Clutch shudder

I have a '71 Dodge pickup. It has a short wheel base, slant six, and a column shifter. It developed a severe shudder when taking off from a dead stop. I pulled the transmission and flywheel, had the flywheel turned, and replaced the clutch disk and pressure plate with the top line unit from NAPA. It still shudders when taking off. Will traction bars help, or is there some other obscure thing I can check?

Some possibilities could be a worn U-joint, a bad center support bearing if the truck has the 2-piece driveshaft, or a bad rear transmission mount. I would assume those have been checked already?

Another more obscure cause could be a worn out engine. If the thrust surfaces on the main bearing that controls crankshaft end play are worn this can allow the crankshaft to move back and forth, which will in turn cause the flywheel/clutch assembly to move and forth. This can cause a shudder and could be verified by trying to force the crankshaft pulley back as far as it will go. Then pry the pulley/crank forward. There should be very little movement.
Another possibility could be a worn out transmission mainshaft bearing which is allowing the mainshaft and clutch disc to move around.

Hope some of that helps. :slight_smile:

ok4450 has most of it but also - bad motor mount, drive shaft uj or axle alignment angle out of tolerance - this is usually a problem if you have jacked the axles for more wheel clearance without shimming the centre mount or turning the axle to reduce the axle prop angle - the prop just winds up a little.