35-36 rear into 34

S

S.Duncan

Member
I've been told in the past that a 35-40 rear with a reground spring will fit in a 33-4 using a stock 34 torque tube and driveshaft. I realize this moves the wheels back slightly, but that would only improve the look. My own experience is the torque tube seems to be 1/4-1/2 inch too long. Has anyone on here done this?
 
The 35 drive shaft has a different number of splines at the diff. side so does the pinion. I have a set of 35 style gears in my 34 Diff case with the back of the drive shaft modified and shortened because the front of the pinion is also longer for 35
 
S.Duncan said:
My 34 driveshaft and 36 pinion are both 10 spline
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True scoop!

Folks should also be aware that there are TWO different lengths of drive shaft and torque tubes on '33 & '34 Fords. The 4-cylinder engine block was longer than the V8 block. The difference in TUBE and SHAFT lengths between the two variants is 1-1/2". DD
 
The center section of the 35 to 48 diff is 9/16 longer than the 34 due to the bigger pinion bearings. torque tube would bolt on, but radius rods will be 9/16 short, and wheels will be 9/16 back from original location
 
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cas3 said:
The center section of the 35 to 40 diff is 9/16 longer (toward the FRONT) than the 34 due to the bigger pinion bearings. torque tube would bolt on, but radius rods will be 9/16 short, and wheels will be 9/16 back from original location
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ALL good info! The '35 and LATER banjo center sections are also 5/16" WIDER than the '32-'34 banjo. In addition, the threaded bolt holes for the axle housings are "clocked" differently between early & late. DD
 
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In answer to OP question.... yes, done it. But not as easy as you propose, as noted by above posts. For one thing, the 34 TT and D/S will not bolt up to a 35 and later banjo. Pay attention to above posts, and when you get both the 33-34 parts alongside the 35-up parts, the problems of mating them together will become obvious. Deal with each issue, and you can pull it off. Easier would be, modify the complete 35-40 rear for the 33-34. Or, if you don't care about the larger 35-up bearings, then modify the 35-up gears to go in the 33-34 rear end. The latter is what I chose.
 
I've already had the 34 torque tube and driveshaft bolted up. The roll pin was even in the right place on the pinion. The torque tube needed to by relieved a bit to clear the later pinion bearing
 
Also, carving a little off the straight spring to go into the curved cross member works with the correct length TT. But your idea to move the whole rear back and use the straight spring would cause the spring shackles to bind up quite badly
 
S.Duncan said:
Does anyone have a torque tube length measurement for a 35-40 rear into a 34 with a reshaped straight spring ?
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On mine with a 40 rear end, straight 40 spring made to fit the 34 cross member, the 34 torque tube and driveshaft were shortened 7/8 of an inch.

Also i used 42 to 48 radius rods unaltered, just moved the stock 34 mount back on the torque tube.
 
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