Re: [DML] Steering geometry

["Walter" <Whalt@xxxx>]

Chris,

The problem you are describing sounds like 'under steering' and is not
related to wheel alignment.

I suggest doing two tests:

1) Buy a tire tread depth gauge (they are cheap) and keep track of how your
tries wear as a function of mileage. I try to do this with every oil change
on all of my vehicles. Make a ledger to keep track of all 4 tires, and keep
three average measurements from each tire: the inside most tread, the center
tread and the outer tread. This will help you to keep track of uneven tire
wear which may be caused by alignment problems or from incorrect tire
pressures.

2) Perform a poor man's wheel alignment comparison. On a stock Delorean,
the only wheel alignment adjustments possible (for both front and rear) are
toe-in adjustment. And since the toe-in for the front and rear is the same
(rear tires are aprox. 3" larger in outer diameter, so 3mm toe-in over a 1½"
longer radius is not significant in this situation) then do the following:
Try to position the steering wheel in such a manner that the front wheels
are pointing straight ahead. Have a friend (or a fish hook) hold one end of
a piece of string against the back of the rear wheel. You hold the other
end and squat down by the front of the front wheel. Pull the string tight
making sure that it is parallel to (and not bending around or leaning away
from the front of) the rear tire. This establishes a line which should be
parallel with the front wheel assuming that your tire's side walls are true.
Use a ruler to measure the distance from both the front and rear of the
front tire (or rim) to the string. In a perfect world these distances
should be equal, but write them down. Then do the same procedure for the
other side of the car and do some math. If your measurements for the other
side are different but opposite to the first side, then your front wheels
are accordingly not pointed straight ahead but otherwise aligned with the
rear wheels. On each side, subtract the rear measurement from the front and
then total the results from both sides. You should get zero. Keep in mind
that if the rear wheels had a toe-in adjustment of zero instead of 3mm, then
a 3mm toe-in for the front wheel would give a 6mm difference from front to
rear as toe-in is measured as a radius.

For example: On my car as it sits in my garage at this moment I get the
following measurements:

For driver's side:
28mm inset for front of left front rim
33mm inset for rear of left front rim
subtract rear from front and I get
-5mm

The negative number means that the front of the tire is steering left.

For passenger's side:
43mm inset for front of right rim
36mm inset for rear of right rim
subtract rear from front and I get
+7mm

This result is positive on the passenger side because the front of the tire
is also steering to the left, but the measurements were taken from the other
side of the wheel.

Add the differences (-5mm) + (+7mm) = 2mm

This 2mm is a diameter measurement since I found it by measuring from the
front AND rear of the rim rather than from the front and center of the rim.
To turn it into a true toe-in measurement, divide by 2.

2mm / 2 = 1mm

So my front end has a total of 1mm more toe-in than the rear wheels. This
is 0.5mm more toe-in per wheel than the rear wheels. I would get a better
measurement if I took them from the tire tread instead of the rim, but
measuring from the rim is easier in this case. Assuming that my rear wheels
are correctly aligned when it left the factory and it wasn't messed up
since, my front end is slightly out of alignment. But since I did this
alignment myself based on how it 'looked' without taking any measurements at
all and going by if the car pulled too far one direction or the other, I
think I did a good job. Before I started, the front of the right wheel was
visibly sticking out about 1/2 inch farther than the left and both of my
front tires were already balled from such a poor alignment. I didn't notice
this when I bought the car, and before I drove it home the tires looked
fine. By the time I got the car home driving a few hundred miles, the
damage was already done. When I finally get my new aftermarket rims on the
car with a pair of new lower control arms, then I will take my alignment
more seriously. Apparently my alignment got so far off from a previous
owner having the car towed by the lower control arms. I can see where the
guy put his hooks on them and bent them!

Walt Tampa, FL

-----Original Message-----
From: Chris C <petleech@xxxx>


>we notice that in a parking lot at full lock,
>the tires seem to scuff, and looking at the tires the tread is rough,
>confirming this. Is this an anomaly of the design and normal for
>these cars or should I conclude that the alignment was incorrectly
>done?