The Stovebolt Site Forums The Shop Area Driveline torque tube spline

HELP!!!!!
Does anyone know why my torque tube spline is 1-3/4" off center in the frame and what can I do to fix it? I've tried to loosen the rear axle at the leaf springs and push the tube over to line it up with the center of the frame, but no luck. Nothing seems to be bent or twisted with the frame.
I'm doin a frame-off on my 50 burb and have the frame finished as well as the engine, which is ready to go back in the frame. Any and all thoughts will be appreciated.P.S. I really luv this site. Thanks Dave

I have never checked, but could it be that the engine/tranny is also off center? I believe The rear axles are different lengths, so I would expect this would translate to the differential being off center too. You could check that.....

Kurt

I don't believe mine is centered either, but everything hooked up fine in the end.

Thanks guys for the info. You may be on to something although thr rear of the engine is central to the frame. Have to do more investigating.

I know from the older manuals that there is a procedure to determine whether the torque tube is aligned properly. They show measuring from each end of the axle tube to the end of the torque tube.

It is pretty common on these trucks for one frame rail to have been pulled on, causing the frame to be out of square. The frames have no center X-members, only riveted in cross members, and have very little resistance to being pushed or pulled out of square. Typically this would've happened when the truck was stuck in the mud in a field or something, and someone hooked a chain to the most convenient spot (spring shackle on one side), and gave it a jerk or two or three with the tractor. This pulls one rail ahead of the other causing the out of square (parallelogram or diamond shaped) condition. When the frame rails aren't square to each other, it shows up as the torque tube not locating on the center of the rear of the transmission.

Usually this shows up after the trucks suspension has been rebuilt, as when everything (rear end saddles and spring eye bushings) are worn out, there is enough slop to allow the torque tube to move on center. When everything is new and tight, it is where it is. So basically, if one rail is ahead of the other, the rear end is not sitting square in the frame, and the amount of this error is multiplied by the length of the torque tube.

An easy way to check your frame for squareness is to simply measure diagonally from common points on the frame from left front to right rear, and visa versa. Use common holes or rivets as your reference points. Pick points as far apart as possible. (Very front cross member rivets and very rear cross member rivets are good) The diagonal measurements should be within 1/4" of each other, an 1/8" is even better. If the cab is on the frame, and it's hard to measure, you can also use a plumb bob to extend your reference points down to the garage floor and mark them out there with chalk or a Sharpie marker. Then you can check your diagonals right on the floor. If you determine your rails are out of square, it's easy to imagine which rail needs to go forward (or back) to get the diagonals the same, and then imagine how that would effect your torque tube alignment.

I have used a Porto-power (bodyman's hydraulic jacking tool) or come-a-longs to push or pull on the frame rails diagonally and get them back to square. If you get it square, and it will stay there on it's own, bolt the torque tube up and you are probably fine. I have gone so far as to weld cross members in, and even add small gussets to the cross members to keep them square. If the rear end is in the truck, but not bolted to the transmission, you will actually see the front of the torque tube move towards the center when you push or pull diagonally on the frame in the correct direction.

All this sounds harder than it is. If you have a bare frame, 15 minutes with a tape measure will tell you everything you need to know. It's not uncommon at all to have an old Chevy truck frame be out of square, and it's easy to check when the truck is apart.

This ought to be in the Driveline forum for all to see.

Try this, jack up the rear of the truck buy the frame so there is no weight on the rear leaf springs and the axle is hanging from the leaf springs. Now check if torque tube spline lines-up with transmission, if it lines-up this could be because one of the leaf spring has a taller arch than the other. When taking the body/frame weight off the leaf springs both springs should have the same arch height caused by the weight of the axle pulling them down. If the spline lined-up Check for cracked/broke leaf spring.

The other thing to check is if the rear spring seat shifted on the leaf spring. Check the rear seat bushings too here is picture with instructions on how to seat the rubber bushings into there normal place. They might be binding. page 2

Let me know what you find out.

Thanks

Moved this dicussion to driveline section of forum.

Did you happen to put the torque tube in upside down? Putting it in wrong would offset it.

I don't think you can put it in upside down as the ring gear is offset and only goes in the banjo one way. Does anyone know what years of open driveshaft will fit in my 50 suburban? When was the first year that a burb had an open driveshaft? Also, will the sm420 4 speed hook up to either type of drivshaft without modification? I would like to use a 4 speed if I can but I'm not sure when the first year was that a suburban offered a 3 speed on the column. Also, does anyone know what the E121 stamped on the side of the 3rd member stands for? This all makes me feel like a nap!!!!
Thanks for any help. DAve

I see where your going.

option 1:
To convert from enclosed torque tube to open drive shaft you could go custom set-up, with axle and have a shop make-up a drive shaft and any tranny that will mate up to your engine.

option 2:
The 1st year Chevrolet Advance Design truck went with open drive shaft was 1955 1st series, you would have to find a 1st series truck drive train
axle, leaf springs, drive shaft (you can have one made-up), 4 speed transmission, you can change out your 4 speed tranny torque tube tail housing for a
open drive shaft tail housing you will have to find a open drive shaft main tranny output shaft and housing, it is more cost effective to find a used
4 speed tranny with a open drive shaft tail housing, I think Chevy used the same 4 speed tranny until 1960. So all you need is the 1955 1st axle and leaf springs.

The first year that Advance Design suburban offered a 3 speed on the column I believe was in 1947.

The E121 stamped on the side of the 3rd member stands for? All I could find is this link

It would probably be easier to fix your 1 3/4" off center problem especially if your doing a full off frame restore. That's my 2 cents worth.

Thanks