Swing arm change from solid to hollow spindle

[duncan32bsa]

Hi there,
Need help again!
As a change from very slowly rebuilding the gearbox, I thought I'd fit the swing arm to try to create some more visible signs of progress.
Naively, I thought this would be straightforward as it came out easily enough. Because I decided foolishly some time back to fit full width hubs I needed to change the swing arm.
Because I was having it powder coated, I fitted new silent bloc bushes (bigger ID) for the crossover shaft.
Now I have two problems.
1) There's a mm or or 2 of steel tubing protruding from the bushes which prevents the swing arm fitting back in the frame. Should I 'just' grind this flush back with the swing arm?
2) The hole in the frame is too small for the crossover shaft. The hole in the frame is about 5/8" and the OD of the shaft is 3/4".
I'm reluctant to start grinding/drilling in ignorance and would appreciate some guidance, please.
Assuming that I do solve this, what lubrication is needed?
I can provide pictures if needed!
Thanks for any help.
Gary

[bsa-bill]

Gary there should be a mm or 2 of tune protruding at each side, this is what is clamped tightly against the frame ( I know it doesn't seem right but it is apparently)
You might need to spread the frame a bit to get the S/A in, sort of goes in on a slant then twist it straight.

[trevinoz]

Gary,
         You will need to open the holes in the frame to a close fit for the spindle.
Do not grind the silent bloc bushes as they have to be tight in the frame and bolted securely with the spindle.
You may have to spread the frame slightly to fit the swinging arm.
I fit the shaft through the bushes with a liberal coating of anti seize lubrication to aid the next dismantling.
There is no lubrication required as such as the swinging arm rotates by distorting the rubber in the bushes which are held tight in the swinging arm and between the frame lugs.
Trev.

[duncan32bsa]

Thanks guys,
tomorrow night's job! I'll let you know how I get on.
Cheers
Gary

[duncan32bsa]

Actually one thing that occurred to me is that I need the help of a rivet counter. (That's a compliment by the way).
The bike is registered as a 1960 GF and the frame number supports that (at least that it is an A10 from 1960).
I had assumed from the parts book that this would have had full width cast iron hubs as standard with a brake rod on the right. This would need a crossover shaft.
If that is the case why is the swinging arm pivot point on the frame only drilled out to take the smaller diameter solid shaft?

Can anyone help?

Thanks again.

Gary

[andy2565]

be very careful when you open the holes out,the swinginging arm pivot point has to run true to the rest of the frame,1/2mm forward or up will throw the wheel out by nearly 4mm.not sure about the thickness of shaft but you should have a full width hub,maybe someone has converted it to the half width hub,i was going to do this conversion but have decided not to.
    just measured the hole for the crossover shaft on my frame which comes out around 20mm,

[duncan32bsa]

Andy,
My plan was to creep the diameter up using an adjustable reamer. Slightly dubious about it though, as I found reaming out the gearbox inner cover bronze bushes surprisingly difficult. The reamer kept digging in.
Gary

[andy2565]

if its possible,do one side,fit the swing arm,with the shaft in that side,then do some measuring,would be best with the forks and wheels fitted so you could check the alignment then file out the other side.never had much success reaming bush's myself,but reaming the steel hole should be easier,give it a go,16mm to 20mm is alot of reaming !

[RichardL]

I'm not so expert in each of the finite model specifics beyond the title year of my own bike ('55), and I'm on a train right now, so can't do research, however, I thought the 1960 Rocket Gold Star used the half-width rear hub. I assume you have a brake pedal pivot hole on the left where pillion loop meets downtube. Personally, if you have the half-width rear hub, it might actually be better to keep that setup. Rear brakes are less critical than front, as you know. Many have complained of spongy rear brake due to the cable connection (stock, it's not a rod). At this point you are choosing between a tricky ream job and a gruelling removal of silent-blocs. If you want a rod on the right, that's a whole additional task. BTW, the brake pedals are different, have acquired the correct pedal for full width? Anyway, saying more belies my claim of ignorance and might be wrong anyway. Anxious to hear what you will do.

Richard L, 

[duncan32bsa]

Hi Richard,
If I hadn't have had the FW hubs rebuilt on stainless rims already, I might seriously have considered sticking with the halfwidth. I have 2 swing arms still both silent blocs (one for each type of SA pivot) so it is a feasible option just an expensive one. This is what you get for advancing on a broad front! I'll double-check the frame number and the pivot hole positions when I get home.
It crossed my mind when I saw the small SA hole in the frame that there might be something dodgy with the frame provenance but
I prefer Andy's idea that someone down-converted the shaft dia in the distant past...
Gary

[duncan32bsa]

It turns out the registration document calls it 'a BSA'. The frame number is GA711035 which doesn't tie it to a model anyway. I guess I need the get the factory records to find out what it was originally. The engine number on the document (I have a different engine now) is DA1012974 which I read as a late 1960 GF. There is a brake pedal hole on the left.

[chaterlea25]

Hi Duncan,
Heres how I kept the holes concentric when making them round again  after welding up, as they had worn oval !!
Before welding I made a template from a fairly thick piece of steel (8 or 10mm?) with a hole drilled in it the correct size
I tacked on some stops to position it in the correct place and then a 5/16 bolt and nut on the left side template into the swing arm pin end plate hole
I filed away most of the weld and finished off with suitable  sized reamer

Hope this makes sense????
John O R

[duncan32bsa]

Hi Johm,
That's sounds like an excellent idea.
Will try.
Cheers
Gary

[trevinoz]

Gary,
          There a couple of possibilities for your frame.
Is it a CA7 frame restamped? Fairly easy to pick a CA7 frame as all the welds are gas welded whereas from about 1957 frames were electric welded.
Another could be a police special as were supplied to South Australia with a single sided brake in the rear and full width in the front.
Trev.

[minibsa]

I agree with Trev, I think you have a 1955 frame! My 55 has a frame No . CA7 105xx which was built Feb 55 so With all you describe I guess a PO has changed the CA7 to GA7. and the other frame numbers are possibly correct.
                       Bob.