Dropped the ZF today and discovered problem. Yet i still can't get it fixed HELP
07-24-2011, 12:43 PM
#21
Le Mans Master
Are all of the parts, except for the flywheel, disc, pressure plate and throwout bearing, the original parts?
Is this a magnesium bellhousing, or aluminum? If it's the magnesium piece, you did remember to reinstall the anti-galvanic spacer between the bellhousing and engine block, right?
Live well,
SJW
Is this a magnesium bellhousing, or aluminum? If it's the magnesium piece, you did remember to reinstall the anti-galvanic spacer between the bellhousing and engine block, right?
Live well,
SJW
07-24-2011, 01:27 PM
#22
Le Mans Master
Member Since: Oct 2007
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2023 C5 of the Year Finalist - Modified
2022 C5 of the Year Finalist - Modified
St. Jude Donor '09-'10-'11
Wow! After seeing several threads with this same issue, I will never buy a SPEC clutch in my life. Ill be putting a Quarter Master in mine. 
07-24-2011, 01:32 PM
#23
Race Director
Caleb, after reading all this, I think it's time for a 4L60E. 
07-24-2011, 01:38 PM
#24
07-24-2011, 01:52 PM
#25
Race Director
Willie
07-24-2011, 02:12 PM
#26
If I was still in my 20's I would not listen to anyone like us in our 40's 100% of the time.
Caleb may have a real time keeping up shifting with TPI Jim's longblock motor being installed.
Time will tell.
Its good to have "Young Blood" back in the C4 hobby building & going racing once again here on C4.
When old timer's like on us are gone,
Caleb will carry the Torch on....... March on leading the way.
Brian
07-24-2011, 03:12 PM
#27
Le Mans Master
Looks like one major headache and so close to ready to drive. I do not look forward to my turn with these manual transmission teething problems.
07-24-2011, 03:36 PM
#28
Team Owner
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St. Jude Donor '05
autos overalll are the way to go for drag racing but rowing gears with some real power behind you is always a blast.
07-24-2011, 05:46 PM
#29
Burning Brakes
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Hey Guys,
Yeah i prob should put an auto in but honestly i never will. I know this tranny can handle way more abuse and power than I'm gonna throw at it. And i just LOVE jammin gears with some serious power.
Alright well i strengthened up the fork this afternoon. I think i could use it in place of a jack stand LOL. It ain't EVER gonna bend anywhere.
Yeah i prob should put an auto in but honestly i never will. I know this tranny can handle way more abuse and power than I'm gonna throw at it. And i just LOVE jammin gears with some serious power.
Alright well i strengthened up the fork this afternoon. I think i could use it in place of a jack stand LOL. It ain't EVER gonna bend anywhere.
07-24-2011, 06:13 PM
#30
Dr. Huxtable, exactly what was the problem you were experiencing. I will be honest, I installed (had installed) a spec clutch last June and it has been slipping like mad for the last 6 months. I put in a new clutch cylinder, slave etc. I auto cross the car, bought the clutch and flywheel they recommended for that and have been totally unhappy with the product. But the top of the thread doesn't give the symptoms of your problem that led you to have to drop the unit again.
07-24-2011, 06:48 PM
#31
Caleb,
If you do happen to call Spec clutches tomorrow,
Ask them the recommended clutch disc to pressure plate cover or clutch disc to flywheel Release distance is.
Its typically .035" to .045" on a diaphragm style clutch,
Around .040" to .050" for a Borg & Beck style clutch.
And around .050" to .060" for a Ford Long style clutch.
You make the check with the transmission installed & a helper sitting down in the Driver's seat.
He depresses the clutch pedal fully to the floor & holds it there.
Don't have him let up even 1/4" of an inch.
Scoot back underneath your Vette & take a Feeler Gauge set with you.
Check for at least .035" release.
You may need to wiggle the clutch disc with a screwdriver to move it back against the flywheel or the pressure plate.
The choice is yours what side of the clutch disc to measure between.
You can stack Feeler Gauges together to obtain .035" to .040".
Such as .025" + a .010".
Likely there is some sort of GEOMETRY Error in the Bellhousing to engine block, throwout fork, ball stud, throwout bearing.
Even getting the incorrect style throwout bearing will screw you up badly.
Such as you have going on now.
You need to determine what is wrong yet.
