Hi all,
I am hoping someone may be able to help me with the rebuild of my 1966 BSA A65 Lightning rear end.
The rear brake drum and dummy spindle components that mount to the left hand side of the swinging arm are where my doubt lies.
The 1966 brake drum with it's bolt on 47T sprocket has a chrome plated steel brake plate. The dummy spindle and bearing are fitted along with the brake shoes, brake shoe fulcrum pin and brake shoe operating cam.
I know that I have a clip missing, that covers a hole in the brake cam housing and I believe that this was originally used for access to the lubrication hole and also to cover it up.
There is a stepped spacer that fits inside the brake plate, which butts up to the bearing inner race and a plain spacer that fits outside it. This spacer measure 11.5mm thick, which is just over 7/16" (I'm not sure if this is right?). There is an outrigger strap with a slight offset dog-leg, brake lever and it's return spring along with all the relevant nuts that fasten everything together.
The dummy spindle nut fastens the whole lot to the left side of the swinging arm and this is a one piece hexagon nut with a thick larger diameter collar that is the same O.D. as the main wheel spindle that goes in through the QD wheel from the speedo drive side. The wheel/chain adjuster bolts butt up to these two components and with them being the same diameter this would make the adjuster screws be of similar lengths to make the wheel aligned true in the frame.
I'm not sure which way round the outrigger strap (which I believe is only there to anchor the brake lever return spring?) is supposed to fit. I have attached a few pictures, one of which is a drawing of the two ways that the outrigger strap can fit. I am assuming I have got this the right way round and it is correct with the spacer in between the brake plate and the outrigger strap? It may be that the outrigger strap should be against the brake plate and the spacer should be in between the outrigger strap and the swinging arm? I'm not sure and would greatly appreciate it if someone could confirm the correct fitting order.
Also in the 1966 parts book the dummy spindle nut shown in the illustration looks nothing like the actual nut I have and there is no mention, or illustration of the spacer?
I would greatly appreciate any help to clear up my doubts on this assembly please.
Thank you, Kev Ev
These illustrations from the workshop manual may assist.
The strap provides rigidity to the brake cam spindle bearing which does not have much support in the brake plate.
Hi Julian,
That's very helpful thanks and shows very clearly the correct orientation for the outrigger strap.
I can also see that in the sectional drawing the dummy spindle nut looks exactly the same as the one I have. In the second picture it looks different and is much the same as the nut that is shown in the 1966 A65 parts book illustration.
I'm guessing that this is just a draughtsman's interpretation?
Do you have any idea why the spacer is not listed in the parts book?
Parts books sometimes have errors and omissions and of course there were mid season changes which they dont contain. These usually resulted in the issue of a parts service bulletin.
The 1966 book has the spacer show on the wrong side - look at part 28 on the right side of the picture then check the description which is "Distance piece left hand"
There were a number of changes for the 1966 season including some at the rear spindle, see below. Parts service bulletin G35 issued January 1966.
Good spot Julian.
I never noticed that the spacer shown on the speedo drive side was marked as L/H.
That's also cleared up my wondering what that spacer was for, as I had mistakenly thought it was shown in the right place.
Thanks again.
Just on the off-chance that this might help, here are a couple of piccies of mine.
(I've removed the brake arm to aid clarity....)
Incidentally, I'm about to remove my rear wheel in order to find out why my brake cam doesn't protrude more. (bolting the end nut up causes the spring to clamp up, preventing the lever moving)
Hi,
In your pictures is the wheel still fully fitted or have you started to take it out? It looks like the spindle is fitted but there seems to be quite a gap where the brake plate sits in the drum or is it an illusion?
Also, is that an aluminium brake plate and should it have the bracing piece?
Dave.
Thanks for that observation Dave..... It's been bothering me a bit too.....
Oh, and no, other than the brake lever removal, nothing else has been loosened.
Here's a further picture of the 'coil bound' return spring- and the non speedo drive right hand side. (speedo and rev counter drive are from the timing side case...)
Hi,
That is the wrong spring. Your brake plate is the later aluminium one and if you look you can see the witness marks of the proper spring on the boss that the cam shaft comes through and the locating hole for one end of the spring. The brace is for the steel brake plate so should not be fitted. The is something wrong with how the short axle has been fitted in the brake drum - perhaps not in far enough. The brake plate should fit so that it almost touches the drum and the shoes are fully out of sight.
Dave.
A further thought. You may have a mismatch with the spindle as well. You will need to compare parts book drawings to see exactly were it needs changing.
Thank you very much Dave, you've identified a few things that were bothering me.
I hadn't realised that the plate was not needed, nor what the marks indicated.....
All apart tomorrow and a much closer inspection of what I have V what I should have.
Thanks again for steering me in the right direction.
This bike has spent 4 (-ish) years of being a BSA factory test mule, then had someone else start it as a project, then a 'know nowt eejit' re doing the whole thing...... (It never stood a chance really....)
But it will be completed to a reasonable standard thanks to the good folk on this site....
Another huge thank you,
Dave.
