[many birds]

I'm trying to figure out what may be causing my clutch problems. I have '75 T/A with a super t-10 and 3.08 rear end. I have: new Hayes street/strip clutch and pressure plate and new fly wheel that was balanced to match the original, new transmission bushing, new polyurethane body mount bushings, new throw out bearing, new pilot bushing, new clutch fork. BTW: this was happening with the old clutch too.

When the engine is warmed up, I cannot get the clutch to engage smoothly. On cold start, it is completely fine. It doesn't matter what rpm I start letting it engage when it's warm. The higher the rpm, the more violent the chatter. The torsion springs on the friction plate are fine/not broken. Any ideas?

[tom s]

I have found the street strip clutch discs will chatter when using a tall gear to get it from a standing start.I watch ebay for the old blk and yellow GM box clutch disc.They have asbestos lining and are by far the smoothest.Tom

[STEELCITYFIREBIRD]

That S-T10 has a 2.64:1 first gear, if factory tranny, My 76 had a 2.74 or 2.76? rear gear and that was never a issue.
Heat seems to be the bad ingredient, makes me think you have an incomplete engagement problem. Clutch gets hot after a few miles from slipping?
I recall a time when my brother owned my bird, I was just a kid, and the engine wanted to "buck" when pulling out from a stop. After some work from the family friend mechanic it turned out to be a misfire from bad ignition wires. That's what I recall, but I was like 10! It was at the tranny shop before that for a new clutch.
HTH

[Bluesugar]

a bad front seal around the tranny's input shaft is never a good thing;
"happening with the old clutch too"?

[many birds]

I've adjusted the clutch freeplay a few times, but the issue persists. The engine is in good tune, no misfires. Could it be the motor mounts? If so, how would I check them? They are the clamshell type. Tyranny and rear end are factory original.

[gtofreek]

A couple things that will cause clutch chatter.

1. Oil on the disk.
2. Loose springs in the clutch disk. These springs should be tight, and under tension. If you can wiggle them around, it will chatter.

[STEELCITYFIREBIRD]

To check the left motor mount, which is the one that will give you trouble, two ways to check.
Set park brake and with hood open try to pull out and see how much engine rises on left or put a jack under the pan rail on the left with a block of wood in between and lift engine.
FWIW, I know I killed a new Sealed Power Mount back in 2004.. in less than 400 miles of driving. My plan is to weld it up solid when the engine goes back in...someday. But mounts are bad, hot or cold.

Logically deducing, if you let the engine warm up completely, but don't drive the car till completely warmed up, what does it do or not do.... as far as engagement???


No slipping of clutch under a heavy load at WOT?

[MNBob]

I have a 79 4spd with a 3.23 and it has chattered since it the car was new. I am looking forward to my 5 speed upgrade with a new flywheel and clutch.

[many birds]

Nope, no slipping under load. If I let it warm up and then drive, I still get the chatter. If i drive it work, starts out fine in the beginning, but after about 10 min of stop and go traffic I get chatter. On the return trip at the end day, if it's hot outside, it chatters right from the beginning of the trip.

Oil leaks: Yes, I have leaks, both engine and transmission. Transmission leaks at the tail and the engine leaks from near the balancer and probably rear main(not sure about the rear main leak however). I don't think the clutch is oil soaked however. The old clutch was not oil soaked either. I've had this car for about 25 years, bought with only 36k on the clock, but the clutch has always chattered.

[PDC]

I had unbearable clutch chatter in Greenie which was solved 100% with a Centerforce Dual Friction unit. Silky smooth engagement, comfortable-medium pedal effort. There are mixed reviews online, but I'm a believer.

[Sun Tuned]

Finger height of the fingers all the same? Ive seen one or two off just a touch and the thing will raise hell backing up a driveway.

[many birds]

Fingers? I don't remember any real obvious difference in height. But I wasn't really looking too close either. But then, why only when things are warmed up? Finger height would be an issue hot and cold.

Centerforce? Are these the centrifugal type? I wasn't sure a street Pontiac would be winding high enough for them to provide solid engagement. That's the only reason I didn't go with that option. I hate the pedal effort of my current situation.

["QUICK-SILVER"]

Originally Posted by many birds

Fingers? I don't remember any real obvious difference in height. But I wasn't really looking too close either. But then, why only when things are warmed up? Finger height would be an issue hot and cold. .

Friction material gets more agressive/bites when it heats up.
If fingers aren't level the clamping sufaces wont be even all the way around.

Wave spings/Marcel, between the friction disc, is suppose to take care of minor imperfections between clamping sufaces. That could be high spots on either flywheel or pressure plate. And pressure plate not level.

Most 'new' clutch chatter problems are caused by friction sufaces being rivited too tight. No room for the wave spings/marcel to do their job.

Over heating a clutch disc, from too much slipping, can make the wave springs/marcel lose their tension. When you pull one of those disc out, it will rattle when you shake it.

BTW How many grooves on the input shaft of your ST-10? Two ring with 2.43 1st gear can be hard on a clutch when running a 3.08 rear gear. Of course that depends a lot on the engine and how low of a RPM you can get your foot plum off the clutch the clutch pedal.

Clay

[73ta]

[QUOTE=

Oil leaks: Yes, I have leaks, both engine and transmission. Transmission leaks at the tail and the engine leaks from near the balancer and probably rear main(not sure about the rear main leak however). I don't think the clutch is oil soaked however. The old clutch was not oil soaked either. I've had this car for about 25 years, bought with only 36k on the clock, but the clutch has always chattered.[/QUOTE]

Oil leak of any kind no bueno. Does'nt need to be oil soaked. Any oil on the flywheel, disc of pressure plate and you are done!

[geeteeohguy]

Is the flywheel true? Was it resurfaced? Is the trans bell housing square and centered to the engine block?

[many birds]

Flywheel was new, it had that cross hatched type of finish. I cleaned it with brake cleaner before installing the transmission. Not sure how to check the bellhousing. It's tight up against the block, lined up using the dowel pins--I had no issues installing the tranny other than being under the car on my back while doing it.