The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => Frame => Topic started by: mikeb on 28.10. 2018 09:02
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in mid-september i posted happily about reassembling the swingarm on my 61 super rocket complete with new silentblocs. unbelievably, over the past month (and only a few runs) I had to admit to myself it was getting loose in the swingarm again. I pulled in down tonight and the 'new' silentblocs are completely stuffed - see photos below and this vid of the movement:
https://youtu.be/QRjzfTcsrrk (https://youtu.be/QRjzfTcsrrk). the second photo below is by driving the centres out - they were so perished it took little effort.
*angry* *problem* *angry* *problem* *sad* *dunno*
i thought the package looked a bit old when i got it so maybe it was decayed NOS, or just new rubbish. shame on the suppliers, i'll be calling them about it. i'm left with two questions:
1. where does one get decent new silent blocs? before someone suggests C&D, I've asked and they say what's on the market is so poor they won't carry them.
2. what's with the random sizing? other people write about the silentbloc outer being too large for the swing arm by up to .010". I've got another spare swingarm with unknown silect blocs in it and those inners are .008-.010" smaller than the ones I just fitted. hence my 'new' spindle and even the 'old' broken metric spindle won't fit. (some 'new' spindles are metric threaded and sized... *eek*). how can i have any confidence the next lot will even fit?
all help appreciated
Mike
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I’m riding around on 60-year old ones, which makes me think age does not wither them in a hurry.
Do you think you got the movement centred right so they weren’t forced too far in one direction and torn (I don’t know if that really happens, I’m just theorising).
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TT - i think i got them pretty well fitted - measured up 20 times and pressed in evenly.
if you look at that second photo you can see the remains of the rubber on top of the old centres - very perished. maybe they've spent 50 years stored in the NZ sunlight - a bit warmer than scotland? (I used to live in glasgow)
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Does anyone do a bronze bush conversion?
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G'day fellas.
About 1991 I had to cut the frame to get the s/a out. Made bronze bushes to fit. About to make new bush's as the old set up only lasted 26 years.
Will post dimensions in a week or ten. F knows where my drawings are.
Cheers
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When I read about those darned metalastic bushes I keep wondering why people don't convert to bushes.
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If c+d say there aren’t good blocs available I’d believe them, which means you will have a problem finding good ones *problem* .....in my experience c+d would rather be out of stock than sell poor quality parts, unlike less reputable suppliers (who will tell you “take it or leave it it’s all that is available in the market”)
Your pic looks like the blocs you bought were old stock, a bit of very old looking rust there?
Bronze bushes like muskrat says is a good solution but you will need to get the “end float” control right, something (eg bronze washers, top hat Bush) needs to stop the side to side movement of the swing arm to a minimum, whilst allowing the spindle to clamp up tight as it does with blocs. The custom machining involved could be pricey.
Alternatively I guess you need to try to find a supplier whose stock is a few years old, before the supply chain became dodgy, the risk being you get more duff ones.
I suppose it’s not too surprising if usable blocs became unavailable, if they are made especially for bsas and can’t be adapted from a “standard” bloc used in larger volumes, the sales volumes for bsas can’t be high!
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Unity seem to imply that they sell a kit for BSAs, on Page 38.
http://www.unityequipe.co.uk/Unity%20EquipeCatalogue.pdf
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I always make tightening the swinging arm pivot one of the last jobs, tightening it with the weight of the bike on the wheels, and someone astride. This means that under normal running, the torsional load on the comparatively thin rubber bush is at its least. Tightening vehicle suspension bushes with the weight of the vehicle on its wheels is also an accepted practice. Tightening the spindle with the swinging arm hanging down means the bush is already in a fair amount of shear by the time the bike is fully roadworthy. Leaving tightening to last will make the bush last longer.
Swarfy
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mmmmm makes sense swarfy-- mine are original and even stood up to stove enamelling 38yrs ago
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G'day fellas.
