Author Topic: Swinging arm and bush removal.  (Read 688 times)

Online cyclobutch

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Re: Swinging arm and bush removal.
« Reply #15 on: 18.06. 2020 13:26 »
Regardless, I think the arrangement sucks.
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Online Greybeard

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Re: Swinging arm and bush removal.
« Reply #16 on: 18.06. 2020 17:15 »
To state the bleedin obvious, BSA did not expect, (or want?) their machines to last a human lifetime. I fancy that by comparing the plunger, (and earlier machines) to the SA models you can see the introduction of built-in obsolescence that has become standard practice.
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Offline BSARGS650

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Re: Swinging arm and bush removal.
« Reply #17 on: 18.06. 2020 17:56 »
In the past, when original bushes were available, I replaced them in the RGS and SR just because of some cracks seen on the outer.  In hindsight I don't think it was necessary as prodding around before destruction revealed they were only really on the surface, wondering what might be further in, decided to change them for peace of mind.  But once the destruction began, it looked like they were pretty solid throughout.  I just replaced the bushes during restoration of my BSA WD B40 only because the pin could not be removed and the end of the block gets damaged cutting it away from the frame gusset.  Maybe they could be tested in the frame before replacing them (with nothing attached - as in stripped down for restoration), attaching known weight to give a certain deflection?
All the best
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beezermacc

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Re: Swinging arm and bush removal.
« Reply #18 on: 18.06. 2020 23:10 »
Just some random observations from personal experience and further thought.... I don't think the silentbloc bushes are deliberate designed obsolescence; it's such a bitch of a job to replace them the vast majority of owners would resent having to do the job or pay the money to farm it out so it would be counterproductive. The cost of the bushes, being fairly cheap, would not warrant the hassle. The whole point of designed obsolescence is to make it easy for owners to spend money on a regular basis. There may be other examples of designed obsolescence on the A10 but I can't think of any (apart from the whole bike - BSA went bust for a reason! The Japanese made the A10 / A65 obsolete). Even when these bikes were being used as daily commuting bikes they would probably be on the road for an hour or two on a weekday, the rest of the time they would be on the centre stand. Consider the maths... 10,000 miles (200 miles a week, 40 miles a workday) at an average speed of 30 m.p.h. = less than one hour per day in a 7 day week on the road and 23 hours on the centre stand so, fitting the bushes in anything other than their centre stand position seems to be putting the bushes under unnecessary strain for 95% of their lives. I've fitted plenty of bronze bushes in my time as well and that's not a lot of fun either! Even though silentbloc bushes allow for a bit of instability I think they are an improvement on traditional bronze bushes. The only time I or anybody else in my sphere of friends have needed to change the silentbloc bushes is when it has been desirable to remove the swinging arm for cosmetic treatment (no, not botox!). I've never come across any which were actually worn out, but I've come across plenty of bronze bushes which were worn out. Silentbloc bushes don't need lubricating of course. The best A10 I've ever had was my 1954 plunger, no silentblocs in sight! However my swinging arm A10's handle better, but the plunger was just such a lovely bike to ride. A friend of mine used to work for a firm called Monroe (shock absorbers) and he says the silentbloc bushes are incredible, the twisting force they will withstand has to be seen to be believed and he reminded me that car suspension bottoms out maybe dozens of times every trip and the movement on a wishbone is greater than the swinging arm travel on an A10. For those people who insist on compressing their suspension whilst tightening their swinging arm spindle remember this.... As soon as you take the weight off your bike that skinny bit of rubber is straining and stretching and trying to release itself from its metal casing and it'll be doing it all the time, like a persistent irritating itch which won't give up until it bleeds, every hour of every day whilst you're not riding your bike, whilst you're asleep at night, whilst you're on holiday, whilst the garage door is closed it's out of sight stretching and straining until it starts to release like that first piece of peeling wallpaper that just gets more irritating and worse and worse until it falls off the wall completely... and as soon as the rubber starts to separate from the casing there's less rubber gripping on the casing so it gets easier for the rest of the rubber to creep away like water rotting through cardboard in a nightmare that at first you can hold back but in the end it just overwhelms you and suffocates you in a torrent of soggy papier-mâché, then the ghosts of the BSA design engineers crowd round you and shake their fists and their fingers look like silentbloc bushes and they twist them until their knuckles crack to demonstrate just how resilient the silentbloc bushes are, and you'll scream and beg forgiveness for not paying attention to section D12 of the BSA A65 workshop manual which retrospectively addresses the urban myth that silentbloc bushes are the work of the devil and should therefore live their lives under permanent stress. I promise not to contribute to this thread ever again - really regret starting it - should know better at my age! Good Night!
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Online berger

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Re: Swinging arm and bush removal.
« Reply #19 on: 19.06. 2020 00:23 »
the witch of a deputy head master at school always had to have her say after the head master had done his rant. she used to say " and just to add!! so here goes ,and just to add silent block bushes should be fully tightened in the resting position. my dad told me and he was a damn good proper engineer. I am not but I always do it on cars *fight* *whistle* I just thought that makes sense if talking about a car on its wheels, so I say bike under it's own weight.
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Online Greybeard

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Re: Swinging arm and bush removal.
« Reply #20 on: 19.06. 2020 10:04 »
Andrew, my remark about obsolescence was referring to the whole machine. Nobody thought these motorbikes would be around in the 21st century. What do you reckon was the predicted lifespan; 20 years?

