Can anyone explain why BSA use rubber in their swinging arm bushes, surely this is one part of the bike that you only want lateral movement in?
So, on that basis has anyone changed their bushes for something less, well, squidgy!!
I always think this is an odd design feature, apart from a pain in the proverbial to remove and can't think of other makers that do it (forget Triumph, they were BSA anyway!)
Hi,
Reduce vibration. There are alternatives as the attachment, I believe they can be sourced from here:
Sheffield British Motorcycles
26-30 Lowgates
Staveley
Chesterfield
S433TT
Telephone: +44 (0)1246 290021
Best wishes...
Quote from: SteveA10 on 05 Mar, 2019, 15:55
Can anyone explain why BSA use rubber in their swinging arm bushes,
Don't forget that Norton used them in their featherbed framed models and they didn't handle too shabbily. An awful lot of cars use them in suspension mounts too.
The truth is that metalastic bushes do a reasonable job at a reasonable cost, last for many many miles and require zero maintenance. You start using expensive bronze bushes and the like and you then need regular lubrication. There's a lot of owners out there that struggle to keep the oil tanks at the correct level and their chains lubricated, so bronze bushes in the swing arm would likely get neglected.
Manx featherbeds did get bronze bushes as standard, but being a racing machine, precision suspension is a must and cost and meticulous maintenance wouldn't be an issue.
Probably like the same Triumph used in T100 range on handlebars, keeps vibration down.
As for maintainance.... A pain when they need replacing as once rubber parts from outer steel there isn't a lot to drift out. In the past I've had to dremel out the wall then try to pick it out. If I remember right Harley use a needle roller one side and phos bronze the other just to confuse.
They do last many many years, never need lubricating, do not corrode, provide a positive location for the swing arm andare proven in several other transport applications, but I don't really know why BSA went for them ;)
:) :)
A50/A65
Largely watertight. Not enough rubber to be quishy. No maintenance/lubrication problem.
Take a look at some of the Hondas etc of similar age(if you can find one) Swing arms rotted out across the area between the frame joints.
Smooth and quiet.
I agree that replacement can be a pain but the only time I've ever replaced them is during a complete rebuild. Certainly never had one "fail".
Overall I would say (opinion only) they are as good as it gets.
Mike 8) 8) 8)
Ariel Swinging Arm frame also uses the Silentbloc set up.
Interesting comments. The original Norton Isolastic mountings were very troublesome and there was a modification early on to remedy that, but they still wore quicker than would be expected.
I take the point about low maintenance, but I was thinking more of best practice as regards handling, do Goldie racers use them for instance?
Certainly when I renew mine I will be looking for a better alternative, so thanks for the heads-up about Sheffield engineering.
Cars use them all over the shop, suspension, engine mounts, etc, but we are talking bikes here, not boxes!
I didn't know Ariel used them, but they were owned by BSA and of course the Sunbeam S7/8 had a rubber mounted engine, which meant they had to put flexi pipe in the exhaust system, the kind of bodge I'd do, but wouldn't expect from a mainstream factory.
As to rubber mounted handlebars, I had them on my Suzuki T500, with over an inch movement at the bar end, they were very quickly discarded for something more solid and the vibes were hardly any different. Nowadays bar end weights would be the way to go to damp the vibes, but we didn't know that then, well I didn't!
Quote from: SteveA10 on 12 Mar, 2019, 16:49
The original Norton Isolastic mountings were very troublesome
The Commando Isolastics were something totally different.
The Norton Featherbed used metalastic bushes in the swing arm in exactly the same manner as the A10 and Gold Stars.
It sounds like you're trying to fix something that isn't broken.
Bought my A10 in 1973. During a rebuild in 1992 I had the bushes replaced whether they needed it I dont know. 27 years on and many miles later no problems with the bushes or the handling. For me that is proof of a sound design.