This was the only labor intensive part of the whole project.
#1938 chevrolet transmission fit a 1936 chevrolet trial#
Doing that precisely required a lot of trial fitting to find and remove the high spots. The only solution to this problem that I could think of was to use a hand file to duplicate the shape of the worn axle housing 1 7/8” inboard of the original location. Also, a really big lathe would be required to accommodate a rear axle housing. On used parts, the spring perch bore is egg shaped so chucking the whole rear axle housing in a huge lathe to machine a round surface is not the answer because the round housing would not be a good fit in the egg shaped spring perch. When new, the spring perch has a round bore and a round machined surface on the axle housing is the mating surface. The second challenge is creating a machined surface for the spring perch to rotate on. The welds were made at the former rivet locations on the flat bars and the rivet holes in the axle housing were plugged by welding. I have no way to buck a rivet head inside the axle housing so I welded the flat bars in the new position. These pieces of curved flat bar have to be moved inboard 1 7/8” per side. This prevents inboard-outboard movement of the spring perches and allows only rotation of the spring perches. First, their positions on the axle housing is set by a piece of curved flat bar riveted to the axle housing. The perfect fit of the finished product proved that cautious approach to be a wise one. Because of that variation, the actual axle shaft axis centerlines seemed to be the most reliable reference points for driveshaft and torque tube length measurements. I took this extra cautious approach because I could see that there was some variation in the distances between the rear cover plate and third member mounting surfaces on the ’36, ’37 and ’51 rear axle housings, probably due to the crude manufacturing equipment of long ago. That required splitting the u-joint to expose the front of the driveshaft and measuring the distance between the front of the driveshaft and the axis of the axle shafts. In order to be sure it would actually fit after all the cutting and welding was done, I measured the spring perch locations and the exact driveshaft and torque tube length on the ’36 pickup. My plan was to keep my ’36 pickup intact and running while the replacement rear end was being prepared. Dealing with this is also described below. The ’37 pinion gear shaft has 10 splines and the ’40-’54 pinion gear shafts have 17 splines. This procedure is also described below.ĥ. The ’37 driveshaft and torque tube have to be shortened 6 ½”. The different distances between the leaf springs require that the ’37 rotating spring perches be moved inboard 1 7/8” per side. Thus, the ’36 u-joint will fit the ’37 driveshaft.ģ. The ’36 and ’37 rear ends are the same width (“track”)Ģ The ’36 and ’37 u-joint rear pieces have the same splines. The required pieces, a complete ’37 car rear end with spring perches and a complete ’51 powerglide rear end were rounded up from street rod builders for scrap iron prices, because that’s what that stuff is to street rod builders, scrap iron.Ĭomparison of the ’36 pickup and ’37 car rear ends and disassembly of the ’37 and ‘51 rear ends disclosed the following:ġ. The next step was to get the pieces and see if the ’50-’54 gears were a fit in the ’37 axle housing. I also learned on that a ’37 Chevy car rear axle is the same width as the ’36 Master car and pickup unit.īased on that, it looked like a ’37 Chevy car rear axle/torque tube and driveshaft with the 3.55 powerglide gears installed might be the answer. The good news was that Chevy car rear axle internals, exclusive of axle shafts and driveshafts, are interchangeable in the 1937-54 span. The bad news was that the 3.55 gear set is hypoid and Chevy cars through ’36 and Chevy trucks through ’39 use spiral bevel gears. It turns out that a 3.55 gear set was used in 1950-54 powerglide equipped Chevy cars. On I found the potential answer to my gear ratio change quest. In looking for another interesting group I found and 1936 Chevy Owners. In response I got either a blank stare or “That can’t be done”.įinally, in 2009 I quit the VCCA after over 40 years of membership because the hands on approach to the car hobby that I enjoy was no longer present there. In decades of membership in the Vintage Chevrolet Club of America (VCCA) I put that question to every other VCCA member I met. Since I completed restoration of my 1936 Chevy pickup in 1976 I’ve wondered what it would take to get a numerically lower rear axle gear ratio than the factory installed 4.11. The following is an article written by Ray Waldbaum.