Welding an automotive gearbox mainshaft
Welding an automotive gearbox mainshaft
(OP)
My question relates to removing (through grinding) 1st gear on a mainshaft, removing a 2nd gear with a lower ration from another gearbox, and welding it onto the original shaft.
I had originally hoped I could do this by tig welding, cooling, repeat. This would have avoided annealing shaft and gear.
However, trying this out has proved this to be easier said than done, and to get a decent fillet means the shaft and gear are softened.
This leaves me with a question, can the shaft, once welded to this new gear be heat treated back to something close to original hardness?
The application is a low mileage dirt track car, normally run in one gear, but it needs a "gate" gear to take it to the first bend, hence the fitting of a lower second gear in place of the original 1st.
Thanks,
Huw
I had originally hoped I could do this by tig welding, cooling, repeat. This would have avoided annealing shaft and gear.
However, trying this out has proved this to be easier said than done, and to get a decent fillet means the shaft and gear are softened.
This leaves me with a question, can the shaft, once welded to this new gear be heat treated back to something close to original hardness?
The application is a low mileage dirt track car, normally run in one gear, but it needs a "gate" gear to take it to the first bend, hence the fitting of a lower second gear in place of the original 1st.
Thanks,
Huw





RE: Welding an automotive gearbox mainshaft
I would consider fabricating a new main shaft from bar stock with new gear blanks, which are integral. This way you can heat treat the bar and gear blanks to what you need in terms of strength, and final machine the gear teeth and main shaft after heat treatment. If necessary, a surface treatment like nitriding can be done to the gear teeth as a final step.
RE: Welding an automotive gearbox mainshaft
I have considered building up the shaft with weld and getting a spline cut into it, with a matching spline in the gear. Maybe the best option.
I have also being doing some reading up on heat treatment of unknown steels, it really is a complex science. I do have one luxury though, i have a few spare, unrequired mainshafts, and could carry out some annealing, HT and tempering tests.
Is it worth trying do you think?
RE: Welding an automotive gearbox mainshaft
Could you post pictures of those gears, and the existing mainshaft and cluster gear?
http://www.morris4x4center.com/jeep-transmission-p...
RE: Welding an automotive gearbox mainshaft
I'll see if i can take some pics later.
Thanks,
Huw
RE: Welding an automotive gearbox mainshaft
RE: Welding an automotive gearbox mainshaft
RE: Welding an automotive gearbox mainshaft
I'm warming to the idea of splining the shaft, it was my first choice way back, however the diameter of the gear that has to be removed is near a damnit the same as the bearing surface next to it (being 1st it's next to the input bearing).
Now, i have tried laying a bead of weld along the shaft between the bearing surface and the clutch spline - it seemed to work OK. So if i could build the area of the removed gear suuiciently, it should be possible to have a spline cut into it. Do the same on the inside of the gear liberated from another shaft and it might work...
RE: Welding an automotive gearbox mainshaft
RE: Welding an automotive gearbox mainshaft
RE: Welding an automotive gearbox mainshaft
RE: Welding an automotive gearbox mainshaft
I'll see if its possible to set the gear position with a spacer fron the reverse gear, otherwise this is bad news.