The tire wear on Helga was getting bad. I didn't want to spend money on
tires without at least improving the chassis 'cause I don't like to
throw money away...
But Helga is a rusty, old beater. I bought it as a parts car - mainly
for the engine. I've now been driving it for 8 months...
So I decided I needed to at least _improve_ the alignment, even if I
couldn't make it "right".
Oh, and I did it in the garage, not under a shade tree. Do I need to
change the subject? *smile*
I have a caster/camber measurement tool. I used it to set both the
caster and the camber on both wheels. Any adjustments to caster or
camber will alter the toe in!
Once I had both the caster and the camber where I wanted it, I started
to check the toe-in. Well, the way I used to do it worked, but it was
hard to get the steering wheel straight and it took a lot of effort. I
figured I could improve the process.
I decided to try a Jim Cathey approch. (This is a complement, Jim. You
seem to have a talent for achieving high-tech results with common tools
and materials.)
First, I built a spreader bar. The manual says that 20 - 24 lbs of
force needs to be applied outward to the leading edge of the wheels.
Here's how I made my speader bar. I took a threaded rod, a couple of
nuts, a short piece of 1.5-inch angle iron, and a 2x2x6ft to build it. I
took the angle iron, marked it for 2 pieces each 1.5 inches long, but I
did not cut it yet because I wanted to drill the holes while it was big
and easy to hold on to. Each of the 2 pieces are identical. On one side
of the angle I drilled a hole big enough for easy clearance for the
threaded rod. On the other angle, I drill two small holes for dry wall
screws to attach the angle iron to the 2x2. Once finish, one of the
angle iron pieces was attached to one end of the 2x2. This one is for
guidance. I put the threaded rod through the big hole, positioned the
second angle iron so there would be a reasonable compromise between
far-apart-for-better-guidance and
close-together-for-long-adjustment-travel. One nut is on the (inside)
end to keep the rod from falling out and the other one presses against
the second angle iron pieces to apply outward force. (It would be better
if I had a long spring between the nut and the angle iron - but I didn't
have one on hand) To determine how long the 2x2 needed to be, I held
the whole assembly under the car and said "About here." I cut off the
extra wood and then use a 3-inch piece to act as a foot on the outer end
of the threaded rod. To do this, I simply drilled a hole that's just a
bit smaller than the rod and threaded the wood block onto the end of the
rod.
To use the spreader, I put the wood-only end of the 2x2 against the
inside of a front tire and the other end (2x2 block on the end of the
threaded rod) on the other tire. That puts the 2x2 itself practically
touching the oil pan. I turned the nut until I figured there was
probably about 24 lbs force on the tire. Here's where the spring would
help. Before putting it under the car, I could use a 25lb weight and
note how far the spring compressed. Then with the rig under the car I
could turn the nut until the spring showed the same deflection and it
would be much more accurate than my guess!
Now I needed a way to see the angle of the front wheels. I happen to
have a level with a laser pointer in it. Straight edge, laser point - I
had an inspiration. First try - I pressed the level against the outer
edge of the rim. No good. The level was too long and ran into the tire
itself when I positioned it so it would not run into the center cap.
That meant I needed spacers that could be attached to the bottom edge of
the level. I found two precision spacers - commonly called 3 inch pieces
of 1/2inch EMT conduit. I attached these to the level with gaffers tape
'cause I have some on hand. (gaffers tape is a lot like duct tape but it
doesn't leave goo behind when it's removed) I positioned the tape so the
conduit - er, spacer - would be bare where it rested against the rim.
The spacers were also tall enough that I could use the "ledge" just in
from the outer edge of the rim. This "ledge" should be more accurate
because it is much less prone to curb damage - but it also requires more
precise positioning.
All right. I could now accurately project the angle of the front wheel
toward the back wheel. But how to spot if the angle is correct? I used a
couple business cards. (don't tell my boss... *grin*)
I have a spreadsheet to determine where on the card the laser targets
needed to be. If any of you want it, let me know and I'll send it off
list.
On my W123, the distance from the front wheel center hub to the leading
edge of the back wheel (where the business card turned laser target was
mounted) is 2580 mm. Approximately.
>From the alignment manual, I got the toe-in angle to be 25 minutes of a
degree, with a tolerance of plus or minus 10 minutes.
Using basic trig, I computed the "desired distance" - that is, how much
out from straight back it needed to be. ( The math is Tangent of toe-in
angle in degrees x length ) Since I did this in a spreadsheet, it was
easy to also figure what that distance would be at the tolerance limits.
Then, I needed to account for the fact that the laser dot is not against
the levels straigh edge. On mine, with the spacers installed, if I set
the level on a table, the laser would exit 41mm above the table top. I
added this to the numbers from the middle section. I used these numbers
to mark a target box on the back of my business card. The idea is that
the card will be attached to the wheel with tape (probably gaffers tape)
so that one edge of the card is touching the rim ledge and the rest of
the card is sticking out like a flag.
The data, in mm:
desired distance 18.76
minimum 11.26
maximum 26.27
laser offset 41
desired distance - with offset 59.76
minimum - with offset 52.26
maximum - with offset 67.27
Enough time spend building tools - I was ready to _use_ them!
I set the steering wheel straight ahead. I didn't have a bolt the right
size to lock the steering gearbox.
Note: if you don't lock the steering - either with the gear box bolt or
column lock - it will probably move and mess you up! I though I was done
at one point, but the steering wheel had moved, so I had to start
again... You've been warned!
I used the column lock to keep the wheel close to center, and then
checked it often, and wiggled it as needed to keep it straight ahead.
I attached the targets cards to the back wheels, installed the spreader,
set the level against the front wheel, observed the location of the
spot, and adjusted the tie rod ends. (The tie rod ends were easy to
adjust because I had removed them from the car the day before to free
them from the strangle-hold of rust. I was generous with the grease as I
put them back together.)
Left side, right side, check steering wheel, left, right, left right,
steering wheel, right, left, etc. until I was happy with the position of
the laser dot and the position of the steering wheel.
Since this car isn't worth spending money for new parts, I also took a
few short cuts doing the alignment. (guess at the 24 lbs spreader force,
no steering gearbox lock, stoping at "close enough", etc.) However, this
method seems to be fairly accurate. I'm eager to try it on one of my
good cars - but not so eager that I won't wait until one of them needs
it...
The final result? I can't say if the tire wear is better - but the
driving is _much_ better. Even with all the loose and worn parts.
And it may not be good enough to truly be called a "Jim Cathey", it's
close enough I feel like strut'n'!
