rear end question 32 to 40?

Not easily,no....but it's do-able. Main problems are the spring, 32's are curved and sit in a curved pocket within the rear crossmember. To do it properly you'd need to change the rear crossmember for one that suits the straight '40 spring, and that becomes a body off project. Guys have been known to grind the leaf springs down to squeeze them into the '32 crossmember but that's not a good thing to do to the spring that holds your car's suspension in place, as the grinding process will weaken the spring properties and causes a concentration of stresses where the spring has been cut away, promoting spring breakage with use.
The other problem is the torque tube , if you want to use the '32 tube and driveshaft , the splines are different and the length from the centerline of the axles to the bolt face of the pinion flange are also different, so you'll end up with a rearend slighty out of center in the wheel arch, even once you've overcome the spline problem. Another minor issue is that although the t/tube bolt patterns match,the inner bore doesn't and the larger '40 pinion bearing doesn't allow the t/tube to seat on the flange and so needs to be machined out a bit. The best plan is to use the '40 tube and driveshaft ,suitably shortened....if you can find a shop prepared to take on the job of shortening and resplining as well as cutting down the torque tube outer length. You'll also need to trim off the forward mounting lug for the radius rods and relocate it ,then re-weld it in it's new position. So like I said,it's do-able but there's a fair bit needed to make it happen.....regards, Colin.
 
I've done it but the car isn't on the road yet. I did the "grind the spring" thing and below is a picture of what the leaves look like to get them into the '32 rear crossmember. Also, if you shorten the '40 torque tube and driveshaft, you'll have to make the torque tube about 3/8" SHORTER than the '32 torque tube. This is because the later banjo casting is about that distance longer from the axle center line to the torque tube flange than the '32. As far as the "hot rod" stigma, at least you aren't putting in a 9" rear with coil overs!
 

Attachments

  • rear spr notched.jpg
    rear spr notched.jpg
    34.7 KB · Views: 67
I bought a '32 coupe from a guy who had built it in '58. It had a '46 rear which was too wide but the spring had been ground for the installation. He had no problems with it all the years that he drove it. I wanted a narrower '40 rear so did the swap and I also ground the '40 rear spring similar to what PeteVS showed above and never had a problem with it. I've heard the spring crack theory, and I'm sure it's possible, but a lot of this stuff that people say won't work today actually worked back in the day and still does today. As usual, modifications are done at your own risk (and others on the road), so use your head, be careful and seek experienced advice when you can't figure something out.

The one problem this car did experience was the result of a out of line torque tube. Best I could tell the tube was out of line as a result of the cooling from the welding done to relocate the trailing arm mounting lug, so we did a replacement in a fixture to keep it from moving as it cooled.

In my experience, the difference in the banjo center section, from C/L of the axles to the torque tube mounting flange, is 1/2" longer on the later rear, which is also why you have to install a 1/2" spacer when using the later gears in a '32-'34 banjo.

Measure everything yourself and have fun!
 
I guess the real question is why do you want to replace the 32 rear? I have a 8BA with a 39 trans, two 97s, Edelbrock heads and Red's headers in a 32 Roadster. It has a stock B rear ( really Model A internals) rebuilt with 3:78 gears and it is fine. I don't side step the clutch but I drive it. 3000 miles now and quiet as a mouse. I also have late 32 rear , same as 33-34 in a 32 sedan with a 265 Chevy, 39 trans and I drive that one too. That rear is stock 4:11 never been apart, NO idea how many miles on it. It's fine too. My only advice is make sure you are changing the rear for the right reason.
 
I put a '35 radius rods on the rear of my roadster. I had a 2" wide main leaf made and used the 2" wide front spring stack from a '40 in the stock rear crossmember. My current project is getting the '35 main leaf ground down to 2" wide and using a front 2" spring stack on the '35 rear end with a shortened torque tube.
 
The 3:54 is available for the early 32 since it is identical to the late Model A. The later 32 you have to use a later 3:54 or purchase one new from one of the aftermarket vendors. Check out Speedway catalog. Even with the later gear set there is a bit of modification that is covered in the V8 Times and this web site as well as the HAMB.
 
You must log in or register to reply here.
Back
Top