The Stovebolt Site Forums The Shop Area Engine Shop 1940 rear end pig/pumpkin swap

my 1940 chevrolet service manual says the Special DeLuxe and Master DeLuxe came with 4:11 rear axel ratio , the Master 85 came with 3:73 rear axel ratio. Houseing is stamped with B + number for 4:11 or C + number for 3:73.
I want to swap the 4:11 ring and pinion from my 1940 suburban 1/2 ton and use the 3:73 Master 85 car ring and pinion . Any done this? Does the closed drive shaft drop down from rear of transmisson so the rear end assy can be unbolted and removed without un hooking bango houseing brake lines ect.ect.

I'd suggest you find out if the car and truck rear ends are actually the same, and can have parts interchanged - that isn't the case on things later on, and I suspect you find they're different

but yes, the torque tube comes free of the trans and the entire rear and tube can come out as a unit

Bill

red58 I'm not sure if the suburban is considered a stationwagon/car or truck? Glad to know I can remove drive shaft and ring and pinion with out removeing houseing. thanks Bill

the burb is a truck based vehicle, the Master series cars are a lighter, somewhat smaller chassis w/ softer suspension, and by 40 I think A-arm front end

Bill

the suburban has leaf springs and knee action shocks front and rear.

I don't think the ring and pinion can be swapped from car to 1/2 ton. I read some information awhile back on the Inliners site that addressed this particular swap. A search there may give you exactly the information you need.

Got in touch with Barry Weeks so I now know car ring & pinnions are smaller than truck and will not fit. thanks for your help looks like patricks 3:55 set or a complete rearend swap. :mad:

None of the rear end parts between passenger and truck will interchange, NONE! However I swapped the entire passenger rear end 3:55 unit into my 46 half ton, look in tech tips(torque tube swap). I eventually removed this rear end for an open drive as I wanted to modernize the trany, but it worked just great for many years.

Thanks Jim, when I emailed Bill last night about the ring and pinions, I had mentioned swapping the whole Powerglide rear end in, but I didn't know the details as I have never done that swap myself. All the details are in your Tech Tip (under transmissions). DUH!! I should know by now to look in Tech Tips first, many questions are answered there! I always forget. I think 6cylindersovertexas uses the Powerglide rearend in his '37 also. I'm assuming you have to lengthen or shorten the torque tube and driveshaft? And the u-joint should fit right on, doesn't it?

In my 46 pickup I didn't have to change the length of the torque tube although the prop shaft/splines at the U joint could have been an inch longer, but worked ok. For the 40 and earlier you'll just have to try it and see, may be just right. Also this swap is made very easy in that the spines of the car and truck torque tube to U jt. are the same. As I wanted to stay 6 lug, so I stuck the 3:55 ratio 54 torque tube in a 48 passenger axle, which btw uses same brake parts as pickup.

Only other mods were to move the spring perch over to fit the springs, lowering block to get back to stock ride height and center the axle in the wheel opening.

Yup, a '39-'40 has a 1-1/2" shorter wheelbase than a '41-'46, so the driveshaft length might be just right. On Joe's '37 the wheelbase is 1-1/2" shorter yet, so I wonder if he had to shorten the driveshaft then? I know he told me at one time, but I forget. You got your ears on out there Joe? Can you add to this?

Yo - Barry!

Everything I know about doing this swap, you guys have covered. I did this swap on my 37 in about 1985. It has been fantastic since then. I did have to shorten the tube and propeller shaft (drive shaft). Everything hooks up fine. The number of splines on a truck up to 1941 are 10, but then went to 17. The Power Glide has 17 splines so below 1941 you have to "mix and match" to get the splines to work out.

I am going to be pulling my Power Glide rear end soon and going to an open drive line. When I pull it, I plan on listing it in the Swap Meet. It will fit 34-38 1/2 ton pick up trucks.

Joe