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Re: Swing spring / camber compensator

To: "Joe Curry" <spitlist@gte.net>
Subject: Re: Swing spring / camber compensator
From: "Bill Birney" <bill.birney@bigpond.com>
Date: Tue, 13 Jun 2000 17:05:16 +1000
Joe et al,

> Drooping is a passive thing

Tuck in, Tuck under, I'm talking about massive positive camber.....

> anything to compensate, the unloaded wheel will fall down and in the
process, TUCK UNDER. ...
> But the rear anti sway bar also performs somewhat the same function.

Again Joe, sorry to disagree, but the anti roll bar will not help really at
all. The problem with the Spitfire rear suspensiion is the roll centre, this
causes the back of the car to actually 'jack up', as traction is lost, this
means that NO WHEELS ARE SUFFICENTLY LOADED to counteract the action of the
spring.

The swing spring counteracts this by effectively lowering the roll centre of
the rear suspension.

So what you need to do to stop this is either:

(1) never ever get into a high speed unloaded condition ... probably not
very realistic. OR

(2) have some way of resisting the motion of the spring action. (Your camber
compensator or the Z bar)

> Z-Bars were declared illegal by the SCCA back in the 60's.

Still a good fast road option, and most definitely not illegal here (the
athourities in fact strongly recommend the use of such a device). I would
say that I have a fair bit of experience at driving a Spitfire at speed, and
have still had a very hairy couple of moments when things have 'jumped out'
infront of the car!

In those cases the old "brake early, get back on and turn in" maxim doesn't
do you a lot of good. The feeling as the back end climbs into the air, and
you start to exit backwards into the scenery with the right foot buried in
the accelorator, praying it won't trip over something is not one I want to
repeat too often!!!!!!!

>  but in theory they should be very effective.  But to do their job they
need to be preloaded with a fairly > significant
> amount of force.  That makes their installation somewhat precarious.

I can say in practice, not just theory (someone was after one, I have one in
the shed, no longer needed as the car will be gaining a copy of the GT6's
new rear end, Subaru diff and CV driveshafts, transport from Oz could be
prohibitive though!). As for the force, there is no more requirement for
force that your camber compensator, it all depends on the degree of wheel
control you are after. They are basically a bolt on and wind up modication.

Bill Birney


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