Author Topic: Swinging arm location  (Read 1588 times)

Offline Jules

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Swinging arm location
« on: 13.04. 2011 07:42 »
Hi all, well I've moved onto looking at my frame. It has been straightened yonks ago and painted, but I just noted that the swing arm nut and the locating bolt on the other side are loose (presumably by the painter  *eek*). On further investigation I can rotate the arm up and down (without the locating bolt in the flange fitted), and also I note that the arm is not central in the frame. The clearance on each side is about 12mm and 8mm, measured about 25mm back from the pivot tube, across to the main frame tubes. There is no info. in the manual about it (just says "return to .....for servicing the swinging arm"), any thoughts appreciated before I start assembling into it, thanks

Online KiwiGF

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Re: Swinging arm location
« Reply #1 on: 13.04. 2011 08:02 »
Have you removed the swing arm? If not then you may not have seen how the bsa system works. It should have silent bloc rubber bushes in the arm and these should clamped against the frame when the swing arm bolt is tightened ...........there are no metal to metal bearing surfaces as such the rubber allows the required movement between swing arm and bolt

If that does make sense let me know

Note removing the arm often results in buying new bits so don't do it uless the frame holes are worn over size or the blocs are no good!
New Zealand

1956 A10 Golden Flash EA7-168x, CA10 913x, left BSA together for Liverpool, 5th Dec 1955.

1949 B31 rigid “400cc hot rod” (favourite bike)

1949 C11 rigid, but why!!! (cos it was cheap)

1937 B21, missing parts so mission impossible?

1952 Armstrong Siddeley Whitley for rainy days (with wife).

GL1800 Goldwing not sure why, maybe cos it always starts

Offline Jules

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Re: Swinging arm location
« Reply #2 on: 13.04. 2011 09:03 »
Thanks Kiwi, no the arm isn't out and I dont really want to remove it, but I'm concerned about the centreing and what sort of torque the big nut should have on it...... any dims and torque would help?? cheers

Online KiwiGF

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Re: Swinging arm location
« Reply #3 on: 13.04. 2011 11:59 »
The silent bloc bushes inner tube should protrude from the swing arm by about 2mm and contact the frame when you do the swing arm spindle nut up so you should have 2mm clearance between the swing arm and the frame it might be a bit more than that

There is no clearance adjustment designed into the system

The silent blocs keep the swing arm from contacting the frame as they dont allow much horizontal movement if any

The spindle should be tightened when the suspension is partially compressed to minimize the stress on the silent blocs do you have a manual? As that will explain the procedure

Sorry don't know the torque fir the spindle but as tight as youvdare should do it ;)
New Zealand

1956 A10 Golden Flash EA7-168x, CA10 913x, left BSA together for Liverpool, 5th Dec 1955.

1949 B31 rigid “400cc hot rod” (favourite bike)

1949 C11 rigid, but why!!! (cos it was cheap)

1937 B21, missing parts so mission impossible?

1952 Armstrong Siddeley Whitley for rainy days (with wife).

GL1800 Goldwing not sure why, maybe cos it always starts

Offline Jules

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Re: Swinging arm location
« Reply #4 on: 18.04. 2011 02:27 »
Thanks Kiwi, I tightened the nut up and achieve the clearance to the side of the frame to the pivot tube (slackened it off again until I finish the bike assembly per your suggestion), however the swinging arm is still biased to one side of the frame as it moves back through the frame tubes. Is this "normal" it looks wrong although I cannot see how to change without major frame surgery  *eek*, thanks

Online KiwiGF

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Re: Swinging arm location
« Reply #5 on: 18.04. 2011 11:50 »
It sounds like you suspect the frame is bent

There are some gold star frame drawings on the net and i think you may need to find these

Not all the dimensions are shown on the regs I've seen but but key dimensionrearranging wheel alignment etc are on the drgs which can be used to measure up the a10, but as far as the swing arm goes it is symmetrical around the front silent blocs tube and the centre of the arm is also the centre of the frame/headstock/front wheel etc

The silencer mounts are equally spaced either side Of the arm on my bike but the frame on my bike is not symmetrical in that the vertical tubes around the tool box are routed a bit differently To the other side i guess to give clearance to the chain

