Stovblt, Any chance you could direct us to that service bulletin? Or scan it in and post it? I have had a similar problem on my 51 which requires just the right engine speed and clutch release and I can avoid the chatter. Jeff
There are many potential causes for clutch chatter. Motor and transmission mounts are a good place to start.
Wear anywhere in the clutch linkage and especially the clutch arm pivot could cause this problem.
You might be able to spot the problem if you remove the lower cover from the bell housing and inspect the clutch assembly.
Almost any other cause will require that you remove the transmission so you can access the clutch assembly and flywheel. Then you can look for things such as a weak diaphragm spring in the pressure plate, a worn disc, or warped surfaces on the flywheel and pressure plate.
I just spent a couple hours leafing through service bulletins. I can NOT find a reference to clutch chatter and engine mounts. Either my memory is bad (quite likely) or I read it somewhere else. There ARE references to perceived rough running of the engine and how to check and set the rear mount, and I'm attaching a scan of the best one of several bulletins on that.
I completely agree with what Rusty says above. I'll add that I have experience with chatter on a Mazda 6 and a grabbing/jumping clutch on a flat head F*rd... both due to oil on the clutch plate. With the F*rd a simple clutch plate replacement cured it... until it threw more oil on the new plate. A pail of fresh gasoline washed the problem away again.
Most clutch plates have springs in the hub, and some had the facings riveted to a "wavy" plate to provide cushioning. Burning or overheating of the clutch would sometimes flatten the "waviness" and make the clutch more severe or liable to chatter. And of course if some or all of the springs in the hub are broken... same thing.
Long story short... I think the most probable answer is that you will have to pull the clutch and put in a new disk. And while you are in there... everything Rusty says above.
clutch chatter can be caued by a combination of several things
The clutch disc and/or pressure plate or flyy wheel surface. Loose or broken motor and trans mounts. Play in the transmission gears, drive shaft spiines and differential gears. loosness in rear suspension bushings. Acombination of the above can make it worse.
sometimes 140 oil in the transmission can help in hot weather.
