A few years ago we were helping a vintage racer with his TR-3 and I had the
opportunity to race his car on several occasions. On one of these the
gearbox began to crack where the bell housing joins the housing for the
trans. This was the second or third case that had cracked in this car.
The power output of the engine was about 135 to 140 hp, so it was not an
engine that would overtax the chassis. In driving the car, I noted that
the more cornering force that was applied to the chassis the more the trans.
would make nasty noises. I concluded from this experience that at least
part of the problem with the case failure was probably due to torsional
loads transmitted to the engine and trans. during cornering, caused by the
twisting of the chassis. The engine trans. combination is supported at two
points at the front mounts and essentially two points at the rear of the
trans. At least if the rear trans. mount is a good, stiff new mount that is
so. I would bet that redesigning the rear mount to have a single central
mount under the trans. that would support and locate the rear of the trans,
but at the same time not resist the twisting torsional loads that would
otherwise be fed into it by the rather flexible chassis , would also solve
the problem.
Regards,
Greg Solow
-----Original Message-----
From: Catpusher@aol.com <Catpusher@aol.com>
To: fot@autox.team.net <fot@autox.team.net>; Kaskas@earthlink.net
<Kaskas@earthlink.net>
Date: Friday, March 26, 1999 4:16 PM
Subject: Re: The Good, the Bad and the Ugly
>For those of you that insist on flogging your TRs, a little TR3 history,
>and my solution.
>Quite a few seasons ago I had a series of races that I successfully
>completed with the smell of gear oil. I was cracking the main case,
>as well as the tail housing. Because I inspected the gearbox after
>every track session, it never caused a DNF, but it was expensive and
>time consuming. The balance and truth of the motor parts, gearbox
>parts, drive shaft, and rear axle flange were all blueprinted with little
>improvement. We tried brand new cases/tail hsgs, and good, used
>cases/tail hsgs. We made certain that all important surfaces were
>flat and true. Tracks with bumpy, banked corners were the worst.
>Willow Springs was one of the worst, but our lap record set with a
>cracking rear case held for a amazing number of years, and the 914
>finished second.
>
>I consulted the GCR & PCS and Tech. I rejected the extra mount
>at the rear of the motor block because of weight and too much added
>time to R & R the motor or gearbox. Friend and fellow TR3 racer,
>Dennis Kelly,(C & D Engineering) came up with some stout aircraft
>cables and turnbuckles that I fitted with considerable thought re the
>gearbox centerline, on each side of the gearbox. They ran from a
>special top starter motor nut and a lower, special gearbox to block
> fastener, to the tail hsg/rear mount interface. The cables were
>tensioned and safety wired, and the problem went away.
>
>We had learned about the better main cases and used these all
>along. It was most convenient for the racer that Triumph never
>changed the main case part number on the all synchro box!
> Triumph had some brilliant people.
>
>HP
>
>
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