Calling all transmission experts -1931 Model A

oldbike99

Senior Member
I am in the process of rebuilding my 1931 transmission with all new internals. I know that the 1931 did not use thrust washers on the ends of the cluster gear, but I was wondering if there was a acceptable case-to-cluster gear clearance specification? Thank you for any help you might provide.
Paul
 
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I have never seen this spec for an A, but for a B it is .004-.012, and for a V8 it is .005-.017. I would definitely try to keep it towards the smaller end of the clearance range. If you have ever heard one with too much, it sounds like every rod in the engine is about to go.
 
I remember reading in Jim Schild's book off of an original print that the max was .020 inch.

This book suggests putting the shim at the rear of the case. I wonder if one could use the shim made for the early, 1928 transmission that used them on both ends of the cluster. I am going to try a different transmission case first, and if needed, look into that shim option.
 
Your transmission case could have been replaced in the past, so it could be any year. If it needs a shim, slide the cluster gear forward and rearward and look at the gear alignment at the front with the input gear, and put the shim at the end that gives the best gear alignment.

Good advice. My understanding is that the early transmissions, that used the shims, also did not use the snap rings for the main bearings. Instead, using a cast-in ridge to position the bearings on the main shaft. Is this correct?
 
I read somewhere that one can use the king pin shim washers. The spacer washer used for the early transmissions is way too thick.
 
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