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Re: rear wheel camber

To: spitfires@autox.team.net
Subject: Re: rear wheel camber
From: Douglas Braun & Nadia Papakonstantinou <doug@dougbraun.com>
Date: Fri, 13 Apr 2001 00:18:11 -0400
I stand by my assertion. Let me explain:

1: The Spit's swing angles are always perpendicular to the wheels
(or you've got some REAL problems).

2: Since the wheels are (hopefully) the same diameter, the outer ends of the
swing axles must always be at the same height above ground.

3: Therefore, if the rear wheels have different cambers, the swing
angles must be at different angles.  Since their outer ends are the
same height above ground, their inner ends must be at different heights.

4: If the inner ends of the swing axles are at different heights,
the left and right sides of the diff must also be at different heights,
which means that the diff must be tilted at an angle.  

5: Since the diff is rigidly bolted to the car body, if the diff is tilted,
the body must be tilted.

6: Since the length of a swing axle is something like 2X the half-width
of the diff, a 10-degree change in differential rear wheel camber 
would cause something like a 20-degree change in body lean.

Note that the spring and its condition did not enter into the above arguments.
The spring does not directly determine the position of the wheels; it
holds the body up, and if the body is held in a tilted position, the
rear wheels' camber will be (slightly) different.

The rear spring is NOT really like a upper control arm.  Changing
its length or position would change the angle of the vertical link,
but the the angle of the vertical link does NOT control the angle of the
rear wheel.

BTW, this sounds like something out of a Monty Python sketch.

Doug Braun
'72 Spit

At 10:12 PM 4/12/01 , you wrote:

>Douglas Braun & Nadia Papakonstantinou wrote:
>
> > This is theoretically impossible, unless the car is leaning horribly to
> > one side.  Maybe one of your axle shafts was once replaced with one of the
> > wrong length, and the entire wheel is sticking out too far (or not far 
>enough)?
>
>
>Not really theoretically impossible, in fact quite possible!  If the spring is 
>collapsed on one side more than the other, that side would have a
>greater degree of negative camber than the other side.  Because the spring 
>acts as the upper control arm, the raising of that component in relation to
>the axle will pull the top of the vertical link closer to the differential.
>
>This is why de-arching the road spring will induce an increase in negative 
>camber on both sides.

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