Shade tree toe in setting (kinda long)

[Eric Rayl <ericrayl@xxxxxxx>]

>And what's the magic procedure with string and wood.  I know how to fix my
>throttle with the above ingredients, but not set alignment.
>
>Thanks as usual.
>
>- --David Boyd
The cave man toe in setting method I used follows.  I did this when in the
midst of front end component replacement mayhem and wanted to drive the car
for a while.

Materials:  stick of 2"x2" reasonably straight, 5' to 8' long, 2-1 quart
paint cans, felt pen, calculator, flat and smooth surface for the car.

1.  Get your total toe in spec. and take the tangent of the angle.  No
trig. on your calculator?, convert the angle to radians and that is the
same (essentially) as the tangent of the angle for small angles.  

Example: e28 spec is 18' of total toe in, or 18/60 of a degree, divide this
number by 360 degrees in a circle, and multiply by 2 and pi (3.14159) to
yeild .0052   This is a dimensionless number but think of it as inches of
toe in per inch of length between your 2 measuring points (near ends of
board).  Another way of looking at it is for every 100" traveled, the front
tires are trying to get 1/2" closer together.

2.  Mark the center of the board, put 2 more marks across the board equal
distances from the center, near the ends some even number of inches apart,
say 80" for my example, and put a F on the end of the board that will be in
front of the car.

3.  Slap board against tire perched on the paint cans, with the center mark
at the fore-aft center of the tire, paint cans are just to get the boards
above the bulge in the tire.  Slide the paint cans around under the board
until there are centered front to back under the marks near the ends of the
board, and flush with the inside (car side) of the board.  Mark the inside
edge of the paint can on the floor.

4.  Same thing other side of car, keep board in the exact same spacial
orientation both sides of car, so if it's a bit warped it won't effect the
measurements.

5.  Measure between the front pair of marks, and the back pair of marks,
subtract front measurement from back.

Example conclusion, let's say the front marks measured 3/8" closer together
than the back, for marks 80" apart as I mentioned above, then toe in would
be .375"/80" or .0047 inches/inch.  Nominal spec is .0052 and tolerance is
.0014 (the .0014 is converted as above from the e28 tolerance of +/-5')so
I'm in.

Caveats:  Tires should be pointed darn near straight ahead when taking
measurements.  If you jack up the car to make a change, let it down then
move it a few tire revolutions backward and forward before measuring again.
 BMW apparently specifies weight in the front and back seats before
setting, do not expect perfection with this method.

Final hint, on an e28 you will change your toe in about .013 inches/inch
per tie rod revolution.  This is a crude number someone elso can fine tune.

Wait a couple digest days before trying this, 'cause if I dorked something
up the world will surely know shortly.

Submitted with a big Happy New Year
Eric Rayl
'87 535is

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