If you can't find the frame diagram let me know or maybe someone else knows the link
New Zealand

1956 A10 Golden Flash EA7-168x, CA10 913x, left BSA together for Liverpool, 5th Dec 1955.

1949 B31 rigid “400cc hot rod” (favourite bike)

1949 C11 rigid, but why!!! (cos it was cheap)

1937 B21, missing parts so mission impossible?

1952 Armstrong Siddeley Whitley for rainy days (with wife).

GL1800 Goldwing not sure why, maybe cos it always starts

Online KiwiGF

  • Last had an A10 in 1976, in 2011 it was time for my 2nd one. It was the project from HELL (but I learned a lot....)
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Re: Swinging arm location
« Reply #6 on: 22.04. 2011 09:28 »
Heres the link to frame diagram
I hope this helps you might need to copy and paste this into your browser address field

http://bsa-a10.hailwood.com/1954abgoldstar.html
New Zealand

1956 A10 Golden Flash EA7-168x, CA10 913x, left BSA together for Liverpool, 5th Dec 1955.

1949 B31 rigid “400cc hot rod” (favourite bike)

1949 C11 rigid, but why!!! (cos it was cheap)

1937 B21, missing parts so mission impossible?

1952 Armstrong Siddeley Whitley for rainy days (with wife).

GL1800 Goldwing not sure why, maybe cos it always starts

Offline Jules

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Re: Swinging arm location
« Reply #7 on: 22.04. 2011 11:18 »
Brilliant, thanks Kiwi, I've printed off the diagram and will see what I can find. Your note regarding the symettry of the silencer brackets and the non symettry of the frame tubes is interesting to. My silencer mounts are very close on one side compared to the other and it looks like the "loop" that has the silencer mount boss welded onto it is bent inwards. VERY frustrating really because yonx ago I paid a reputable guy in Melbourne to straighten up the frame before it was painted. I reckon there is a lot of work required now to sort it out, not just the swinging arm either  *sad2*, cheers

Online bsa-bill

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Re: Swinging arm location
« Reply #8 on: 22.04. 2011 11:28 »
A slow walk behind a row of A10's at any rally /show will reveal silencer end pipes at unequal distance from the rear wheel, very few in fact will be equidistant; the question now fifty years on is were they like this out of the factory.
I rely on a handful of washers, the crank on the silencer hanger and a little spacer on the right hand front exhaust tab
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Offline Jules

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Re: Swinging arm location
« Reply #9 on: 22.04. 2011 11:40 »
Thanks Bill, that puts that piece into perspective for me, the biggest thing I need to determine though is whether the swinging arm mounting is bent such that the rear wheel will "crab" away from the front wheel. I'm crssing my fingers that the guy who straightened the frame did so by aligning the front and back regardless of the state of the swinging arm mounting. The only way I can see how to establish that is after its all assembled  *sad2*. I will walk through the dimensional info. that Kiwi has kindly pointed out for me though and see if it increases or rduces my worries, thanks guys................

Online KiwiGF

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Re: Swinging arm location
« Reply #10 on: 24.04. 2011 14:29 »
Hi glad to help, ref frames I wonder how many have not been straightened at some stage anyway I think these frames will take a fair bit of "butchery" compared to modern frames especially if heated up first but from a safety/handling point of view I suspect a professional frame straightener will concentrate on getting the basic geometry right and the rear loops will be a secondary consideration depending on his brief....Spacers might be a better option than more bending etc

Anyway I checked my frame by getting it vertical using a spirit level across a bar through the swing arm holes after making sure they were not too worn and another bar through the rear suspension top mounts and another through the headstock from there you can use string and the diagram measuements to check if things are more or less as they should be

This basic check method was enough to give me piece of mind but the other option is to get the frame checked by a specialist $$$$$$$$$
New Zealand

1956 A10 Golden Flash EA7-168x, CA10 913x, left BSA together for Liverpool, 5th Dec 1955.

1949 B31 rigid “400cc hot rod” (favourite bike)

1949 C11 rigid, but why!!! (cos it was cheap)

1937 B21, missing parts so mission impossible?

1952 Armstrong Siddeley Whitley for rainy days (with wife).

GL1800 Goldwing not sure why, maybe cos it always starts