The splines on the right rear axle are gone, it's rounded off. We tried to weld the wheel hub on but the tire/hub came off in just a short while. (the neighbor/welder welded a good weld on the back and spot welded on the front of the castle nut, but didn't put the cotter pin back in. would it need that even? The threads on the axle for the castle nut are a little jerked around, but you can still run the castle nut up.
So.....
now what?

1990 Honda 300TRX 2WD

 

If I understand you right, you welded the back of the hub to the axle, then screwed the castle nut on as best as you could, then welded that. I'd say the cotter pin is not necessary.

 

Right, that is what happened.
So...what's a fix now?
replace the whole axle?
Let's keep this as simple as possible.

 

Yes, I suppose you have to replace the whole axle at some point. But if what you've done works, ride it. You won't have to replace the axle until you need to do rear bearings. But for now, just ride it. Meantime, browse ebay for a used axle. Buy it and have it ready. To get the old axle out, you'll have to cut it with a torch.

 

Ok, after calling the local Honda shop and getting an estimate of $450-500.00, I decided we'd be more conservative.
We got a new castlenut, a few washers to use as shims to take up that space that was made from the worn splines on the older axle and a new cotter pin.
We tightened the castlenut really tight and put the pin in. We tested it to see if it pulls with the other side and it does if you hold it up. Also, there was a hill we used to go up and it'd always pull to the right rear if it got in a situation like that and now it just pulls straight ahead, so it's puling with the driving side.
I'm just trying to make it work for the kids to have fun and be safe as they can on a fourwheeler.
We've come a long way since it was given to us. Now, just to get the rear brakes from squeaking and we're doing good. That thing runs like a top.
It ain't fancy, but it works and gets the job done.
Here is a pic of what my son and I did:



HERE is a lil video of it in action.
There is a lil lag at the beginning, but it's him jumping up and down on it. lol

 

Ok, well, back to the drawing board...somehow..SOMEHOW...it's worked loose again.
Those washers are on there still..it just wiggles.
I can't figure where this play is coming from.

 

THIS AXLE
Is this what I need to replace it?
Is that a big job? Are there instructions somewhere???

 

looks it to me.. but i looked at the ebay ad manufacturer's number and it doesn't match the microfiche's number 12. but then again, i don't know where to cross reference the OEM numbers. sorry

Honda Motorcycle Parts: ATV Accessories, Dirt Bike Scooter Cruiser Touring OEM Parts Off Road Motorcycles Sport ATVs Starter Motors Honda Parts Direct

 

Hmmm..whenever/wherever an axle is located... is this a big job? Anywhere that would have instructions? Like I've said on another thread, if I've got instructions, I can build a rocket!

 

it'd be worth the investment of $20-30 for the service/repair manual if you're gonna keep the quad for any length of time. i've seen them online, ordered from Honda, and at O'Reilly's auto parts store. i'm starting to buy the books myself.