Clutch chatter
 

I installed a lightened flywheel + new V8 pressure plate, but got so much chatter that I had to pull the motor again. Ouch. I found heat marks on the pressure plate in one quadrant (the upper on in this picture):
Attachment 132247
And using a dial indicator I found that the finger opposite the heat marks stands about 0.030" higher than the other fingers when everything is bolted up tight. It also has a shiny wear mark on it as if it were contacting the throwout bearing more than the other fingers (the RH one in this picture):
Attachment 132248
So I am guessing that uneven release of the pressure plate is causing chatter. Here are the fixes I can think of:
1. Return pressure plate for exchange and hope the next one is better
2. Grind off high finger to match others
3. Put shims under the mounting ear under the high finger to match other fingers.

Any thoughts or comments on how to deal with this before I buckle it up again? Thanks!

Giles

Re: Clutch chatter
 

Can you adjust the fingers with the bolts on the cover??

Bob

Re: Clutch chatter
 

Are you certain the chatter is/was coming from the pressure plate? I have measured several PP that had odd-height fingers that did not chatter (although I was extremely nervous they would!). I will PM you the name of a company to call to speak with.

Re: Clutch chatter
 

I can't be sure that the finger height difference is the problem; it's just that it's the only irregularity I've found so far. I'm looking for ideas!

Re: Clutch chatter
 

I noticed in the photo that the clutch disk being used is typical of what most suppliers today are offering. It may not have anything to do with chattering, but if you look close you can see that there is not much holding each of the six springs in place. I have seen a number of these clutch disks fail because a spring became dislodged and jammed the clutch.

I refuse to install one in any of my cars. Several fellow club members and myself made it a point to look through junk boxes at swap meets for a properly made clutch that was still serviceable. We were able to obtain several Nova clutch disks and after bead blasting they were perfectly good to use.

For years the Nova company produced a quality clutch disk for the Model A. Unfortunately they went out of business a number of years ago and these clutch disks with poor spring retention started showing up.

In the last year or so Bratton's Antique Auto started offering a clutch disk very similar to the Nova clutch. As far as I know Bratton's is the only one offering it. There may be other suppliers doing the same, but I am not aware of it.

The four photos show a Nova clutch installed on a flywheel with a pilot shaft inserted. Note how the springs are retained. Another photo shows a typical clutch disk being offered by most suppliers. Note there is very little holding the springs in place. Another photo shows the clutch disk offered by Bratton's. Note the springs are retained much the same as the Nova clutch disk. The last photo show an original Henry clutch disk. They didn't have springs. I am told that the inception of springs was to better control chattering.

Tom Endy

Re: Clutch chatter
 

When I first bought my 29 Tudor it shook like a paint mixer every time I let the clutch out from a stop. The disc was almost new and the flywheel and pressure plate looked fine. I installed a new swap meet disc and good used swap meet pressure plate, then lightly sanded the flywheel with my palm sander. Now it's as smooth as an automatic.

I also dialed in the flywheel cover while it was apart. So, I'm still not sure what the exact problem was, but at least it's fixed.:)

Re: Clutch chatter
 

Check out the clutch disc for a loose center hub and also for warpage. This is, be sure that the disc doesn't wobble. I've seen discs get distorted on installation and cause chatter.

Re: Clutch chatter
 

Yesterday I indicated in the three fingers and shimmed the pivots to get them all within 0.005" of each other. They started out at -0.030, -0.020, and 0.000. This required cutting the appropriate thickness brass shim stock (I've got an assortment). Kind of like flywheel housing shims. I got it all bolted up today and went for a drive, and there is no more chatter! Smooth as can be. I was afraid that the repro clutch disk was contributing to the problem, but it appears to be fine. So it appears that inconsistent finger heigth can be a source of clutch chatter.

Re: Clutch chatter
 

Gillitos, the finger heights are critical. The heights are set on a jig with spacers where the clutch plate would sit, with the pressure plate bolted down (or same as)
If one finger acts differently from the other two, then the holding or friction is acting earlier, at one place of the flywheel/pressure plate. This results in uneven loading around the crankshaft centerline, and results in the hotspots in one area of your p.p. and f.wheel. (with lots of jumping and banging) as you had.

Great to hear you've nailed it!

Re: Clutch chatter
 

Re: Clutch chatter
 

Many things can cause the chatter, so, as much of a job the clutch replacement is, might as well check and repair anything wrong. That can include crank flange, flywheel, disc, input shaft, pressure plate, bellhousing/clutch cover.