Does anyone know the grade of steel used for the lower shaft of a Halibrand Champ (301) quickchange? I am finally going to look at assembling my magnesium Halibrand transaxle case but as a quickchange and will need a longer one-piece shaft machined to fit. Just want to know what to start with.
A thought I had: rather than trying to source the correct grade of steel as raw billet, how about getting hold of a shaft known to be strong enough but slightly bigger, e.g. a mainshaft out of a heavy-duty gearbox, even a damaged one, and machining it down? Either way you'd have to do any heat treatment that might be necessary.
Studebakerjoe is spot on. Go with 300M, and work with a good heat treater to obtain optimal characteristics. This steel displays excellent strength and elongation characteristics, meaning that with proper heat treatment it will be both strong and tough. It can be welded successfully, however it requires reheat treatment to regain its material characteristics.
You didn't say whether you were going to machine it or have it done but thinking this discussion would be better placed with whoever is going to machine it, cutting splines can require some specialized cutters/setup.
As Studebakerjoe notes, many...many racing oriented, automatic transmission main shafts are made of heat treated 300M. Especially transmissions with trans. brakes in them. The shaft needs to be able to withstand the shock of letting off the brake. Should work just fine in your application. Mike
I hope this helps decide between 8620 and 300M alloys. I was originally in the 8620 camp, but I like the 300M having better overall strengths and more cobalt, moly and nickel content. Machinability of the 300M (comparable to 4340) will be a bit lower, as expected with the addition of cobalt. https://www.makeitfrom.com/compare/...86200-Ni-Cr-Mo-Steel/Grade-300-Maraging-Steel
Just something to think about, heat treated lower shafts are optional with some manufacturers. 300m is probably the best material, but I'd bet that 4140 would last forever. I have only ever heard of one lower shaft breaking. I'm sure it happens, but pretty darn rare.
Thanks everyone - I like the idea of finding an existing shaft large enough to machine down - could be cheaper to start anyhow...
As above 4140 would be good as can flame [surface] harden the spline at the change gear end which is the only wear area ? Made alot of stuff for my pulling tractor with good results. I used to make stuff at work from what was called 4140 half hard [nick name] can't remember number, maybe 4142. About 38rc so still machine able with carbide with good wear resistance.
Define cheap? That shaft has a far amount of work in it. Takes a bit of abuse. Knowing exactly what you have to begin with is a big plus. You will never really know what you have just grabbing something that 'should be' good material unless you have it analyzed. Cant really do a post machine heat treat either if you dont know what it is.
I used to be able to order any heat-treated material through work. Full annealed up to what the material max was. I had one job we used a full heat-treated alloy for, thankfully we had a machinist, nothing scared him. 4140 or 4340 would be good choices. 4142 has a little higher carbon content.
Just a thought, What about starting with a drive shaft from an early Ford truck. Will have the correct splines at least on one end.
I haven’t found any early Ford solid driveshafts (37-48) that are large enough OD to have enough meat to machine to fit the standard bearings used in a quickchange. Maybe some Lincoln? IDK. Even if it was the right OD and you could use the splines on one end, you’d still need to cut some on the other end.
The 1938-52 Ford 3/4 ton was the basis for the Champ (301) Halibrands. I have never seen an original driveshaft for one, but I would almost bet that Ted would've used those dimensions. There may not be enough material to make the shaft that @Magfiend needs but it wouldn't hurt to look at one. Might also be able to splice two lower shafts together, even if it's just for mock-up.
Off the top of my head, you might consider looking for a torque tube drive like the Corvettes used and see if shaft is large enough to be machined to your application. Second thought is that you might contact one of the aftermarket axle suppliers like Moser and see if they can manufacture what you need. They should have the knowledge of what will work along with the tooling to manufacture what you need. Obviously if you have room to make the shaft larger than the original component you will improve your chances for reliability.
Turning down the diameter of a larger shaft might be difficult if it's surface hardened. I used 8620 for a transmission countershaft, hardened and ground, that worked well.
All Corvettes have used hollow wall tubing, including the modern ones that have a torque tube mounted transaxle. Perhaps you're thinking of the Pontiac Tempest? Those shafts are not large enough diameter (.650 / .750").
We use 350M for the lower shafts in a lot of our racing applications. If you can give us the specs I can see if we've got something that would fit the bill...or if it's not off the shelf we could look at making one for you. Looks like a cool piece!
If you want to find a big shaft to machine down that has plenty of material look for a big farm tractor axle shaft. Plenty of thickness and length enough to probably make more than one.
Thanks for pointing that out. I bought one years ago to get the bellhousing but never looked inside. It had a hefty splined shaft sticking out one end and I assumed it went all the way thru the torque tube. It is actually very similar to a driveshaft inside the torque tube.
Offering lower shafts for the old Halibrand 101, 201, and 301 quickchanges would be a potential market opportunity for Winters.
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