|
Thanks to Bryan for this tech update to the info below! |
Hi Michael, I read your diy alignment article and think it's a great guide. I do have one idea that might make the job a little easier. Laser levels are widely available nowdays for stuff like hanging pictures and mounting shelves. These can be had for about US$30 or even less on sale. Instead of the plastic tube water level, the laser level can do the same thing with one person. Just project the horizontal laser line and use the ruler as before to check the difference between two spots on the ground. Also, I think the laser can replace the fishing line as well. Except it'll still need to be aligned parallel to the centerline for proper toe measurement. Regards, Bryan |
I received a lot of interest from fellow British Car owners when I mentioned
doing my own alignemnts with homemade tools, so I took a couple of days
and put
together this explanation of how I do it, and what tools I use. If
everyone understands this, then I'll give horror stories of aligning a
Spec Racer (Sports Renault) or
Formula Car.
The Do-it-yourself Alignment
When I first said it took $20 in tools I made a quick guess off the
top of my head, but here is what you need and a guess of the cost.
15' of clear vinyl tubing about 5/16" diameter $3.00
2 12" rulers - swipe from office supply at work :-) $0.00
10-20 pieces of fairly stiff floor tiles 12X12"
left over from the last time you replaced kitchen floor $2.00
16" bubble level from Roses on sale $3.00
Piece of wood long enough to span one wheel from lip to lip $0.00
6" machinists ruler with 1/32" or better markings $4.00
Carpenters Plumbob on sale at Sears $2.00
Some kind of fixture for measuring Caster $????
Fishing line - about 40 feet $1.00
4 jack stands - should already have $0.00
Magnetic base carpenters Protractor
$4.00
I didn't miss the $20 guess by much. These are the minimum you need.
There are some other ones that may help. A Lucas or similiar digital
protractor is a great tool. If I were to spend much money on any one tool
it would be one of
these. I think they are about $90, but if anything is worth the money
they are. They will just make the job much easier.
OK first make sure your tires all have proper air preassures in them.
First you will need to find a level spot. For this I use clear tape and
attach the two rulers to the
ends of the clear vinyl tubing. then you fill the tubing with water.
I usually use the tubing like a straw and draw the water up into the tubing.
You need two people to
use this as a water level. The idea is the water will be level at both
ends of the tubing when the tubing is held upright. You can then stand
one ruler where one wheel
will be and the other ruler where another tire will be and if the water
is at the same level on the two rulers then those two spots are level.
You can then adjust the
"pads" where the tires will be by making stacks of tile. Each tile
is usually about 1/8" thick so it takes a few tiles to bring up all the
low spots up to the highest spot. In
your garage you may want to mark these spots and take notes of how
many tiles each place needs.
Next you need to find out how true your rims are. I jack up each wheel
and sit the jack stand next to the wheel and sit the machinists ruler on
the jack stand with it
extending just to the rim. Then rotate the wheel one turn and see how
much runout you have. On most alloy wheels they will have less than 1/32"
which is just fine.
On factory steel wheels some wheels may have as much as 1/4" which
will ruin your measurements. Find 2 places on your wheel that are 180 degrees
apart and have
the same runout measurement. On almost all wheels there is 2 places
you can use to measure on, though you may have to search for the spot.
I then mark the spots
with a pencil or magic marker.
Alternatively you can either check the tire for trueness and use the
tire for measuring, or you can make chalk marks around the tire on the
edge of the tread and use a
nail or something sharp to make a scribe line around the tread surface
near the outside and make all measurements to the scribe line. To do this
jack the wheel up so
it can spin freely and drive a nail through a piece of wood. Lay the
piece of wood on the floor so that the point of the nail just touches the
tire tread. When the tire is
spun around you will have a true line scratched around the tire. I
have found this method of measuring to not be as convenient as using the
rim, so use the rim if it is
possible. If your rims are true you can assume them to always be true
unless you run over a curb or something. This means you don't have to check
them every time
you align your car.
Next I like to find the centerline of my car. I do this by using the
plumbob draped over my inner suspension mounting points and measuring half
way between them
and finding the center-line. This of course does not work on all cars.
Some cars don't have suspensions that are mirrors of each other, but most
do. I will drop the
plumbob to the floor and make pencil marks on the floor. Then I will
measure on the floor. I found a friends Corvette to have a perfectly straight
frame, but to body
of the car to be about 1/2" crooked on the frame. You can't go by the
center of the bumper or anything like this. Once you have found the C/L
carry the mark up to
the chassis or body. I made a fine white line on the front of the frame
and the rear of the body under the bumper on my Mustang GT with a paint
marker. Now I
measure from the centerline for all measurements.
Now put the car on the leveled pads. It is best to have rolled the car
back and forth a few times to get the suspension settled. Also I should
mention that I have made
pads out of one square foot cuts of 2"X12" boards with small angled
ramps on the fronts of them. This lifts the car up 2" making suspension
parts easier to get to. I
then level with the tiles on top of these pads. It works fairly well
making the suspension parts easier to reach.
First I like to check the castor. I seldom make any chages to this adjustment.
It is also not that critical to have exaclty to some spec, but it is important
to have each
side even. For this I use the Magnetic base protractor. It is accurate
to .5 degrees which I think is adequate for castor measurement. On a Strut
car I simply place it
on the strut and measure the angle of the strut. This may be off slightly
from the spec books, bit the error is correct from side to side and it
is fairly close. If you have
a car with upper ball joints first check your spindles for a machined
flat spot that is parallel with the ball joint axis. If this exists then
you can simply place the
protractor on this surface and measure castor. Many cars have this
machined surface for various reasons. If it doesn't then all is not lost.
You will need to make some
sort of fixture that will "reach in" to the ball joints. You will need
a vertical flat surface with two "arms" extending to the ball joints. A
2X4 with 2 long bolts through it
may work. You want a vertical surface parallel with the ball joint
axis. You can measure this with the surface with the protractor again.
You can also measure this in a
similiar method to how I will measure camber later for more accuracy.
This is of course only necessary if your car has some way to adjust castor,
which many do not.
Next I like to measure camber. This is the most important measurement
in autocrossing in most people's opinion. I use the short level attached
to a piece of wood
and the machinists ruler for this. I cut the piece of wood so that
it will span across from the top wheel lip to the bottom one. I then attach
the level to the piece of
wood. I use the wood for a couple of reasons. First I can shim between
the wood and the level to correct for errors that may occur in the cheap
level. I have found
most of them to have some small inaccuracies in them. Also you may
need to notch the wood to clear the wheel in the center for the hub or
something. I also have
different lengths of wood for the different wheel diameters I work
with. To correct for errors I use the plumbob. It will hang vertical. I
then shim between the wood
and the level until it is indicating level when the board is completely
vertical.
Now you must have the two places on your wheel you found to be true
to each other, vertical (straight up and down). If your entire wheel is
true then it is a great
benefit at this point. Take the piece of wood and the level and span
across your rim with the level vertical. Now use the bubble and pull out
from the top of the wheel
until you are holding the level vertical. Now measure from the piece
of wood to the top of your rim. It will be a distance of about 1/4" or
so (assuming you have
negative camber. Take this measurement with the machinists ruler. Be
as accurate as you can. Then you need to take that distance and divide
it by the span distance
of the piece of wood. For a 15" wheel you can just use 15" and a 16"
wheel 16" etc. Then look up this number in your old Trig table in your
high school trig book.
You will need to find the arc tangent of the number you have. The degrees
of this will be the camber angle.
I have a 10 line basic program that will print a chart for converting
these angles I have included in the end of this. I have also included a
chart that will convert this
measurement without dividing and looking up the measurement. I now
prefer to keep my measurements in inches of gap at the top of the wheel
rather than converting
them to degrees. I keep my log books in this measurement rather than
degrees for each car. It only causes a problem if I change the rim diameters
of any one car I
am working with.
For toe in measurement I need to reference the centerline of the car.
First you need to get the measuring points on your wheels at 9 and 3 o'clock.
