Skimming brake drums

Information relating to the Matchless G12 or AJS Model 31 650cc twin
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Skimming brake drums

Postby bob121 » Thu Jun 07, 2018 6:31 pm

I've never had this done. Does it actually work, if done right. The front drum is out of round and no fun when heavy on the brakes. I've got to pull the front end back down anyway. So I could get it done if it's worth it. Is there any one in the West Midlands, or preferably the black Country that can do it. Also can it be done on a built wheel or will it need to be dismantled.

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Re: Skimming brake drums

Postby bitza » Thu Jun 07, 2018 6:52 pm

If your wheel is laced up and true, give central wheels a call they advertise a while you wait service pre booked I suppose I had my wheels rebuilt by them and drums looked like they had been lightly skimmed they are based at Coles hill.

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Re: Skimming brake drums

Postby bob121 » Thu Jun 07, 2018 7:00 pm

I know them. Always had mixed feelings about them. Not really sure why. I'll definitely consider it an option.

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Re: Skimming brake drums

Postby Rob Harknett » Thu Jun 07, 2018 7:21 pm

Had drums skimmed on an old car years ago, they were well scored having had the linings go down to rivets. That was years ago. Always replaced drums or disc on car more recently. I guess you are sure its drum needs truing up and not linings.

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Re: Skimming brake drums

Postby SPRIDDLER » Thu Jun 07, 2018 8:04 pm

bob121 wrote:Also can it be done on a built wheel or will it need to be dismantled.

I've no personal experience but I've heard it said around the drip-tray that it's best to have the skimming done on a complete wheel since the re-spoking afterwards can distort the newly skimmed drum. I find that hard to believe but.............. :?
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Re: Skimming brake drums

Postby Groily » Thu Jun 07, 2018 8:41 pm

Must hang out round the same drip-tray Spriddler cos have often heard the same. Probably more risk with the tinnier things on some other makes than with our chunky liner in chunky hub. When I skimmed one of mine, I did it 'wheel fully assembled'. That was having made the liner myself, knowing it was round (and concentric) when it came off the lathe. Freezer for the liner and heat for the hub, in it went, then screwed in as per original. BUT, there was a small difference after fitting it and re-spoking - and it was better for the skim afterwards.
However, as Rob says, linings come into it, and so do headstock bearings and fork bushes for that matter.

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Re: Skimming brake drums

Postby JEAN-NOEL » Fri Jun 08, 2018 6:22 am

Hello Jason,
Have a look at Classic Brake Service site, in High Peak, Derbyshire.
They have linings for all applications. Their linings are bonded and rivetted on the shoes (belt and braces !) and then machined to the drum diameter. If it is necessary, the drum is skimmed with the Wheel built.
J.N.

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Re: Skimming brake drums

Postby SPRIDDLER » Fri Jun 08, 2018 7:46 am

Rob Harknett wrote:Had drums skimmed on an old car years ago,

That reminds me........back in the late 60's (when I was saving for the £450 deposit needed for my first house !!) I did a bit of dealing and bought a 1930's Austin 7 Ruby with Bowden cable brakes for 15 quid. When braking my foot went up and down like pumping up a tyre. I sold it quickly, although briefly, for 25 quid. I watched the buyer leave my house 400yds up a slight hill. He went straight through the cross-roads at the bottom and abandoned the car on the pavement outside Holyer's butchers and walked back to demand a refund. I did sell it permanently a week later, but from a friend's house on level ground.

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Re: Skimming brake drums

Postby McBob » Fri Jun 08, 2018 11:31 am

I've tried to get my front drum skimmed and not found the combination of willingness and correct equipment in the same place. Is there a d.i.y option, maybe involving emery cloth or such attached to a brake shoe and spinning the wheel interminably to remove the high spot?

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Re: Skimming brake drums

Postby bitza » Fri Jun 08, 2018 5:02 pm

Yes the wheel or wheels need to be complete prior to being skimmed.

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