BSA designers were given a brief to keep costs down and at the time these clever bonded rubber bushes became available.

I have fitted lots of these bushes to motor cars of the 50's and 60's.
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Offline ianbsa

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Re: Swinging arm and bush removal.
« Reply #21 on: 19.06. 2020 10:25 »
Anybody who has tried to remove a swinging arm which is rusted in will know what a PITA this job is. My first piece of advice would be..... if you don't have to remove it, don't! I've had to do this job quite a few times over the years and I reckon I've perfected a method which works well. It's a bit brutal but recognises the futility of trying to remove the swinging arm spindle when it is rusted in! If you try to remove a spindle that is completely rusted in you will bend the side plates that support the swinging arm. Also covered is silentbloc removal. The link will take you to a word doc with pics that some may find useful. I did this last week and it took me about 40 minutes.
https://docs.google.com/viewer?a=v&pid=sites&srcid=ZGVmYXVsdGRvbWFpbnxwcmlvcnltYWduZXRvc3xneDo1YmY2NzkxODk4YTQ0Njll

Nice work indeed, I love it when someone comes up with a new fix for a nasty problem.  Cant remember how I did mine though knowing me it was probably with huge amounts of heat on the SArm...the bike was going to be repainted anyway.
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Offline Jules

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Re: Swinging arm and bush removal.
« Reply #22 on: 19.06. 2020 12:20 »
a beautiful end to a great starting thread BM, love it  *clap*  *thanks*
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Online RichardL

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Re: Swinging arm and bush removal.
« Reply #23 on: 19.06. 2020 13:48 »
Well, despite my temptation to do so, I'm not chiming in on the under load versus at rest issue. I'm here to say that, when it comes to reading lengthy rants, Andrew's are my favorites.

Richard L.
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Offline trevinoz

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Re: Swinging arm and bush removal.
« Reply #24 on: 21.06. 2020 00:04 »
The silentbloc was also good enough for Norton to use on the Featherbed frame.
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Online groily

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Re: Swinging arm and bush removal.
« Reply #25 on: 21.06. 2020 07:40 »
Indeed. The 2 best handling Brit frames of the era. Far be it from anyone to suggest there's any connection of course, as there be other reasons  . . . but all the same  . . .
Nonetheless, I am glad not to have had to tackle removal on either my A or a slimline that shares shed space. The only swing arms I've had to 'do' have been heavyweight AMCs, with bronze bushes. Less awkward and no pre-tension issues to worry about there -  but even so, they're not a 'just do it before nipping down the pub' sort of job. Luckily, they last well.
By contrast, how much easier are a lot of moderns with taper rollers etc - which is just as well when it comes to replacing endless rear chains without resorting to a soft link. While it took a day or more to repair the last AMC I did, fitting an endless chain and new sprocket kit on my Yam XJR was 'only' a morning's worth of sweat. Pleased, for once, to concede that there had been progress over half a century. (Until I wanted to replace the plugs on the Nipponese beast, that was.)
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Bill

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Re: Swinging arm and bush removal.
« Reply #26 on: 21.06. 2020 11:45 »
If you don't want to use a spring link (which I have no problem with - it's cranked links that fail) why not rivet the chain in situ?
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Online groily

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Re: Swinging arm and bush removal.
« Reply #27 on: 21.06. 2020 13:11 »
Could have RD and many owners and some shops do. But they are made, and  factory fitted, endless and their riveting is probably better than mine. Lot of power and torque in these things and I just wanted that feeling of confidence, even if being daftly paranoid!

Nothing wrong with split links on our stuff, I do agree - and no practical option really either. Many modern 'boxes have overhung gearbox sprockets, so no need to play with the transmission to replace rear chain, just hoick out s/arm spindle.
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Bill

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Re: Swinging arm and bush removal.
« Reply #28 on: 27.06. 2020 12:37 »
Having ridden thousands of miles on silentblock's
Plain needle rollers
& needle + radial rollers , give me a silentblock any day fo the week.

Almost impossible for one to collapse and have your rear end dancing the Char char every time you open the throttle or back off.
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