Axle Repair

[300zx 7]

My C161 has worn half moon key ways in the axle and hub. I can get new hubs, but I don't want to tear down the transmission to repair or replace the axles. I am also working on the output shaft of a Howard Rotavator that has a wallowed out key way. I know we have discussed this problem before and all of the possible repairs, but I don't remember any one mentioning a weld repair using a brass or copper key. I have seen mentioned on another forum clamping a brass or copper key in the damaged key way, then weld repairing the damage. The weld won't stick to the brass or copper, so then knock out the key and dress up the shaft. Has anyone tried this?

[tarcoleo 119]

I'm sure there are several here with first-hand experience with this technique.

An opinion is offered; the melting points of copper-base materials are a lot lower

than that of the steel axles. So in order to prevent melting the copper material

before it does its job as a dam for the molten steel pool, it needs to be large

enough so that it takes longer to heat the copper than the steel and so remains solid.

I'd also like to learn if this works from someone who's done it.

Tom in RI

[300zx 7]

Tom, a really good point. Copper or brass melt around 900 F and Steel around 1500 F. I just talked to my brother-in-law and he said that he had bought round rod from weld shops to use as dams in round holes that needed to be built up. What ever it was, he said he knocked it out with a punch when he was done. He said it was like a type of lead material. I think I will check with a local weld shop.

[300zx 7]

Turned out it was carbon. I couldn't find a source here, so he is sending me some from Missouri. I will let you know how it goes.

[1961551 2]

i have repaired these using nothing to fill key way. i tried a carbon key. i got alot better weld penetraion directing the heat away from the slot and filling up too key way. i then dressed the weld with a dremel cut off wheel the same size as the key way.made it a little tight. moon key fits very snug. used a file to rough in axle. then used a long strip of 240 grit paper to finish axle. the repair turned out excellent in my opinion. less than an hour. the dremel cut off wheels came from home depot.

jimmy

[can whlvr 991]

not to rain on your idea,it could work,i had a hub that to much heat was put to it to try and get it off,about a year later i was cutting grass when the machine stopped moving,turns out the heat made the axle brittle and broke,i could see that the metal had turned blue like,and was full of cracks,and also watch the seal,you could melt it also,ive heard of dremel the key way to bigger key and cutom fit a special key to fit or see if a machine shop can make the key way bigger on hub and dremel the shaft,ive done the special key and it works,no heat to axle.

[Duff 206]

Maybe an off-the-wall idea, but could you simply cut a new keyway with a Dremel tool on the opposite side of the axle from the one that's hogged out and just 180 the hub on the axle to match?

Duff :banghead:

[bell 11]

Maybe an off-the-wall idea, but could you simply cut a new keyway with a Dremel tool on the opposite side of the axle from the one that's hogged out and just 180 the hub on the axle to match?

Duff

Duff, I like this idea best.

Even better yet...

Some axles are longer than others. Example: A 8 speed axle has approximately 1" to 1-1/2", maybe 2" between the hub and the transmission case. Why not just cut off the end of the axle (where the damaged keyway is) and cut a new one...?

I'm going to try this and see how it works out. I have a 8-speed with DESTROYED keyways. They went so far as to drill through the hubs and the axle and use bolts to "pin" the hub to the axle... With the hubs right up against the case, it will be the same width as the round hood 4-speed it will be replacing. :thumbs:

[TT-(Moderator) 1,127]

Cutting a keyseat 180

[300zx 7]

Thanks for all of the input, guys. I am going to try the straight 1/4" key way on the output shaft of the right angle transmission on the Howard Rotavator first. I will use the 1/4" carbon dam and weld repair it with a mig welder to reduce the heat. Then grind the shaft with die grinder. If this fails, I can always take the shaft out and have a machinist do the repair or drill through the shaft and install a spring pin. The input shaft has a spring pin (with no splines or keys) for the attachment to the PTO shaft, so a spring pin on the output shaft should handle the same load. I'll take what I learn there and apply it to the C161 auto axles. I will let you know how it goes. I wouldn't put a spring pin in the C161.

[tarcoleo 119]

Use of a carbon 1/4" key as a dam is a great idea. And limiting the amount of heat

that the body of the axle "sees" is also well advised.

Steel becomes embrittled when red-hot metal is cooled too quickly. Ductility is restored if the steel is slow-cooled to allow brittle carbides to precipitate out of the metal and collect at the edges of the metal grains where they are not a problem.

Therefore, if there were a danger of embrittlement due to over heating during the repair, reheating and slow cooling might be advisable.

And yes, you likely will cook the shaft seal during the operation. Suggest it be removed and the hub be secured on the axle against the transmission as a heat sink to limit the heat "seen" by the rest of the axle.

Good luck, Tom in RI

[300zx 7]

Thanks Tom, will do.

[sorekiwi 761]

Here's one I had done a month or two ago:

The slot in the axle widened to 5/16" with a woodruffe cutter in the mill. Then a 5/16 wide key had .031 shaved off each side of the "top" part, where it slides into the hub to bring it's width back to 1/4".

I removed both my axles to do this, but I dont think it'd be to hard to do it with the axles still in the transmission (assuming the mill in question was big enough!!)

[bell 11]

or drill through the shaft and install a spring pin. The input shaft has a spring pin (with no splines or keys) for the attachment to the PTO shaft, so a spring pin on the output shaft should handle the same load.

If there's any gear reduction (at all), the load will be much less on the input shaft. You are going to see the maximum load on the wheel hubs. I don't think a spring (roll) pin would last long on a wheel hub. But, if you have no other options, it would be worth a shot.

[chris11 184]

I have machined two key ways on crank shafts when the use a super charger. It seem to help. Maybe trying them on a axle my help.

[smoreau 658]

on my 875 the keyway in th axle looked very bad on both sides and wouldn't hold a key any more. both hubs were shot also. almost twice the size of the original keyway. So I looked at the hubs and they had a keyway the entire width of the hub. the shaft is only a moon key removed both axles ( doing a restore at this time ) and have a freind cut keyways from the end of the axle to the edge of the seal in the same spot as the orignal moon key. filled the hole and warn spots with jb weld. put the axles and hubs back on and no play, and I think its stronger then original moon key. just hope the key isn't the fuse for this sunstrand trans . this tractor wont be doing work any more. its retired to easy trips around the yard and showes :hide: