1950 Desoto Custom

[falconvan]

I just brought this home over the weekend. Neat old Mopar that has already had some nice upgrades. It'd been fully rewired and converted to 12v and has a nice front disc brake conversion kit on it. The only thing I'm not real crazy about is the semi-auto trans and the Fluid Drive. The motor runs excellent and it drives pretty decent but it leaks oil from the front crank seal, the oil pan, the rear main, and the side tappet covers which has made an unbelievable mess underneath. Just a lot of 70 year old dried out gaskets and seals. So I think i'm going to go ahead and pull the drive train, clean everything up and put a full gasket kit in it and reassemble. 

 

While I'm at it I'm trying to decide to keep the stock trans setup or switch to a regular three speed manual using a Plymouth bell housing, trans, flywheel, shift rods, etc. I know I'd have to more the rear cross member but does anyone know if the column shifter has the positions for a standard three speed?

[desoto1939]

With the fluid drive the gear shift is on the column and it should be a 3 speed if I remember correctly. So you would have the option of not using the FD but just the option of shifting manually.

 

I have a 39 desoto and it was the first year to have the three on the tree. So thry to pushing the clutch pedal and then try to see if you can shift manually into a gear. remember it is an H pattern    Left leg of the H pattern up is reverse straight down is 1st then up and over to the top is 2nd and then down to 3rd.  If you can do this then you have a manual shifting.

 

Keep in touch  Also are you a member of the National Desoto club. The 2020 National Desoto Convention will be held in Wisconsin this year.  We also have model coordinators that can also assist with questions.

 

Rich Hartung

Desoto1939@aol.com

[RobertKB]

1 hour ago, falconvan said:

While I'm at it I'm trying to decide to keep the stock trans setup or switch to a regular three speed manual using a Plymouth bell housing, trans, flywheel, shift rods, etc. I know I'd have to more the rear cross member but does anyone know if the column shifter has the positions for a standard three speed?

 

I say, if it isn't broken, don't fix or change it. Not sure what Fluid Drive you have. Some have a reverse and two ranges, low and high. Once the car is in gear you can drive it like an automatic, especially using the high range. An old time mechanic I know worked in a Chrysler dealership and many Mopar products this age withe Fluid Drive. He said they were basically indestructible.

 

Nice find by-the-way!

[falconvan]

Thanks; I think I've got the Gyromatic. It has two solenoids on the trans and a high/low range on the shift. It feels mushy taking off in high range and wouldn't shift into 4th unless you got it almost to 40MPH and let off the gas. By then the RPMs are really high and it doesn't always upshift. The idle is hanging; may have something to do with it. Also, if you sit stopped in gear with your foot off the clutch it only runs a few seconds before it dies. 

 

But it does cruise pretty nice in 4th once you get it to shift and get going. I drove it home for an hour at about 55-60 mph and it rides pretty smooth. 

 

I'm also wondering when they rewired the car and did the 12 volt conversion if that has something to do with the issues? 

 

I think I would rather fix what's there as long as it can be made to work right.

[lepic56]

12 minutes ago, RobertKB said:

 

I say, if it isn't broken, don't fix or change it. Not sure what Fluid Drive you have. Some have a reverse and two ranges, low and high. Once the car is in gear you can drive it like an automatic, especially using the high range. An old time mechanic I know worked in a Chrysler dealership and many Mopar products this age withe Fluid Drive. He said they were basically indestructible.

 

Nice find by-the-way!

I agree with Robert, My Dodge does not have Fluid Drive , it is a regular 3 speeds,,  but I wish I had a Fluid Drive.. but it's your call.. they are so much fun to drive, maintain and repair.  

[lepic56]

5 minutes ago, falconvan said:

Thanks; I think I've got the Gyromatic. It has two solenoids on the trans and a high/low range on the shift. It feels mushy taking off in high range and wouldn't shift into 4th unless you got it almost to 40MPH and let off the gas. By then the RPMs are really high and it doesn't always upshift. The idle is hanging; may have something to do with it. Also, if you sit stopped in gear with your foot off the clutch it only runs a few seconds before it dies. 

 

But it does cruise pretty nice in 4th once you get it to shift and get going. I drove it home for an hour at about 55-60 mph and it rides pretty smooth. 

 

I'm also wondering when they rewired the car and did the 12 volt conversion if that has something to do with the issues? 

 

I think I would rather fix what's there as long as it can be made to work right.

how about the two solenoids,,  they must be 6 volts,,  have they have been disconnect or  did the solenoids have a step-down voltage to 6 volts apparatus of some sort???

[falconvan]

They have new wiring on them so I would think they must have stepped it down somewhere. The whole car has been rewired and it looks like they did a good job but that doesn't mean everything is right.

