1966 BSA A65 Lightning Rear Brake again

[Kevev]

Hi Guys,

I'm hoping that you will be able to help me with a few details on my rear brake assembly.

I have bought a new 41-6031 brake lever return spring from Draganfly and although it appears to be the correct item as far as I can see, it does seem a little loose on the brake plate 'pillar'. My brake plate is a chrome steel brake plate and the 'pillar' that contains the brake lever cam accommodates the 68-7054 outrigger strap, the 65-5674 oil hole clip as well as the return spring. I would have thought that the inside diameter of the return spring would have been a better fit on the outside diameter of the brake plate cam 'pillar'? It is quite slack and I would like to know if anyone can tell me if this is correct?

I would also like to know if the 30-0729 washer fits in between the brake plate and the 42-6036 anchor strap on the fulcrum pin and what are the dimensions of the anchor strap (this is how it is described in the BSA parts book but I've always known it as the rear brake torque stay arm). If anyone could tell me, the important dimension I am interested in is the distance between the centres of the holes, as this is what will determine that the rear brake lever is in the correct position.

Id anyone has any detailed photographs of these rear brake parts I would really appreciate seeing them.

Thanks again.

Kev Ev

[geraldhattrick75]

I've just measured the hole centres of the arm as 173mm Kev.

I'll wheel the bike out tomorrow and take piccies and get some more accurate measurements.

Mind, I've still been left guessing at some of the details.

Dave

[Kevev]

Thanks Dave, much appreciated.

Kev Ev

[geraldhattrick75]

OK Kev, here are some of the images I took (incidentally I'm altering last night's reading to 171.5mm):

Remember that this assembly is my interpretation of what I have been told and experimentation on my part....

Let me know if you need any more specific image details.


(or if I've missed the point....)

Dave.

PS Sorry, the last two are upside down.....

[DAVE BRADY]

Hi Kevev,

The only thing I have is the line drawing in the workshop manual.  It does appear to show the washer between the bake plate and the anchor strap.  With the anchor strap fastened on the swinging arm lug there should be just enough space to fit the washer.

Dave.

[DAVE BRADY]

A bit off thread but, Dave, I notice that you have not had a chance to check the assembly of your rear wheel/brake. I have highlighted with arrows the gaps that do not look quite right. 

Dave.

[geraldhattrick75]

Thanks for that Dave, and for your continual offers of advice... Good advice too.


First off, the arrow pointing to what looks like a gap between the brake plate and the brake drum is in fact a failure on my part to adequately show that the drum does in fact tuck under the rim of the brake plate (hopefully the new photo will show it a little better.

Secondly the gap either side of the stub axle is the two thin washers I have put either side of the swing arm- to prevent the paint being scratched when the stub axle is tightened up.
(On reflection, maybe not such a good idea..... I can always remove them if you think In ought to)

I can't seem to find diagrams that show my precise set up....

I have now removed the 68-7054 strap from the alloy brake plate. (I also had the cracks in the spring locating hole welded up, while it was all dismantled.......)

[DAVE BRADY]

Hi,

I will scan a drawing of the aluminium plate setup and post it.  I think that if you only have the manual for the earlier brake it will not be in it.  I have a manual with both.

Dave.

[geraldhattrick75]

You're heading for a glittery- tinselly Christmas card at this rate.......

[Kevev]

Thanks for the photos and information guys, it's very helpful.

I can see quite clearly that the spacer fits between the brake plate and the anchor strap.

Does the alloy plate have this spacer of is the casting raised to provide this offset?

It's not so important to me as mine is the steel back plate but it would be nice to know. I have another A65 frame and lots of parts and will probably have a go at building another one and will look at finding a rear end with the alloy brake plate.

Cheers once again.

Kev Ev

[DAVE BRADY]

Good morning,

This is not straight forward as the drawing in my '69/'70 manual is completely the wrong one.  It is not even for the one I have already posted.  Anyway, there is a spacer that fits on the stub axle.  The stub axle comes through the brake plate and there is round bit before the flats that locate in the swinging arm.
The 'collar' has part number 68-6132.
I will take some photos.

Dave.

[DAVE BRADY]

Hi,

First image is close up showing the 'collar' that goes on after the brake plate.  It is as near as 'damit' 3mm.  If too thick or too thin then chain alignment could be affected as well as the alignment of the brake anchor strap which on both of my A65s does not have a washer between it and the brake plate.
The thin washer on the outside of the swinging arm, as on Dave's, serves to protect the paint although the parts book does not show one.
Second image shows the relationship between the surface of the brake plate and the sprocket screws with the top of the heads being almost flush with it.
Also note the grease nipple - this can be a bit iffy as regular greasing of this could result in grease getting on the the brake linings so apply grease sparingly or only during a strip down of the brake.  Otherwise blank it off to prevent water and grit ingress.
I hope this is useful.

Dave.

[Kevev]

Hi Dave, the subject is confusing and for me what makes it more so is the difference between the steel brake plate and the alloy one.

With the help of information and photos from people on the forum I have managed to deduce (I think I'm right but....) that the steel brake plate has a spacer that fits over the rear brake drum dummy spindle in between the brake plate and swinging arm. This spacer (on my bike) is 0.438" thick. It is shown on page 60 of the 1966 BSA A65 parts book on the wrong side of the bike and is item 28 in the illustration and part number 68-6057, described as Distance Piece (left-hand). The alloy plate has a cast in raised section in the centre and therefore in the 1967 BSA A65 parts book on page 58 you can see that the left hand spacer has disappeared. This is because it is, in effect, cast into the alloy brake plate. The 3mm thick spacer on yours may have been put in for alignment purposes?

Now the anchor strap: -

On the steel brake plate and again referring to page 60 of the 1966 BSA A65 parts book, there is a 'washer', item number 44 in the illustration and part number 30-0729. I believe this washer should be fitted in between the anchor strap and the steel brake plate. On my bike this 'washer' is 0.135" thick. If you look at the alloy brake plate in the 1967 BSA A65 parts book on the page 58 illustration this 'washer' is missing. Once again I believe it has been incorporated in the alloy casting.

[DAVE BRADY]

Hi Kevev,

The spacer on the aluminium plate is referred to "Collar, brake plate..." on page 56/57 of the 1970 parts book and has part number 68-6132.  I have this on both of my A65s.  Unfortunately the sectional drawing in the appropriate workshop manual is the wrong one and is therefore misleading.
It shows a combined drum/sprocket and 'pull back' type chain adjusters.
I have attached it so that you can see the anomalies.
I suspect that there are three permutations here.  Combined drum and sprocket with steel brake plate, bolt on sprocket with steel brake plate and bolt on sprocket with aluminium brake plate.
All I can say for absolute definite is that I have the latter configuration on both of my A65s.
 
Dave.

[Kevev]

Hi Dave, I see the part you mean in the 1970 parts book.

From my copy of the BSA General Fasteners & Spacers Excel spread sheet I see that the dimensions for this 'collar' are given as 1-7/16" O.D. x 1" I.D. x 3.32" thick.

The sectional drawing is confusing too as it appears to be upside down?

So many combinations of parts on this area of the bike.