Packard Forum Index » Post-War (1946-54)

I have a 1951 Business Coupe with a 3 speed that has worn out synchronizers and the rear axle is noisy and has a lot of backlash.

Will a 3 speed with over drive and the complete rear axle from a 1954 4 door clipper fit?

How about the drive shaft?

I know I cant change differential pigs because there is to much difference between the years.

An educated guess would be yes...1951 thru 1954 were basically the same chassis and I believe the Biz coupe and the Clipper sedan shared the same 122" WB. Should be an easy swap.

You'll have no problems other than the 54 axle might or might not have a different wheel bolt circle.

Just to save you some troubles, do try running some 90 weight GL-1 gear lube in the tranny before you swap it out. They do not like the usual GL^4 (too slippery)and will clash. Also, on your existing rear axle, make sure the pinion nut has not backed off.

These are both common problems and and might be very easily repaired in an hour. In my experience, the synchros are seldom bad in any of these cars, but even rarer on an overdrive car as the freewheel assists the shifting.

I would like to use the overdrive trans and the Higher numerical rear axle from the 54.

Better acceleration for the Newport Hill climb and lower cruise engine speed...

I am pulling the engine and trans on the 51 anyway .

Stuck valves and a few cracked rings I think..

G'day wilco,
to you and your '51 Business Coupe which I invite you to include in the Packard Owner's Registry here on PackardInfo.