We had the same problem using 240Z drums on the TR's - the TR shoes are vast
compared with the original Datsun items. As you say, the cracks look
alarming, but we have not (yet) experienced a major failure. The only other
problem is the peculiar wear on the shoes, which end up thinner on the
mounting face side of the drum. This is presumably caused by the drum
opening up to a bell shape under duress. I've gone back to original new iron
drums - better shoe wear and a more consistent pedal. If any of you IRS
owners out there have a scrap Stag in the back garden.......
Jon Wood Classic Racecraft
----- 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: Wednesday, June 18, 2003 6:45 AM
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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