Building an engine & a bike from random parts - 1979 - 1981

Well, I've been so busy with cleaning and mocking up, took everything for granted, and then discovered this...
Needless to say, the swing arm is shot - the hole for rear axle. I can be re-bored and a steel insert made and welded. A pretty straight forward thing, but I don't have the machinery for it.
At least I got a rare reusable boot and the clamps. There is a crack in the boot but not all the way through, so not a big deal with a bit of glue. Perfect to me.





I will use this swing arm to explore notching for a wider tire, and when I have a replacement it will be more straight forward.
If I can find a machine shop which can do it for 50 bucks, of a bike buddy who can do this, then it will be brought back to life. I have my doubts though ..

Stan:

Are you sure it's hooped? The only thing that matters is that the hole lines up with the gear case hole on the other side. Since the gear case is bolted to a welded flange, there might very well be slight dimensional offsets required in the other side of the swing-arm to make things line up.

If I insert the axle, it really wiggles. That's the opposite from the gear side, so nothing would be really holding it stable. This is on the left side.

The exact hole is oval, there is no way any amount of tightening would keep it from sliding back and forth. So yes, it is not round.

I'm trying to figure out what you mean and I think I know it. Except this is as I said on the other side of the gear. I shouldn't be like this anyway, unless designed, and this doesn't look anything like intentional.

I am going to remove the back wheel tomorrow or so and this will be exposed on my bike to compare. As far as I remember, all was dead solid. But direct comparison will confirm.

As to mounting rear, it is recommended to keep the axle gear not completely tightened to the swing arm before tightening the axle. I don't think this was covered in the manual, but that's a good common way to do it. Wheel and axle, then tighten to the proper torque the connection between the final drive and the housing of the swing arm.

Report will come later of course as I progress.

StanG wrote: If I insert the axle, it really wiggles. That's the opposite from the gear side, so nothing would be really holding it stable. This is on the left side.

The exact hole is oval, there is no way any amount of tightening would keep it from sliding back and forth. So yes, it is not round.

I'm trying to figure out what you mean and I think I know it. Except this is as I said on the other side of the gear. I shouldn't be like this anyway, unless designed, and this doesn't look anything like intentional.

I am going to remove the back wheel tomorrow or so and this will be exposed on my bike to compare. As far as I remember, all was dead solid. But direct comparison will confirm.

As to mounting rear, it is recommended to keep the axle gear not completely tightened to the swing arm before tightening the axle. I don't think this was covered in the manual, but that's a good common way to do it. Wheel and axle, then tighten to the proper torque the connection between the final drive and the housing of the swing arm.

Report will come later of course as I progress.

Makes sense, I didn't realize from the pix that the hole is 'ovaled' - thought it was just 'off centre'. Yes, something goofy if it's ovaled - and hard to imagine how that would happen - maybe a rear-ender bent the swingarm?

Even it you were to get the hole welded up, you'd have to come up with some sort of a 'line bore' to insure the hole is lined up with the old in the gear case and parallel to the swing arm pivot. Kieth Fenner could figure it out

This one will be a bit of a pig to clamp up in a mill but in a nutshell, if the swing arm bolt holes are trued up parallel to the rear axle bolt fore and aft + top and bottom, that would be the goal. The hole will have to be plunged with an end mill and if it was me having this done, I'd have it fitted for a brass bushing with maybe a 1/8" wall give or take.

This one will be a bit of a pig to clamp up in a mill but in a nutshell, if the swing arm bolt holes are trued up parallel to the rear axle bolt fore and aft + top and bottom, that would be the goal. The hole will have to be plunged with an end mill and if it was me having this done, I'd have it fitted for a brass bushing with maybe a 1/8" wall give or take

Yes, it would require a bit of a set up... One half side is fine - if you insert the axle it sits there nicely while there is a half moon gap on the other side. I was thinking about welding it up then using a file to carefully file it down to size having one side good and the axle. Ideally would a proper machine shop of course, and I like your idea about having a brass bushing there. But this would require that correct set up. A bit of work but I can see it done properly. I know I could do it if I had the tools. I am afraid this might cost a lot if given to a shop... It's very lucky to have that one half not damaged - it could function as a reference point guide.

I might give it a shot - a bit of weld built up and a file. It would need to go to a shop to properly enlarge for the bushing.. I think I'd go with bronze instead though.

I think perhaps the original bike had the axle nut loose and the axle kept moving and cost this damage. That would take time and it amazes me to know that someone was riding like this!