VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1937-1945 1940 Prop shaft bushing and oil seal replacement

Is it possible to drill out the three rivets that appear to hold the tube to the pinion carrier, then slide the tube forward. Once the tube is off the shaft, I plan on driving out the seal and bushings with a long steel bar with a socket sized to the inside of the torque tube. Can I do it this way? Thanks, Roger

The dowels are very easy to remove. They can be drilled out or make a smaller hole, thread in a screw and yank out.

Thanks Gene. Can do.

I have drilled and tapped for 10x24x1.25, screwed in a stainless machine screw. Then clamped a vise grip plier on the screw and tapped, tapped and tapped. Then got a 20 oz ballpeen and commenced beating. Put a propane torch on the rivet and beat the plier with the 20 oz hammer. Stripped the threads. Abandoned rivet and went to next, Broke off tap flush with head. Went back to first rivet and cut head off with a chisel. Hardest rivet I've ever seen. I drilled the threaded hole with a 1/4" drill. Problem is I don't know what diameter the rivet is because it does not show distinctly from the pinion carrier. I fear I will end up with an eccentric hole since I can't determine the exact center. Is there a way to tell rivet from housing when they are flush with each other? The visual difference between the two, I can't see. ANYBODY have an idea out of this ? Thanks Roger

The only thng I can tell you is the rivet is 5/16" in diameter.

Maybe a thin penetrating fluid would soak around the perimeter of the rivet and help show the separation? Soak it and then wipe it off the surface and it may show the separation.

Gene, it's helpful to know the diameter is 5/16. I couldn't find that anywhere. Canadiantim, I'll try a penetrating oil. The best I''ve ever used is PB Blaster, but I wouldn't call it thin. What would you recommend? Thanks for the help. Roger

Any penetrating oil should find it's way in there. Even better if you can wet the whole area with the penetrating oil to get it to carry some dirt/grease into the crack to help define it. Running some emery paper, etc over the whole area can help get the oil in the seam as well as clean up all surfaces to help define the different metals and help the dowel shaft stand out.

New dowles are available from the Filling station.
If the length of the dowels are pretty much destroyed try pulling out the bushing, The bushing has just a slight dent iin it and may push loose the damaged bushing.

I have a feeling that two different things are being discussed here. Rivet for the bushing behind the u- joint or the rivets next to the pinion at the differential

Thought it was the three dowels/rivets near the pinion...

I'm not sure how the topic shifted, but it has. My problem is with the rivets that pin the torque tube to the pinion carrier. I have gotten some good info however. I am currently pursuing a path of using heat, penetrating oil, threaded machine screws and old fashioned beating on vise-grips. I already have the pins for the bushings if I ever get to them. Thanks to all for helping. Now I'm on a quest for the 5/16 rivets I'll need. My local Ace Hardware and Fastenal Fasteners did not have any such animal. Guess I'm off into cyberworld in search of the archaic rivet. Thanks, Roger
P.S. Were they originally rivets or dowels that fastened the torque tube to the pinion carrier? I found some 5/16 dowels at Fastenal. They were precision size tolerance.

Roger,

If I understand correctly what you're trying to do, I'm afraid you're headed down a path that leads to pain and misery. The torque tube/differential housing unit is a factory assembly not intended to be disassembled. If you can get access to the 1940 Chevrolet shop manual, look at the illustration of the rear end assembly on page 85. The fasteners you're referring to are shown to be rivets. I'm assuming you chose this procedure for replacing the forward propeller shaft bushing and seal in order to avoid disassembling the rear end. Yes, you should be able to drill them out, but there's a high likelihood of some metal shavings entering the front pinion bearing. After you get the rivets drilled, your next challenge will be to extract the torque tube from the differential housing. I've never done this before, but my guess is that the torque tube is assembled to the housing with an interference fit and will not come out easily. If you do manage to get the torque tube out, you will then be able to remove the forward bushing and seal as you described.

If I'm right and the torque tube is an interference fit in the differential housing, and you do manage to get them apart, reassembly will be difficult as it will be hard to press the torque tube into the housing just right so the original rivet holes line up perfectly to each other. Having surmounted that obstacle, now you face the show-stopper: how are you going to buck (back up) those rivets to set them properly? It looks to me like the only way would require disassembling the rear end which I am assuming you were trying to avoid, and inserting some kind of custom-made backup plug. I'd like to have seen the riveting machine that Chevrolet used to set those rivets. If you don't get those rivets set right, the lower one or two are going to leak. Precision dowel pins won't work because they are case-hardened and would be difficult, if not impossible, to set.

