Early 50's clutch chatter

[Joseph P. Indusi]

My friend is thinking of acquiring an early 50's Chevrolet pickup truck. Seems there is a small oil leak from the engine and the clutch chatters. Truck was supposedly rebuilt, but not used much. What are the leading causes of the clutch chatter? The oil leak if from the rar main may or may not be the cause. Any help would be appreciated.

Joe

[rhb1999]

Warped flywheel and pressure plate?

[NTX5467]

Clutch chatter usually relates more to the surface condidtion of the flywheel. If they "surfaced" the flywheel when the engine was rebuilt, it could have had some hot spots in it that didn't "surface out". These areas usually don't have the same surface finish as the rest of the clutch disc's contact area. The type of surface which was left might be different from what the factory specs for a new one might have been . . . too "agressive", for example. Clutch pressure plates are subject to hot spot issues, too . . . which somebody might have tried to "surface out" too.

I kind of doubt the rear main seal seep might cause the issue, considering the path that oil would have to take to get to the clutch engagement surface on the flywheel. BUT, a long-term valve cover gasket leak could do it.

Seems like the Ford Flatheads were prone to clutch issues due to the fact the lower bellhousing was poorly braced to the back of the engine, allowing a certain amount of "flex" in the total engine/trans combination. The Y-block, with its "deep skirt block" added extra bellhousing attachment points to fix that issue.

It could well be that to really fix the issue will require a new flywheel, pressure plate, friction disc, and release bearing. Getting QUALITY (new ones whenever possible, rather than "rebuilt"!!) items is important, although the engine's power is modest and some might desire to purchase or supply lower-quality items for that reason. If possible, I'd check NAPA or try to get Borg-Warner (or similar OEM-level supplier) parts. With the possibility of a closed driveshaft, doing it more than once is not desired. In any event, I'd plan for the "worst case scenario", which would be replacing the complete clutch mechanism (flywheel, pressure plate, clutch disc, release bearing), but it might also be possible that adjusting the clutch pedal's linkage might lessen the chatter . . . worth a try, first.

Just some thoughts,

NTX5467