Broken 4WD front axle repair

Had a situation where someone gave me the front axle to a 4WD Shibaura SD2243 tractor where the axle shaft snapped off the wheel hub. This axle had two bearing surfaces to accept two radial bearings and an external spline to accept a drive gear.

At first I thought this was going to be difficult, since I would expect the axle spline to be metric and I might have to design a special tool for it. To my surprise I didn’t have to. Looking at the spline a lot closer its geometry was very close to a 90 degree V-shape groove. That made this whole project a lot simpler. First I made the blank, then I use a simple 90 degree V cutter to make the spline. The drive gear fitted up just nicely onto the spline. About .001” backlash.

I then finished by machining the bearing surfaces and substituted an American thread form for the end of the axle shaft. I also had to make a new locking ring.
An internal diameter hole was machined in the wheel hub and the axle shaft press fitted into it. The peripheral interface between the axle and hub was then welded together (not shown). This made for an extremely strong part. Much more than the original design.

The tractor is now back up and running. So the tip of the day is you might not have to go metric on an original metric design.

Excellent work. A true craftsman.

Awesome work. I wish you lived near me. Can you make gears?

(quoted from post at 17:58:15 08/11/15) Awesome work. I wish you lived near me. Can you make gears?

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That’s a loaded question. In short…yes, but mostly spurs and helical gears. When you start talking about hypoid gearing, spiral bevel gears and enveloping worms you’re getting into an area that requires very special tooling.

In my experience if you’re repairing a gear the most difficult part is determining what gear it is. That is, what’s its diametral pitch or module (if metric), tooth thickness, pressure angle, any addendum modification, etc. Keep in mind also that gears operate in pairs. One gear is useless by itself, so it’s a good idea to identify the mating gear (or pinion) as well. You want to know their center distance, backlash and contact ratio, hardness to name a few. I could go on, and there are exceptions to the rule, but in general I think you get the idea.

If you have a gear that needs to be replaced I first would see if you can find one on the internet. Sometimes price is prohibited or the gear just doesn’t exist. If either of those conditions exist and if you have an engine lathe and a milling machine, or access to one, then you can pretty much make a fairly large range of standard gears yourself. Again, the typical problem is finding out what type of gear it is (i.e., it’s geometry).

If you need help I’d be more than happy to help you. If you got the basic geometry, or willing to measure it, I can calculate what gear geometry you have and give it to you. Then you can purchase a cutter and make your own gear.

The one thing I would say is don’t be afraid to try it yourself. If I can do it you can too.

Haha, sorry for the loaded question.

I have a Mitsubishi 4wd compact tractor with a bad trans. I got it that way with the intension of parting it out, but then I started thinking it would be a handy little tractor to have around if I could fix it economically. It has a couple of chewed up gears in the trans, probably three and that’s just looking in the top. They are straight cut gears. I haven’t torn it down yet, so could be more than I’m seeing. New OEM parts for this tractor are hard to find. I found used gears or new (made in India) gears on the internet for about $700, but I’m in Canada, and since our $ has gone down the pipe, I’m probably looking at over $1k Cnd $ with shipping, plus bearings and other bits and pieces.

I don’t have access to an engine lathe and haven’t used a lathe since I was at school, so I’m pretty sure any gears I made wouldn’t look as good or run as smooth as yours. Once again, awesome work on that axle shaft.

LOL…I been there myself. Ran into that type of $ problem many times. For example, my latest adventure was a starter issue. I have a 1956 International Harvester (IH) where the brushes on the starter completely worn out. I went to the IH/Case parts dealership and they would not sell the brushes by themselves. They would only sell me a complete rebuilt starter, which was $325 USD and that’s with trading in my old starter. Anyway…to make a long story short, I was just about to give up and buy some carbon graphite rods and machine my own brushes. However, digging a little deeper…much deeper, I did find out what make and model the starter was. I was able to find the brushes at a typical auto store for $5 USD. That was for all four brushes. Now my starter is working fine and the tractor is up and running again.

Where I was going with that is my guess is your transmission might use just standard metric spur gears. If that’s the case, and if you can determine what type gears they are you might not be restricted to searching only for the original or OEM (for the original) gears for your transmission. You might be able to find the same gears used on a totally different application; being much more available and much cheaper.

Good Luck!

Yeah, the Mitsubishi Satoh tractor I have was sold for a few years as a Case 234 tractor. I didn't try CNH for the parts yet. When I looked at the parts diagrams for Kubota and most of the other compacts they all seem to use a very similar transmission. Thanks for the advise. When I get it apart I'll take a close look at the gears and see if they are a standard metric pattern.