Swinging arm question

Maestro, SEI-V
penman
Posts: 325
Joined: 08 Mar 2016 09:20
Location: Milton Keynes, UK
Location: Milton Keynes

Swinging arm question

Post by penman »

I have been searching on this forum for information on the swinging arm. The one on my K2 seems different to the one on my 1978 500W. First the problem. When I prepared the bike for MoT, I greased the swing arm and it seemed to be fine. When I got to the MoT, about 10 miles, there was just detectable play in the swing arm and the tester felt it was within acceptable limits. By the time I got home, there was significant play and now I suspect old hardened grease has given way and wear is becoming more obvious. As always, it's not easy to say, but I think this is wear in the bushes, rather than side to side float. I wouldn't take it for an MoT like it is now.

Now the questions. I gather the pivot spindle is threaded into the frame, presumably on the right hand side only? So the 30mm nut I see on the RHS is a lock nut for that side? I can't shift that nut and I'm in danger of damaging it, but someone mentioned using an impact wrench, so I'll try that today. Are the bushes pressed into the swing arm, and are they easy to get in and out? Do they need to be reamed? The parts book shows a "clearance washer" which looks as if it's between the RHS of the swing arm and the frame and a range of sizes is mentioned. Is the idea that this shim takes up the end float, or does tightening the pivot adjust it as well?

Sorry about all the questions - I like to know what I'm in for! If there is another thread answering this, maybe someone can let me know, but I couldn't find it!

Many thanks,
Joe.
1984 Moto Guzzi V65
1969 Honda CB450
1975 Triumph T160 Trident
2019 BMW F750GS Sport
1978 Morini 500
penman
Posts: 325
Joined: 08 Mar 2016 09:20
Location: Milton Keynes, UK
Location: Milton Keynes

Re: Swinging arm question

Post by penman »

An update - I have stripped the swing arm and I think most of the wear is in the pivot spindle:

Image

To be honest, it doesn't feel all that bad, but it results in too much play in the swing arm and the wear is easily visible. I'm not sure about the bushes, I can't actually see any wear, but of course you can't really see inside the bush very well. The spindle came out easily enough but it looks as if I'll have trouble getting the bushes out, I don't have a press, though I've often wished I had one! I may try just replacing the pivot spindle and see if that reduces the play enough. Hopefully NLM sell them, though no doubt they are horribly expensive. Or I could make one - now that's an idea.

I would appreciate the benefit of anyone's experience with the bushes - in particular, do they need to be reamed?

Regards,
Joe.
1984 Moto Guzzi V65
1969 Honda CB450
1975 Triumph T160 Trident
2019 BMW F750GS Sport
1978 Morini 500
User avatar
72degrees
Posts: 1549
Joined: 31 Aug 2007 21:24
Location: West Midlands

Re: Swinging arm question

Post by 72degrees »

Can't help with the reaming query. Last time I needed bushes on a Morini was the 2C and I went for custom made 'nylon' ones supplied and fitted by harrymuffin many years ago. As to the clearance washer and side play Evguru has one of his excellent youtube videos on adjustment.
https://www.youtube.com/watch?v=uz-mnkTi8JA
3potjohn
Posts: 1243
Joined: 02 Jun 2007 13:58
Location: Devon

Re: Swinging arm question

Post by 3potjohn »

I replaced my bushes using new ones and a new SS single,all from NLM.The old bushes were very difficult to get out, though some have cut through longways which may help.I tried a local enginering firm, and the chap waved a hammer with a head the size of a breeze block, which we avoided thank goodness. THey should be line reamed.Another ploy is using PTFE bushes if you can get them made up.
penman
Posts: 325
Joined: 08 Mar 2016 09:20
Location: Milton Keynes, UK
Location: Milton Keynes

Re: Swinging arm question

Post by penman »

Many thanks for the replies and for the link to Paul's video, which I hadn't found previously. Now I have it in pieces it's all pretty clear. I'm fairly sure most of my wear is on the pivot pin because if I insert the un-worn part of the spindle into the bushes, it feels like a good snug fit. So, my first plan is to make a new spindle in stainless and see if that will work with the existing bushes. I might make a test pin in aluminium, just the length of the bush first to test for fit - that'll be a lot quicker and easier than making the whole thing in stainless, only to find that the bushes are oval or whatever. I'll give it a bit more thought, but that's the current plan.

