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Crankshaft endplay? It should have been checked and adjusted if necessary as a part of the engine rebuild.

I have not read the service letters, but having read Howards comments about the snubber, and observing that probably half the cars out there are missing a snubber, I have my unfounded uneducated guess that lack of a snubber is not the core problem, so I remain a bystander to the chatter issue. As to a replacement snubber, can do...as well as counsel to fabricate one from a modern shock link...separate sidebar..

I sent you a PM David. Crankshaft endplay???? How the heck do I check for that?!?! A couple of observations.... I did adjust the snubber today. The service letter says 'no more that 3 turns of the turnbuckle or +/- 1/8" of preload' and when I loosened off the lock nuts, I gave it the better part of two revolutions and that seemed to be pushing quite positively on the transmission. When I put my finger on the stem of the metal ball, I could feel a definite forward offset of it in the socket, against the rubber, so I feel it is pushing fairly positively against the tranny. After letting the car down off the jacks, the first clutch engagement felt better and I thought I might have actually affected a difference. But, after a couple of trips around the block, the chatter issue is still there and I am now thinking a new disc might be in order. Possibly even a new pressure plate as well; if I am going to all this work to tear everything down again, it would seem prudent to go the extra $$bucks. Problem is I don't know for sure if the clutch components are the root cause. You mention crank endplay and if that is truly an issue here, I could end up having to take the engine back out and retransport it several hundred miles to the rebuilders to do what they should have done in the first place!!! To say I would be majorly pissed were that to be required, would be an understatement!!! The other thing... if I put the e-brake on and try and start out in first gear, it doesn't chatter, it just loads up the clutch. Then when I release the brake, the initial engagement after that is quite normal and smooth. I am wondering if that is from the disc and plate heating up a bit and that somehow alleviates the chatter. Does that make any sense to anyone?? Or signal a root cause??? All I CAN say, is there was zero chatter before I removed the engine and the only things that I know have been changed are: the flywheel has been machined, the clutch disc relined and I did take some 400 grit sandpaper and broke the glaze (or shiny surface) of the pressure plate in a nice, even, cross-thatched pattern. So, other than crankshaft endplay, the root cause SHOULD be SOMEWHERE in those items and the most obvious to me right now is the clutch disc. I am open to any and all input and suggestions on this and thank anyone for taking the time to weigh in. Chris

You should be able to see the Marcel spring with the clutch in the car if you can see the edge of the friction disk.

motoiq.com/clutch-technology-part-3-clutch-disc-construction/

This is a discription and photo of the Marcel spring.

Good luck, John

The fact that it does not chatter when the clutch is hot is the same as fading brakes, the clutch plate material has less friction when hot, this seem's to indicate that when the clutch is squeezed between the flywheel and pressure plate it is grabbing too aggressively.

Have you check to see if the Marcell spring is there?

Your disc may have one or two of them.

youtube.com/watch?v=I2-UXYu5l1Q

U_Tube, Marcel spring
John

Thanks, John. I agree with your heat/fade comments and the more I winnow through the 'possible suspects' here, the more it seems to point to the disc. In hindsight, I did kind of take exception to the material used to re-sinter my clutch; it seemed almost like brake shoe material and something that stood out to me was that it did not have the 'pinwheel' grooves in it that one sees in a clutch - it was just flat. I wonder if that, alone, could make it grab more aggressively. I'm not sure, from an engineering standpoint, what their purpose is (maybe cooling??) but unquestionably they would decrease the surface area of the clutch face by a fair amount.
I have not checked to see if there is a Marcel spring in between the discs as of yet, as I am thinking I will just dismantle the whole drive train and remove the clutch as I feel it is too hard on the tranny and rear end to have it chattering like that. Can't be good for anything behind the clutch. I will report my findings/progress. Chris

Hi All,

Just finished up with the clutch R&R this morning and wanted to post a quick update...
I got the rebuilt pressure plate and disc from Kanters and the sintered material on the disc seemed quite different from the new discs that the clutch and brake house put on my old one. The Marcel spring was also very evident in the new one, maybe even 2 of them in there. The old disc had a very thin, wavy material between the discs, definitely not the same as the specimen from Kanters. Also, their disc had the Packard script imprinted into the metal of the centre disc, the old one does not. When I removed the old clutch and pressure plate, I noticed that the wear pattern on the disc was very 'splotchy' and uneven, and I can't really tell why. The flywheel looked fine, as did the pressure plate. Anyway, as soon as I let the car down off the jacks and fired it up, in backing out of the garage, I could tell it was smooth as silk. (and reverse was my worst chattering gear before) I took it for a good spin and could not get over the buttery smooth starts and the seamless shifts, truly a remarkable transformation! I don't even have to rev the engine hardly at all and can take off from a stop without so much as a hesitation or a chatter. Definitely the disc was the culprit. Hope this might be of some info and help to anyone else out there fighting with this issue - many thanks to those who weighed in with advice and assistance. One more thing checked off the never-ending list!!! LOL
Also a nod to Kanters for their excellent service and knowledgeable parts desk guys; everything shipped right and on time, the first time. We're lucky to have suppliers like that out there, supplying parts for 80+ year old cars!!!
Chris

Good to hear you got it all straightened out. John