[Shotimes] (1) Detailed On -The- Car Spin Balancing (Extremely Long)(Part 1)

[George Fourchy]

This is the first of three posts which contain my detailed on-the-car spin balancing
instructions.  Take special care to notice the places where you can be
injured....the car can fall off the jack, the emergency brake might auto-release
which would allow the car to try to roll with the other drive wheel being on the
ground, or a weight or piece of gravel can fly off the wheel or tire, causing great
harm to an eye or other body part.

Enjoy, and all questions are welcome.
........................................................................

First sent in July of 2000.  

There may be some changes to previous versions as over time I figure out better ways
to get this done.  


It is possible to injure yourself doing this, if you are not careful, so pay close
attention where I have mentioned caution, as I don't want anyone to take out 
an eye, or get run over, because a bit of caution wasn't observed.   You also 
need to make sure you are not in the path of a loose weight, as it is going moocho
mph as it flies off the rim if it isn't fastened securely, and they have sharp
corners.....goodbye eye!!   Goggles or some sort of eye protection is a good idea.

Rotating assemblies as heavy as our tires and wheels can be out of balance in 
two ways, Dynamic balance, and Static balance.  Static balance is the simpler to 
fix, and simply means that there is a bit more weight in one sector of the tire
tread than anywhere else, and must be compensated for on the opposite rim.  This
type of imbalance can be corrected with a bubble balancer.  Anything more than a
half ounce or so should be split, half on the inside, and half on the outside.  This
splitting procedure prevents the occurrence of Dynamic imbalance, where one sidewall
of the tire/wheel is heavier than the other, (inner vs. outer) which can 
cause high speed wobble, in and out, of the tire.   This type of imbalance usually
is only noticable at speeds higher than 60 mph or so, due to the stiffness of the
tire's sidewalls.   Dynamic balance is only discernable by spinning the tire.  A
tire can
be statically correct, but grossly out of balance dynamically.  With the advent of
steel belts, dynamic balance has become more of a problem because of automated mass
production of tires and inability of human operators to insure each belt is laid on
the carcass exactly in the center, or overlapped exactly the same amount everywhere
around the circumference of the tire.  As technology has advanced from the old days
of bias plied clunker tires, the complexity of tire construction today has kept the
balance problem from completely going away, although it is less likely to be a
significant one, except to SHO owners!

OK....to the meat of the situation.

Materials required...: Outside, flat concrete, floor jack, 2x4 or 4x4 blocks, piece
of carpet or other soft material to kneel/sit on while addressing the tire, brake or
carb cleaner, rags, weights, wheel weight pliers if you use clip on weights, a short
handled sledge hammer to apply them, and most importantly, one or more SHOs with
possibly out of balance tires, and a soda.  The wheel weight pliers have a hammer
face to apply the weights, but I ALWAYS slam my fingers with it because I must hit
them so hard, because it is small and has no inerta.  A short handled 3 or 4 pound
hammer is much better...you can control it easier by going slower, missing your
fingers, and not damaging the wheel or weights.  A nice addition would be 
a tire crayon, which you can mark the tire while it spins out of balance if you have
another person that can operate the car while you sit by the tire.   This will save
a LOT of time by finding the heavy spot much quicker than trial and error, which is
the only choice you have if you are alone.   You can get the tire crayon at a mass
production type auto store, like Grand Auto or Pep Boys, that have rows and rows 
of car stuff.  NAPA or Kragen or Chief might not have them, due to lower inventory. 
A tire shop may not have an extra one to give to you.  A regular child's crayon
usually doesn't work as it is not dense enough to make a visible mark on a black
tire.  You will also want a hammer and cold chisel, to mark the stud nearest in line
with the valve stem.  After you do all this work, your wheels are 'keyed' to the
hubs, since you have balanced the hubs too, so you want to put the wheels on the
hubs the same way every time you take them off.  Marking the stud end with an 'X'
allows you to know which one is the 'stem stud'.

CAUTION.....

If you have a limited slip differential, chances are you will not be able to do this
operation on the fronts unless you jack up the entire front end and remove the other
tire.  Ford rear wheel drive differentials with limited slip can be balanced one
wheel off the ground at the time (at least mine can) but I don't know about the
Quaifes....I'd REALLY tread lightly at first.  If you do need to take the other
wheel off, leave the rotor on, and snug down all 5 lug nuts.  You will be spinning
that side as well, and it needs to be as balanced as you can get it.

CAUTION.....

If you have a car with an automatically released emergency brake, you must exercise
additional caution, and insure that the car is blocked securely, as it could roll
when you are not prepared and cause injury.  

To balance front wheels mounted on the car using the engine to spin them......:

Apply the emergency brake.  In addition, block the rear wheels, both of them, with
wood blocks high enough that it would be extremely difficult for the car to climb
over them.  If it should fall while spinning, the emergency brake ain't gonna stop
it, buddy!!!  Jack up the corner desired using the jack pad just behind the rear of
the front fender.  On Gen 1's at least, there is a flat area just right for a floor
jack.  Use a wood spacer to avoid the jack denting the underbody, and to spread the
load of the jack over a wider area.  About 1 inch off the ground is sufficient.  A
jackstand is heoretically required to insure the jack is not the sole support for
the car.  If it falls off the jack while spinning, obviously it is instantly
underway out of control, although you are in the driver's seat, but not prepared to
be driving and steering, so damage could occur.  If you need to take it higher to
get the jackstand underneath, that's fine.  I suggest putting it directly under the
rear bolt for the subframe on that side...that's a nice strong location that holds
the jackstand in place.  

Remember that the tire will spin twice as fast as the speedometer indicates, because
the differential is multiplying the engine speed times 2.  If you have a MTX, start
in 4th gear and spin the tire up gently, so the car doesn't try to leap off the jack
via the other front wheel.  It will have a small amount of traction to the ground at
first.  Spin the tire up to 30 or 40 mph on the speedo...that's 60 to 80 actual
wheel mph.  If you have an ATX, start very slowly, and let it shift up to 4th gear,
or third if you want to lock out the O/D.  The car will rock as it shifts, so don't
take the speed way up until it is finished, or it might fall off the jack.  Change
speeds slowly while searching for imbalanced speeds, to give it a chance to tell you
if there are any particular speeds where the vibration is stronger.  You need to
balance it at these lower cruising speeds before you go way up to over 100,
otherwise you will spend too much time at the high speed, when it wouldn't be
necessary if you got it close at a slow speed first.  

Now the subjective part begins.....how much, and where?  Experience has taught me
how much weight to start with, and I always start at the valve stem...that part is
easy.  If there is just the slightest shimmy in the wheel, it usually will be taken
care of with 1/2 ounce or less.  If there is a noticable shimmy in the wheel, and
the seat and/or door, which should be open, shakes just a little bit, then start
with one ounce.  You can get a good indication of exact balance from the driver's
seat by using the door as a guide.  If it is open, the outer end is away from the
center of shake (the centerline of the car), and will move the most, even with a
small amount of imbalance.  It is the equivalent of the balance technician holding
his finger out from the fender back in the old days when everyone used Hunter
equipment.  So, if the door edge bounces up and down noticably, start with an ounce
and a half, split between the front and back of the rim.  If it is any worse than
that, you have a big job ahead, and you have to get the static balance problem taken
care of first, then fix any dynamic problems later.  You cannot go as fast at first
when there is this much imbalance, as it will be impossible to tell how much to use.
 Only use the minimum speed that gives you a definite steady shake, and fix that,
then work up in speed from there.

End of Part 1....