By the way, the old grease in there was practically like a coat of varnish and when I'd greased it, the grease had just cut a narrow channel through the old grease. Despite the varnish-like coating, there is still evidence of corrosion on the pivot pin. The bushes look OK though. I've had a close look ar them and they look promising - I expect I'll soon be proved wrong!

Regards,
Joe
1984 Moto Guzzi V65
1969 Honda CB450
1975 Triumph T160 Trident
2019 BMW F750GS Sport
1978 Morini 500
norbert
Posts: 750
Joined: 15 May 2007 15:15
Location: Lübeck/Germany

Re: Swinging arm question

Post by norbert »

The axle shows some wear. My experience is that often the wear of the axle is more the problem than the bushes. When I notice play in the swingarm first I try it with turning the axle 90°. If you are lucky the play disapears and may be ok for some more years.

norbert
EVguru
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Re: Swinging arm question

Post by EVguru »

The OEM bushes are cast Iron and the pin is hardened.

Stainless Steel is not a compatible bearing combination with cast Iron. Even if your bushes were smooth, you'd have a tendency for galling.
Paul Compton
http://www.morini-mania.co.uk
http://www.youtube.com/user/EVguru
penman
Posts: 325
Joined: 08 Mar 2016 09:20
Location: Milton Keynes, UK
Location: Milton Keynes

Re: Swinging arm question

Post by penman »

EVguru wrote:The OEM bushes are cast Iron and the pin is hardened.

Stainless Steel is not a compatible bearing combination with cast Iron. Even if your bushes were smooth, you'd have a tendency for galling.
Thanks for that Paul, what would you suggest? I am hoping to avoid the need to replace the bushes because I don't really have the facilities to do it. I'll go ahead with assessing the condition of the bushes, but if you can suggest a more suitable material for the spindle that would be helpful. Given the small movement of the swing arm, is galling likely to be a big problem?

Thanks!
Joe.
1984 Moto Guzzi V65
1969 Honda CB450
1975 Triumph T160 Trident
2019 BMW F750GS Sport
1978 Morini 500
penman
Posts: 325
Joined: 08 Mar 2016 09:20
Location: Milton Keynes, UK
Location: Milton Keynes

Re: Swinging arm question

Post by penman »

norbert wrote:The axle shows some wear. My experience is that often the wear of the axle is more the problem than the bushes. When I notice play in the swingarm first I try it with turning the axle 90°. If you are lucky the play disapears and may be ok for some more years.

norbert
Thank you for that. I've had a look at both the bushes and the pivot pin. Certainly the wear is concentrated in two areas 180 degrees apart around the pin. If I rotate the pin I can certainly find a spot where the play is minimised, so I'll give that idea a bit more thought.

There is wear on the bushes, though it looks pretty slight and it looks pretty even, though it's difficult to judge that by eye.

Are the new bushes a different material? I've seen mention of SS spindles (which is what started me down that route), so I'm guessing the matching bushes are brass or phosphor bronze? Are they easier to insert? Apologies, more questions than answers at this stage.

Joe.
1984 Moto Guzzi V65
1969 Honda CB450
1975 Triumph T160 Trident
2019 BMW F750GS Sport
1978 Morini 500
'It must be a .....'
Posts: 365
Joined: 12 Sep 2010 12:25

Re: Swinging arm question

Post by 'It must be a .....' »

Hi, I've changed the swinging arm bushes on several bikes over the years and replaced them with phosphor bronze bushes; which were once available from the club and I think NLM still stock them along with stainless spindles.
The original bushes don't last long even when greased regularly yet I've never had to replace any phosphor bronze bushes that I've fitted.
In the past I've changed them with a press in a local garage, a large vice and the last time I did the job I used a tow hitch bolt with an extended socket handle. The bolts are available in different lengths from caravan/trailer suppliers; the bolts/threads are strong enough but the threads need to be greased to reduce the friction.
Hope this helps?
PS Once fitted the phosphor bronze bushes will need to be reamed to fit the spindle.
penman
Posts: 325
Joined: 08 Mar 2016 09:20
Location: Milton Keynes, UK
Location: Milton Keynes

Re: Swinging arm question

Post by penman »

