Heat cracks are just an indication that you are trying hard or haven't
looked at the part for a couple years.
----- Original Message -----
From: "Bill Babcock" <BillB@bnj.com>
To: "'Dave Talbott '" <dtalbott@archrepro.com>; "'Jack W. Drews '"
<vinttr4@geneseo.net>; <fot@autox.team.net>
Sent: Tuesday, June 17, 2003 10:45 PM
Subject: RE: brake drums
> Hey, I knew Dave was out there lurking. And it looks like we're in
> agreement with our blase attitude about alfin drum liner cracks. And Hardy
> too! Wow. People are going to start feeling like they're not ready to race
> unless their drums are well cracked. How 'bout it Kas, shouldn't it be a
> requirement?
>
> -----Original Message-----
> From: Dave Talbott
> To: Jack W. Drews; fot@autox.team.net
> Sent: 6/17/2003 2:22 PM
> Subject: Re: brake drums
>
> Jack:
>
> Having raced 240Z's for some years with rear drum brakes, I can say your
> problem is not an isolated one, however it has not usually been cause
> for
> concern in a race. I have taken many drums off with cracks and clear
> evidence of heat, but never actually had the ferrous linings come
> adrift.
> They are especially subject to cracks as they get close to their maximum
> size, the dimension for which is typically cast into the aluminum on the
> face.
>
> 240Z's in the Improved Touring S-class tend to have a bit more grunt
> than
> the brake system is designed for, so to assist the overworked fronts,
> you
> try to bias as much to the rears as you can handle from a driving
> standpoint. That usually involves high friction linings for the rears
> and
> attention to bleeding and adjusting out the rears frequently. You end
> up
> replacing a lot of shoes, and the drums don't last too much longer than
> the
> shoes, especially if you take them out of service somewhat before they
> enlarge to their maximum dimension. It is a maintenance intensive
> approach,
> but they do work, and the drums are available through various supply
> houses
> for not a whole lot of dollars. Ventilating the backing plates as well
> as
> heat-dispersing coatings on the drums seem to make things last a bit
> longer.
>
> Maybe others have different experiences with the potential hazard of the
> cracks, but I've never seen a Datsun drum cause any real problems. I do
> seem to remember Hardy being very attentive to his drums, of course
> Hardy
> lavishes lot's of attention on most everything .
>
> Dave Talbott
>
> ----- Original Message -----
> From: "Jack W. Drews" <vinttr4@geneseo.net>
> To: <fot@autox.team.net>
> Sent: Tuesday, June 17, 2003 1:42 PM
> Subject: brake drums
>
>
> > My TR4 race car has Datsun 280Z rear brake drums.
> >
> > This morning I removed and inspected them, and found that one of them
> had
> > three cracks across the iron friction face. Yuk. I have used these
> drums
> > for five years and they never even needed turning. I inspected them
> last
> > winter and did not see cracks at that time, but maybe they were there
> and
> I
> > didn't notice them.
> >
> > At any rate, be forewarned that this kind of failure can occur. The
> thought
> > of it happening during a race is not pretty.
> >
> > uncle jack
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