Symptoms of a bad clutch slave?

[Jon K]

I am leaking brake fluid from somewhere toward the transmission, I believe. I have noticed that my clutch is either slipping or something else is up - but basically I will floor the car in 5th and boost will start to build, and then, nothing. Like, the revs don't go up and the car isn't going any faster. I checked for boost leaks and it seems too coincidental that I am leaking brake fluid and now I have issues with the car going.

Could the clutch not be fully engaging? I have a 6 puck clutch and it is usually pretty chunky when trying to slip it. Now, however, it feels very stock like and I don't get that jitter when starting from a stop no matter how much I slip it (puck clutches don't like being slipped). Additionally, it seems like I can change gears with only putting the clutch in about 1" or 1.5" from the top. It's almost like the clutch isn't coming back out all the way though the pedal feels normal!

Any help?

[winfred]

the hydraulics usually won't mess with the engagement of the clutch unless they are for some reason jambed (very rare) or puked fluid on the clutch, if it's leaking id definetly change the slave

[infurno]

When my slave went bad, the peddle sank to the floor and would not rise. I didnt experience your symptoms

[Turbo Ready]

Jon, thats a tough one. If the clutch was not engaging, you will be building revs and the car would barely move, but you said that you were not building revs which is strange.

Not building revs under boost sounds like an engine issue. If on the other hand the clutch was not releasing, you won't be able to start it, it would be like starting in gear, the car will launch forward while you crank the starter.

What I would do if I were you is to start the car in neutral, depress the clutch, put it in first gear and slowly release the clutch pedal to see where the clutch "bites."
This will tell you where the clutch engages with reference to pedal travel.

Second test would be to repeat above except depressing the clutch pedal just above engagement, hold it there for 30 seconds at that same spot. By doing so you are checking to see if the slave or master cylinder is leaking, if they are leaking, the pressure would drop and the clutch will engage, the car will move.

[Jon K]

the hydraulics usually won't mess with the engagement of the clutch unless they are for some reason jambed (very rare) or puked fluid on the clutch, if it's leaking id definetly change the slave

Yeah its weird the car just doesn't seem to pull right. I am going to datalog on my drive up to the garage to see what's leaking tomorrow. I am getting really frustrated with **** lately.

Winfred if the slave is leaking could it have air in it? And what would air do to the setup? I can picture if air got in it it would not let the fluid back up the line, and that could sort of hold the clutch in somewhat?

[Jon K]

Jon, thats a tough one. If the clutch was not engaging, you will be building revs and the car would barely move, but you said that you were not building revs which is strange.

Not building revs under boost sounds like an engine issue. If on the other hand the clutch was not releasing, you won't be able to start it, it would be like starting in gear, the car will launch forward while you crank the starter.

What I would do if I were you is to start the car in neutral, depress the clutch, put it in first gear and slowly release the clutch pedal to see where the clutch "bites."
This will tell you where the clutch engages with reference to pedal travel.

Second test would be to repeat above except depressing the clutch pedal just above engagement, hold it there for 30 seconds at that same spot. By doing so you are checking to see if the slave or master cylinder is leaking, if they are leaking, the pressure would drop and the clutch will engage, the car will move.

Yeah the car will start just fine without catching gear. It almost seems as though if I drive it for a while it gets weird. I can't imagine the engine having issues - I will check the turbo tomorrow when it's not raining. I will probably order a new slave cylinder on monday and do that one day this week or next weekend. I am going to try to the clutch above engagement point and see if its leaking if it catches.

The 6 puck used to be real grabby/jerky, and now it's not so. I hadn't driven the car for a couple weeks almost so maybe the slave was leaking and letting it sit it go air in it and now I am having issues? Dunno.

[Jon K]

Also what brand slave cyl should I get?



Fahrzeug Technik Ebern (FTE)-FAG
Clutch Slave Cylinder
1 per car.

$58.19


or




Febi-Bilstein (Alternate Brand)
Clutch Slave Cylinder
1 per car.


$42.96

[winfred]

air would reduce the travel of the piston not hold it out further, air in your brakes doesn't cause them to lock up, same type of system

[winfred]

flip a coin either should work fine, i don't think either are made from plastic, yet, fag is oem but i can't remember getting a bad bilstein


Also what brand slave cyl should I get?



Fahrzeug Technik Ebern (FTE)-FAG
Clutch Slave Cylinder
1 per car.

$58.19


or




Febi-Bilstein (Alternate Brand)
Clutch Slave Cylinder
1 per car.


