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Vacuum operated fluid drive


Brody41WindsorC28

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Hello. I picked up a 41 Chrysler years ago and got it running. At the time I had never even heard of fluid drive. I had to do a bunch of stuff to get the engine running because it had sat for 40 years or so. The fluid drive didn't have any issues tho. Immediately I started driving it everyday. To work. There was even a while where it was my only car. Anyhow.... I ended up jamming it in storage once a situation happened with the shifting. It stopped upshifting when I let off the accelerator. Stuck in first and third. But now I'm looking to get it out of storage and have the parts lined up or at least a plan of action to fix what went bad.... As I said it's the vacuum operated high-low range 4 speed. I picked up a new vacuum diaphragm and am going to toss that in... What's the deal with the shift relay and governor?? I keep reading about these on the post war cars but I can't remember them on my car. There is wires at the carb if I remember right. Is that for kickdown? Is there anything else other than the vacuum diaphragm that controls upshift? There's good oil in the case and coupling. It's been years since I changed it tho so I don't remember what I put in. I do remember researching the proper fluid and I'm pretty sure it's good.... Any help would be greatly appreciated! 

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Imperial Club web site, repair section, transmissions.  Just about everything you need is there.  Fluid for fluid drive section, universal tractor hydraulic fluid, do not over fill. For transmission SAE 10, nondetergent motor oil is recommended, but you can probably use detergent without issue as there are no suspended incomplete ignition particles to deal with in the transmission.  I believe the technical code for the early semi autos was M 5.

 

Most discussion about using the hydraulic fluid suggest adding to what's is there to bring to proper level rather than drain and refill.

 

There is a trans to carb electrical circuit that is involved with kick down.  

 

Most faults with these transmissions tend to be external and control function problems, wiring, connections, governor points, corrupt grounds leaky vacuum lines, rather than internal breakage and wear.

 

Good luck, hope you get on the road again.

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20200709_082459_compress88.jpg.955ee3be1efc280e71538df7d2dc6649.jpgYou really need the factory shop manual to fully understand the 1941 Chrysler transmission operation and repair.

There isn't much technical info on this transmission online that I've ever found.

.The factory 1941 through 1948 Chrysler shop manual covers your early diaphram shifter type transmission 100%.

The 1941-early 42 transmission is known as the M-4 Vacamatic in the Chrysler.

Simplimatic in the DeSoto.

You should be able to find a shop manual reprint online.

As for your questions....The relay is part of the downshift circuit...the governor controls upshift and downshift speeds.

 

Edited by Dodgeb4ya
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