New Clutch Issue
Thread Starter
Instructor
Joined: Sep 2012
Posts: 125
Likes: 5
New Clutch Issue
So Yesterday I finally got all the parts in to do my SMF flywheel conversion swap for 93 zf6 on an lt1. After spending all day getting it out and back in, when it came time to bleed the clutch after getting all the air out, the pedal was extremely stiff but could be pushed to the floor, however it felt mushy coming back up. After that no matter what gear you were in you could go to the back and rotate the tires without the engine turning over. So somehow it is now permanently disengaged. Ill list the parts I used below. Something I noticed when putting the clutch pack together is that the pressure plate arms, when torqued down all the way, were all flat across, not arched in to the front of the motor. That I thought might be a problem because it would not leave enough room for the plate to disengage. I think I might have a bent shift fork or I somehow damaged the pressure plate extending it to far.
Maybe I have a bad combination of parts, I dont know....
Spec Heavyweight Steel Single Mass Flywheel
Luk Stock c4 pressure plate
F body sprung hub clutch disc.
If anyone has any information please let me know. I am going to start tearing this thing apart soon to see why things are not working.
Maybe I have a bad combination of parts, I dont know....
Spec Heavyweight Steel Single Mass Flywheel
Luk Stock c4 pressure plate
F body sprung hub clutch disc.
If anyone has any information please let me know. I am going to start tearing this thing apart soon to see why things are not working.
Melting Slicks
Joined: Jan 2009
Posts: 3,482
Likes: 196
From: folsom california
did you install the clutch disc with the disc "hat" pointing away from the engine ?
the "stock c4" pressure plate may be wrong, pre Lt engines used a (conventional) "push" style clutch; all Lt engines / ZF trans combo's used a "pull" style clutch..they are not interchangeable/
a SMF for an LT engine / ZF trans has to be specific for that application, the more common flywheel for an F series that uses a T56 trans is thicker (by about 0.090 inch) and is not interchangeable unless it is machined thinner
the "stock c4" pressure plate may be wrong, pre Lt engines used a (conventional) "push" style clutch; all Lt engines / ZF trans combo's used a "pull" style clutch..they are not interchangeable/
a SMF for an LT engine / ZF trans has to be specific for that application, the more common flywheel for an F series that uses a T56 trans is thicker (by about 0.090 inch) and is not interchangeable unless it is machined thinner
Last edited by mtwoolford; Apr 5, 2015 at 03:07 PM.
Le Mans Master
Joined: Dec 2006
Posts: 5,139
Likes: 482
From: H-Town Texas
http://www.specclutch.com/cars/Chevy...te/1993/Single
This would be the Spec flywheel for this application. I can't be sure about the f-body disc, but it seems to me that I've heard they are interchangeable with the Vette. Though they are two different transmissions. (T56 vs ZF6).
Could have a worn pivot stud, which would explain the pedal feel, but not the wheels turning freely in gear.
Also check the release bearing. If it has a nylon sleeve, it is the wrong one for a '93 Black tag trans.
This would be the Spec flywheel for this application. I can't be sure about the f-body disc, but it seems to me that I've heard they are interchangeable with the Vette. Though they are two different transmissions. (T56 vs ZF6).
Could have a worn pivot stud, which would explain the pedal feel, but not the wheels turning freely in gear.
Also check the release bearing. If it has a nylon sleeve, it is the wrong one for a '93 Black tag trans.
Burning Brakes
Joined: Apr 2009
Posts: 1,228
Likes: 10
From: That one city...you know that one. Idaho
did you install the clutch disc with the disc "hat" pointing away from the engine ?
the "stock c4" pressure plate may be wrong, pre Lt engines used a (conventional) "push" style clutch; all Lt engines / ZF trans combo's used a "pull" style clutch..they are not interchangeable/
a SMF for an LT engine / ZF trans has to be specific for that application, the more common flywheel for an F series that uses a T56 trans is thicker (by about 0.090 inch) and is not interchangeable unless it is machined thinner
the "stock c4" pressure plate may be wrong, pre Lt engines used a (conventional) "push" style clutch; all Lt engines / ZF trans combo's used a "pull" style clutch..they are not interchangeable/
a SMF for an LT engine / ZF trans has to be specific for that application, the more common flywheel for an F series that uses a T56 trans is thicker (by about 0.090 inch) and is not interchangeable unless it is machined thinner
As for the rest of it we need the OP to tell us what parts are in use better then in the OP.
Melting Slicks
Joined: Jan 2009
Posts: 3,482
Likes: 196
From: folsom california
Admittedly my memory , on occasion, plays tricks on me, but I do remember installing my clutch disc with the "hat" pointing out, away from the engine. Sooooo I referred to the factory service manual, and while the literature made no mention of the clutch disc orientation, each illustration showed the clutch disc "hat" pointing out, away from the engine.