$42.96

[Turbo Ready]

If the slave was leaking, you might find the pedal softer than usual. Why your 6 puck is not as sharp as it used to be is tough to figure out. If a car is left parked for a while rotors will rust quickly, not too sure if the same moisture and condensation will cause your pressure plate or flywheel to do the same.

Another almost impossible cause, brake fluid getting into the clutch assembly, but as I said, that would be very unlikely.

[Jon K]

Actually wow brake fluid on the clutch... that might make sense. The clutch seems to be pretty not grippy all things considered.

Winfred/Turbo is it possible for brake fluid to get on the clutch?


Wow now that I think about it...


the drops on the pavement were about 3" or so apart right from the area around the trans I think. The trans has those two bolt holes in the trans there... maybe it dripped out of the bell housing? Holy turds I hope not.

[Turbo Ready]

Actually wow brake fluid on the clutch... that might make sense. The clutch seems to be pretty not grippy all things considered.

Winfred/Turbo is it possible for brake fluid to get on the clutch?

If it did you might get a strong odor. The way the slave is mounted to the tranny it's almost impossible for it to do so unless there is a pin hole leak and it's spraying onto the clutch, but at that rate you will be loosing a lot of fluid.

Best thing to do is to pull the slave, watch the line.

[Jon K]

Watch the line?

[Turbo Ready]

Watch the line?

Ya, the brake fluid line going to the slave, they don't take too much abuse. I would soak it first with WD 40 or similar and then crack it open with a line wrench before loosening the slave cylinder.

[Jon K]

i might order the UUC stainless line just cuz.

[Turbo Ready]

i might order the UUC stainless line just cuz.

Nice, take pics please.

BTW, just went into my garage to look at a gearbox and the possibility of fluid getting onto the clutch, it's next to impossible.

You could still be loosing fluid at the front end of the slave at the plunger, which will get into the bell housing which will then drip to the ground.

I have seen cases where oil from the back end seal got onto the clutch, but IIRC you rebuilt the engine in the car and would have changed the seal.

[Jon K]

This engine is NOT rebuilt this is 200k mile stocker still. I really don't want to have to take the trans out again that **** is not cool.

[Turbo Ready]

This engine is NOT rebuilt this is 200k mile stocker still. I really don't want to have to take the trans out again that **** is not cool.

Oh oh. Don't worry too much about dropping the tranny, just pull the slave and see if there is anything wrong with it.

[Jon K]

Ok car is on the lift - the slave itself doesnt look very wet. However, there was blue brake fluid (ATE super blue) forming a droplet right where the trans meets the oil pan...

the clutch is slipping in 5th gear pretty noticably. Soo... i haven't pulled the slave yet, but yeah..

[Jon K]

Oh also, there is some blue brake fluid on the external of the slave. I wrapped a paper towel around it and saw blueish. ****.

[Ferret]

Oh also, there is some blue brake fluid on the external of the slave. I wrapped a paper towel around it and saw blueish. ****.

Busted seal up the front of the slave spraying fluid onto the clutch?
If you've got that crap on your clutch disc, you're kinda buggered iirc because it soaks into the material if its standard clutch material?

If it's slipping, either the slave is locked in an extended position, or you've got fluid in there from somewhere...

[Jon K]

I will order a new slave, and i think i will just slip the **** out of the clutch to burn the **** off.

http://clutchnet.com/photos/6button_solid01.jpg

"The solid hub metallic button discs are capable of withstanding the highest possible loads that can be transmitted through a disc of its size."

So its a metallic ceramic puck. I bet I can just roast the crap off once i get it to stop leaking.

[Ferret]

I will order a new slave, and i think i will just slip the **** out of the clutch to burn the **** off.

<snip>

"The solid hub metallic button discs are capable of withstanding the highest possible loads that can be transmitted through a disc of its size."

So its a metallic ceramic puck. I bet I can just roast the crap off once i get it to stop leaking.

Niiiiiiiice, just make sure you dont weld the pucks to the flywheel :P

[Jon K]

I still don't get how the fluid is getting in the trans bell housing

[Barney Paull-Edwards]

Rear crank seal I`me afraid,crankcase breather a bit shitty allowing pressure to build, gotta go somewhere.Never used a six puck plate but a four puck that is smooth has fluid on it,should be grabby, not designed to be gentle but bite hard.Believe it or not, one car in my shed has a pipe witha washer nozzle on the inside, pointing at the clutch, if the plate got oil on it a little pump sprayed coka-cola on it to dissolve the oil, old Lancia trick copied by many! Always wondered why they had a connection from the roll-cage to the injectors?????? Might account for 640hp from a 2 litre.

