I'm relatively happy to see disc brakes on production cars that would have
had drums, and I consider putting them on to be a safety item, only if they
are period fitment in style. My thinking is that while the drum brakes are
more original, and there is a terrific argument to be made that one should
drive within the capabilities of the car, I think that coping with the
characteristics of drum brakes in a racing environment requires a quite
high level of both driver and preparation skill. Rather than depending on
a drivers ability to cope with fade and uneven brakes pulling to one side
or the other I'd like him to fit the discs, which he is far more familiar
with from all of his other driving experience, and make the track safer
for me! I don't agree with upgrading existing disc brakes to bigger discs,
larger calipers, etc., when the originals are adequate.
I say relatively happy, because while perhaps practical this goes against
the idea of preserving the cars as they were. BTW, I'm pretty sure that
the Healey 100-S was 4 cylinder and 4 wheel disc brakes.
Brian
BTW, I disagree with this new rule of having to edit replies. Sure, that's
appropriate in many cases, but certainly not in all.
At 10:17 AM 11/29/01, WSpohn4@aol.com wrote:
>Thanks for the MGA kingpin info, Mark. I am blind copying the vintage race
>groupo with my reply, as they may have some useful comments.
>
>I broke one kingpin racing at Spokane in the 70s, and replaced them with NOS
>factory parts which have lasted since. I run 5.5" wheels (used to be
>magnesium, but now steel steel Twincam, as I wanted to have the car as close
>to how I raced it in the 70s as possible) and am now using Comp TAs instead
>of racing rubber (used to be able to get nice sticky recaps from California
>on old Dunlop race carcasses - markedly faster than BFGs!). All of these
>changes probably take some of the stress off my kingpins.
>
>The info about the Listers is interesting - I had known, but had forgotten
>that they and Devins used MGA parts. They are also much more likely to use
>bigger wheels and stickier rubber, and will test the design limitations of
>the MGA suspension much more quickly than we will. $800 might be a good deal
>for peace of mind. If anyone researches this more let us know.
>
>While the Twincam hubs use the same bearings as the MGB, I do not know (have
>never bothered looking) to see if the spacing between the inner and outer are
>identical on both models. Even if they were, that just means that you could
>install your hubs on an MGB spindle - you'd still have to mount the caliper
>somehow, so custom mounting plates would be needed.
>
>None of that is any big deal, but the fact remains that it is not allowed in
>many (most?) racing organisations - you simply cannot swap parts from
>different models. XKE Jags are not supposed to run XJS brakes, etc. (though
>some do), and brakes are fairly easy to see modifications on, although the
>suspension behind them perhaps a bit less obvious.
>
>I went back to steel Twincam wheels and ditched plans for rear trailing arm
>and coil-over tube shock suspension, and fuel injection, to avoid doing what
>most racing organisations _must_- react to - when they see you running a car
>with obvious mechanical modifications beyond the period in which it was raced.
>
>Many people modify just because they can - the fitment of later Girling 3 pot
>calipers to Twincams is one example, when the originals are perfectly
>adequate for competition use if properly rebuilt and maintained. When asked,
>they respond that they are making their cars safer. Bullshit! Stick
>ventilated Camaro discs on an MG, and it is not one iota safer than it was
>with the adequate factory parts.
>
>Obviously this does not hold true for models that ARE inherently unsafe,
>whether underbraked, or otherwise, MGA 1500 cars for example. I can easily
>side-step the issue with them, by saying that they should be allowed to use
>later disc brakes from the same (MGA) model. I have a little more trouble
>with cars that never had an almost identical model that had better brakes.
>Examples are Austin Healey 100 (no 4 cylinder Healey with discs ever existed,
>so do you push the principal and allow the 100-4 the same upgrade rules as
>you clearly would the 100-6?) and Swallow Doretti - true, the brakes were
>Triumph derived, but there was only one model of Swallow, and they all came
>with drums. Should you allow people to bolt on TR3 (or TR4, TR6?) parts?
Brian Evans
Director, Canada
MCI Wholesale Internet Services
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