Technical Gear changed 1949 Desoto

Hello I need help with gear changes on 1949 desoto . it's a semi automatic

 

we need more info. What caliber is it?

 

Honestly I don't know this is my first purchase on a car like this everything is fine it's in great condition .. I just need help the gears .. I know where reverse and first gear is the problem is getting to second and third and once I move the lever down I'm not sure whether that's second or 3 and it ends up stalling

 

semi-automatic? What caliber??I was yanking your chain. But at least now we have a little more information, from your first post, I wasn't even sure if you were talking about a ring and pinion change or what.

 

4 spd semi-auto M6 transmission with Fluid Drive coupler.
Low range and high range and reverse.
Column shifter looks like 3 on the tree, but it isn't.
Start engine, with trans in neutral or an y other gear, with the clutch pushed in.
Once running, let clutch out, and engine does not stall, and you are not moving until you put foot on the gas pedal.
In high range, you drive to about 20 mph, take foot off the gas, trans automatically shifts into 4th gear, if you floor the engine to say pass a car, it will automatically downshift, as it will when you roll up to a stop.
If this trans is a regular 3spd and fluid drive you can shift as per normal or leave in 2nd or 3rd, and drive around like that, even from a dead stop without using the clutch, and engine will not stall, because of the fluid drive coupler, works much like a Polaris ATV with a cvt....

 

Yes it's a semi automatic 3 speed 6 cylinder

 

Yes flat six fix ... it's a fluid drive that's what I'm thinking it is because it has a fluid drive logo by the glove box .. honestly I started off of third and that's when is let go of he gas and it shifts to four but when I accelerate it makes a weird noise and it ends up slowing down

 

I'm thinking Richie Cunningham.

 

Go here www.p15-d24.com
This could be an electrical problem with the kickdown, the governor, and other possibilities. I would suggest getting the service manual too.
Fluid level in coupler too low possibly, usually these do no leak, and/or go low.
Seek out guys like Dodgeb4ya, he is very knowledgeable on this system and design.
Rusty Otoole on this forum, knows quite a bit about these too.
Does the trans go back to 3rd when you come to a rolling stop, have you tried low range to see what happens when the trans shifts from low 1 to low 2.
This set-up is very reliable and bullet proof when maintained well. They are not neck snapping by no means but very cool to drive if you are not in a hurry.
That old Desoto should be able to cruise at 70 mph all day long if all is well...

 

Also the shifts are ,up is first,middle is neutral and back up is reverse and down is third so how do I get from 1st to second and 3rd to fourth,.. if there's even a fourth gear

 

How about this story "bucko",http://www.allpar.com/cars/desoto/suburban-1951.html

 

Yes I've tried low range ,, I did the exact same thing once I hear that the gear needs to be changed I let go of the gas pedal and go back on it but the thing is that's where it stalls even tho when I have my foot all the way on the gas pedal it won't go it will just slow down and stop

 

there are only two forward gear positions on the shifter. You get high gear by letting off the gas pedal, and let it shift automatically.

As mentioned, there are some electric parts involved, and if there are problems with the wiring, or the electric parts, or internal worn parts inside the transmission, it won't work right, even if you do understand how to operate it.

My experience with those was almost 40 years ago, replacing the transmission in a friend's 50 Desoto with the good used one from his 51 dodge parts car. I took apart the broken trans to figure out what was wrong with it...I found out what was wrong, but I forgot what it was over the yeas. Neat stuff. It was challenging to keep them working when they were not very old, even more so today.

Good luck

 

1st to 2nd gear, let off gas pedal it will up shift at certain specified speeds, same for 3rd to 4th, yes there is a 4th, it is a semi-auto electrically operated hydraulic trans, very simple rugged and reliable.

 

Do you have a shop manual to help you figure it out? if not, maybe you ought to see if you can find one. Mine's out in the shop...

 

Looky here,

 

No I do not have one ..

 

now you do!

 

T

Thankyou! so it might be electrical problems in the trasmission ?

