The Stovebolt Site Forums The Shop Area Engine Shop I swapped my rear end!

Well I finally upgraded my rear end. I now have an open driveline. I removed the old torque tube differential and kept the rearend housing. I installed a pumpkin from a '55 half ton (fit right in perfect). I also changed the tranny to another sm420 that has an open rear yoke. Really came out nice! I posted a bunch of pictures of the whole process on my Yahoo Photo Album . It's in the "rearend swap" file. I haven't been able to go for a longer cruise 'cause it won't stop raining. This opens up possibilities later on if and when I switch to a later model 6 cyl. motor.

John,

Awesome job Man!

It looks like it really turned out very well.

Also, nice photo album with great documentation of what you did to make it all happen.

I am assuming you were running 4:10 gears before the rear end swap? If so you will have to let me know if you really can feel a difference between the 4:10's and the 3:90's.

congrats!! I've been wondering if it's possible to just keep the 54 axle housing in place and replace the pumpkin and axles from a spare open driveline axle that just seems to have bolts in all the same places and same measurement here and there....and you did it first!!

Nice job John, now you'll be able to get around town a little faster. Great to know you can just change out the pumpkin to retain the stock axle width. Great pictures.

George

Nice photo documentation. I appreciate you sharing that information John. Looks like your son is a fine welder.

very nice, man,, I wish I had just a little of the talent you guys have.............Fred

Thanks alot guys. The weather finally cleared up so I went around the block a few more times this evening. Even though it's only a 3.90 rear end (the other was a 4.11), I can really tell a difference in speed. The tranny is way quieter too. My next step is to take it out on the main thoroughfare. I want to get it to top speed and see what she'll do....but I got to build alittle more confidence.

Terrific job John. Thanks for sharing it.

Cheers mate

Bob

Let me ask you guys a question. :confused:

I have a 54 sedan closed drive line rear end under my 37 1/2 ton truck. I also have a 55 car rear end in my possession. Will a 55 car rear end pumpkin fit into a 54 car housing? Well, that's not really a truck question I guess, but does anyone know or know anyone who knows?

It sure would make things easier for me as I work toward that T-5 installation, which, of course, requires an open drive line.

Thanks,
Joe

Excellent job! Pictures are worth a thousand words they say and this is a perfect example. One question about removing the spring perches from the 55 axle. Can I do it with a grinder or does it need a cutting torch?
Thanks.

John,

Wonderful pictorial..why did you R&R the perches. Did I miss something?


Stuart

oldblu40 - To remove the spring perches, I used an electric angle grinder with a 1/8" thick abrasive wheel. Carefully cut throught the weld and it'll pop right off.

automarc - The torque tube directly ties the rearend to the transmission. It is the only thing that keeps the whole rearend housing from rotating backwards when you step on the gas. So you remove the torque tube, the welded on spring perches keeps the rearend housing in one position.

Nice job is right on! I did the same to my '49 torque tube to '57 3.90 open drive line conversion. I use a '62 3 sp+od, .70 od x 3.90 = 2.73 final drive in od, around 2100 rpms at 65 or so.

I'm looking at a truck with a 55 235, 4spd Saginaw, and a 55 Chev car rearend..
Does anyone know what the gears in that rearend might be?
Thanks, Shoop

I heard sometime ago, that a 1966 3/4 pumpkin will fit these old rearend housings. Does anyone know if this is true ?

Thanks,Tim

is the rear end housing the same on a 37 as it is on a 45??? I sure would like to know. I need to put a open line in a 37. Thanks for any info as if this is do-able to.....and ole Joe ask if the 55 open would fit into his 54 sedan closed rear end?? Now there is TWO questions, anyone one know?

nice job!! why isn't the original spring setup suitable for open driveline?? would you elaborate?? I will eventually try the same project but I was going to leave the stock axle housing in place. thanks

Tim, that works for 3/4 and 1-ton trucks after '47. The Eaton H0xx axle was used until '72, '67-'72 trucks had a much more highway friendly 4.10 gear ratio available.

Thanks for the info.

You used a '55. What years will work. I will be working on a 46 burb. Would like to have the info before I go to the junkyards.
Thanks
Jim

By the way, I learned a ton just looking at the picts!!!
Jim