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fluid drive trans questions


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Hello i am new to the world of the fluid drive trans.I need to get in touch with some one who knows something about them.I have a 1950 windsor that free wheels in any gear,i can push if freely.The trans is out of fluid is that why,if seems to me the trans feels like it is not connected to the engine(coupled).The clutch works,and it feels like the tranny is spinning smoothly.How is this possible is it due to the lack of fluid.

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This whole subject has been gone into thoroughly in the Dodge and Chrysler boards. Look for Fluid Drive threads back for the last year, or do an archive search. There are 2 or 3 long threads covering the filling of the trans and fluid drive with oil (they are separate) along with how they work, and the correct driving technique.

Your car has the fluid drive unit, plus M6 self shifting transmission. It is one of the early efforts at making an automatic, it shares some characteristics of the automatic and manual transmission. It requires a different driving technique than either. Nothing difficult or hard to learn.

The transmission is not connected to the engine. The fluid drive unit allows slippage between engine and transmission. Whether it is normal to be able to push the car in any gear I don't know as I never tried this with mine.

Your post is a little confusing. Do you mean you can push the car with the motor off? Or when it is running it won't move?

Go and study the old Fluid Drive threads, they should answer all your questions.

If not, come back and ask again.

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Guest Bob Call

I had a 1950 DeSoto with the fluid drive. As Rusty said this was a transition period from manual to automatic transmissions for Chrysler Corporation.

It has a fluid coupling (torque converter) that drives a flywheel and clutch like a manual transmission. The transmission (M6) is actually a four speed automatic operated by oil pressure and the shifting controlled by electric solenoids operated by a governor. To drive the car, you start the engine and disengage the clutch as in any manual transmission car. You then move the shift lever to the low range and then engage the clutch to start the car in motion. It automatically shifts from first to second gear. After the car is in motion it is shifted into high range with the clutch and shift lever. In high range it automatically shifts from third to fourth gear. When you let up on the accelerator the transmission freewheels in first and third gear. When you come to a stop sign or light, no need to touch the clutch or shift lever unless you want to shift back to low range. When you come to a stop the trans downshifts to third gear at about 11 MPH. Low range downshift is about 3 MPH. Acceleration from a stop in third gear is a bit slow to say the least. When driving in high range, pressing the accelerator to the floor between 35 and 40 MPH will down shift from fourth to third for a "passing gear".

As to your question about freewheeling, unless the transmission is in second or fourth gear it will freewheel. At a stop, engine off or on, the trans will automatically be in a freewheeling gear, first, third or reverse.

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  • 2 weeks later...

As an example of how misunderstood Fluid Drive, et al, is in the 21st century, I just found this description in an ebay listing for a decrepit '50 New Yorker: "The transmission is an Air Flow which means it's a manual, but once it warms up it becomes an automatic". Wow, that's quite a trick! Since it's actually a Prestomatic Fluid Drive, I guess that would be


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For normal driving you are supposed to start off in hi range (3d gear) and the trans automatically shifts to 4th. This does result in leisurely acceleration. But let's face it, if you wanted the fastest car you would have bought a Corvette. If you want the coolest film noir car you get a Fluid Drive Chrysler, a double breasted suit and a fedora LOL.

Bogart drove 40s Plymouths and Dodges in all those great Warner Brothers classics.

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