99 Forester clutch issues

[DQ81]

my 99 forester has the pull type clutch. It's a EDM Turbo S.

 

Replaced pressure plate, TOB and friciton disc.

 

Since then strange clutch behaviour.

 

Fork seems to move back and forth very freely and after having "rested" clutch travel in the pedal is normal and engagement etc too. After a few shifts it bites lower and lower. If I push to high RPM it seems to speed this process up. Untill the pedal gets stuck. I can pull it back up and it eventually becomes usable but it's obviously not right.

 

I did notice that the play the TOB has in the pressure plate is about 1cm or more. Seems excessive. No spring to it either which as a result means my fork doesn't push towards the firewall as I'd expect.

 

The old pressure plate and TOB have the same play so I though nothing of it untill now have issues. 

 

Fluids been flushed and bled as precaution. No change. By the looks of it with the IC off the slave simply can't engage the fork enough to pull the clutch to disengage, although the first few times it does. What gives? Is my TOB popping in and out of the pressure plate? Or has my bone dry otherwise never problem having slave gone bad?

 

Going crazy on this. need this thing for daily driving. Insight is apreceated.

 

cheers

[golucky66]

If you keep moderate pressure (not enough to actually press it to the floor) on the clutch pedal and it sinks to the floor then you need a clutch master cylinder. Might explain why the pedal keeps getting lower and lower as you drive.

[DQ81]

If you keep moderate pressure (not enough to actually press it to the floor) on the clutch pedal and it sinks to the floor then you need a clutch master cylinder. Might explain why the pedal keeps getting lower and lower as you drive.

That's a good idea. I don't wanna just throw parts at it. Though if it sinks it could be a bad master or slave... loss of pressure.

 

When it gets caught it seems to get caught on the pivot point that the pedal is mounted to. I don't think it's the mc. It would be very coincidental. but stranger things have happened.

 

who has done a pull type clutch recently and had the bearing in and observed back and forth play? or on the fork once installed, or would like to have a look under the hood of their car for me? I've got a good half inch/1.5cm of play. I'm wondering if that is correct, although there is no obvious link between that being off and my clutch's behaviour. It all point to hydraulics

 

ideas?

[Fairtax4me]

Have you pulled the rubber dust boot off of either cylinder to check for fluid? Fluid inside the boot means the cylinder is bad.

 

It's also somewhat common for the rubber hose(s) to degrade internally and will prevent fluid from exiting the slave cylinder properly.

 

There will always be some play in the release fork/TOB mechanism. That's nothing to worry about.

[DQ81]

If you keep moderate pressure (not enough to actually press it to the floor) on the clutch pedal and it sinks to the floor then you need a clutch master cylinder. Might explain why the pedal keeps getting lower and lower as you drive.

 

I make the clutch "misbehave" on demand now. High RPM shifts basically.

 

I performed this test today before driving, after letting the car sit for a while and after some harder driving. No sinking so I guess my MC is ok. Once the clutch gets stuck after harder driving it requires pulling the pedal back up 3 to 5 times in order to pump it and it to regain enough pressure to pop back up by itself. 

 

Have you pulled the rubber dust boot off of either cylinder to check for fluid? Fluid inside the boot means the cylinder is bad.

 

It's also somewhat common for the rubber hose(s) to degrade internally and will prevent fluid from exiting the slave cylinder properly.

 

There will always be some play in the release fork/TOB mechanism. That's nothing to worry about.

 

I have pulled the dust boot off, one of the first things I did when reinstalling the slave, did again when master and slave were flushed yesterday. Dry. I can compres the slave by hand and there is no feeling of fluid along the wall of it, seems to seal well.

 

It's good to finally get an answer on the fork/TOB mechanism and it's play. Searched the internet far and wide without much result.

 

The rubber hose is a good call. I'll see if I can find one tomorrow. I had an '80 Chevy Blazer once that had sat for so long the hoses on the front brakes functioned as a one way valve, pump the pedal once and on they went, wouldn't let go though. 

 

The thing that gets under my skin most and baffles me most is that it is RPM related. At the least made worse by high RPM. If I drive like a granny the bite point drops a little but is pretty much ok, it varies more than it should be the pedal pops back up every time without fail and though the pedal effort is a bit heavy it's a functioning clutch. As SOON as I go up in RPM, wether at WOT or part throttle building up very slowly to it, the bite point starts to drop. If I build RPM slowly and shift it's not as bad but after 2 shifts this way the pedal stays dropped. 1 hard pull at WOT is enough to make it drop otherwise.

 

Once I've done this "test" the bite point is at the firewal or sometimes I can't shift anymore. I can regain some clutch actuation by pulling the pedal up, push in, pull up, push in until it pops up on it's own again, usually about 5 times and then pump it a few more and it won't be back to "normal" but the car can be driven. Take it easy and it slowly comes back to normalish as described above. 

 

I live in the city and it's all stop and go traffic most of the time. Clutch needs to work and well. Plus, it's pretty hard not do WOT pulls in 1st and 2nd when it's safe out of bordem. 

 

Anyone have a theory on the relation of RPM. So far I've heard or considerd: crankshaft play fore/aft, which to me seems pretty rediculous. The idea being that at higher RPM the crank would move and cause a deeper clutch which just doesn't compute to me.

 

I've also had it proposed to me that the slave/MC either internally leaking or having air trapped will cause my issue at higher RPM due to vibration of the drivetrain agitating whatever is causing the problem ie. air or internal seal leaks. Again, to me not so plausible.

 

I have my own theory (or hope as the fix would be the simplest).

 

That at higher RPM the fork needs more pressure to release the bearing which normally wouldn't be felt or noticed at a high rpm/WOT shift by the driver because of quicker more spirited shifting and hydraulics doing what they do when they function well, amplifying applied pressure. So that as a result at higher RPM my bite point becomes deeper because there is more pressure to overcome. Any takers? lol

 

Something else occured to me just now, my fork has no spring holding it in place (pulling it towards the radiator). The play in the fork that is normal could be deleted as pressure plate is spun faster at higher RPM thus making the distance between the pin on the slave and the clutch fork farther and moving the point at which the clutch engages/disengages....

 

Any takers on that one?

 

Most importantly: what to do with my RPM related clutch drop and pressure loss....

Edited October 28, 2016 by DQ81

[forester2002s]

Clutch-fork broken/cracked?

 

Have said that, I can't think of a scenario when high RPM or WOT would make a difference to clutch feel/performance.

[DQ81]

Clutch-fork broken/cracked?

 

Have said that, I can't think of a scenario when high RPM or WOT would make a difference to clutch feel/performance.

Cluthc fork broken etc. would yield same problems all the time, just like about every other thing you could imagine clutch related. Fork is cast piece, not the stamped one, it's in very good shape. it makes no sense. I'm clutching at straws. But its 100 procent true. It's RPM influenced if not caused and baffling.

 

I wish I could film the "pedal feel". I'll try and get something on video that makes sense if I can. Untill then... Beuller?

Edited October 28, 2016 by DQ81

[Fairtax4me]

Best reason I can think that it would change at higher rpm is that you may be engaging and releasing the clutch faster. Quicker pedal movement means higher pressure moving through the system. A quicker release may be causing debris to block the return flow of fluid? Just a wild guess.

[DQ81]

Took that into account and pulled slowly to high rpm and very slowly and deliberately depressed clutch.

 

Makes no difference.

 

The RPM symotom is best explained as if the result of high revs is as if it's revs suck the clutch pedal down. Rev it up, then depress the clutch and the hydraulic resistance has shifted considerably towards the firewall. Deeper bite point iow.

 

It has me baffled and frustrated.