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mnskaggs46

1941 DeSoto fluid drive problems

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Since these components are more than 60 years old and there is no way to tell how mechanically sound they are just by looking, it is a wise idea to have the replacement also checked and repaired as necessary. It will avoid unnecessary labour and headache just to find out later that this replacement is not too hot in function. This is my humble opinion. Cheers and have day. trini.

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You should check the two pilot bushings in your replacement FD coupling before installing it and make sure they too are not worn out. You will need a small diameter precision bore guage or a used input shaft (no slop) to check the oilite bushings.

I had a job on a 1942 S10 DeSoto about 10 years ago that the FD bushings had galled and siezed up. I replaced them and all is well to this day. Those oilite bushings should never have grease get into them as they are porous and prelubed with 10W oil from the manufacturer. I do apply a very small amount of light oil to the input shaft before installing the M4,5,6 transmissions.

Be gentle with the FD unit and not over flex the FD driven plate as there is a copper bellows seal unit and graphite ring that can leak if you are rough with it. DO NOT hang the transmission (input shaft) on the coupling while trying to install the transmission! The FD coupling might leak afterwards if you do.

Bob

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You should check the two pilot bushings in your replacement FD coupling before installing it and make sure they too are not worn out. You will need a small diameter precision bore guage or a used input shaft (no slop) to check the oilite bushings.

I had a job on a 1942 S10 DeSoto about 10 years ago that the FD bushings had galled and siezed up. I replaced them and all is well to this day. Those oilite bushings should never have grease get into them as they are porous and prelubed with 10W oil from the manufacturer. I do apply a very small amount of light oil to the input shaft before installing the M4,5,6 transmissions.

Be gentle with the FD unit and not over flex the FD driven plate as there is a copper bellows seal unit and graphite ring that can leak if you are rough with it. DO NOT hang the transmission (input shaft) on the coupling while trying to install the transmission! The FD coupling might leak afterwards if you do.

Bob

Bob - Mel here. Had fluid drive rebuilt before putting everything back together. Still doesn't want to shift properly. Checking the electrical system and vacuum system since it has vacuum downshift. Thanks again.

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Ron got it running. Still working on the problems with shifting. Checking the vacuum lines and electrical system. Project for this winter along with replacing the water pump. Thanks for the question. By the way do you know an expert on fluid drives, sure would like to pick his brain.

Mel

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The shift diaphram might have a break in it. Read the factory instructions on diagnosis. Thats how I learned to fix them.

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