[Jon K]

Its not the rear seal. The rear seal does not leak brake fluid

[Jon K]

I popped the slave off. Its the slave shaft! I threw a paper towel around it... its blue. ****ing piece of crap.

[Ferret]

I popped the slave off. Its the slave shaft! I threw a paper towel around it... its blue. ****ing piece of crap.

Must be spraying **** past its front seal under pressure - lovely!

[Jon K]

Yeah figures right? I want to punch the slave cylinder in the face.

I am going to order a FAG *ha* slave cylinder and the UUC E34 stainless steel clutch line. I will spray brake cleaner up in the bell housing to try and get some of that crap to wash down.

[bahnstormer]

pics?

[Barney Paull-Edwards]

Try the coke method, it clears crap off the plate a treat but does not contaminate it.

[Jon K]

pics?

pics of?

[winfred]

we just did a tranny in kyles tcd turbo'd 535 and the rear main was puking all over the puck clutch, degreased it and scuffed the carbon off the buttons with a rolllock, t'was good ta go and hooking up like it's supposed to


I will order a new slave, and i think i will just slip the **** out of the clutch to burn the **** off.

http://clutchnet.com/photos/6button_solid01.jpg

"The solid hub metallic button discs are capable of withstanding the highest possible loads that can be transmitted through a disc of its size."

So its a metallic ceramic puck. I bet I can just roast the crap off once i get it to stop leaking.

[Jon K]

Thats the beauty of ceramic puck clutches.

In fact, tonight on the way home I was just pissed so I floored it in 4th and built boost and watched the tach slip upward. After about 1 second of slipping, then a baby momentary slip again, the clutch cleared up and pulled hard.

[Turbo Ready]

Jon, I was out all day today just reading the thread.

So it was the brake fluid spraying onto the clutch as I thought. You are a lucky guy, I have hardly ever seen them do that :D

Guess it was spraying onto the clutch, knew it was possible but very rarely happens.

Have fun pulling the tranny :p

[Jon K]

Jon, I was out all day today just reading the thread.

So it was the brake fluid spraying onto the clutch as I thought. You are a lucky guy, I have hardly ever seen them do that :D

Guess it was spraying onto the clutch, knew it was possible but very rarely happens.

Have fun pulling the tranny :p

That shouldn't be necessary. The ceramic pucks don't absorb the fluid like an organic. I was able to do a 4th gear pull with slip at 5,000 rpm, but after maybe 1 full second of slip, the fluid must have momentarily burned off and i was pulling to redline full-force. Once I get a new slave cylinder, I'll be able to burn the fluid off the clutch combined with spraying brake clean up in the housing. If it doesn't resolve itself, which I am very convinced it will, I will just wait until I have the motor out in a month or so and drop another $120 6 puck (maybe 4 puck) disc in.

[Turbo Ready]

That shouldn't be necessary. The ceramic pucks don't absorb the fluid like an organic. I was able to do a 4th gear pull with slip at 5,000 rpm, but after maybe 1 full second of slip, the fluid must have momentarily burned off and i was pulling to redline full-force. Once I get a new slave cylinder, I'll be able to burn the fluid off the clutch combined with spraying brake clean up in the housing. If it doesn't resolve itself, which I am very convinced it will, I will just wait until I have the motor out in a month or so and drop another $120 6 puck (maybe 4 puck) disc in.

Oh you have a ceramic 6 puck clutch, I was just read your reply about seeing the cylinder spewing fluid onto the clutch. Wow nice that you were able to burn it off and get the car pulling all strong again :D

Seeing that you are using this clutch, what's your impression? I have to make a decision sometime soon as to which direction to go regarding this. I have the much sought after lighter flywheel from an e28 for my e34 m30 b35 engine and do not want to wear the flywheel prematurely.

I will be turbocharging the e30 once I get the m30 broken in and running well NA before going FI. I will be concerned about both clutch bite and at the same time longevity of the flywheel. I know one compromises the other, but need your input.

Thanks.

[Jon K]

Oh you have a ceramic 6 puck clutch, I was just read your reply about seeing the cylinder spewing fluid onto the clutch. Wow nice that you were able to burn it off and get the car pulling all strong again :D

Seeing that you are using this clutch, what's your impression? I have to make a decision sometime soon as to which direction to go regarding this. I have the much sought after lighter flywheel from an e28 for my e34 m30 b35 engine and do not want to wear the flywheel prematurely.

I will be turbocharging the e30 once I get the m30 broken in and running well NA before going FI. I will be concerned about both clutch bite and at the same time longevity of the flywheel. I know one compromises the other, but need your input.