The Feeler Gauge check for clutch disc release is the most accurate of all tests.
Most BlowProof - Scatter shields have a 7/8" to 1" hole on the bottom.
6' O clock position.
That gives you access to insert your Feeler Gauge(s) in to check.
On stock bellhousings that are fully encased I have drilled 1" inch holes at the bottom 6" O'clock position.
Make my check then.
You likely don't want to do that to your Magnesium ZF Bellhousing.
But if It was my Vette , I would drill that hole.
Choice is yours of course.
You have the grinding & rubbing problem sorted out for now.
That's for sure.
BR
If you do happen to call Spec clutches tomorrow,
Ask them the recommended clutch disc to pressure plate cover or clutch disc to flywheel Release distance is.
Its typically .035" to .045" on a diaphragm style clutch,
Around .040" to .050" for a Borg & Beck style clutch.
And around .050" to .060" for a Ford Long style clutch.
You make the check with the transmission installed & a helper sitting down in the Driver's seat.
He depresses the clutch pedal fully to the floor & holds it there.
Don't have him let up even 1/4" of an inch.
Scoot back underneath your Vette & take a Feeler Gauge set with you.
Check for at least .035" release.
You may need to wiggle the clutch disc with a screwdriver to move it back against the flywheel or the pressure plate.
The choice is yours what side of the clutch disc to measure between.
You can stack Feeler Gauges together to obtain .035" to .040".
Such as .025" + a .010".
Likely there is some sort of GEOMETRY Error in the Bellhousing to engine block, throwout fork, ball stud, throwout bearing.
Even getting the incorrect style throwout bearing will screw you up badly.
Such as you have going on now.
You need to determine what is wrong yet.
The Feeler Gauge check for clutch disc release is the most accurate of all tests.
Most BlowProof - Scatter shields have a 7/8" to 1" hole on the bottom.
6' O clock position.
That gives you access to insert your Feeler Gauge(s) in to check.
On stock bellhousings that are fully encased I have drilled 1" inch holes at the bottom 6" O'clock position.
Make my check then.
You likely don't want to do that to your Magnesium ZF Bellhousing.
But if It was my Vette , I would drill that hole.
Choice is yours of course.
You have the grinding & rubbing problem sorted out for now.
That's for sure.
BR
07-24-2011, 07:27 PM
#32
Race Director
Did you ever check to see if your should bolts made the Pressure Plate bolt down flush to the FW?
If the shoulder bolt holes are not deep enough, the bolts will not pull the PP down tight to the FW,,, its a 5 minute fix if you need to counter bore the holes another .030 or .060 " etc
If the shoulder bolt holes are not deep enough, the bolts will not pull the PP down tight to the FW,,, its a 5 minute fix if you need to counter bore the holes another .030 or .060 " etc
07-24-2011, 11:38 PM
#33
Burning Brakes
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Dr. Huxtable, exactly what was the problem you were experiencing. I will be honest, I installed (had installed) a spec clutch last June and it has been slipping like mad for the last 6 months. I put in a new clutch cylinder, slave etc. I auto cross the car, bought the clutch and flywheel they recommended for that and have been totally unhappy with the product. But the top of the thread doesn't give the symptoms of your problem that led you to have to drop the unit again.
Caleb,
If you do happen to call Spec clutches tomorrow,
Ask them the recommended clutch disc to pressure plate cover or clutch disc to flywheel Release distance is.
Its typically .035" to .045" on a diaphragm style clutch,
Around .040" to .050" for a Borg & Beck style clutch.
And around .050" to .060" for a Ford Long style clutch.
You make the check with the transmission installed & a helper sitting down in the Driver's seat.
He depresses the clutch pedal fully to the floor & holds it there.
Don't have him let up even 1/4" of an inch.
Scoot back underneath your Vette & take a Feeler Gauge set with you.
Check for at least .035" release.
You may need to wiggle the clutch disc with a screwdriver to move it back against the flywheel or the pressure plate.
The choice is yours what side of the clutch disc to measure between.
You can stack Feeler Gauges together to obtain .035" to .040".
Such as .025" + a .010".
Likely there is some sort of GEOMETRY Error in the Bellhousing to engine block, throwout fork, ball stud, throwout bearing.
Even getting the incorrect style throwout bearing will screw you up badly.
Such as you have going on now.
