How to Identfy Correct Transmission Yoke For 1976 Cadillac Transmission

[carlhungness]

         The transmission on my  1976 Cadillac Engine, 500" has a large
32 stamped on top, off to the left side. I asked a man at a transmission shop to loan me a yoke for this transmission so I can set proper drive-shaft-u-joint angles. The one he pulled doesn't fit.
         Are there any numbers on the transmission I can cross-reference to get the right yoke? I sort of hate to go back to him and tell him to try again without some knowledge. He's a 40 year trans man, successful shop, etc. so his first guess was wrong and hoping I can get some info that might help. He told me not to buy a new
one yet as I don't have a drive-shaft, and we'll order at the same time.

         
           

[savemy67]

Hello Carl,

My ATSG reference guide for the THM400 indicates that Cadillacs used a 32 spline output shaft.  If the trans shop has a pile of yokes for full size GM cars, look for a yoke that accepts a 32 spline shaft.

Respectfully submitted,

Christopher Winter

[The Tassie Devil(le)]

Don't these large cars have Double Cardan Joints on either end of the drive shaft?

As you are going to install the engine/Trans into an earlier chassis, then I would be going for a simple slip yoke that uses a single universal, say from any Chevrolet or Pontiac car that used the TH400 transmission.

Don't use one out of a Corvette that fits the Muncie Rockcrusher transmission, as that will be too short overall, as these will fit, but weren't designed to sustain much forward and backward movement as these Vettes with the Independent rear end, the drive shaft is sort of fixed in operational length.

Bruce.  

[bcroe]

The transmission on my  1976 Cadillac Engine, 500" has a large
32 stamped on top, off to the left side. I asked a man at a transmission shop to loan me a yoke for this transmission so I can set proper drive-shaft-u-joint angles. The one he pulled doesn't fit.
         Are there any numbers on the transmission I can cross-reference to get the right yoke? I sort of hate to go back to him and tell him to try again without some knowledge. He's a 40 year trans man, successful shop, etc. so his first guess was wrong and hoping I can get some info that might help. He told me not to buy a new
one yet as I don't have a drive-shaft, and we'll order at the same time.

All TH400s use the same dia (32 spline) output shaft.  But some
early ones had a an outer dia of about 1.69 inch, then all went to
1.89 inch.  76 Cad may also have an O ring on the shaft forward a
bit from the splines.  Then the yoke has an outer sleeve extended
forward beyond the splines to form a sliding seal with the O ring, the
yoke will have an air vent in the center.  Putting this yoke on a non
O ring trans will cause a leak at the air vent, a yoke with no vent
must be used.  Bruce Roe