1966 BSA A65 Rear Brake Mounting Detail

[Kevev]

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

[JulianS]

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.

[Kevev]

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?

[JulianS]

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.

[Kevev]

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.

[geraldhattrick75]

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)

[DAVE BRADY]

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.

[geraldhattrick75]

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...)

[DAVE BRADY]

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.

[geraldhattrick75]

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. 

[Kevev]

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

[geraldhattrick75]

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)

[geraldhattrick75]

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?

[DAVE BRADY]

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.

[DAVE BRADY]

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.