Shimming the Rear Transmission Mount, Vibration, Etc

The Hydramatic Transmissions (used in all 63 body styles and 62 series, 75 series, and commercial chassis in 1964 body styles) often have shims between the rear transmission mount and rear crossmember to reduce lower speed vibration.

In the  1963 Shop Manual, Propeller Shaft and Rear Axle Chapter 7, Section 10 Propeller Shaft Assembly Removal and Installation, information found on page 7-11 it states:

"Horizontal or vertical alignment of propeller shaft should not be necessary on 1963 model cars, other than making certain that the propeller shaft is properly  aligned in relation to the transmission.  Any vertical deviation from the correct installation that might cause propeller shaft vibration at low speed (0-50mph), can usually be corrected by adding .075 inch shims at the engine rear mount (rear trans mount).  Not more than four shims should be used otherwise there will be insufficient clearance between transmission and floor pan.

Usually the addition of shims will eliminate low speed vibration caused by misalignment of propeller shaft at transmission.  However, other factors contributing to this condition could be due to universal joint failure, excessive tire or wheel runout, wheel, tire, or brake drum out of balance, and tires other than the original equipment being used."

In the 1964 Shop manual, Propeller Shaft and Rear Axle Chapter 11, Section 10 Propeller Shaft Assembly Removal and Installation, information found on page 11-11 it has very similar information with the exceptions noted in bold below:

"Horizontal or vertical alignment of propeller shaft should not be necessary on 1964 model cars, other than making certain that the propeller shaft is properly  aligned in relation to the transmission.  Any vertical deviation from the correct installation that might cause propeller shaft vibration at low speed (0-40mph), can usually be corrected by adding .075 inch shims at the engine rear mount (rear trans mount).  Not more than three shims should be used, otherwise there will be insufficient clearance between transmission and floor pan.

Addition of shims will eliminate low speed vibration caused by misalignment of propeller shaft at transmission.  However, other factors contributing to this condition could be  universal joint failure, excessive tire or wheel runout, wheel, tire, or brake drum out of balance, and tires other than the original equipment being used."

It has been my experience that the Hydra-Matics were prone to have these shims, but having gone through 30+ 1964 parts cars, including 20+ with Turbo Hydramatics, I  do not recall any with turbo Hydramatics having shims.  This might be due to the  shorter tranny and longer driveshaft improving the overall angle?

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Comment by Jason Edge on August 14, 2012 at 10:17am
Nothing right now. I would use wide fender washers to shim to 0.15"
Comment by David Thomas on August 14, 2012 at 9:35am

Jason, My 63 came with two shims installed from the factory. I had some work done on my car about 15 years back and the mechanic didn't re-install them. If you have the original type shims, I would like to buy a couple.

Thanks, David

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