 

It could be, but seriously go to the site I mentioned and do a search, also ask Bob H aka Dodgeb4ya, he is an expert with your set-up, tell him Rocky sent ya

 

And read this, this will tell you what your car is capable of, http://www.allpar.com/cars/desoto/suburban-1951.html

 

Will do ! Thanks Rocky.. would u sent me the link again to get a hold of Bob H

 

www.p15-d24.com you will need to become a member to be able to PM Bob

 

My engine in my 55Fargo pickup, a 237 with a George Asche custom built intake, tru split exhaust, rebuilt Carter B&B big truck carbs, a 25 inch 237 engine.

 

Your car has the Fluid Drive and M6 semi automatic trans. It has certain features of both manual and automatic transmissions. But, other than the clutch pedal, you drive it like an automatic.

The gear lever has 3 positions. Toward you and up, Reverse. Straight up, Low range. Straight down, High range.

To go for a drive try this method. With the trans in neutral, and the hand brake set, start the engine and let it warm up until it will drop down to a slow idle (400 RPM)

Step on the clutch, shift into High range, and release the clutch fully. You are now sitting still with the car in gear and your foot on the brake like an automatic. Release the hand brake, step on the gas and take off.

When you get going over 14MPH lift off the gas. You should hear a soft *click-clack* from below the floor boards. That is the trans shifting into high gear of high range. Step on the gas and go someplace.

If you want to stop for a light step on the brake as you would with any automatic. When you want to take off step on the gas, when you reach 14MPH lift off the gas and shift up.

The trans will shift down automatically when you stop and it will kick down if you floor the gas pedal at any speed up to 50MPH.

For going slow, starting off on a hill, or going in deep sand, snow or mud you can use Low range. It works the same as High range, but will shift up at 6MPH. You can shift from High range to Low range using the clutch and shift lever.

Shift into reverse using the clutch. Do not slip the clutch, use the Fluid Drive for that. The clutch is small and will not stand much abuse. The worst thing you can do is gun the engine and slip the clutch like mad. Just put it in gear at idle and use the Fluid Drive.

The Fluid Drive and M6 trans are simple, rugged and reliable. Most faults are very easy to fix . Usually all that is wrong is, they need to be topped up with oil or there may be a loose or broken wire. These 2 things account for about 90% of things that go wrong.

Any other questions just ask.

 

There are 3 main things that mess up these cars shifting. 1) engine worn out or out of tune. Should idle down to 400 - 450 RPM smooth and quiet. If it will not idle down it will not shift right. 2) Trans and Fluid Drive filled to the right level with TDH tractor fluid, ISO22 or ISO32 grade. Or straight 10w oil. 3) wiring frayed, broken, or otherwise messed up. Usually under the hood because the heat dries out the insulation. There should be a little metal box the size of a box of Tic Tacs on the air filter support or on the firewall. 2 wires from the coil to the box, 2 wires from the box to the carburetor and 2 wires down to the transmission. I can furnish a wiring diagram if necessary. They are just ordinary wires, you can replace them easily.

One other thing that seldom happens, is the governor gets gummed up. Can be fixed with a shot of Brake Kleen spray and a piece of white paper but we won't go into that.

As you can see most of the things that go wrong, can be fixed for a few bucks in your garage. Other than that, they are pretty rugged and seldom wear out.

 

Thankyou very much rusty o'Toole I will try these methods out if I still can't get my desoto running normal

 

Another question why does the car end up stalling ? is it because I'm not shifting ?

 

how about you make a video of you driving and it stalling, and put it on youtube? it's really hard to tell from just a short description, what is really going on.

 

Your car should not stall. It should idle down to 400 to 450 RPM, about half the speed of a modern engine. It should idle smoothly and pick up speed without stalling bucking or misfiring.

If it won't something is wrong. Exactly what is wrong, I have no way of knowing. You could start by doing a compression test. Your compression should be about 110 PSI in all cylinders. As long it is above 80 and fairly close to the same in all cylinders you should be good to go.

Next is tuneup. Points, timing, clean spark plugs, good ignition wires etc etc. It might even be necessary to adjust valves and rebuild the carburetor, I have no way of knowing from this distance what is the matter.

They are a simple basic engine and not hard to tune up if you understand them. Unfortunately few mechanics are left who even know about carburetors and points ignition. The best thing is to get a repair manual and go by that. My method is to inspect measure and test, but change things as little as possible until I know what is going on. If you rip and tear things apart you will soon have things so messed up nobody will be able to figure it out, without going right back to basics and redoing everything. So get a manual and carefully check one thing at a time until you have it purring.