Drive Shaft

[lalkie64]

I have replaced the 4-speed in my 52 B3B with a 3-speed.  Does anyone know if the drive shafts are the same length?  I put the 4-speed shaft in but it seemed to strech the shaft quite a bit.  It seems to work.  I would appreciate any help.  Thanks Larry

[Merle Coggins]

The 3 speed is a much smaller transmission. I don't know the measurements but I'm sure it's shorter, meaning you'd need a longer driveshaft. If you know how much shorter it is you could probably have a driveshaft shop add that much to your shaft.

 

Merle

[Don Coatney]

I posted incorrect information for a 2 piece driveshaft. Sorry.

 

[Young Ed]

That may not be 100% correct for an old truck. At least for my 46 pickup the slip joint is between the ujoints.

Assuming you know the correct yokes on both ends this diaghram shows the correct way to measure. The "A" measurement is what you want.

 

[Don Coatney]

This is for a 1 piece driveshaft. Was your truck a 2 piece?

[Merle Coggins]

Yes, trucks are a 2 piece driveshaft with the slip joint just behind the front u-joint.

[Don Coatney]

Then what I posted is incorrect

[Dodgeb4ya]

All 1946-53 Dodge 1/2 through 1 ton  trucks use a one piece driveshaft. 1948 up use a slip yoke at the front end of the shaft.

Shown is a 1951-53 one ton 126WB, 4 speed Fluid Drive trans driveshaft. And some earlier and different 1/2-3/4  ton front slip yokes off the one piece dodge shafts 1948-53. There are 29 different 1/2 through 1 ton drive shaft listings in the parts book for B1,2,3 and B4 trucks!

Merle posted the proper answer to the driveline needing to be longer to reach the shorter little 3 speed transmission.

Edited June 8, 2013 by Dodgeb4ya

[wallytoo]

must be a terminology thing. i'd always considered a driveshaft like bob posted to be a "2-piece".

perhaps the more specific answer is that truck driveshafts have the slip-joint between the u-joints, while some car shafts have the slip joint "outside" of the u-joints, and a rigid connection between the joints.

wally

[Dodgeb4ya]

It must be a terminology thing- yes I suppose. I quickly scanned Google and came up with these 2 piece driveshaft searches...

 

[4852dodge]

When I changed my truck from a 3 sp top shift to 4 speed the drive shaft was the same.  The u joint mount on the 4 speed was shorter than the 3 speed making up the difference in case lenght.  This was on a 1 ton it might be different on the lighter models.

[lalkie64]

thanks for the help guys.  I havent worked on the truck for a while but will look at the yoke length.  Thanks again

[desoto1939]

In one of my old U joint catalogs I have pictures that they did have availble the slip joint style driveshaft for the late 30's cars.  I show a picture of a slip joint driveshaft for my 39 Desoto.

 

Sinc e you chnaged to the 3 speed I would recomend that you get an entire new DS made with the modern cros style u joints and then also get spares for each end.  This way you have a modern DS and also modern u joints that can be lubed via a zerk fitting.

 

The cost to reto the old shaft will be about the same for a new one and then with the old one being cut and welded you still have an old ds and this could be off balanced.  Get the entire new shaft made and you will be better off.

 

Rich Hartung

Desoto1939@aol.com