Brake drum skimming

[Rex]

Can anyone recommend someone who can skim a brake drum on a built wheel, preferably in the South of England?
I know SRM do it, but I'd probably have to sell the bike to pay their bills...
Thanks.

[Butch (cb)]

Maybe Hagon?

[muskrat]

Down here most brake and clutch shops can do it with the rim still wired in.
Cheers

[worntorn]

You can do it yourself with stick on emery cloth. With a bit of patience you will end up with a perfect job. Really doesn't take long.


Glen

[BritTwit]

Down here most brake and clutch shops can do it with the rim still wired in.
Cheers

I would try a brake and clutch shop that specializes in big trucks.  They have brake laths that can handle large diameters.

[A10 JWO]

My local bike shop has a lathe and the owners Dad does these on a Saturday for £25. Bikewise Progress Road Rayleigh Essex. You just need a man with a lathe.

[Rex]

That would be a very large swing'd lathe.
Apparently it's also possible on a reasonably-sized milling machine.

[coater87]

 There is a feature on many larger lathes called a Gap Bed, its a part of the ways that is removable by the chuck.

 It takes about 5 minutes to take out, and 3 hours to put back in properly if you hardly ever use it. Its a lot of tom foolery to get that gap back in perfectly.

 Lee

[RoyC]

Done on a milling machine  -  https://www.youtube.com/watch?v=qvLvoNMhbG8 

[Rex]

There is a feature on many larger lathes called a Gap Bed, its a part of the ways that is removable by the chuck.
 Lee

I was allowing for the gap bed.....it's still one Hell of a swing!

[BSA_54A10]

I used to get mine done at a bike shop.
He had a large face plate set up with an arbour that he slipped in the back of the hollow spindle on his 6 " lathe.
So with the wheel mounted at the back, he used a pedistal grinder on a slide.
Perfect job and no skipping.
BSA used nickle silicon iron for their drums and that is bloody hard.
Most drum machines that use a lathe type tool will skip and put grooves in your drum.

[Sluggo]

Here in the US its the land of prolific litigants and their lawyers.  So, this can be challenging to find someone to do this. I have a local guy who runs a machine and fab shop who is also passionate about motorcycles but he is the exception to the rule.  Most places as soon as you say "Motorcycle" they cant get off the phone or away from you fast enough.

Depends on the brake hub assy as some distort more than others and Ally hub with cast liner or cast iron hub entirely? or a bolt up arrangement can differ..  But it IS worth doing as it does make a huge improvement.  Down in California is a shop called Vintage Brake and they reline and will skim and can transform a old bikes brakes, but for me, shipping a complete assy is very expensive,
See: http://www.vintagebrake.com/ 
But perhaps some good info can be learned from them.

I know a local guy, "Panhead Jeff" who in his day job is an engineer and while his interests are primarily American bikes he played around with upgrading early HD and Indian brakes and got really impressive results, as Radar said about his Indian Scout "I can skid both wheels now and it never did that before"
So, because of the aforementioned aversion to liability, Jeff could not find anyone who would reline old shoes with some of the modern materials so he bought a variety of high tech brake materials in bulk and relined them himself.  He found some carbon fibre or other high zoot materials that worked really well. 
I tried some of his bikes and was really impressed with the results, He skimmed the drums, optimized the actuation, and with the modern materials transformed the braking.

As he pointed out, A drum brake has more theoretical contact area than any disc brake so its a question of getting it working right and dealing with the heat issues.  Most vintage bikes I serviced when my shop was active were using about 25% of their contact pad due to poor fitment, installation and poor bedding in.  Probably the biggest misunderstood drum brake out there is the Conical brakes/hubs fitted to 1971-73 Triumphs and BSA.  (They actually work quite well when properly adjusted)  They dont deserve their moniker of "Comical brakes"

[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.

[Sluggo]

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.

That does sound much easier and simple, well worth doing, especially the arcing in of the shoes as few people do that and it makes a big difference.    Depends on the materials used as well, but "Bedding in" the friction material after install is another neglected area.  I have read some pretty indepth recommendations in a variety of OEM Shop manuals and while many materials have changed over the years, it seems to be still a good idea.

I imagine just turning the wheel by hand is probably adequate for arcing in and truing the drum, but one note of caution if someone is considering driving the wheel by the motor or using another bike/car/electric motor while lifted off the ground.  The tire at speed changes shape and when there is only a small gap between the tire and the ground (Center stand or lift) the tire CAN grow and make contact which can have an unfortunate result.  Have seen a few bikes launched across a work shop or off a lift.   There is an amusing story Bob McKenzie and a few others up in BC Canada circulate about "The Devil Bike" which was a BSA single,, it took off on its own by other means but it would be sad to hear of a BSA coming to woe for this reason.

When I came back from overseas and took a job in a trucking company maint shop I saw this in even more dramatic fashion.  At the time they were calibrating a K-DEC unit which was on board computer monitoring system (Kind of a Nanny Cam monitor).  They had a Freightliner conventional up on jack stands in the shop and running it hard thru the gears.  For some reason I could not put my finger on it made me nervous so I left the shop to do yard inspections on other units.  At 65-70 MPH there was a huge explosion and debris began falling from the sky.   What happened is the Drive tires had re-cap tires on it and had grown in size enough to contact the shop floor.  2 things resulted,,, It launched off the stands and into the backend of a flat bed trailer in the shared shop bay luckily the mechanic in the other bay was clear of the wreckage. The explosion was the cap on one of the 4 drive tires which weighed around 70 pounds separated from the tire carcass and launched thru the roof of the shop which scattered debris in a wide arc.  Clearly this is far more massxforce=distance than any BSA but the law of physics is not to be trifled with.

It was the shop foreman who was running it, and I imagine had it been me or the other mechanics we would have been fired on the spot.  It was a sore topic never to be spoken of again during my employment there.

[orabanda]

Suggest you look for someone who refurbishes truck brake systems.

They usually have a stand-alone machine designed to machine truck and trailer (bogey) brake drums (the large cast iron ones you see on every truck).

A local shop does all my bike wheels. I supply the complete wheel (with tyre fitted, spokes tensioned, etc), but bearings removed from the hub. This allows his large centres to engage in the hub.

5 minutes work, and $20 later, a concentric and beautifully finished braking surface.

After the wheels have been spoked, the hubs will be up to 0.010"out of round.

Richard