Most drums warp in the middle where it touches the hub. It would take too
much machine work to chase that. Checked that area to see if there is any
warpage there.

Sometimes it's not the drum or the hub. A bad rear bearing can cause the hub
to wobble and make it feel like a warped drum. With the rear wheels off the
ground, try to move side to side and check for free play. If it wobbles by
hand, it can pulse when you drive.

BenT

On Tue, Jul 27, 2010 at 10:32 AM, Shawn Wright <vwdiesels@gmail.com> wrote:

> On Mon, Jul 26, 2010 at 2:18 PM, David Beierl <dbeierl@attglobal.net>
> wrote:
>
> > At 03:57 PM 7/26/2010 Monday, Shawn Wright wrote:
> >
> >> new ones, and have to decide which ones I should have machined. The old
> >> ones
> >> appear to have plenty of life left - although I don't have calipers
> large
> >> enough to measure them, they seem to be very close to the new ones in
> >> diameter. What would you do?
> >>
> >
> >
> > Are there any things to watch for in having them machined, or can any
> >> decent
> >> brake shop do it properly?
> >>
> >
> > I had mine machined once and they came out all wobbly.  Shop said that
> the
> > way VW did the center hole doesn't work very well with US-type brake
> lathes.
> >  YMMV.
> >
> >
> Hmm. Last night I swapped the old drums back on before heading back to the
> campsite. The warp on them is barely noticeable compared to the new ones! I
> think I'll just leave them on until I can find a decent shop confident in
> turning them right.
>
> I did manage a measurement with my caliper depth gauge - the old ones are
> about 0.4mm larger than the new. I didn't calculate the overall size, but
> this doesn't seem like a lot of wear.
>
> --
> Shawn Wright
>