

[Legacy777]

I don't see how heavy braking has much effect on the clutch pedal. Are you holding in the clutch while braking?

[BSOD2600]

Part of the braking sequence, I am. Mostly, ride the brake hard, then when I notice the RPMs around 1.5K, I'll depress the clutch. This is the point when I notice it feels looser than normal and/or it's slow/sticky to return back to normal.

[log1call]

Do the two pedals share a pivot? Could that be moving/binding?

[94EJ22T]

i've had this same problem on my 94 turbo for over five years. Last August I installed a new clutch master and slave cylinder. this helped the problem slightly but it still happens. if anyone uncovers the mystery of the sticky clutch pedal please let me know.

[BSOD2600]

Yea, this problem still happens and is getting annoying. Took the Denny way exit #166 off I-5 in Seattle. Bottom of this short off-ramp there is a stoplight. Went on the brakes hard, near the end depressed the [soft] clutch to get out of gear and it was sticky/slow to pop back. After a few pumps, all was well again.

[JDMSLIK]

I got this same problem going on with mine too, except more so when I'm flooring the gas. It doesn't feel like a weak cup in the master nor a leaking slave so I'm wonder if it's possibly a weak return spring in the master or on the pedal mechanism.

I'm a tech here at the subaru dealership in Prince George. I brought the issue up with my boss and he remembers a couple of these complaints and he ended up replacing the bushings on the shaft of the pedal mechanism.

I just got the car on the road this last weekend so I haven't had time, but does anybody know if all 3 pedals share the same shaft for the pedals?

[BSOD2600]

Another example of this happening the other day...

Emergency braking on dry pavement, ABS goes off, etc. After I get rolling again, the clutch pedal is only coming half way back up, but I can shift ok. I make several shifts this way, then lift the pedal with my toe and it comes all the way up. Pump it a few times and all feels ok again.

Do I need to replace the spring which the clutch pedal itself uses to push itself back to the disengaged position? 36037AA130 (Pedal Return Spring) and 36037AA140 (Assist Spring B) ?

[BSOD2600]

Fixed!

I had this same damn problem on the '94 SS I bought several months ago, except it was a LOT worse. Any stop I would come to on a downwards sloping hill, the next time I would depress the clutch, pedal would only be half-way. Would take a few pumps to get back to normal. Yes, I had bleed the clutch several times but it never helped. Also, only after a few weeks of driving, the new clutch fluid was black.

Decided instead of buying a whole new master cylinder, I'd just replace the parts which actually need replacing. Also installed a newish slave cylinder (from the TW). Got a clutch repair kit - 37240AA000 for $44.


I had an extra master cylinder laying around, so I took that apart first, installed the new repair kit, installed it on the SS, and then took the SS old cylinder apart.

Old cylinder is obviously leaking


Once the plunger and spring clip are removed.


New vs old internals


Old TW vs old SS internals



After getting everything put back together again, I bled the clutch with the help of a friend. After a bit, the stream was coming out clear, yet the damn clutch pedal wasn't returning all the way to the top like it should. The last ~2" of travel, it was sort of 'sticky', weak and didn't want to come up. After more fruitless bleeding, I started to play around with the adjustment nut on the master cylinder rod. Bingo! Screwed it out several more turns and suddenly the pedal is nice and tight and comes up all the way like it should. I've been driving around town for the past few days and no longer have my soggy pedal anymore, as I originally described in my first/other posts.

[Soul Shinobi]

Still makes me wonder just how it got that way. The pedals sharing a pivot is likely relevant, but maybe flexing of the firewall is related? Just brainstorming here.

[BSOD2600]

My guess after taking the master cylinder apart, is those two rubber seals / flanges have gotten weak over time. Fluid must be passing past them (which makes sense why it got so black so quickly after changing the fluid). If fluid is getting past, air must also be getting in/out from the poor seal. Not entirely sure how all the mechanics would work (software engineer, not mechanical ) to explain how/why things get soft during deacceleration though.

