Pulled trans again for chatter - here are results

[Timothy B.]

As I indicated in an earlier thread about my having to bite the bullet and pull my trans again to see why I have a chatter problem, I did so today and found some interesting things. I would like some advice from those with experience.

My car is a 67 small block, and I installed a new LUK rep set clutch assy last November. Flywheel was resurfaced. From the start I had a light chatter on low speed engagement that wouldn't go away. Advice from this forum and from LUK was to pull trans and check runout of flywheel.

Upon removal of clutch pressure plate, I observed that the pilot bearing was loose in the crank - came out by hand and spins freely in the crank!! It didn't go in that way for sure, in fact I had trouble driving it in. This bearing came with the LUK kit, and was not magnetic (I checked it). The original pilot bearing that I removed prior to installing the Luk kit in November had to be pulled out with a puller as is normal, and wasn't excessively worn either. I went ahead and installed the new one that came with the Luk kit since I had it.

Flywheel and pressure plate both look pretty good (however they were only installed a couple of months and maybe a hundred miles or so). I can tell however that there is some minor spotting on the flywheel, probably indicating some uneven engagement. I checked runout and it is about .003" best I can tell using a dial guage. How much runout in a flywheel is too much?

By the way, I did NOT get the flywheel and/or clutch assy balanced last November thinking that it wasn't necessary, but now maybe I should...

Advice?

[Joe L.]

Re: Pulled trans again for chatter - here are resu

Brad-----

If the pilot bushing went in "hard", but is now loose, my suspicion would be that it was not driven in "straight and true". I can't think of any other reason for it loosening up.

I think that the .003" TIR, if that's what it actually is, should not be a problem.

The flywheel, pressure plate and disc assembly should ALWAYS be precision balanced before installation. The only exception would be if you were re-installing a used pressure plate and disc on the same flywheel that it came off of, unsurfaced and indexed to the same relative position on the flywheel as it came off. That sort of situation is the exception and not the rule. Otherwise, ALWAYS have the assembly balanced. Period.

[Timothy B.]

Re: Pulled trans again for chatter - here are resu

Thanks Joe. Do you know the PN for the correct GM bushing? The last one came from the Luk kit, but this time I will use GM if possible. However since the one I took out originally was fine I supposed I could reinstall it...

What is the GM specified maximum runout for a flywheel? I looked in my service and overhaul manual and I couldn't find it in the specs. I measured it on the car using a dial indicator while slowly rotating the flywheel. I could probably get a better reading if I pull the spark plugs and may try that tonight.

I found a shop that can balance the flywheel/clutch assy and will get that done. I have another dilemma however, and that is whether I should reinstall the same pressure plate and disk that I took out. They are Luk parts and as I mentioned they were only installed 2 months, but who knows for sure if they are contributors to my chatter. Is there a way to "test" a pressure plate for even engagement/disengagement?

[Brian Monticello]

Re: Pulled trans again for chatter - here are resu

Tim,
I wouldn't risk using the flywheel and clutch you pulled out. For $150 you could have peace of mind. Think of how badly you will be cursing if you put everything back together and still have the chatter problem.

I was it your situaiton (I'm Allcoupedup from the other forums) and had TERRIBLE chatter and problems with the clutch engaging (or is it disengaging) upon startup. My problem could have been oil contamination, damaged PP spring, por pilot bushing/input shaft fit, an improperly surfaced flywheel (mine was mirror smooth)... I will never know.

I got the flywheel resurfaced at a different shop and threw in a brand new disc and PP and never looked back. This time I made sure to check input shaft/pilot bushing fit and applied the smallest trace of the spine grease as possible.

Good luck!

Brian

[Timothy B.]

Re: Pulled trans again for chatter - here are resu

Brian, did you go with the Luk parts again or something else? Everyone recommends Luk, but this is not the first time I have heard of folks having to swap them out...

How much runout did you have in your flywheel?

[Brian Monticello]

Re: Pulled trans again for chatter - here are resu

I went with LUK again. My flywheel had .0015 run out taken at the farthest distance from the center.

I spent about an hour with LUK tech support and sent them hi-resolution pictures. They insisted that I applied too much spline grease and it flug out and ruined the clutch lining. That did not explain the fact that my TO bearing violently bounced due to uneven pressure plate finger height and that the clutch was stuck and I had to push in the clutch pedal and rev to get it unstuck. There were so many things that could have gone wrong with my install (it was my first time) that I chalked it up to experience and started with a fresh new set.

Brian

[Mike McKown]

If you didn't have any of Brian's clutch symptoms,

send me your old, used Luk clutch. I'll even pay postage.

If you have the clutch/flywheel balanced, have them done seperatley. Not as an assembly. Whoever puts in the next clutch or R&R the one you have will probably not be happy if you do it as an assembly.

.003 runout on the flywheel just beyond the wear surface wouldn't disturb me.

If your old pilot bushing goes back in good and tight and is not burred on the input shaft surface, no reason you can't reuse it. Just make sure it is tight.