Fluid Drive

[Guest DaveKop]

I am starting to look for an early post war Chrysler product likely a DeSoto - most likely with fluid drive. My father had three of them 41 DeSoto, 46 DeSoto and 49 Chrysler. I was still young when he switched to a Buick. I know very little about these tranmissions and if I test drive and look at these cars what are the trouble signs? From what I read here and elsewhere it looks like there are only a couple of shops around the country that rebuild these.

Could someone direct me to a place where I can get comprehensive information about the transmissions, how they changed over the years (like the addition of a torque converter at the end of the production) and troubleshooting problems? I seem to read here that they are rather trouble free but it was slipping or non-shifting fluid drive that caused my dad to junk two of the cars.

Dave Kopesky

dkopesky@comcast.net

[Jon Robinson]

Dave:

The Fluid Drive Chrysler products are great cars and terribly underrated. The transmissions are super-reliable, and when they give you trouble, it can nearly always be repaired in a matter on minutes.

I'm sorry to hear your father junked two of these cars over shifting issues when, usually, these can be solved with things as simple as adjusting engine idle speed, cleaning a governor switch, or fixing a broken wire. Your dad might have been able to save these cars with literally five minutes of work.

The 1939-'40 Chryslers and DeSotos had only the Fluid Drive clutch with manual three-speed transmissions behind them. They really weren't trying to pass for automatic transmissions but, rather, cushion the drivetrain from the blows given by the bad roads of the time. They were also more controlable on ice and snow.

In 1941, they started to put automatic gearboxes behind the Fluid Drive unit, and they were called Vacu-Matic and Simpli-Matic. They work OK, but the gear ratios are strange, and the downshift is accomplished with vacuum mechanisms that can be a little unreliable. In 1946, the gear ratios were perfected, and they downshift was accomplished hydraulically, and the transmissions became, I'm sure, the most reliable automatics on the road at the time.

In 1949, the eletrical components and wiring were simplified even more, and with the V-8s in 1951, Chrysler replaced the Fluid Drive unit with a true modern torque converter under the name Fluid Torque. They work really well, too. In 1953, they came out with the system in which the Fluid Torque unit shares oil with the engine, which works OK, but it's a silly system, and it takes 12 quarts of oil to do an oil change.

If you're test driving a Fluid Drive car, and it doesn't shift, drop the idle speed and see what happens. If it still doesn't shift, disconnect the transmission wiring from the spark coil, and if it shifts OK, you know you have an electrical problem that can be solved easily.

With Fluid Drive, no problem is ever a big deal. The worst thing that can ever happen to them is a leaking Fluid Drive unit. I know one man who knows how to install the new seal, and there are rebuilding services that do it, but you'll just have to throw a lot of money at them. It would take some kind of real disaster to create the need for the gearboxes to be rebuilt. I've never even heard of anyone having to do it. You can buy up gearboxes for a song and install one if yours really does go bad. If the gearbos starts to leak, and reputable transmission show can throw new seals in them just as they would any manual transmission.

Here's your start, and tell us what you wind up with. Write to us with any questions.

JON

[Dan Marx]

I have several relays for the Fluid Drive. I have one posted in the WPC For sale forum. The box is marked for an "under drive transmission", I assume this is a type of fluid drive? Any info would be greatly appreciated. If any one needs these, they will be cheap. have six relays.

Dan