It sounds like it may be too late to reverse course, however, for future reference, if you need to replace the front propeller shaft bushing and seal and you don't want to use an "Oakey" bushing, take the rear end apart, then remove the torque tube/differential housing assembly from the axle housing at the 10-bolt joint between the two. Now you can extract the propeller shaft and pinion assembly out the back and use your long rod and socket to reach into the torque tube and shove out the front bushing and seal. I strongly advise consulting the shop manual on the procedure for removing the propeller shaft/pinion assembly from the torque tube.

Mark

Mark, you are right on target with what I want to do. I was just trying to avoid messing up the ring/pinion adjustment. It seems to be working fine with no leaks or noise. I was under the impression that the three rivets were force fitted, not bradded on the inside. Apparently not so. I already have two rivets that I drilled through. Maybe I should tap and install bolts to replace the rivets. At any rate, I think I'm going to separate at the axle housing ten bolts. Knowing what I know now, what I thought was the long way was really the quicker path. I didn't know much about the pullers and know even less about the condition of the prop shaft where the bushing and seal are located. Just wanted to be able to examine the prop shaft before putting new bushings and seal in place. I'm 73 and I want this to be my last trip in. It will be totally and carefully reconditioned to factory specs from radiator to gas tank. Thanks for your attention to my problems. Roger

Rog,

Here described in text and photos is how I pulled the bushing and seal using simple hardware store items and a short length of 2 1/2" exhaust tubing.

https://vccachat.org/ubbthreads.php/topics/334876/1936-chevy-3-55-rear-gear-conversion.html

If you've removed the rivets at the torque tube connection with the pumpkin casting that's a problem. I'd consider replacing them with grade 8 button head screws with the heads on the inside of the torque tube to make sure there's no interference with the driveshaft. An easier solution might be to get another torque tube/pumpkin from a street rod builder. They throw those away. While you're at it, a 3.55 gear set is a nice improvement. My bone stock '36 PU pulls the 3.55 gears no sweat and it's much more pleasant to drive now.

Ray W

I've removed the ten nuts from the studs on the rear end and cleared everything on the front end of the torque tube. The pinion carrier will slide forward about a half inch on the studs but seems to not want to separate completely. I have the front and rear of the t-tube supported so that the faces of pinion carrier and rear end are parallel. Also took the wheels off the floor slightly. Looking at the illustration in the shop manual, I can't see anything to keep the pinion from separating from the ring gear. Am I missing something?

Roger

You have to pull the left and right axles, at least until they've cleared the differential assembly. Once they are pulled clear, with the ten nuts on the front face of the axle housing removed, the torque tube/differential housing unit should pull forward and out of the axle housing. Note that the differential assembly w/ring gear comes out as an assembly unless you've disassembled the differential already. Two reasons for disassembling the differential unit prior to pulling the torque tube and housing are: (1) It makes the torque tube/housing unit lighter and easier to handle, and (2), you're going to have to disassemble the differential unit anyway in order to extract the propeller shaft/pinion gear from the torque tube and its easier to break loose the four large cap screws that hold the differential side bearing caps in place while the unit is still bolted into the axle housing. When removing the second of the two bearing caps, take care that the differential/ring gear assembly does not roll out and fall on the floor or on you.

When you pull the propeller shaft/pinion gear assembly from the torque tube, note that there are two (normally) shims in front of the front pinion bearing. Be sure to retrieve these shims and don't forget to install them on reassembly--they set the correct pinion depth engagement with the ring gear.

Thanks Mark. I think I have it now. All I have to do now is get down and dirty.

That joint has to be an interference fit, otherwise it would leak. I think there would have been some type of press involved.

I finally have the torque tube assembly on my bench. I've drilled and punched out two dowels. i'm using a 6' t-post and a impact socket that has an OD of 1 3/4". In trying to drive out the bushings, it seems I'm hitting a solid ridge or something. I dosed it with PB Blaster and I'm waiting for it to soak.
The diagrams I have to look at don't show any ridge inside the front part of the tube. My new bushings and seal measure 3" in all. In the tube, from front bushing to back of the seal is 8". Someone installed an Oakie? I would appreciate an insight . Thanks, Roger

The Oakie would be a one piece sleve. The original bushings were a front and rear. They usually came out easily and there was no ridge.

If the socket fits in the front end it should fit in from the rear and go all the way though. On some models there may be a rivet or 2 locking the bushing in place, may take some finding as they will be flush on the outside of the tube.
Tony

Apparently the Oakie must be about 5" in length. That would account for the total length (8") of material in the tube. The rear bushing has moved some because the hole drilled through it slid forward and out of sight. I'll get a bigger hammer. Thanks Gene for the info. Roger

Now that I have the prop shaft out, I find the bushing area badly scored. Thinking of having it metallized. I have the bushings, what is the correct diameter of the shaft or the required clearance? Thanks, Roger

Up to .010' clearence.
That is the advantage of the Oaki bushing. It rides on the drive shaft area forward of the original bushing. I remeber you said it had an Oakie.