Fluid Drive

[MATT47025]

Were the Pilot house trucks offered with a Fluid Drive? Were these automatic?

 

[B1B Keven]

Yes.

No, they worked like a centrifugal clutch. 

[41/53dodges]

They did exist, they had both a standard clutch and the fluid drive, which was just a torque converter. It shifted just like any other standard 3 or 4 speed, just allowed you to not use the clutch at a stop

[Merle Coggins]

The light trucks were first offered the Fluid Drive Option in 1950, for the B-2 models. My truck has that option, with the optional 4 speed transmission. (3 speed trans was standard)

 

Basically, the Fluid Drive is a self contained fluid coupler (not a torque converter) that transmits power via hydrodynamics (like in a torque converter) although there is no torque multiplication (like in a torque converter). The output of the Fluid Drive is a clutch drive plate, which the clutch bolts up to (like the flywheel). The transmission then connects like a normal clutch setup. The main difference in the transmissions is a longer input shaft to account for the differences in the pilot bearings of the Fluid Drive coupler.

 

With Fluid Drive you can stop and start the vehicle without depressing the clutch, but you still need to use the clutch to shift the transmission like you normally would. When I'm just cruising around in town (up to 30 MPH) I will often leave my trans in 3rd gear and just drive like an auto, with brake and gas only. It'll be a little sluggish off a start sometimes, but not too bad. Once above 30-35 MPH I'll need to shift to 4th gear, using the clutch. The advantage of Fluid Drive, besides what I just described, is that you can't stall the engine. No matter how fast you release the clutch the FD will take over and smoothly transmit the power from the engine to the transmission. This is also beneficial for absorbing driveline surge.

 

Fluid Drive was commonly used in the Dodge, DeSoto, and Chrysler cars of the 40's and early 50's. In the cars they also used a standard 3 speed with the FD, but most often it was used in combination with the M5 or M6 Semi-Automatic transmission. This went by several names. Gyro-Matic, Sympli-Matic, Tip-Toe-Shift, etc. In 1953, for the B-4 models this transmission was first offered in the trucks. Its moniker was, "Truck-O-Matic".

 

The Fluid Drive Assembly

 

[MATT47025]

Thanks,

So how would I identify a pilot house with fluid drive?

[Merle Coggins]

It should have a badge on the hood sides, just under the "DODGE" badge. Some were a simple script badge. Others have a solid block with the Fluid Drive script embossed into it.

 

[HotRodTractor]

I had Pilothouse parts truck with a Fluid Drive and the 4 speed transmission at one time. I wish I would have kept the clutch and transmission out of it. Too late now. It was extra rough with the motor being locked solid so i didn't bother getting too deep into it after I rescued what I could.

[tom'sB2B]

I have a fluid drive truck. 3 speed on the tree. 1950. I'm happy with it.

[Dodgeb4ya]

A 1952 FD Truck nameplate badge....

[JBNeal]

I spotted a Fluid Drive near Denton a few years ago that had seen better days...the hood was gone, but the larger bell housing with the rear-facing vent was the indicator.  FYI I  summarized some info from one of Bunn's books, as well as found some literature of an early Fluid Drive

[Jeff Balazs]

Another distinguishing feature of the fluid drive trucks is the dashpot equipped carb. Usually a model DTG1 Carter B & B.

I have a 52 3/4 ton with FD 4 speed. The arrangement works very well when the carb is properly adjusted. In my opinion this option does complicate things though. The longer bell housing and fluid drive specific elements limit what you can do as far as transmission swaps if you wish to retain the feature.

The extra rotating weight and mass seem to compliment the general characteristics of these engines nicely giving it a bit more of the "flywheel" effect.....which I really like.

I would sum it up like this......I am glad I have it.....but it is a bit more work to restore a truck so equipped. I will probably use it most often taking off on hills and inclines where it has some decided advantages over the standard arrangement.

 

Jeff

[ol'skool]

Does anyone have resources or pictures of setting up the wiring/relay, etc for the fluid drive. Carb to the relays to the transmission. Stuff like that. Working on a 53 pickup with a fluid drive but it's all apart and the small pieces are missing.

[Merle Coggins]

There is no electrical components involved with a Fluid Drive. Do you have a Truck-O-Matic? There are some solenoids and whatnots associated with the M6 transmission, but I don't have anything on that.

[ol'skool]

There is the solenoid and governor on the transmission. Both had wires running to them but were cut. Were the trucks wired differently than the cars?

[Jeff Balazs]

Sounds like you will need to get your hands on a wiring diagram for a 53 with the Truck-O-Matic option. As Merle mentioned there are no wires associated with the fluid drive. I suspect if the wires were cut it was because there was a short or some other fault. If you don't already have a manual for your model you should definitely get one. There may be a few T-O-M owners here that can clarify this?

 

Jeff

[Merle Coggins]

That sounds like the M6 semi-auto transmission. It should be wired the same as in the cars but I can't confirm that. Maybe someone has a service manual that covers the B4 models and can copy the wire diagram for a Truck-O-Matic for you.

[ol'skool]

Thanks Merle. Some one cut the wires and started to disassemble the truck. My job is to get it back together, running and driving. So, any information is appreciated.

[JBNeal]

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