1966 BSA A65 Rear Brake Mounting Detail

[geraldhattrick75]

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.

[DAVE BRADY]

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.

[geraldhattrick75]

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.

[DAVE BRADY]

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.

[geraldhattrick75]

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.

[DAVE BRADY]

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.

[geraldhattrick75]

Will do Dave.

Get back to you shortly...... Mind, still waiting for my repaired brake plate.
Regards,
Dave

[Kevev]

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.