This is where it is
helpful to have true wheels, then you don't have to move the car. You
will need the jack stands and fishing line for this, plus the machinists
ruler. you want to set up
the fishing line outside the sides of the car an equal distance from
the centerline of the car. I tie the fishing line to the jackstands so
that the line when streched will be
about equal height to the center of the wheel hubs. This does not have
to be exact, but close to the wheel hub center. measure out from the centerline
to about 3"
outside the wheels. The setup will look like this when viewed from
above:
jack stands --> X--------------------------------------------X
---======----------------------======----
| |
| |
| |
Car ---> | |
| |
| Wheels |
| V |
---======----------------------======----
X---------------------------------------------X
/^
Fishing line/
It is important to get the fishing line parallel to the centerline of
the car. You can't measure to the rocker pannel or the wheel hubs or anything
initially because they
may or maynot be parallel to the centerline. So the first time measure
from the centerline that you found before. Now it is good to then measure
from the bottom
corners of the door or the rocker pannel or something and record the
measurement in your log book. It will make the setup much faster of you
want to change your
toe quickly at an event. It should be noted that a prefectly level
pad is not necessary for toe setting. It is good to get the car on a fairly
level spot but exactly level is
not important.
Then to measure the toe measure at the front edge of the rim and the
rear edge of the rim and subtract the difference. That will give you the
toe measurement.
Obviously for toe in the measurement at the rear of the wheel (from
the fishing line to the edge of the rim) will be less than the measurement
at the front of the wheel.
The reverse is true for toe out and the two measurements will be equal
for zero toe. The measurements you will be working with will actually be
less than what is
usually referenced in spec books because the diameter you are working
with is the rim diameter, the measurement most cars use is taken at the
tread surface, so you
may need to make some conversions depending on the specs for your car.
Find out how the specs you are working with are measured. Some cars give
angles of toe
in degrees, some are inches of toe on each side, and some are total
toe added together between the sides. Make sure you are working with apples
and apples not
apples and oranges.
Each time you make a toe adjustment recheck your steering wheel if you
have not locked it. When you adjust one side the steering wheel usually
moves and must be
re-centered before you take new measurements. Locking the wheel some
way will make the job easier.
As you are making changes take a note of what one shim here and one
turn of the tie rod there changes and how much. You will notice that a
camber change
changes the toe drastically, but as toe change does very little to
the camber, etc. When you get used to these things then changing your toe
settings as you are
changing your tires at an event is a rather simple matter and changing
it back to the original toe setting when it is time to drive home is easy
if you have made a few
marks. On my Mustang GT I have marked the strut tops as to what change
is what camber and I have 2 makrs on each tie rod end. I used to change
the camber and
toe at each event, but I now leave the negative camber in and dial
in a little extra toe-out before an event and can feel confident about
resetting it correctly before I
drive home. I check it occasionally just to make sure the frame hasn't
changed.
It takes a couple of hours the first time, but once you have done this
a couple of times you can do a complete check of your alingnment in a couple
of minutes in your
garage and at an event you can locate a flat spot and check a car completely
before you run. It is really fairly easy to do once you get used to it.
