Hi gang,
I can add a bit to this. I have a Devin SS with the same setup. The MGB
hubs/spindles will not fit at all on the MGA kingpins. Everything (kingpin
and all) must be substituted to work on the MGA (a simple swap from what I
understand if you take the MGB shock as well). On the Devin this is not
possible. I ended up with racing kingpins and trunioins from Ron Gammons in
the UK. Gammons runs a Devin SS in England and makes special kingpins with
less threads, thicker size in certain areas and less stress risers. He also
modified the old bronze T-series trunnions to work with them. As I recall I
paid around $500 for everything I needed and it arrived in short order.
Gammons recommends checking them frequently and replacing when needed. Brown
and Gammons is well known in MG circles for their racing and replacement
parts company.
Some Devins and Listers have special kingpins made from 4340 with fabricated
trunnions. Lister made their own hd kingpins and trunnions in the 1950s after
breaking the stock parts.
Harold Pace
In a message dated 11/29/01 7:20:59 AM, WSpohn4@aol.com writes:
<< 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?
I don't know, and fortunately don't have to make decisions like that. I do
feel that the further away from stock you get, in the places that show to
people walking through the pits, the more pressure there will be on the
sponsoring group to start enforcing their rules, and the less like vintage
racing and the more like regular rules-ridden competition this sport will
become. I say try and try again to make something work within the confines of
available period parts, and only then consider going 'outside' as the Triumph
crowd recently felt obliged to do when a spate of front hub failures
instigated the production of a different design of hub.
Bill
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