Bumpsteer could go either way with a shorter rack. It's zero when the end of
the rack intercepts a line drawn through the inside suspension pivots, the
end of the steering arm intercepts the line drawn through the outer
suspension pivots, and an imaginary line drawn through the steering link
intercepts the intersection of imaginary lines drawn through the suspension
arms. Shortening the rack can move the rack ends further out of the plane of
the suspension ends and change the angle of the links for the worse. You
won't know until you either model it or measure it.
Bill Babcock
Babcock & Jenkins
-----Original Message-----
From: owner-fot@Autox.Team.Net [mailto:owner-fot@Autox.Team.Net] On Behalf
Of Ed Diehl
Sent: Tuesday, January 25, 2005 3:39 PM
To: Herald948@aol.com; walt@hot-tr6.com; EDWARD BARNARD; Justin Wagner;
fot@Autox.Team.Net
Subject: RE: Quick Ration Steering Racks
HEY, GUYS. ONE LITTLE THING MAY BE OF INTEREST. A TR7 RACK CAN BE ADAPTED TO
A SPIT AND IS SHORTER THEREBY REDUCING THE BUMPSTEER WHICH, ON THE SPIT IS
HORRENDOUS. RATIOS, MAYBE BETTER? CHEERS, ED..
Herald948@aol.com wrote:In a message dated 1/24/2005 11:53:35 PM Eastern
Standard Time, writes:
>I put one into my hot TR6 about 1.5 years ago. I bought it from Scott
>Harper at Team Triumph. I like it very much. I mounted the quick ratio
>rack in aluminum blocks and the suspension has all poly bushings, stiff
>springs and Spax shocks. It is my understand that this setup has
>Spitfire steering rack guts in a TR6 housing. It took about 1 full turn off
of lock to lock.
>Steering is very direct and quick. The steering effort when parking is
>higher but I don't mind. When I would autocross or even road race it
>seemed like I had to do an awful lot of cranking and cranking with the
>stock steering. This quicker ratio rack is much better.
>Walt Hollowell
>Abq.NM
============
Walt, I'm confused here. Physically, TR and Spitfire racks are about the
same externally, although I can't vouch for the angle of the pinion shaft as
it connects to the steering column. But they're about the same length or
width or however one wants to describe that measurement.
Meanwhile, the Spitfire rack is something like 3.75 turns lock to lock (GT6
is a bit over 4 turns). The early TR4 steering rack, which as I recall also
mounted solidly as opposed to the rubber bushings used on later TRs), was
also 2.5 turns lock to lock, so I've long wondered if this "new" quick-ratio
box is much more than a "replica" of the original TR4 rack.
I have an early TR4 rack that I've been saving to toss into the autocross
Spitfire 4 (assuming that I -- or my daughter and/or son -- ever actually
dig it out and start autocrossing again). I've also got some early Herald
steering rack mounts, which were "solid" as opposed to the later
rubber-bushed mounts. Or maybe I'll just toss all this good stuff, and the
Spit's motor, into a street Herald.... ;-)
--Andy Mace
Ed Diehl
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