Front brake cam spindle end play

[Phil C]

Hello all, I've just started putting my front brake back together (1965 B40F) and I notice when I put the cam spindle through the plate and put the lever arm on it, secured by its nut and washer, there is some end-to-end play of the spindle in the hole in the plate.  The spindle, complete with cam, lever arm etc,  will slide back and forth through the hole, maybe 2mm.  The photo's attached show the gap, first with the spindle pushed one way, then the other. I'm not sure which end the gap would be with the shoes in place, but thought I'd just check: should there be movement like that? Or do I need to reduce/get rid of it somehow, maybe with a washer under the lever arm?

The lever arm doesn't push over the whole of the square drive on the spindle, and I guess it's not meant to, as the square drive is tapered. That, I guess, ensures a tight fit of the lever arm on the square drive. So I'm reluctant to start filing the square hole/drive.

Maybe it's meant to be like this?

Any thoughts/advice please?

Phil.

[Davidat19]

I think you are right to leave your file in the box. I really dont see any problem with a little movement there.....

[JulianS]

I am sure the lever to brake plate movement should be less than 2 mm. It does not look right. Just checked my A10 back brake which takes the same cam and there is 12 thou movement.

I think the square on the cam has a slight taper ensuring the lever is, as you found, very tight.

Is the lever the same way round as before dismantling.

[Phil C]

Not sure. I've tried it a couple of ways and that doesn't seem to make any difference. Not meant to be a washer, is there?

[JulianS]

No washer.

If you assemble as it is I suggest make sure the shoes do not touch the hub other than on the braking surface.

When the shoes are fitted, put the plate into the hub, tightening the nut will apply the brake and lock it so you may be able to tighten the nut further.

[Phil C]

You can see from this photo that even if the arm went right to the end of the square drive there would still be a slight gap. Only slight, admittedly. But the arm doesn't go to the end of the square drive, so I have that 2mm gap. This seems a bit odd.

Any further thoughts?

Does the arm normally go right to the end of the square drive? As the drive is tapered, I assumed it shouldn't go all the way on.

Phil

[AdrianS]

I wouldn't worry too much about the brake lever. If it seats virtually to the bottom of the square, then just tighten it well and it will be fine!
Both my B40 and Bantam have got a little play in the cam but haven't measured how much. Also the grease packed into the cam bearing in the brake hub does "dampen" down the play a little. As said before, as long as the shoes don't rub against the brake plate or the back of the brake drum then don't worry. If your grease nipple is no longer useable then either replace it or pack the cam spindle with grease before reassembly. Unless the bike is a daily rider, then it wont need frequent re greasing. Put also a bit of copper grease on the pivots on each end of the brake shoes.

[Phil C]

Copper grease?  Not ordinary grease?   Phil.

[JulianS]

I would use a smear of high melting point grease on the shoe pivot, the cam and the cam spindle.

[Phil C]

I was planning to use Morris K42EP.   

Phil.

[AdrianS]

Copper grease is anti seize grease with a very high melting point.
Any grease used inside the brake drum must be high melting or there is a risk of contamination of the braking surfaces. Use whatever you are happy with! I use copper grease because I have it and use it also on car braking systems.

[Phil C]

I think the Morris K42EP is stable at 150c for short periods and 120c continuous.  Is that okay?   Phil.

[AdrianS]

Unless your brakes bind on or you are going at some speed down a Big hill and have to apply brakes to slow down and stop you should be ok! Only use it sparingly on the brake pivots. Alternatively, buy some copper grease - it is not expensive from places like Eurocarparts (especially when using their discount codes) - it is useful for many many applications !

[Phil C]

Thanks again for your advice. Just to let you know what I did, in case you're interested (I know, you've been on the edge of your seats), I carefully opened up the square hole slightly with a little warding file, so that the lever went a bit further, but not all the way, on to the tapered square drive. So there's still some play, but not as much as there was. The lever will still wiggle, but I'm not overly concerned,given the advice you've given me.

By the way, I was quite surprised to see that the inner cable, just above the clevis, passes very close to the mudguard stay - as near as dammit to touching, I'd say. I wonder if they're usually like that.

Phil.