Here is the chart I promised. It goes up to 6 degrees of camber. The
way you use it is to look up the gap between the level and the rim at the
top on the diameter rim
you are using and look on the left column and find the number of degrees.
I have included the tangent of the angle just for good measure.
deg tan 17 16 15 14 13
-----------------------------------------------------------------------
0.1 | .0017 0.0297 0.0279 0.0262 0.0244 0.0227
0.2 | .0035 0.0593 0.0559 0.0524 0.0489 0.0454
0.3 | .0052 0.0890 0.0838 0.0785 0.0733 0.0681
0.4 | .0070 0.1187 0.1117 0.1047 0.0977 0.0908
0.5 | .0087 0.1484 0.1396 0.1309 0.1222 0.1134
0.6 | .0105 0.1780 0.1676 0.1571 0.1466 0.1361
0.7 | .0122 0.2077 0.1955 0.1833 0.1711 0.1588
0.8 | .0140 0.2374 0.2234 0.2095 0.1955 0.1815
0.9 | .0157 0.2671 0.2513 0.2356 0.2199 0.2042
1.0 | .0175 0.2967 0.2793 0.2618 0.2444 0.2269
1.1 | .0192 0.3264 0.3072 0.2880 0.2688 0.2496
1.2 | .0209 0.3561 0.3352 0.3142 0.2933 0.2723
1.3 | .0227 0.3858 0.3631 0.3404 0.3177 0.2950
1.4 | .0244 0.4155 0.3910 0.3666 0.3422 0.3177
1.5 | .0262 0.4452 0.4190 0.3928 0.3666 0.3404
1.6 | .0279 0.4749 0.4469 0.4190 0.3911 0.3631
1.7 | .0297 0.5045 0.4749 0.4452 0.4155 0.3858
1.8 | .0314 0.5342 0.5028 0.4714 0.4400 0.4085
1.9 | .0332 0.5639 0.5308 0.4976 0.4644 0.4313
2.0 | .0349 0.5937 0.5587 0.5238 0.4889 0.4540
2.1 | .0367 0.6234 0.5867 0.5500 0.5134 0.4767
2.2 | .0384 0.6531 0.6147 0.5762 0.5378 0.4994
2.3 | .0402 0.6828 0.6426 0.6025 0.5623 0.5221
2.4 | .0419 0.7125 0.6706 0.6287 0.5868 0.5449
2.5 | .0437 0.7422 0.6986 0.6549 0.6113 0.5676
2.6 | .0454 0.7720 0.7266 0.6811 0.6357 0.5903
2.7 | .0472 0.8017 0.7545 0.7074 0.6602 0.6131
2.8 | .0489 0.8314 0.7825 0.7336 0.6847 0.6358
2.9 | .0507 0.8612 0.8105 0.7599 0.7092 0.6586
3.0 | .0524 0.8909 0.8385 0.7861 0.7337 0.6813
3.1 | .0542 0.9207 0.8665 0.8124 0.7582 0.7041
3.2 | .0559 0.9504 0.8945 0.8386 0.7827 0.7268
3.3 | .0577 0.9802 0.9226 0.8649 0.8072 0.7496
3.4 | .0594 1.0100 0.9506 0.8912 0.8318 0.7723
3.5 | .0612 1.0398 0.9786 0.9174 0.8563 0.7951
3.6 | .0629 1.0695 1.0066 0.9437 0.8808 0.8179
3.7 | .0647 1.0993 1.0347 0.9700 0.9053 0.8407
3.8 | .0664 1.1291 1.0627 0.9963 0.9299 0.8635
3.9 | .0682 1.1589 1.0908 1.0226 0.9544 0.8863
4.0 | .0699 1.1888 1.1188 1.0489 0.9790 0.9090
4.1 | .0717 1.2186 1.1469 1.0752 1.0035 0.9319
4.2 | .0734 1.2484 1.1750 1.1015 1.0281 0.9547
4.3 | .0752 1.2782 1.2030 1.1279 1.0527 0.9775
4.4 | .0769 1.3081 1.2311 1.1542 1.0772 1.0003
4.5 | .0787 1.3379 1.2592 1.1805 1.1018 1.0231
4.6 | .0805 1.3678 1.2873 1.2069 1.1264 1.0460
4.7 | .0822 1.3977 1.3154 1.2332 1.1510 1.0688
4.8 | .0840 1.4275 1.3436 1.2596 1.1756 1.0916
4.9 | .0857 1.4574 1.3717 1.2860 1.2002 1.1145
5.0 | .0875 1.4873 1.3998 1.3123 1.2248 1.1374
5.1 | .0892 1.5172 1.4280 1.3387 1.2495 1.1602
5.2 | .0910 1.5471 1.4561 1.3651 1.2741 1.1831
5.3 | .0928 1.5770 1.4843 1.3915 1.2987 1.2060
5.4 | .0945 1.6070 1.5124 1.4179 1.3234 1.2289
5.5 | .0963 1.6369 1.5406 1.4443 1.3480 1.2518
5.6 | .0981 1.6669 1.5688 1.4708 1.3727 1.2747
5.7 | .0998 1.6968 1.5970 1.4972 1.3974 1.2976
5.8 | .1016 1.7268 1.6252 1.5236 1.4221 1.3205
5.9 | .1033 1.7568 1.6534 1.5501 1.4468 1.3434
6.0 | .1051 1.7868 1.6817
1.5766 1.4715 1.3664
This is a hard process to explain without hands on aids. I taught a
seminar for our sports car club on how to do this and evryone thought it
was easy after they did it a
few times. I got several phone calls the day after the seminar as everyone
went home to do it for the first time themselves, but they were all able
to align their own
cars correctly.
It is realy easy to do and it gives you a great deal of confidence in
how your car was set up. I will try to answer all questions. I'm sure I
was not as clear as I would
have hoped to be in some places.
Calvin Sanders
If you have any experiences, facts, hints comments or data that you think might be useful on the site, please
and I will post it, with an acknowledgement of your contribution (if you so wish).