Here's the Unity page. I haven't seen their kit.
Cheers
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TT/musky - that unity kit looks interesting - has anyone tried one? or have a guess about the quality of stuff unity supply?
they spec the spindle as 3/4" whereas i thought it was 13/16" (mine measures to that). more sizing mystery???
Swarfy - yes i made sure the wheel was on the ground and me on the seat before tightening the spindle nut.
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you may well find out b*st**d john has got unity's stock, take another mortgage out be prepared to get talked AT! I , I wish you well--- merry christmas
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Hi All,
Andy Higham posted a thread on Britbike forum on converting the swingarm to needle roller bearings
The inner sleeve dimension would need to be changed for the hollow spindle
Andy is a clever guy and has a build on his B31 to Goldie replica here
http://www.britbike.com/forums/ubbthreads.php/topics/640945/1
It has his own designed electric start and Suzi based clutch
http://www.britbike.com/forums/ubbthreads.php?ubb=showflat&Number=622841&Searchpage=1&Main=66918&Words=%2Bbearing&Search=true#Post622841
and published a drawing here
https://www.dropbox.com/s/ffxgy54qcp1z262/BSA%20swing%20arm%20bearings.pdf?dl=0
John
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hi guys, MikeB i am sure you cold get someone in NZ to make some based on the `silent block` measurements ,that is what i would do if i needed some. Perhaps Musky can supply a pattern with dimensions for you? good luck, cheers
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hi mike there you are all done for you just need a lathe man,(you may be one ?) i have one down here that i use for stuff like that, good luck, cheers
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Mike... Looks like you did everything just fine. No wonder you have reason to question the quality of replacement parts. Forum rules probably ban the use of a more expressive phrase.
berger...Are you referring to that fine fellow trading from a famous City just up the big hill from your present abode?
With all the measuring and general assistance you have recently offered, I hope you go to the pub (often)
Swarfy.
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yes to both swarfy first meeting through a mate when I was possibly 16 years old, no not the pub the other one , I thought very wrongly that things would be kind to me with me having the same interests but I was so wrong about that [ ie supplying a part of BSA manufacture of which was openly said got 100's, of them!! but was determined to sell soft margarine made in india that my engine would destroy inside 40 miles ], enough said *shh* some people may love the service but most want to kill!!! my PRV is at full flow now *fight* *bash* *pull hair out*
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When I read about those darned metalastic bushes I keep wondering why people don't convert to bushes.
" ... I’m riding around on 60-year old ones ... "
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looks like decent silentblocs are now hard to find so i've just ordered a set of bronze bushes from unity (john p?). will feedback when they arrive
this is getting expensive
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G'day Mike.
How much are they $ with postage?
I'm gonna try the needle roller set up next.
Cheers
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i forgot to ask the total Musky (not like me) tho the bushes kit is 125 UK pounds so i guessed the postage is a small fraction and wasn't going to change my buying. i'll let you know when they turn up. he's got to make them yet. needle rollers would be nice.
Kiwi - those drawings (for a B44, right?) show a 5/8 spindle so may match an earlier a10 without the crossover. tho i guess the design is the same. wish i had a lathe (and somewhere to put it)
got a rally on the 17 so may be taking the b33 again
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G'day Mike.
Gee I'd like to see the kit. When they arrive make a detailed drawing of the bits.
It won't help you but I recon I'd make them for 1/2 that.
I know they (Unity) have to turn a profit and the quantity sold would be small so mark up is greater. BUT.
Cheers
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it will help me if they actually fit - would make it worth the $ too, even at twice the $ of metalastic
it would be a good project to make some if i had a lathe... one day...
i'll report back when they arrive
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Have you received the unity kit yet? Intrigued to see pictures of before and after.
Nevermind found the other post
https://www.a7a10.net/forum/index.php?topic=13733.0
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re that thread - they are still great, as you would hope. no more silent blocs for me *smiley4*