shadow brake drums.....

[1660bob]

Hi All,
having recently built up my wheels with new drums(VOC) I fitted front wheel to forks yesterday to check the fit clearences in relation to my alloy brake plates.Imagine my horror as I spun the wheel to see the ribs on both drums oscillating side to side in relation to the stationary brake plate edge.The drums are distorted/misaligned by an alarming amount-so much so that the brake shoes catch heavily at one point, but free off for the rest of a wheel turn. The distortion is easily visible as the wheel spins-I can not figure where i went wrong-I cleaned meticulously around all of the mating faces of hub/spoke ring/drum etc so i am happy nothing is trapped under the flanges.The hub appeared fine-i.e. no visible damage.Spoke rings are original and seem OK.The only thing i can think is the drums have somehow distorted as the bolts, in some instances a very tight fit, were tightened. I know nothing is perfect but the run out seems excessive- I had the drums powder coated prior to assy. but surely the heat could not distort them?(two of them were powder coated from VOC in any case but it was poor so i had all four re-done to match.Any Ideas,cheers, Bob.

 

[Albervin]

All I can suggest is to take them off and lay them on a sheet of glass. Some may suggest float glass but an ordinary sheet of glass shelf is what I use. If the drums "rock" on the glass then there is the problem. Trouble is, did you check for flatness before the powder coating? Does the wheel spin true? Are the forks parallel? What exactly is the run-out in " or mm ? Are we talking thous or 1/16"? The eye is a fine and accurate tool but sometimes we need to get some references.

 

[Black Flash]

check very carefully that you can get a thin feeler gauge between the spokes heads and the back of the drums. it is known that new spokes have a lager bend.
I found the same problem on my shadow wheels. Peter Barker (A-HRD) sells lasercut shims to space out the drums.
they solved my problem.
HTH
Bernd

 

[Bracker1]

Sounds like the drum is not seating on the hub. Make sure their isn't any of the powdercoating bits in between. Especially the inner edge. Sometimes it the simple things. Good Luck, Dan