Brake Drum Tolerances

[davewes]

I'm just trying to improve braking and remove some judder from my front brake (full width 8" iron drum on my 58 Gold Flash). The drum has about 5 thou ovality - could someone please let me know if this within reasonable tolerances or should I get it machined. Thanks

[duTch]

 Hiya Dave 

 I know its just the Q. how much, but there's quite a few recent discussions on this and how to rectify if you do a search.

 I have to check mine out too, and it was a NOS hub until I put it to use six months ago

[davewes]

Thanks Dutch. Yea I've done a bit of research through the Forum's excellent database and have used the adhesive abrasive paper trick to bed in the brake shoes, and am also changing the steering head bearings as part of a brakes/steering/forks refurb.

[muskrat]

G'day Dave. Nearly 8 years since your last post. Good to see your still here and the bike must be going well.
5thou" isn't much but you will still feel a judder.
I would get it machined but with the rim laced in (spoke tightening can pull the drum out of round). Then the shoes will need radiusing to match.
Cheers

note to self: both mine need doing but brakes only slow you down!

[Peter in Aus]

note to self: both mine need doing but brakes only slow you down!

Love it
Peter

[worntorn]

Thanks Dutch. Yea I've done a bit of research through the Forum's excellent database and have used the adhesive abrasive paper trick to bed in the brake shoes, and am also changing the steering head bearings as part of a brakes/steering/forks refurb.

Dave, you can use the stick on abrasive paper other way out to make the drum round again. 5 thou isn't much, the abrasive paper will do a perfect job.

I had recently had two bikes with juddery front brakes, both are now fixed with this method.

Glen

[KiwiGF]

Thanks Dutch. Yea I've done a bit of research through the Forum's excellent database and have used the adhesive abrasive paper trick to bed in the brake shoes, and am also changing the steering head bearings as part of a brakes/steering/forks refurb.

A note of caution on this, the paper trick can result in both shoes contacting at the same time, a SLS brake works far better if the leading shoe contacts first.

A way around this is to place a thin spacer (say 020”j under the trailing shoe so it’s lifted slightly off the brake cam, then remove the spacer after doing the paper trick.

[davewes]

Thanks for the responses chaps, very useful as always. Muskrat, the bike has gone well over the 8 years but of course not without some challenges/fun. I'll post the story soon as a contribution to this great Forum.