1947 desoto gearbox

[hemsbydodge]

hi folks,

please could i get some advise on this desoto that i have shipped into england from washington state.

atahe car is a 1947 desoto custom, with a fluid drive, but i have a few problems with the fliud drive and that gearbox.

1. the fluid drive does not disengage, as if it has been welded up or something similar, was this a common job done to this fluid drive to make them drivable?

2. I cannot engage first gear, the column shift moves into place, but the gate is solid, not fault can be seen from the outside, do any of the two soliniods have any play in the first gear, as at present the 6 volt electrical supply is disconnected. what do the two soliniods do and also what does the small generator do?

many thats ,

I entand to put the car on the road as a standard car, although totally stock, it may prove too be too slow and hungry on gas to use over here

shaun

[greg g]

well there is some terminalogy that has to get understood first. The fluid drive is a hydraulic device bolted to the crankshaft and itermediate to a standard clutch. the transmission behind the fluid drive is likely an M6 semi automatic. the clutch needs to be used to change or enter gears. Your transmission is a dual range with two gears in each range. Low range (located with the shift lever in the up and toward the dash board position)has a very low set probably good for 10mph in the lowest gear and 18 to 20 in the upper gear of low range. This gear set is normally ignored unless you are driving off road or in extremely slipery conditions. The upper range for normal driving is located with the lever down and toward the dash. This features 2 higher gears, a lower one for starting from a stop and an upper for highway speeds (18 mph and up) Reverse is located by putting the lever in the up and towards you position. The clutch must be used to select reverse from neutral the center position of the shift lever, and again for shifting from reverse to either of the forward drive gear sets. the normal first gear position does nothing.

The two electrical items are as you noted a solenoid that does the gear changes, and a governor that decides when the upshift can be made, and when a down shift can be accomplished. There is also a connection to the carburetor and possible one for the coil, as some had and interupter that shuts down the ign momentarily to put some slack in the drive line to ease shifts. When drivig a lift of the accelerator, will prompt an upshift. A downshift can be adressed by flooring the pedal under a governor determined speed. The trans mission will also downshift when the car comes to a stop or slows to a governor determined speed. Normal driving can be accomplished without using the clutch, just the gas and brake, similar to a modern automatic, until reverse or low range wants to be selected, when the clutch will need to be used.

I would suggest you go to ALL PAR.com ad search for either M6 or tip toe in the transmission section. Also a look into the repair section of the Imperial Club website will allow you to review a technicians training pamphlet which will also better explain the systems and their functions.

http://www.allpar.com/i/search-results.html?cx=partner-pub-7826641504095217%3Amu641f-qklj&cof=FORID%3A10&ie=UTF-8&q=m6&sa=Go#1609

http://www.imperialclub.com/Repair/Transmission/index.htm

ONE VERY IMPROTANT NOTICE, there is no mechanical conection between the engine and transmission, so there is no compresson braking applied to the drive line. A PROPERLY OPERATING PARKING BRAKE is a must (or a set of wheel chocks) for parking on anything but dead level terrain.

Welcome and Good luck.

Future posts should probably go in the general discussion area as the tech area is usually reserved for folks to post tricks tips and shortcuts they have used for various procedures.

Edited August 15, 2011 by greg g

[hemsbydodge]

hi greg ,

thanks for taking the time to describe the gearbox setup ,should have it sorted soon now,

many thanks

shaun

[Rusty O'Toole]

A little late but better late than never.

To answer your last question first. When your DeSoto was new it had a top speed of between 85 and 90 MPH and overall performance similar to the contemporary Bentley or Rolls Royce. Whether this is adequate for your needs I do not know but it should be good enough. You will not be holding up traffic if that is what worries you.

It is suggested you keep your cruising speed around 50, possibly up to 60 out of respect for your car's age. You will soon find what you are comfortable with once you start driving it.

Your engine will run beautifully on the cheapest low octane gas. Leaded or unleaded makes no difference, your car came with hardened valve seats from new. If using unleaded it can't hurt to add a little Redex or upper cylinder oil but it is not mandatory.

When it was built, gas was about 70 octane. Mileage, 17-18 on the highway rather lower in traffic. On the whole not bad for a car of its size. You are unlikely to do much better with a more "modern" engine, certainly there would not be enough savings to justify it.

The Fluid Drive is an early effort at an automatic transmission. It has characteristics of both an automatic and manual transmission.

Recommended driving technique

Start the engine in neutral and let it warm up with the hand brake on. Once it idles down smoothly, step on the clutch pedal and shift into high range (pull lever straight down). This range is recommended for all normal driving.

Release clutch fully. The car will idle in gear like an automatic. Release hand brake, step on gas and drive away.

You will start off in 3d gear. To shift into 4th, lift your foot off the gas pedal at any speed above 14 MPH. You should hear a *click-clack* from under the floor boards. This indicates you are in high gear. Step on the gas and go someplace.

If you require extra power for passing or hill climbing, press the gas pedal to the floor and the transmission will "kick down" into 3d at any speed up to 50 MPH.

