Rear diff swap chapter 2

[tom'sB2B]

I went ahead a got the axle from the 52 desoto. I disassembled everything today and it looks like its not going to work. I think I'm screwed. I don't think the new differential assembly is going to fit in my carrier. In the picture, the left hand diff is my old one (4.10) and the right hand one is the new one from the desoto (3.54). I haven't taken any close measurements to see and I'm reluctant to take it apart if it isn't going to fit.

I worried the whole thing is going to be a bust.

Any help is appreciated.

[Tony_Urwin]

I don't understand why you would need to swap carriers. If the third member doesn't swap right in, the carriers are not going to fit either. I swapped a DeSoto third member into my B-1-C rear axle housing with no problems. I had to swap the pinion flange, but it fit fine. I sleeved the pinion flange (Speedy Sleeve was CR 99159) cuz it had the usual groove worn into it.

There were two different axles and differentials for 1952 DeSotos. One for the 6 cylinder models and one for the straight 8's. Myabe you were unlucky enough to get one from the 8 cylinder model. You might be able to use the entire DeSoto rear axle assembly from the straight 8, though. It would require spring perchs on top of the DeSoto axle housing, and swapping the pinion flange. Myabe longer brake lines on the axle housing. Both the 52 truck and 52 DeSoto should have 10 spline axles, I believe. The DeSoto axle housing might be a little longer than the B2B, but the trucks have a little extra room in the rear fenders. Take a look at pictures of our trucks and you will see what I mean.

That's my understanding, but I get most of my knowledge from the real mechanics on this forum...

Edited October 4, 2010 by Tony_Urwin

[tom'sB2B]

My intention is to just swap out the gear assembly into my original carrier, though I can't quite decide if it is going to fit. The Desoto axle is 2.5 inches shorter than the one I have on the truck, so I don't think that is an option for me. I guess I will just have to try to swap it out and see if it works.

[Dodgeb4ya]

If the mounting gaskets are the same size and # of holes the complete carrier will bolt right in to your truck housing. Don't attempt to swap internals from one to another. If you do you will be hard pressed to get the ring and pinion gears set up correctly. Special tools required. Just swap the carrier assembly into your axle houising!

[greg g]

2.5 inches is 1 .25 on each side, is that difference really critical? As in will the tires rub on sheet metal or springs?? A couple spacers between the rim and hub should address it.

[Tony_Urwin]

I'm running 1.25" wheel adapters on my truck. You can buy spacers in different thicknesses for 40 or 50 dollars that would add some width.

[Phil Martin]

swapped ring and pinion from 3:73 into 4:10 rearend in b4b that I had. I know your suppose to have gauges and all to set it up. But how important is that in these old trucks with slow speed. I didn't have ant problems with mine.

[Dodgeb4ya]

swapped ring and pinion from 3:73 into 4:10 rearend in b4b that I had. I know your suppose to have gauges and all to set it up. But how important is that in these old trucks with slow speed. I didn't have ant problems with mine.

I need to hire you! You are good!

[grey beard]

In my humble opinion, you guys are mixihg several issues up here. First of all, to my best knowledge, Desoto never made a straight 8. That was Chrysler, and it was used only in New Yorkers and Imperials. Secondly, it is not possible to swap a car rear assembly into a Pilothouse without much fabrication and welding due to the fact that truck rears sit on top of the sprinhg pack and car rears bolt up from the bottom - the spring perches are on the wrong side.

Swapping center secrtions worked for me. The donor was a 1948 Windsor with a 3:73 rear ratio. I had to keep and use the Windsor axle shafts because the spline count was different on the truck. This ratio woried out very nicely on the highway. A 3:54 might be even nicer, but the gift horse into whose mouth I was looking at the time didn't complain, so I won't, either.

When you get into this stuff, you will also discover, as I did, that there are two different size u-joints used on our MoPars. The type with the bolts and cross bars is about 1/16-inch larger diameter than the newer clip type, but the bearings and the crosses are the same. My local Carquest carried both sizes on the shelf for 18 bucks. Go figure . . .

Good Luck

[Tony_Urwin]

I've never seen a DeSoto with the straight 8 either. But the parts book says they exist. And, yes, the spring perchs would have to be welded on top of the axle housing. Pretty basic welding job for a decent welder, probably 45 minutes or so

[greg g]

spring perches are a pretty easy thing to deal with. New ones can be purchased from Tractor supply in the trailer parts section for small money. Cut the car ones off, weld the new ones one. the most difficult part is assuring that you retain the proper pinio angle and welding the new ones at the proper position to retain that angle.

[Dodgeb4ya]

I also swapped a 1950 DeSoto center section into a 47 Dodge PU. Just swapped the yoke-2 hours done.

[Gary Manes]

There were a few odd years long before the war when the Desoto was available with a straight eight, but after the war only the V-8. I believe it was a 273 cu hemi.

Desoto only had a six cylinder option after the war until the V-8 became available which was initially limited to the Firedome.

I was looking at a 1954 Firedome last week, and offered a 1954 Chrysler 265 with powerflite for my '48 Desoto coupe. That is why it is kinda fresh in my mind.

[tom'sB2B]

I figured out why it won't work. The '52 desoto axle that I found has a 10 bolt pattern carrier and my truck has a 11 bolt pattern. Damn! What a rookie mistake! I'm just going to put my old 4:10 back on until I can find something that will work. I know that there's a thread growing on rear end swaps, but it would be interesting to know what year and model cars will work for a direct swap for those of us that aren't interested in swapping axles..a '48 windsor and a '50 Desoto will work. What else?

[Dodgeb4ya]

All my straight "8" chryslers up to 1950 and my chrysler hemi cars are all the bigger rear end 10 bolt carriers- didn't know that DeSoto used the bigger rear ends except in the wagons. You got one odd ball DeSoto carrier!

Bob

[Young Ed]

Perhaps it came out of a long wheel base car?

[tom'sB2B]

it came out of a 1952 four door desoto, that's all I know

[wayfarer]

I figured out why it won't work. The '52 desoto axle that I found has a 10 bolt pattern carrier and my truck has a 11 bolt pattern. Damn! What a rookie mistake! I'm just going to put my old 4:10 back on until I can find something that will work. I know that there's a thread growing on rear end swaps' date=' but it would be interesting to know what year and model cars will work for a direct swap for those of us that aren't interested in swapping axles..a '48 windsor and a '50 Desoto will work. What else?[/quote']

As you have found so far, nothing will be an exact, one-for-one swap. Swapping the entire axle assembly has some benefits; better gear ratios, better brakes, easier to source parts. Installing new spring perches is pretty basic. Get out your tape measure and compare widths to some on the following charts:

http://www.rosevillemoparts.com/reference_enginetrans.php?SID

http://www.differentials.com/pdfs/39.pdf