Le Mans Master
Joined: Dec 2006
Posts: 5,139
Likes: 482
From: H-Town Texas
Maybe we have a conflict of definition in the term 'hat'. The extended side with the srings on the srung hub will go in facing the flywheel, on the SMF set up. The FSM doesn't mention it because the Dual Mass did not have a recess to house the spring hub as there wasn't one on the ZF clutch set ups.
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Burning Brakes
Joined: Apr 2009
Posts: 1,228
Likes: 10
From: That one city...you know that one. Idaho
Admittedly my memory , on occasion, plays tricks on me, but I do remember installing my clutch disc with the "hat" pointing out, away from the engine. Sooooo I referred to the factory service manual, and while the literature made no mention of the clutch disc orientation, each illustration showed the clutch disc "hat" pointing out, away from the engine.
IF (and this is what I suspect happened) you use a SMF for a push style clutch, (no space for a sprung hub) a pull style pressure plate, and a sprung hub clutch there is no room for that sprung hub. If the hub is towards the engine it will hit the flywheel, and you wont be able to release the clutch. If the hub is towards the pressure plate it will force the throwout bearing away from the engine.
From what I get out of the OP the OP needs to buy a different flywheel, or buy an unsprung clutch disc.
Thread Starter
Instructor
Joined: Sep 2012
Posts: 125
Likes: 5
Im sorry everyone for taking so long to get back here on the forums, I have been really busy and I had to go home for a few weeks so Ive been away. However I finally got back around to messing with the car and now know what is going on. Anyway I am using the SPEC SC05S2 Flywheel with an Fbody same year disc and Stock pressure plate. Now I removed the transmission again to check the hydraulics and everything was working like it was supposed to so I put the transmission back in after bleeding it extensively. As it turns out the clutch throwout bearing is binding on the tranmission input shaft... It travels up the shaft then seizes and the only way to get it to return to the engaged position is to pry the transmission out. I dont know why this would be any different than the old throwout bearing but it is. And it has to be maybe just a few hundreths to small. I tried sanding it out but it still binds. I guess Ill have to find a new one.
Melting Slicks
Joined: Jan 2009
Posts: 3,482
Likes: 196
From: folsom california
Im sorry everyone for taking so long to get back here on the forums, I have been really busy and I had to go home for a few weeks so Ive been away. However I finally got back around to messing with the car and now know what is going on. Anyway I am using the SPEC SC05S2 Flywheel with an Fbody same year disc and Stock pressure plate. Now I removed the transmission again to check the hydraulics and everything was working like it was supposed to so I put the transmission back in after bleeding it extensively. As it turns out the clutch throwout bearing is binding on the tranmission input shaft... It travels up the shaft then seizes and the only way to get it to return to the engaged position is to pry the transmission out. I dont know why this would be any different than the old throwout bearing but it is. And it has to be maybe just a few hundreths to small. I tried sanding it out but it still binds. I guess Ill have to find a new one.
Now your throw out bearing issue, early style "black tag" trannies used a throwout bearing with a larger I.D.; later "blue tag" trannies used ones with a smaller I.D.; blue tag throwout bearings will usually have a nylon collar inserted into the throw out bearing's inside diameter to make up the difference; check and make sure you got the right throwout bearing for your 93.
Thread Starter
Instructor
Joined: Sep 2012
Posts: 125
Likes: 5
If you're mixing and matching ZF parts and F body parts, it's a gamble, yes, people have done it, but the ZF transmission and the T56 used in F bodies required different clutch set ups. As I recall..and we all know what that means, back in the day some F body flywheels were modified for use in vettes by cutting 0.090 inch off the flywheel surface.
Now your throw out bearing issue, early style "black tag" trannies used a throwout bearing with a larger I.D.; later "blue tag" trannies used ones with a smaller I.D.; blue tag throwout bearings will usually have a nylon collar inserted into the throw out bearing's inside diameter to make up the difference; check and make sure you got the right throwout bearing for your 93.
Now your throw out bearing issue, early style "black tag" trannies used a throwout bearing with a larger I.D.; later "blue tag" trannies used ones with a smaller I.D.; blue tag throwout bearings will usually have a nylon collar inserted into the throw out bearing's inside diameter to make up the difference; check and make sure you got the right throwout bearing for your 93.
Thanks for the input. I double checked I do have the right bearing for my ZF. Its a black tag That came from I think an 89 that I swapped in my car. After I removed the transmission and pressure plate again, I test fit the T.O.B. on the input shaft. Turns out it was tighter than Mr. Scrooge's purse strings. After looking inside the bearing there appeared to be a machining defect, there was a lip on the front edge of the bearing. So I took a 1 in socket wrapped in 80- grit sand paper and filed the lip down. I touched it up with some higher grit paper for smoothness and also sanded the input shaft smooth, not that it wasn't already. I just didn't want any hiccups. So I finally got it all back together and it is smooth as butter with no binding or sticking of any sort. Thanks for everyone's help in the matter.