Hi Gerald,
Nice detailed pics but you have a different brake plate to mine. Mine is the early steel plate although there are a lot of similarities in the mounting, it looks as though there is no spacer like mine has, inbetween the alloy plate and the outrigger strap.
Always good to see details of the different types of components.
Cheers,
Kev Ev
Well I've stripped the rear wheel and brake drum down and the only issues that came to light were: the spring is the wrong type (as suggested.... Any idea of the correct part number please?)
And the spring retaining web is badly cracked... (now being welded)
On the good side the brake plate does fit close to the drum. The reason it looks like there is a big gap is simply down to the drum being Black. (Is it possible that the sprocket is on the wrong way round? (I fitted it so that the sprocket recess sits neatly over the drum ring))
Is it definite that I don't need the 7054 strap? (The reason I ask is that the rear plate doesn't look particularly strong)
As a thought, if I omit the 7054 strap, as suggested, the spring that I originally fitted (see photos) will no longer bind when the nut is tightened......
Hmmmm, might be worth a go.
What do you think?
Hi,
It would be best to get the proper spring then 'job done'. I am still not sure about you brake plate so I will go and look at mine and post a photo.
Dave.
Hi,
Photos as promised. Two bikes, one with hex head screws and one with allen screws. Note that the brake plate is just about flush with the heads of the hex screws and the plate almost sits in the sprocket ring. Yours appears to sit a bit proud.
Dave.
Thanks for the pictures Dave, they certainly show some differences that I'm going to have to investigate..... (you wouldn't think a sprocket and brake plate could be so confusing... (mind, opening a packet of cornflakes confuses me sometimes)).
At the risk of pushing my luck here, could you possibly get a slightly wider angle shot- to include the shape of the return spring so I know what it actually looks like.
Hope I'm not being too much of a pain here....
I've just ordered a new chain and link, which should help me to check the alignment.......
Thanks again for your help Dave, it is genuinely appreciated.
Best regards,
Dave.
Morning,
Photo attached.
As standard the gearbox sprocket is 20 teeth with the chain being specified at 106 links. With the 21 tooth sprocket I have found that although the connecting link can be fitted, the chain will not be slack enough. It will seem like it is just about OK but as the suspension works the chain will be pulled tight and premature wear will occur. I found this out by trial and error after a couple of chain failures.
Rather than fit a 'half' link and end up with two joins, I fit 108 links plus the connecting link. This will mean that the wheel is about half way back but the correct up and down movement can be set. If the wheel reaches the end of its adjustment before the chain needs replacing then take off the extra two links to give 106. Now, as the chain has worn a bit it will fit fine.
If you have standard length suspension you will notice that when unladen the swinging arm slopes slightly down to the rear. When adjusting the chain this must be taken into account as when the bike is sat on/loaded or goes over a bump the swinging arm will come up to be level making the chain tighter. It is at this point that the chain needs to be adjusted. If done in the unladen position then the chain will go tight when loaded. So allow a bit more slack then check when the bike is loaded.
Dave.
Dave.
That's perfect Dave, it shows everything and really answers my questions.
I've ordered a 110 link chain and a split link, so I ought to be able to get it right. (I can always buy a 1 1/2 link if I have to....
I'll take off my sprocket and see if it might be the wrong way round ie recess on the wrong side....... And let you know how it goes.....
Best regards and thanks again,
Dave.
Hi,
Looking at your images it looks like the sprocket is on the right way. I would be looking more at the brake plate and how it sits in the drum.
Make sure that no extra spacers been put in. The brake plate should almost touch the edge of the drum.
Dave.
Yeah Dave, I did check that and it looks ok..... (see photo)
Nothing actually seems wrong.
I'll do a rebuild once I've checked everything out again.... And report back.
Thanks again for your help,
Dave.
Hi,
As you have taken the short stub axle out try sitting the brake plate in the drum without the shoes etc. The brake plate should sit against the inner race of the bearing with the correct clearance to the drum. If this looks right then try it with the stub axle in place. This will show if there is a problem or not with the stub axle/brake plate relationship. Then repeat with the shoes etc. in place.
Incidentally, did the wheel spin freely when it was still fitted?
Dave.
Will do Dave.
Get back to you shortly...... Mind, still waiting for my repaired brake plate.
Regards,
Dave
Some nice detailed photographs on here that are very helpful.
I wish I could find more of this type of photograph showing the early steel brake plate like the one on my bike.
I recently bought a new 41-6031 brake lever return spring from Draganfly and although it appears to fit ok it is very loose on the cam housing. I would have expected it to be a better fit with the inside diameter of the spring being a lot closer to the outside diameter of the cam housing pillar on the brake plate? Has anyone had any issues with this, or can offer any advice?
Just a point about the sprocket to brake drum hex head bolts being close to the brake plate. The correct BSA 68-6095 bolts are 5/16" UNF but with a reduced 13/32" hexagon head. If you fit a standard 5/16" UNF bolt the larger standard hexagon head head will be too close to the brake plate and can bind against it depending on what position it ends up in after tightening.
I once fitted some socket head cap screws on the sprocket to brake drum but found I had to turn the heads down, as the standard heads fouled on the brake torque stay arm. This meant that the socket was not as deep for the allen key to get so much purchase on.