Brake drum skimming

[worntorn]

Right Sluggo, just turn the wheel by hand. It can also be  done with the wheel in place in the bike, then everything is in the " home" position.
It's quite rewarding to feel the pulsation of an out of round hub slowly switch to perfectly even drag all the way around.
I use a c Clamp (G Cramp UK) to clamp the brake lever at a light drag, then gradually tighten the clamp as the high spots abrade away.

Glen

[RoyC]

I did mine using the stick on emery paper, I did it off the bike, stuck the paper onto the shoes and then turned the brake, it didn't take too long.
I then stuck the paper onto the brake drum and turned the brake to arch the shoes.
WARNING, It soon removes the brake shoe material so don't over do it.
Roy.

[rocker21]

round here (oxon/Bucks borders) there is a very clever enginer who has built his own jig for doing this and he does it with the wheel assembled and with the tyre on as he uses the tyre as the drive for spinning the wheel, a very simple jig and very good. he has done quite a few for the local classic bike scene. it works well and is very accurate. he preferes to do them this way as he says this is what the wheel is like when in use and thats the way it needs to be trued up .

[groily]

(If the pic comes through) a little tool I made for the job, which attaches to the spindle of an assembled wheel.
Just a flycutter bit on a bar but has done a decent job when needed.

[rwbeard]

The stick on emery does a perfect job in no time. Uses your wheel as a lathe. It only takes off what is needed, no more. You can feel when it's perfectly round, all pulsation disappears.
Use  stick on 180 grit stuck to the shoes and grinding on drum first, then when the drum is done go the other way round to arc the shoes to the drum.
The whole job can be completed in the time it would take to load the wheel in the car and drive it somewhere local.
I have a big lathe here that can handle a wheel. I used to true drums in the lathe but don't do it that way anymore.

Hi there,
I know that it’s some time since this was posted.
I have a 190mm front brake fitted to my RGS replica and it vibrates when braking is applied.
I like your idea, sounds so simple, so will give it a try - but how do you glue/apply the emery paper?/cloth? to the brake shoes and the drum securely? What type of glue, and just as importantly how go you get it off?

Thanks for your help

Regards Rojah

[Jules]

I would expect double sided tape would do that job ok Rojah, easily removed from both surfaces afterwards, but Roy could probably be more specific perhaps....

[KiwiGF]

The stick on emery does a perfect job in no time. Uses your wheel as a lathe. It only takes off what is needed, no more. You can feel when it's perfectly round, all pulsation disappears.
Use  stick on 180 grit stuck to the shoes and grinding on drum first, then when the drum is done go the other way round to arc the shoes to the drum.
The whole job can be completed in the time it would take to load the wheel in the car and drive it somewhere local.
I have a big lathe here that can handle a wheel. I used to true drums in the lathe but don't do it that way anymore.

Hi there,
I know that it’s some time since this was posted.
I have a 190mm front brake fitted to my RGS replica and it vibrates when braking is applied.
I like your idea, sounds so simple, so will give it a try - but how do you glue/apply the emery paper?/cloth? to the brake shoes and the drum securely? What type of glue, and just as importantly how go you get it off?

Thanks for your help

Regards Rojah

I used “car moulding tape” which is (sort of) double sided tape, should be cheap, you stick it to the drum then peel the backing layer off and it leaves a sticky residue behind on the drum to stick the sandpaper too. It comes off the drum with brakeclean fluid or similar.

[morris]

Some double sided carpet tape from any DIY shop will do the trick. I used 80 grade metal emery.
But if the pulsating is as severe as mine was, the emery treatment won’t work and the drum will need a skim. Any well equipped workshop should be able to do that. Won’t need to disassemble the wheel, just taking the tyre off will do. I paid €25 for one wheel

[RDfella]

Before skimmimg any drum, check the spokes. If some are tighter than others, they'll pull the drum out of round and 'normalising' that merely creares a 2nd problem. Indeed, a bike that's had a new rim fitted recently is a candidate for checking, as many of today's rims are nowhere near round at the weld and building a wheel often means having to tension spokes irregularly in order to get a nearly-round rim. I've had to return new rims before now - and panel beat others because they were so bad. Try to pull that into almost-round with the spokes and the drum will be the shape of the wheel rim before you started.

[Butch (cb)]

Interesting that this thread has reactivated. My SP370 has a definite warp at the front. Front rim is original but has been replaced at some point so something presumable wasn't done quite right, but perhaps as an off roader it had previously taken a bit of a ding. Might try the emery cloth approach first, though the shop mentioned way up earlier is actually fairly local to me.

[Rex]

Sticking the self-adhesive abrasive pads on the brake drum surface to radius the shoes works well, but sticking the pads to the shoes to cure brake drum ovality or warping sounds dubious.
It would some abrasive to remove 10 thou+ of work-hardened cast iron..

[rayjay]

I had my front drum skimmed and brake shoes relined and machined to fit by a guy  in the West Byfleet  (south of london) area. He can swing an 18 inch wheel with tyre fitted but 19 inch has to have tyre removed. transformed my stopping power, can almost bottom the forks now. (PM me for name and tel no. )

[a10 gf]

I had my front drum skimmed and brake shoes relined and machined to fit by a guy  in the West Byfleet
transformed my stopping power, can almost bottom the forks now.

Hello, you may post info in this board https://www.a7a10.net/forum/index.php?board=46.0

[Butch (cb)]

... though the shop mentioned way up earlier is actually fairly local to me.

I rang that shop btw. They no longer offer that service - not a lot of call for that sort of thing these days.

[worntorn]

The stick on emery does a perfect job in no time. Uses your wheel as a lathe. It only takes off what is needed, no more. You can feel when it's perfectly round, all pulsation disappears.
Use  stick on 180 grit stuck to the shoes and grinding on drum first, then when the drum is done go the other way round to arc the shoes to the drum.
The whole job can be completed in the time it would take to load the wheel in the car and drive it somewhere local.
I have a big lathe here that can handle a wheel. I used to true drums in the lathe but don't do it that way anymore.

Hi there,
I know that it’s some time since this was posted.
I have a 190mm front brake fitted to my RGS replica and it vibrates when braking is applied.
I like your idea, sounds so simple, so will give it a try - but how do you glue/apply the emery paper?/cloth? to the brake shoes and the drum securely? What type of glue, and just as importantly how go you get it off?

Thanks for your help

Regards Rojah

I use stick on emery paper.
Auto supply stores sell it in discs.
I have a roll of 100  discs in 80 grit that I am slowly using up.
I cut strips of the correct width from the centre portion of these 7" discs.
It doesn't leave any residue when peeled off, in fact it removes dust in the pores of the brake linings. When used the other way to arc the shoes, it comes off the drum cleanly.

Glen