Thanks.

Flywheel should be ok. The clutch is great in terms of price and function. Its a little jolty (when brake fluid isn't all over it) due to my choice of unsprung and 6 puck. But, it grabs positively - supposed to be good for over 650 ft lb of torque with the "3x" pressure plate - its a bit on/off but I am used to that in all the cars I drive.

I wouldn't worry about the flywheel honestly.

[Turbo Ready]

Flywheel should be ok. The clutch is great in terms of price and function. Its a little jolty (when brake fluid isn't all over it) due to my choice of unsprung and 6 puck. But, it grabs positively - supposed to be good for over 650 ft lb of torque with the "3x" pressure plate - its a bit on/off but I am used to that in all the cars I drive.

I wouldn't worry about the flywheel honestly.


Thanks for the input Jon, I will definitely look at this clutch. I can understand the on/off feel, how but does it affect launching from standing still? More prone to stalling? Guess you have to keep the revs up a lil bit higher from that of an OEM clutch to launch.

Whose clutch kit is that BTW?

Thanks

[Ross]

I will order a new slave, and i think i will just slip the **** out of the clutch to burn the **** off.

http://clutchnet.com/photos/6button_solid01.jpg

"The solid hub metallic button discs are capable of withstanding the highest possible loads that can be transmitted through a disc of its size."

So its a metallic ceramic puck. I bet I can just roast the crap off once i get it to stop leaking.
You know better than to do that don't you? Just wash it down with solvent/brakleen if it's oily.

[attack eagle]

I'm glad you found it was the slave... spray it with brake klen jon, don't roastit off. That will just leave residue on it.

With out two people it can be real pain to diagnose clutch hydraulics, but at least you know what it is now and it is easy to resolve.

[Jon K]

Yeah I will spray brake kleen up in the trans housing to see if I can wash as much crap as I can out of there. If slipping it/spraying it doesn't work (which I doubt) I will be taking the motor and transmission out over the winter anyway.

[Ross]

Creamic clutch shouldn't absorb the oil. Slipping and heating it wont do it much good

[Jon K]

Creamic clutch shouldn't absorb the oil. Slipping and heating it wont do it much good

its that it's on the flywheel surface I am sure. When I drive the car, if I floor it and build boost and just stay in the throttle even after it start to slip, a second of slipping occurs and then the flywheel hooks the clutch up and I accelerate. Then, when I press the clutch again, I bet its spraying fluid back on the surface :)

I think all the fluid in there will leave the disc due to velocity of spin, and what is left on the flywheel I can burn off with friction/heat. I can smell the crap for a few seconds after the above process

[Turbo Ready]

its that it's on the flywheel surface I am sure. When I drive the car, if I floor it and build boost and just stay in the throttle even after it start to slip, a second of slipping occurs and then the flywheel hooks the clutch up and I accelerate. Then, when I press the clutch again, I bet its spraying fluid back on the surface :)

I think all the fluid in there will leave the disc due to velocity of spin, and what is left on the flywheel I can burn off with friction/heat. I can smell the crap for a few seconds after the above process

Jon, had a few questions in my previous post to you.

Thanks :D

[Jon K]

Thanks for the input Jon, I will definitely look at this clutch. I can understand the on/off feel, how but does it affect launching from standing still? More prone to stalling? Guess you have to keep the revs up a lil bit higher from that of an OEM clutch to launch.

Whose clutch kit is that BTW?

Thanks

The pressure plate makes it such that its got a very limited area of "working". So, yeah if someone hopped in and tried to drive off it might be a little stall-happy. But, if you get the revs up to like 1500 - 1800 rpm and slip it as best you can (you get about two thunks of the pucks hitting before you have to be moving, else it just thunk thunk thunk thunks itself and it just sounds real nasty) you can get a nice take off from a traffic light without looking like an idiot. If actually launching, I use the anti-lag function of my ECU from 4800 RPM and let the clutch out at a semi slow fashion and keep my toes on the clutch at the very top of the pedal range to modulate it a little bit. It's still pretty hard to get just right. Eventually I want to have enough tire on the back to just let the pedal out at an even speed and not spin the wheels.

[Turbo Ready]

Sounds great Jon, realized that it has a very short engagement duration. Since it bites the pressure plate so quickly and with almost instant grip it will be tough not to leave lots of rubber when launching agressively.

I will be tracking my car often so this might be an issue when launching. On the flip side, you can make up the time between shifts if you did do a moderate off line launch.

Thanks for the feedback. Keep up updated with your progress :)