[falconvan]

Transmission looks like this one.

[Doug&Deb]

The Gyromatic doesn’t take a 12 volt conversion well. I have the same trans in my Coronet and it works great. The other problem you may run into is converting to electronic ignition. It can be done but research this forum for the correct way to do it. Without knowing how the 12 volt was done I’m afraid you will have to do a hand over hand check of the wiring. If you have a service manual check how your wiring compares to stock. Good luck.

[falconvan]

Yeah, I read that in a few other places. I guess another option would be to find one of the three speed manual transmissions that came with the Fluid Drive coupling. It seems like one of the 48 Dodge sedans I had was set up like that.

[Doug&Deb]

I would check yours first. That trans is pretty bulletproof. It’s probably something simple. 

[falconvan]

If I can find someone that has successfully converted one to 12 volt I'll probably keep it. So far all I'm reading is a lot of stories of people who tried it and it couldn't get it to work right.

[Doug&Deb]

Are you determined to keep the 12 volt conversion? A properly maintained 6 volt system works great. If staying 12 volt then I’m sure someone has successfully done this. 

[falconvan]

Yeah, I think so. I'd like to leave the work the previous owner did to the car and work from there. I'm just about convinced to leave the Fluid Coupling and just go with the standard 3 speed manual that was in the Dodge Fluid Drive cars. Seems like they are cheap and plentiful plus it would basically be a bolt in. 

 

Since I'm pulling the motor and trans to fix all the oil leaks, I hate to put the Gyromatic back in without knowing if I can get it to work right. It would suck to have to pull it again if I cant get it worked out. 

[lepic56]

how about the 1948 - 1949 MTSC  library on these sites:: My Mopar.com or the Imperialclub.com , On the subjet of the  transmission they have quite a few  sessions than you can watch and read,,  it does not matter if it 6 volts or 12 volts for the diagnostic.  But a 6 volts solenoid on a 12v system may overheat with long period of being energized?? I don't know, it will work for some times ,, but how long,,??  I'm sure there are a lot of members that did the convertion to 12 volts that can be better than me!!  lol

 

Topic http://www.mymopar.com/index.php?pid=451

[falconvan]

Started disassembly today. Look like the oil leaks were mainly coming from the front and rear crank seal. The amount of built up sludge under the car is unreal and look like it has been going on for many years. 

So the plan for the engine is just a good cleaning and replacing all the gaskets as long as the insides look good. I also got this rebuilt 360 with the car but I think I’d rather stay with the flathead as long as it’s in good shape internally.

 

I have to make a decision on a transmission. The clutch surface on the fluid coupling is grooved and cracked really bad. Plus the the Gyromatic didn’t shift right at all so fit now I’m thinking of either a regular 3speed manual Fluid Drive from a Dodge, or switching over to the Plymouth 3 speed manual. I really don’t want a gear shift sticking through the floor so that leaves a five speed swap out. But it was good progress for day 1. 

Edited February 29, 2020 by falconvan

[RobertKB]

Please use the flathead!

[falconvan]

Absolutely. Sold the 360 today. 
 

Looks better after a couple cans of degreaser and an hour with the power washer.

[RobertKB]

Glad to hear! Yes, the old flattie looks better already! A bit of silver paint will help also. I use varsol to get the last of the grease off before painting. Nothing wrong with putting it back in they way it is either as the car is a survivor. Going to enjoy your project going forward. Please keep the posts coming!

[falconvan]

Will do! I’m going to go ahead and pull it apart. Other than the oil leaks it ran great, quiet, good oil pressure, plugs burned clean; but when I pulled the side covers it had a ton of sludge in around the valve springs. It needs a serious internal cleaning and everything checked.

[Dartgame]

If you were going to keep the original tranny - another way to go would have been to rewind the 6 volt solenoids to 12 volt. 

[falconvan]

After finding the flywheel surface of the Fluid Coupling in really bad shape and the seal leaking badly, I decided just to change over to Plymouth parts and have a regular three speed manual.. I'm going Friday to pick up a good running 218 and three speed; will resell the 218. 

[ACJCF2]

My 1949 Coronet was converted to 12 volts with alternator when I purchased it and the Gyromatic worked fine once I returned the idle speed to a correct 475 r.p.m. A new 12 volt battery livened the shifts up as well. I found no evidence of any Runtz or other step down aids within the system. I'm going a different route and pulling the Gyro and adapting a 200R4 transmission.

Edited March 21, 2020 by ACJCF2
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[falconvan]

That sounds cool; what adapter plate are you using?

[ACJCF2]

I'm going with the Wilcap adapter and starter.