'It must be a .....' wrote:Hi, I've changed the swinging arm bushes on several bikes over the years and replaced them with phosphor bronze bushes; which were once available from the club and I think NLM still stock them along with stainless spindles.
The original bushes don't last long even when greased regularly yet I've never had to replace any phosphor bronze bushes that I've fitted.
In the past I've changed them with a press in a local garage, a large vice and the last time I did the job I used a tow hitch bolt with an extended socket handle. The bolts are available in different lengths from caravan/trailer suppliers; the bolts/threads are strong enough but the threads need to be greased to reduce the friction.
Hope this helps?
PS Once fitted the phosphor bronze bushes will need to be reamed to fit the spindle.
Thanks for this useful and practical advice. I'm gradually getting the feeling that the original bushes are a bit past their best. I made an aluminium test pin, which slides easily into one bush but the other bush is too tight. I can also see and feel a raised ridge around one bush, about 1/3 of the way down, but no corresponding groove in the pivot pin, which is a bit of a puzzle. I think I'll phone NLM on Tuesday and if they have the parts in stock, I'll get new bushes and pivot. Maybe I can borrow a reamer or get a local engineering shop to do it. Anyway, it has to be fixed!

Regards,
Joe.
1984 Moto Guzzi V65
1969 Honda CB450
1975 Triumph T160 Trident
2019 BMW F750GS Sport
1978 Morini 500
EVguru
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Re: Swinging arm question

Post by EVguru »

You can get the old bushes out with spacers and a good bench vise, or with a length of stout allthread.

I make PTFE bushes to run on a custom stainless spindle without grease drillings.

The bushes need to quite tight in the swingarm and then an adjustable reamer is used to size the bushes so the pin is quite a heavy push fit.
Paul Compton
http://www.morini-mania.co.uk
http://www.youtube.com/user/EVguru
penman
Posts: 325
Joined: 08 Mar 2016 09:20
Location: Milton Keynes, UK
Location: Milton Keynes

Re: Swinging arm question

Post by penman »

EVguru wrote:You can get the old bushes out with spacers and a good bench vise, or with a length of stout allthread.

I make PTFE bushes to run on a custom stainless spindle without grease drillings.

The bushes need to quite tight in the swingarm and then an adjustable reamer is used to size the bushes so the pin is quite a heavy push fit.
Thanks Paul, tell me more about your PTFE bushes - any in stock? If I was to bring you my swing arm, could you send me away with new bushes and spindle? I can certainly see the advantage over cast iron.

When you say the pin needs to be "quite a heavy push fit" I presume you are talking about the PTFE bushes, not the metal ones.

Thanks,
Joe
1984 Moto Guzzi V65
1969 Honda CB450
1975 Triumph T160 Trident
2019 BMW F750GS Sport
1978 Morini 500
texaskitty
Posts: 89
Joined: 17 Jan 2016 06:37
Location: Melbourne, Australia

Re: Swinging arm question

Post by texaskitty »

A long time ago, to aid removal of my 500's swing arm bushes I used a hacksaw to cut through each bush. If you do this, take a lot of care not to cut into the swing arm itself. Watch each end of the cut as you go and do not rush it. Look closely to see if your cutting leaves a high spot in the middle of the bush; it might help to put a hacksaw blade (blade only) upside down in the cut and see if it rocks up and down at the ends, suggesting a high spot in the middle. If there is a high spot there, slowly cut that down taking care not to cut too deep at the ends.

If you are very careful, you should be able to cut all the way through, or virtually all the way through, without cutting the swing arm. This will relieve the pressure and the bushes should come out pretty easily with a drift and hammer.
penman
Posts: 325
Joined: 08 Mar 2016 09:20
Location: Milton Keynes, UK
Location: Milton Keynes

Re: Swinging arm question

Post by penman »

texaskitty wrote:A long time ago, to aid removal of my 500's swing arm bushes I used a hacksaw to cut through each bush. If you do this, take a lot of care not to cut into the swing arm itself. Watch each end of the cut as you go and do not rush it. Look closely to see if your cutting leaves a high spot in the middle of the bush; it might help to put a hacksaw blade (blade only) upside down in the cut and see if it rocks up and down at the ends, suggesting a high spot in the middle. If there is a high spot there, slowly cut that down taking care not to cut too deep at the ends.

If you are very careful, you should be able to cut all the way through, or virtually all the way through, without cutting the swing arm. This will relieve the pressure and the bushes should come out pretty easily with a drift and hammer.
Thanks. I have done this before on swing arm bushes, and as you say, it can be tricky to avoid a high spot in the middle, though possible. I'll have a go at pressing them out first and resort to the hacksaw if necessary. Just following up Paul Compton's PTFE suggestion at the moment!

Regards,
Joe.
1984 Moto Guzzi V65
1969 Honda CB450
1975 Triumph T160 Trident
2019 BMW F750GS Sport
1978 Morini 500
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