Duster vibration

Tech Question


Bill Fogler, Medina, OH, 1970 Plymouth Duster 340

I have a 1970 Duster 340 4-speed I had purchased as a 6 cylinder conversion. It has always had some vibration at 60 MPH. The trans has been rebuilt and a new driveshaft installed. The diff is a 8¾” #489 housing. The nose was previously up. I added 3 degree shims and is now 1 degree up. The trans is 3.5 degrees down and the driveshaft is 2 degrees down. I believe this to be the cause of the vibration. Do you have any advice as to the proper degree angle or shim size I should use in order to correct this problem?


Bill, you have way to much u-joint angularity for street use! At the trans, you want close to zero, and rear end, pinion 0.25 to 0.75″ deg nose down.

Be sure you understand that these angles are axle pinion and trans mainshaft referenced to the propshaft. I.e., the u-joints’ working angles.


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