750 swinging arm

H

harpmeister

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UK
The bronze swinging arm bushes on my SF1 need replacing and I was just wondering what my options are regarding replacements and any problems I might encounter fitting them.

I have emailed a couple of suppliers to see if they have bronze bushes in stock but so far (2 weeks later) I haven't had a reply.

If these are no longer available does anyone know the correct grade of bronze to use and the exact dimensions and I can turn them up myself or is it better to upgrade to something like needle bearings.

Thanks

Joe
 
harpmeister said:
The bronze swinging arm bushes on my SF1 need replacing and I was just wondering what my options are regarding replacements and any problems I might encounter fitting them.

I have emailed a couple of suppliers to see if they have bronze bushes in stock but so far (2 weeks later) I haven't had a reply.

If these are no longer available does anyone know the correct grade of bronze to use and the exact dimensions and I can turn them up myself or is it better to upgrade to something like needle bearings.

Thanks

Joe
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Most probably you will need the spindle/axle as well.  This usually wears a lot more than the bushes, especially on the drive side (mainly because we all lubricate our swing arm bearings so religously...not :D).  Andy W. doesn't list this axle, I haven't seen a new one since 1990.

Personally, I'd prefer to stay with the bushes, but the hassle to manufacture a new axle is a bit too much for most.  One alternative would be to grind the axle and fit a set of under-size bushes, the case hardening is quite thick, a couple of thou off the outside won't hurt it at all.

The easy alternative is a needle bearing kit, I can supply these if you can't find them any closer.

piet
 
You can get worn swing arm axles hard chromed. Gets rid of all the wear marks/grooves and doesn't require undersized bearings.
I've only had it done once, but it worked perfectly. Better than new.
 
Dellortoman said:
You can get worn swing arm axles hard chromed. Gets rid of all the wear marks/grooves and doesn't require undersized bearings.
I've only had it done once, but it worked perfectly. Better than new.
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That?s a really good suggestion Cam, I?m quite shocked that such an easy solution, that addresses the root problem hadn?t been hadn?t occurred to me before. Clever.
 
Hard-chroming to original size would only be viable if original size bushes were readily available.  Mostly, these aren't, as they're useless without an axle in decent condition, which is now unobtanium.  Hard-chrome involves a grind, chrome and another grind to size, which is usually more expensive than what most expect.  A simple re-grind and making slightly under-size bushes is far more cost-efficient.

Depending on the amount of wear found in the bushes, one might get away with hard-chroming the axle slightly over-size and reaming the bushes to suit.  But this is also a process well out of reach of the average DIY'er.

piet
 
It wasn't actually a Laverda swinger axle that I had hard chromed. It was a for bevel Ducati, but the process is the same. Bushes were (are?) readily available but new shafts were hard to find.

The new bushes still had to be reamed after they were pressed into the swing arm. I don't have the gear to do that, so I took it to an engineering shop. Only problem was the young bloke (an apprentice) who did the job buggered it up. He reamed one bush, then turned the swing arm over and reamed the other, without any reference to the alignment of the first bush. He should have used some method to preserve the alignment, like reaming right through from one side to the other. I doubt the reamer would be long enough to do that, so some ingenuity may have been required.

There was probably only a few thou misalignment, but it was enough to stop the hard chromed shaft from sliding through. It was a nice fit in each bush individually, but wouldn't go through both! I reckon he realised pretty quickly he'd just buggered a brand new set of bushes.

I know the manager of the engineering shop reasonably well. He occasionally refers customers to me if they need some engineering design work done. He's a decent bloke and took responsibility for the cock-up. It turned out to be a good learning experience for the apprentice. He made up a new set of bronze bushes and figured out a way to ream it so that both bushes were aligned, so he did a perfect job in the end.
 
I had a little bit of play in my Pantahs swingarm, it pivots through the engine cases, the fix was an oversized swingarm pin that's available from the factory. It was well snug and fixed it well. That surprised me at the time.
 
Dellortoman said:
Only problem was the young bloke (an apprentice) who did the job buggered it up. He reamed one bush, then turned the swing arm over and reamed the other, without any reference to the alignment of the first bush. He should have used some method to preserve the alignment, like reaming right through from one side to the other. I doubt the reamer would be long enough to do that, so some ingenuity may have been required.
Click to expand...

I'm sure that the use of a pilot/guide is essential with a hand reamer. Alternatively, setting the swinger up in a lathe or mill concentrically and reaming with the tool in the chuck would also work. I'm far from qualified fitter and turner (Maurice is closer to that than me  :D) so I'm only extrapolating what little I know.

Good to hear your man came good anyway, Cam. I went to needle rollers when I wore out my first set of bushes and have had no trouble with them.
 
A very good friend who knows his machine tools  makes the bronze bushes very slightly undersize on the outside but adjusts the internal diameter to the spindle before fitting.
He then glues them in the swingarm with the spindle fitted, so eliminating the need for line reaming.

Paul
 
Paul that was exactly what I was planning to do, don't know if it will work or not but cannot see any reason why it won't though someone with far more experience may be able to point out some of the pitfalls.
 
Paul Marx said:
A very good friend who knows his machine tools  makes the bronze bushes very slightly undersize on the outside but adjusts the internal diameter to the spindle before fitting.
He then glues them in the swingarm with the spindle fitted, so eliminating the need for line reaming.

Paul
Click to expand...

Good idea! I have to install a set soon ..... I will remember that ... thank you!
 
Hard chroming is a good idea as you could grind it to the correct size. But if it becomes dry as the thread suggest nobody slackens and greases anymore then it will not last very long. Dry chatter will shatter it. If
 
harpmeister said:
The bronze swinging arm bushes on my SF1 need replacing and I was just wondering what my options are regarding replacements and any problems I might encounter fitting them.

I have emailed a couple of suppliers to see if they have bronze bushes in stock but so far (2 weeks later) I haven't had a reply.

If these are no longer available does anyone know the correct grade of bronze to use and the exact dimensions and I can turn them up myself or is it better to upgrade to something like needle bearings.

Thanks

Joe
Click to expand...
Joe,

did you manage to find out "correct grade of bronze to use and the exact dimensions" for the bushes? I'd be interested to have them. Also, does anyone has exact dimensions for the spindle axle?

Thanks in advance to anyone who could help with this.

Alberto
 
steppenwolf said:
Joe,

did you manage to find out "correct grade of bronze to use and the exact dimensions" for the bushes? I'd be interested to have them. Also, does anyone has exact dimensions for the spindle axle?

Thanks in advance to anyone who could help with this.

Alberto
Click to expand...
hi all can anyone help me with this? thanks
 
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