mhooke

I have a '65 327/365 that has recently undergone a complete restoration, including a correct new Luk clutch/pressure plate/throw-out bearing package and resurfaced original flywheel. We also installed a new pilot bearing, and torqued everything to spec. We didn't have everything balanced before installation, but we did properly adjust the free play at the top of the clutch pedal, with about 1 1/4 inches of free play, which interestingly left only about half an inch of threads beyond the nuts at the end of the clutch rod. We tried to be careful not to contaminate or "glaze" the clutch disc with any oil during installation.

The car has now been driven about 150 miles. From the start, the clutch pedal manifests a vibration or shudder when I press my foot slightly against the clutch pedal. In other words, when I press through the free play at the top of the pedal and first meet resistance, I feel a vibration in the pedal. the vibration stops as I press the pedal all the way down. The vibration occurs both when such pressure is applied to the pedal with the car is sitting still in neutral and also when I am driving the car and shifting into the gears (although it seems more pronounced going into first and second). I also can sometimes hear a very slight "whirling" sound (not always) when the car is in neutral and the clutch pedal is not depressed at all. This very slight sound immediately goes away if I simply push lightly on the clutch pedal and let it back out.

I've done a lot of research here and on the NCRS TDB and learned about most of the likely causes -- contaminated clutch disc, bad or incorrectly installed throw-out bearing, misalignment of bell housing, misalignment of pressure plate, worn out engine mount, worn out tranny mount, bad pilot bearing, worn clutch fork -- the list seems to be endless.

The experienced mechanic who helped me install the clutch was pretty confident that the problem stems from the throw-out bearing. So we were able to detach the gear lever assembly and disconnect the tranny enough to expose the throw-out bearing. We know about the proper installation procedure (under the clutch fork clips, etc.) and even used photos posted on this site to confirm our correct installation of the bearing. The bearing, which was the composite type included with the Luk package, looked okay to me. It showed some slight circular wear pattern when it contacts the clutch teeth or prongs, but otherwise looked intact.

My friend still thinks the problem is with the throw-out bearing and thinks we should simply reinstall the new all-steel bearing that I recently bought from Long Island Corvette. I'm more skeptical and think maybe it's the pilot bearing. We haven't taken everything apart and so would have to do quite a lot more work to get to the bushing. And if we're going to do that, maybe we should have everything balanced, etc. Anyway, I thought it'd be worth soliciting some other views before proceeding. I really don't want to do this but once (or counting this second time, twice). Thanks very much in advance.

Mike

phil2302

Replace the throw out bearing.

Frankie the Fink

I assume you removed the inspection plate and checked things out thoroughly. A little grease on the pressure plate during assembly can cause similar symptoms.

GCD1962

Could also be the PP itself if the tension of each finger is not correct

MikeM

I'll throw my hat in the ring and say you have a defective pressure plate.

Contact an expert like the manf. and see what they say.

Plasticman

Taking up the clutch free play (just light contact to the pressure plate), and feeling vibration sounds like a diaphragm pressure plate with unequal fingers (either bent, misadjusted, or broken), or the pressure plate is not mounted correctly.

Now if you were hearing any squealing or any noise, it would be the Throwout Bearing for sure.

At any rate, trans needs to come back out and parts inspected, and use a steel throwout bearing.

You state: pilot bearing (as opposed to bushing). Did you really use a bearing? And why?

Good luck,
Plasticman

Powershift

If you installed a pilot bearing instead of the original type bronze oillite bushing, I would check it carefully and even recommend changing it back to bronze.

If you leave it in, as a minimum, do alignment checks of the bell housing to make certain everything is properly centered and within allowed specs. Probably a good idea to do this regardless.

FWIW: I have a similar very small vibration that I can feel (with my hand on the clutch pedal) when the TO bearing just starts to spin. For me it is because of an old 30 years + TO bearing. A new one should not have noticeable vibration, but you still may be able to feel it thru the pedal when it first starts to spin.

Larry

GTOguy

You have two issues going on here: run-out of the clutch cover assembly and normal gear and bearing noise inside your transmission. When you push in the clutch all the way, you disconnect the engagement of the trans to the engine. Internal components stop rotating. The 'whirring' stops. If the 'whirring' is bothersome,a transmission overhaul with new, quality bearings should alleviate it. As for the pulsating pedal, something is causing the throwout bearing to wobble. Could be an improperly torqued clutch cover, a defective clutch cover, or flywheel runout.

MikeM

I suppose it's also possible a chunk of lining broke out of the disc causing uneven finger height as well.

I'm not sure I'd go to the trouble of pulling the transmission out unless the clutch pedal pulsating was irritating or the condition got worse.