[Kecksauce]

You are the friggin' man.



Time to order parts!

[skoobywrx]

i did a full master cylinder replacement and still sometimes get a sticky clutch when hard braking. makes me concerned, if i ever want to autox this car.....

i removed the slave cylinder as someone suggested i do, and just run the master cylinder. is this ok?

[Legacy777]

How can you just run the master cylinder???

[skoobywrx]

doh i mean, run without the damper, lol....

without the damper and a new slave, it still sticks..
need a new master cylinder?

[93Leg-c]

TW vs old SS internals

The TW internals is the one on top and ss on the bottom, right? Is it just the spring that's different or were there any other differences? When driving do you notice any difference between the TW and ss clutches?

[BSOD2600]

They are the same part number. I took that pic simply to compare how much each of the old parts were worn down. The spring looks different because the shaft on the bottom one came out and the spring is not compressed as much.

Since replacing the internals, I haven't had my original problem at all.

[93Leg-c]

Gotcha! Thanks!

[Japanac]

Looks like I have exactly the same problem.... tnx a lot for this post will post update when I get it replaced

[georryan]

If the problem persists, check out a new pedal assembly. I've had intermittent clutch issues for a while now. I've completely bleed the clutch, changed out the master cylinder and the slave cylinder (multiple times). I even got rid of the secondary bleed point to make the system simpler. I always made it better but not perfect. Last night I changed out the pedal assembly and the clutch feels brand new, and better than it ever has.

My problem was the clutched worked fine, but under heavy acceleration, sometimes it would feel like I didn't fully disengage the clutch. Also, like you, it wouldn't always come all the way up, but I felt that was more of a spring issue than an "air - in - the - lines" issue. Turns out I was right. I don't know what the problem was exactly, only that the design of the two pedal assemblies was different. My old one had a nut on the end of the rod that rotates for adjustment or something, and it was a major pita to replace.

Anyways YMMV, but hopefully you've figured it out.

[93Leg-c]

georryan, was the replacement pedal assembly from the same year and model or from something different?

[georryan]

I'm not sure what year it came out of. I have a 91 and and it came out of some legacy I'm pretty certain. I ordered it from blackbart here on the board.

It was a little different in that it was missing a brace that went along the firewall from the brake cylinder portion to the clutch cylinder portion. Although, not having that made it a heck of a lot easier to put back in the car.

[LikeUCare]

Has anyone figured out for sure what is causing this? I have the same issue with a brand new master/slave cylinder installed.

Under hard braking the clutch pedal doesn't want to come back up all the way. I have played with the adjust on the master cylinder pushrod under the dash but that doesn't really help much. Before and after the clutch master/slave cylinder install the symptoms are the same.

This seems to be a common issue with this platform, below post has same presentation. Anyone actually find a root cause for this? Is is the bushings or springs in the pedal assembly?

http://bbs.legacycentral.org/viewtopic. ... 9&start=25

Thanks in advance for the assist, this is an annoying symptom on my daily driven 94SS with 5-speed.

[Alphius]

I have the same issue with a newish master/slave as well on my 94SS. Only occurs under extreme emergency braking, almost enough to activate the ABS on dry pavement. After such an emergency stop, the clutch pedal only has about half travel but one or two pumps brings it back to correct operation.

I too remain puzzled by this, but I have a couple suspicions. None of them are too easy to test though.

The other interesting thing is that I own BSOD2600's car now, and he claims the problem was fixed up above. Maybe it is that seal he talks of and it's starting to wear out again? My other suspicion is that since my car has a cut clutch reservoir to fit under the intercooler, that possibly under hard deaccell I get some air intrusion in the master and it gets soft for a second. This is what it feels like to me.

[LikeUCare]

Interesting, I have a cut clutch reservoir to accommodate the 06-07 WRX intercooler. I never thought about that potential. It does seem if I brake harder on a downhill that it is worse.

I am going to try to overfill the reservoir to see if that makes a difference one way or the other.