You could do anything that you wanted to the crank except, add material. No
welding, or whatever except balancing. Read the meaning of balancing in the
dictionary, it means to " make even". Does not say to take away or add, just
make even. It is interesting in this rule as with the TR-6 I had to move the
harmonic trouble spot to a higher location in revs so I added a bunch of
weight to the crank and even added brass plates to the sides of throws to
get the harmonic in a position that was outside of the area in which I would
use the engine. Worked like a charm and, as I was balancing, it was
allowed. You gotta read the rules. Used nitriding as a tool most of the
time, made a 50% strength improvement in the TR-6, TR-250 crank..
The difference between the Spitfire big bearing crank and the small bearing
crank is the oil passages. The big bearing is not good. I had a terrible
time with it and finally plugged the stock hole and cross drilled, this
fixed it and redrilled the main feed to the throw. I've written about this
in my books as most already know. The same with 1500, same problem, oil
passages wrong for high revs and racing. Okay on the stockers though. This
all happened as they were trying ( and did) commonize parts in the engines
across the model line. Bad move for racers.
Sometimes I was very popular at the factory and sometimes not, when I
hollered and yelled about the 1296 MK 4 crank I was not popular (I was
correct) but not popular. Then they did the same thing on the 1500,
different folks to deal with at that time, not the same old Triumph good
guys who had been shipped out to rescue engineering in the M.G. plant in
Birmingham. Mergers do not always do a good thing for the customer.
----- Original Message -----
From: "Jim" <britbits@netzero.com>
To: <fot@autox.team.net>
Sent: Thursday, May 14, 2009 3:20 PM
Subject: [Fot] Broken Cranks: Was - Any connection between these problems?
> That raises an interesting question.. Back when the cars were new.. What
> was "allowed" (wink wink) for crank prep? Different alloys?
> Nitriding/Tuftriding? Or just balance the factory piece and keep your
> fingers crossed?
>
> I'd always heard the small bearing crank was better for taking abuse (aka
> high revs) than the later big bearing 1296 and 1500 cranks.
>
> The only LBC crank I'd ever heard described as "bullet proof" is the
> Cooper
> S crank, EN40B steel and nitrided from the factory.
>
>
> Cheers,
>
> Jim
> Dallas
>
> -----Original Message-----
> From: fot-bounces@autox.team.net [mailto:fot-bounces@autox.team.net] On
> Behalf Of michael cook
> Sent: Wednesday, May 13, 2009 8:38 PM
> To: budscars@comcast.net; norlinengineering@comcast.net;
> fot@autox.team.net
> Subject: Re: [Fot] Broken Cranks: Was - Any connection between these
> problems?
>
> When I purchased the Triumph competition Dept. Spitfire Mk 3 (1969 FP
> champ)
> from Kas, he said "DON'T go more than six races without replacing the
> crank.
>
>
>
> Being budget-minded, I went six races and decided "Just one more."
>
>
>
> The crank broke at #3 in practice for the seventh race. I still have the
> rod
> as a paperweight - it has a nice hump bend in the middle.
>
>
>
> Mike Cook
>
>
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