You need to determine what is wrong yet.
The Feeler Gauge check for clutch disc release is the most accurate of all tests.
Most BlowProof - Scatter shields have a 7/8" to 1" hole on the bottom.
6' O clock position.
That gives you access to insert your Feeler Gauge(s) in to check.
On stock bellhousings that are fully encased I have drilled 1" inch holes at the bottom 6" O'clock position.
Make my check then.
You likely don't want to do that to your Magnesium ZF Bellhousing.
But if It was my Vette , I would drill that hole.
Choice is yours of course.
You have the grinding & rubbing problem sorted out for now.
That's for sure.
BR
If you do happen to call Spec clutches tomorrow,
Ask them the recommended clutch disc to pressure plate cover or clutch disc to flywheel Release distance is.
Its typically .035" to .045" on a diaphragm style clutch,
Around .040" to .050" for a Borg & Beck style clutch.
And around .050" to .060" for a Ford Long style clutch.
You make the check with the transmission installed & a helper sitting down in the Driver's seat.
He depresses the clutch pedal fully to the floor & holds it there.
Don't have him let up even 1/4" of an inch.
Scoot back underneath your Vette & take a Feeler Gauge set with you.
Check for at least .035" release.
You may need to wiggle the clutch disc with a screwdriver to move it back against the flywheel or the pressure plate.
The choice is yours what side of the clutch disc to measure between.
You can stack Feeler Gauges together to obtain .035" to .040".
Such as .025" + a .010".
Likely there is some sort of GEOMETRY Error in the Bellhousing to engine block, throwout fork, ball stud, throwout bearing.
Even getting the incorrect style throwout bearing will screw you up badly.
Such as you have going on now.
You need to determine what is wrong yet.
The Feeler Gauge check for clutch disc release is the most accurate of all tests.
Most BlowProof - Scatter shields have a 7/8" to 1" hole on the bottom.
6' O clock position.
That gives you access to insert your Feeler Gauge(s) in to check.
On stock bellhousings that are fully encased I have drilled 1" inch holes at the bottom 6" O'clock position.
Make my check then.
You likely don't want to do that to your Magnesium ZF Bellhousing.
But if It was my Vette , I would drill that hole.
Choice is yours of course.
You have the grinding & rubbing problem sorted out for now.
That's for sure.
BR
After much time fooling with it tonight i've determined that the flywheel, disc, & PP assembly are to thick.
When i mounted up the slave cylinder and depress the clutch it felt way wrong. Had my father in law hit the clutch while i looked in there. re pulled the slave cylinder and found that it was completely out, i mean hyper expanded. It was just barely able to touch the fork. Which if you think about it for a few minutes and how the system works that means the flywheel, disc and PP assembly is to thick.
That pushes the throwout bearing back further and the fork back further, and the opposite end far away from the slave cylinder. That would also explain the rubbing of the fork against the PP.
Overall BAD DESIGN or lack thereof. I'll be calling them tomorrow.
I Personally think the flywheel is to thick.
Did you ever check to see if your should bolts made the Pressure Plate bolt down flush to the FW?
If the shoulder bolt holes are not deep enough, the bolts will not pull the PP down tight to the FW,,, its a 5 minute fix if you need to counter bore the holes another .030 or .060 " etc
If the shoulder bolt holes are not deep enough, the bolts will not pull the PP down tight to the FW,,, its a 5 minute fix if you need to counter bore the holes another .030 or .060 " etc
Last edited by Dr.Huxtable; 08-04-2011 at 05:17 PM.
07-24-2011, 11:43 PM
#34
Burning Brakes
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Disgustingly hilarious
, I too could pull my ZF quick after so many attempts to make it work,,, trying PUSH type TOB's etc.
Bought the TKO00, installed it, and have never pulled it back out since the day I put it in
I hope you figure it out soon, for SBC's,, the FW's have standard thicknesses as do the friction disc, so I can't imagine what the problem might be...short of a mismatched PP
Just had a thought, make sure your bolt shoulders bottom out in the countersunk holes,, you cna check this by making sure the PP is tight against the FW
, I too could pull my ZF quick after so many attempts to make it work,,, trying PUSH type TOB's etc. Bought the TKO00, installed it, and have never pulled it back out since the day I put it in
I hope you figure it out soon, for SBC's,, the FW's have standard thicknesses as do the friction disc, so I can't imagine what the problem might be...short of a mismatched PP
Just had a thought, make sure your bolt shoulders bottom out in the countersunk holes,, you cna check this by making sure the PP is tight against the FW
Sorry I don't have anything to add but I'm envious of you guys pulling the clutch and trans etc and knowing which bolt goes where. If you don't mind me asking will the fsm show which bolts and the lengths and where they go?