Low range is the same except you pull the lever straight up. Recommended for starting on steep hills, driving in deep snow, sand, or mud or for slow speed driving. Shifts up from 1st to second when you lift off the gas, except it will shift up at 6 MPH.

It is possible to start in low range, then shift into high range using the clutch in the usual way.

Reverse gear likewise, to shift into reverse pull the lever towards you and up.

There is no "first gear" position as such. There are only the 2 forward gear ranges, "first" was omitted.

If you remember the VW Beetle "Automatic Stick Shift" of the seventies, it was very similar to Fluid Drive.

By the way there is engine braking with Fluid Drive but only when in 2nd or 4th. When you are in 1st or 3d the transmission freewheels to allow the gears to shift.

Edited August 26, 2011 by Rusty O'Toole

[Rusty O'Toole]

If you want to see a 1947 DeSoto in action watch this chase scene from Sunset Boulevard.

http://www.youtube.com/watch?v=ZhP5hbnaSVI

The chase occurs between 9.55 and 12.25.

See how one performs with the original engine and fluid drive ha ha.

[55 Fargo]

If you want to see a 1947 DeSoto in action watch this chase scene from Sunset Boulevard.

http://www.youtube.com/watch?v=ZhP5hbnaSVI

The chase occurs between 9.55 and 12.25.

See how one performs with the original engine and fluid drive ha ha.

Hey Rusty this vid is no longer available. How can I see it, sounds interesting.

[Rusty O'Toole]

That is wild. I watched the video this morning before posting it. They must have taken it off today.

The video was Part 1 of Sunset Boulevard, a 1950 movie starring Gloria Swanson, William Holden and Erich Von Stroheim.

Between 9.55 and 12.25 minutes into the film, there is a chase scene where 2 heavies in a 1947 DeSoto coupe try to repossess Holden's Plymouth convertible.

I thought it might be of interest to the 1947 DeSoto owner.

I don't know where you could get the movie if it is no longer on Youtube. I have an old video tape of it, that is how I knew the DeSoto was in there. Perhaps you can get it from one of the old movie sites on the net.

[55 Fargo]

Hi Rusty, I believe I have spoken with you on AACA Chrysler Board. I have a 47 Chrysler Coupe, without, fluid drive, I have a 218 long block and standard 3sdp trans and dry clutch, 3.73 rear end, and do not think I would go back to fluid drive, although I have a fluid drive and M5 trans sitting in my garage.

I am hopeing at some point to rebuild a 251 with full flow oil filtration, and correct engine # for a C38 Royal.

My plan is to get some more hp out of the 351, and install an 3 sp R10 OD trans.

I know i should go back to a Fluid Drive for correctness, but my car is just an old driover that I fixed up. This car was ready for scrap, was extremely rough, but I saved her from becoming chinese steel.

I bought the car from my uncle in 1988, and did not work on her till 2005, and have been driving her since 2007.

[Rusty O'Toole]

Hi Rusty, I believe I have spoken with you on AACA Chrysler Board. I have a 47 Chrysler Coupe, without, fluid drive, I have a 218 long block and standard 3sdp trans and dry clutch, 3.73 rear end, and do not think I would go back to fluid drive, although I have a fluid drive and M5 trans sitting in my garage.

I am hopeing at some point to rebuild a 251 with full flow oil filtration, and correct engine # for a C38 Royal.

My plan is to get some more hp out of the 351, and install an 3 sp R10 OD trans.

I know i should go back to a Fluid Drive for correctness, but my car is just an old driover that I fixed up. This car was ready for scrap, was extremely rough, but I saved her from becoming chinese steel.

I bought the car from my uncle in 1988, and did not work on her till 2005, and have been driving her since 2007.

There is nothing wrong with changing to a manual trans. A 251 should work great in your car. I know guys who rebuilt their old flatheads, thinking they would keep them stock and put up with the lack of performance, and were pleasantly surprised at how well their car performed with a fresh engine.

It is characteristic of the old Chrysler corporation flatheads that they can keep running without complaint in an advanced stage of wear, even though they are down on power. You might not realize how big a difference it makes until you drive a freshly rebuilt one. A good 251 might surprise you.

Your 3 speed and 3.73 gears would make a good combination for performance.

I have thought about using a Chrysler overdrive 4 speed from the seventies/early eighties if I could figure out how to make the column shifter work.

[55 Fargo]

Thanks Rusty, I also think a freshly rebuilt 251, with some things done to raise hp, will make a huge difference than my unrebuilt 218 from a Plym Bodied Canuck Dodge.

I will keep my current format 3spd trans and dry clutch, with a 3.73 diff, and am in the process of acquiring a R10 OD trans locally, that will probably need a rebuild too.

The 251 rebuilt, and getting the HP to ay 130-140 hp, should be very noticeable compared to my current tried 218, that runs great with decent oil pressure, but lets face it, she left the factory 60 years ago, and running this great, is a marvel to it's Chrysler engineers.......Fred