DeTomaso Mailing List: June 2001, Message #76

John-

I've run into this in a similar situation.

Last year sometime I made the change to 17 rims and tires and at the same
time decided to have my 73 aligned.  My goal during the alignment was to get
the rear tires to 0 camber.  However, it was determined during the alignment
that there were no more spacers on the lower left control arm to remove, so
I had to settle for a pretty significant amount of camber.

After mentioning this to the forum most agreed that the rear section of the
car had collapsed in on it self which can happen with these cars.  However,
one day as I stood admiring my car.  I noticed a prominent sag on the left
hand side of the car.  Wow, I had never noticed this before.  After
measuring shock length, I determine that the car was setting .75 inch lower
on the left hand side than the right hand side at the shock which can
translate into a pretty large amount once you get out toward the tire.

So now I've determined that my problem doesn't lie in the rear of the car
collapsing in on itself but instead on the fact that the sag from the
springs has caused the camber to be off.  I guess it comes from all those
years of carrying fuel and a driver.

I like the lowered look on the left hand side of the car.  So I've thought
about compressing the right hand springs.  But then of course I would need
extended upper control arms which is probably a good investment considering
the cost of replacing a ball joint in the stock ones.

Chance Dorsey
#5365



----- Original Message -----
From: John Taphorn <jtaphorn@kingwoodcable.com>
To: Multiple recipients of list <detomaso@realbig.com>
Sent: Saturday, June 02, 2001 8:03 AM
Subject: Camber Ramblings


> I'm a little embarrassed that I hadn't thought or recognized this before.
I
> figured I'd share a recent learning.  I just fit new and larger wheels to
my
> lowered car.  As a consequence, it seemed appropriate and wise to raise
the
> car's ride height.  This would afford me additional suspension travel in
the
> rear before the dreaded tire to inner frame rail interference occurred.
>
> Digression:  When checking rear wheel fitment, I removed the shock and put
> my old 255/60/15 tire on a stock wheel through it's full range of motion.
> If the rear suspension is compressed far enough, the wheel will contact
the
> inner frame rail.  Ah ha! No surprise to me that increasing wheel
> backspacing and tire width makes this episode more common.  Frankly, the
> geometry of the rear suspension is such that if the rear suspension is
> compressed far enough, any size wheel/tire combination will hit the frame
> rail.
>
> I had aggressively lowered and added rake to my car to optimize track
> performance.  As a consequence, I frequently dragged my lowered floor
pans,
> destroyed my front spoiler and compressed my right rear suspension far
> enough on turn 1 at Texas World Speedway to cause my narrow 255/60/15s to
> contact the inner frame rail.
>
> Since I'm now fitting taller and wider tires, a new approach is warranted.
> After raising the car approx. .75" at all four corners, (It is still lower
> than a car with stock spring/shock combo) I rechecked my camber
adjustments.
> The front wheels went from .5 degrees negative to .5 degrees positive.
The
> rear wheels went from 0 degrees to .5 positive.  I am surprised to learn
> that the ride height adjustment influences camber so significantly.  I
knew
> that some change was inevitable; but, I thought it would remain more
> constant through it range of motion.
>
> Learning:  I know recognize why I could not eliminate my negative camber
> with stock length upper A-arms on my lowered car   The common explanation
on
> the list had been it was caused by a collapsed wheel house.  A condition
> that I knew did not apply to my car.  Rather, I submit on cars with
> adjustable suspension, it is a consequence of lowering your car's ride
> height.  Lowering generates more negative camber that at some point can no
> longer be exorcised with the stock length upper A-arm and removing lower
> A-arm shims.
>
> Practically speaking,  I suppose there are benefits to the suspension
> increasing negative camber under compression.  High speed cornering that
> would cause the suspension to compress and induce more negative camber
would
> occur in an environment when the tire's sidewall/carcass is more apt to
roll
> and therefore, benefit the most.
>
> JT
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