The Stovebolt Site Forums The Shop Area Driveline Shorter axels

So I got me a problem, but before I tell you the problem, I will let you know a couple things. I have welders, lathe, the equipment to heat treat and knowledge to go with it money is very tight.

Ok I am converting my 38 GMC to 4 wheel drive, the rear axel will work the way it is( or I can cut it down later). I need to shorten one of the front axels down about 4 inches. What i was thinking of doing was cut the 4 inches somewhere in the middle of the axel. Then drill hole in the ends of the axel to accept a rod. Then cut the 4 inches I cut out down to fit in the holes in the end of the axel then weld the axel back together, then after all that quench it in oil for a heat treat.


I am retired and have a lot more time then money and I do know how to heat treat. So give me some opinion

Assuming you are talking about the axle shaft, you are contemplating saving the flanged end and the splined end and taking 4 inches out of the middle, then welding it back together. I have seen a few axle shafts that twisted and broke, these were medium duty trucks. The shafts appeared to be forged steel, with a grain that was pretty apparent. Without knowing the metallurgy of the material, I think it is weldable but I doubt you will ever achieve the original strength. If you have several shafts to experiment with and little cost, might as well give it a try.

Not sure this technique would work for axles, but as a former career machinist, I have done similar to what you’re suggesting. However, I bored one end (after drilling undersize, you’ll need a boring bar to keep it concentric) then cut the other end down to fit inside for a pressed interference fit. Only a thousand or so is needed. This would eliminate one side of the pin and the interference fit would help keep it concentric. Cut a small bevel on both sides for the weld (1/8” would be sufficent), so you can turn it down flush.

You’ll need to weld a bit on one side then the opposite side letting it cool between welds. Heat treating after would certainly help.

I doubt you will have good long lasting results. Maintaining concentricity will be a challenge in itself, let alone trying to keep it true as metal tends to pull when welding. Beyond that, because axles are subjected to a lot of torque, I believe the weld will be a weak point that will eventually fail.

Just my opinion.

John

I thought about cutting at the flange but everytime I think about doing it that way i just can't figure out how much I have to cut, the numbers keep getting all jumbled up in my head

I like that idea better then mine that gives me more to think about

I've seen several of my dirt track racing competitors narrow rear axle tubes and shorten the axles. They usually cut the flange off, bored the center out, and press-fitted the flange onto the shortened axle shaft before MIG welding it on both sides of the flange. Very few of them broke the welds, even under the stress of repeated high RPM full throttle applications and rough track surfaces.
Jerry

After reading that has crossed my mind, the tube i am not worried about, I have a makeshift jig that will keep it true, plus a couple backyard mechanic tricks

Cutting it at the flange and doing it the way Jerry suggested makes the most sense to me.

John

Well gentlemen, I was on Facebook watching some videos, when one of the videos was of some middle eastern shop got a truck axel in to fix. The axle was broken in half. Now remember in the middle east they can't afford new so they have to fix stuff, kind of like the U.S. use to do. Anyway he cut the section out cut a hole on both pieces with a lathe then cut and threaded a piece that wa long enough for the middle. He then screwed all 3 pieces together the welded it all up then on the lathe again to clean up the weld and it was all done. I think here in the states it is easier to buy some stuff then it is to fix

If you had a milling machine, a better solution might be cutting the splined end off and re-machining the splines. It would take an indexing wheel to get the splines correct. And if the shaft diameter at the cut is smaller than the splined OD, you could build it up with weld prior to cutting the splines. The splined end would be subject to less stress than a weld in the middle, with the bulk of the cross section being original material.
Jerry's suggestion of shortening the flanged end would work, but you'd need to do something about the axle bearing where it runs on the shaft unless it's a free-floating axle like on heavy trucks.

But a front axle would need a u-joint near the outer end, and maybe using a slip on yoke welded to the shaft there would work. A press fit of the yoke on the shaft prior to welding would be even better.