I have never tackled a clutch or trans job. The last shoppe tossed everything into a bin so all the bolts are mixed up. My motor Will be in my hands soon but i fear I won't get it into the car anytime soon.
I have never tackled a clutch or trans job. The last shoppe tossed everything into a bin so all the bolts are mixed up. My motor Will be in my hands soon but i fear I won't get it into the car anytime soon.
07-25-2011, 07:20 AM
#35
Race Director
VARIOUS info I got from Centerforce tech, Roger Warner, during my ZF swap escapade.....
You FW should be no more than 1.0", actually a little less from the back of the flange to the disc surface.
1. The clutch requires 3/8" to 7/16" of a linear inch in order to release the clutch, you can use the rest of the travel from the throwout bearing for free play. The installed height of the fingers from new to completely worn out will raise about 7/16"
2. The centerforce flywheel thickness is .950"-.960" from the clutch surface to the back of the mount flange
3. In regards to the transmission input shaft, I recommend dry graphite or leave the input shaft dry. As for the bearing retainer collar that the supports the inner diameter of the throwout bearing, I recommend a light film of high temp grease such as disc brake grease, do not use white lithium grease as it this grease can not handle high temperature.
You FW should be no more than 1.0", actually a little less from the back of the flange to the disc surface.
1. The clutch requires 3/8" to 7/16" of a linear inch in order to release the clutch, you can use the rest of the travel from the throwout bearing for free play. The installed height of the fingers from new to completely worn out will raise about 7/16"
2. The centerforce flywheel thickness is .950"-.960" from the clutch surface to the back of the mount flange
3. In regards to the transmission input shaft, I recommend dry graphite or leave the input shaft dry. As for the bearing retainer collar that the supports the inner diameter of the throwout bearing, I recommend a light film of high temp grease such as disc brake grease, do not use white lithium grease as it this grease can not handle high temperature.
07-25-2011, 09:34 AM
#36
Melting Slicks
when there's massive interference, somethings not right . obviously. I put a spec three plus with their light weight billet flywheel, new throw out bearing, new clutch fork, in my '96 and assembly was a breeze with no problems....I can't understand the massive problems that you are having. There just absolutely has to be a parts mix up somewhere.
07-25-2011, 09:46 AM
#37
Burning Brakes
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Yeah exactly there just has to be. I mean it's beyond bad. Like i mentioned the ball stud is completely secure and as far back as it can go and the slave cylinder can just touch the fork fully extended. that's just not right. I'm call SPEC in a few min
Before i do anything I'm gonna ask them to tell me the part number i need for my car for the flywheel and see what they say. Cause i know the part number i have
Before i do anything I'm gonna ask them to tell me the part number i need for my car for the flywheel and see what they say. Cause i know the part number i have
07-25-2011, 09:54 AM
#38
Race Director
I like your comments.
I am a field engineer for a major automotive components manufacturer.
yes, I break rules all the time for my customers.
Especially if its the first time. (If they ask me to do it again and again - when it was their fault - just because I did it once, its a different story)
I am a field engineer for a major automotive components manufacturer.
yes, I break rules all the time for my customers.
Especially if its the first time. (If they ask me to do it again and again - when it was their fault - just because I did it once, its a different story)
Last edited by H P Bushrod; 07-28-2011 at 04:43 PM.
07-25-2011, 11:05 AM
#39
Tech Contributor
Flywheels
Year Span Engine Includes Steel Aluminum
1994 1996 5.7L LT-1,LT-4 SC05S SC05A
I have the SC05S in mine and had this issue.
07-25-2011, 11:49 AM
#40
i just went thru the same problem with a mcloude clutch and fly wheel and talked to there tech guys the soloution they came up with was to take the light weight flywheel i just bought from them and take .125 thou from the face of it it worked like a charm no more issues when i called back and asked why they did not do it at the factory they had no good answer
any way it solved my problem
any way it solved my problem