On 16 Jan, 16:13, Nate Nagel wrote:
Peter Cole wrote:
DougC wrote:
On 1/15/2010 4:27 PM, (PeteCresswell) wrote:
A new 6" rotor is only about twenty bucks, but I've accumulated a
few rotors that *look* ok, but pulse badly.

Tried boiling in water for awhile on the latest one, but no
change.

I thought sand blasting for a moment, and then it seemed like
that would be asking for irregularities in thickness.

Anybody got a tried-and-true method of refurbishing a rotor that
doesn't require a machine shop?

For $50 each plus shipping, I can make them work like new.

*--------

Seriously, it would be interesting to see exactly what the problem is.

To make sure they're not warped, you would need....... a machine shop.

You coat one side with dye (or just draw a grid on it with a permanent
marker) and then scoot it around gently on a granite flat, and any
"high" spots will have the marking ink rubbed off before everywhere else.
~

The classic way to get a cheap flat surface (i.e. for lapping) is to use
some plate glass. I've checked auto heads/blocks for flatness with a
ground (e.g. Starrett) straightedge (~$10).

yup, I have trued up oil pump covers using a piece of thick plate glass
and some wet/dry sandpaper (not having a milling machine in my garage.)
* Ought to work for rotors as well, I'd be a little worried about the
thinness of the metal however, the rotor might actually flex while
you're sanding it, so I can't guarantee you'll get perfect results.

On the car I've used a file applied to the disc with the engine
running to remove the overhang at the edge. For a disc still fitted a
similar method could be employed on a bicycle say using a drill chuck
applied to the tyre to turn the wheel and an abrasive pad against the
disc.