Well, you jdo have 4-wheel independent suspension, so, yes it could need a 4
I can't imagine that there is no Caster or Camber adjustments. Given the
construction of the suspension system, you can be sure there are adjustments
for all three planes of each corner.
There is an imaginary line that runs through the center of the upper and
lower ball joints and the spindle that the tire spins around. These three
points make a plane that is called caster angle. I am not sure what the rear
caster angle should be, but I assume it should be zero, that is it should be
prefectly perpendicular to the ground. The caster angle of the front tires
should be leaning towards the rear of the car.
Camber angle is the angle at which the tires hit the road. In a solid axle
kind of car, this angle is zero, but in an independent suspension, the
engineers can design this angle specifically for the particular car. The
front tires typically have a zero angle, or near zero, while the rear tires
can have a more pronounced angle. Greater camber angles will provide
stability in cornering, but will have increased tire wear on the inside
edges. For a private passenger car, I would suggest that the best angle is
zero for all four tires, but I am almost certain that some cars will have a
definite camber angle that can be seen if one bothered to look.
This is an adjustment that is generally only found on the front tires. It
defines how parallel the tire on the left is with the tire on the right. The
rear tires could have a toe in/out angle, but it will be zero. The rear
tires should always be parallel, but the way the independent suspension is
built, there could be an adjustable setting that can be knocked out of
adjustment, perhaps by striking a curb or pot hole. I can't address the fact
that your BMW has or does not have an adjustable rear toe in/out, but there
is no particular reason that it couldn't have one. It wouldn't be very
useful, but it could still be there. Perhaps toe in/out on the rear axle has
a different name that has escaped me at the moment.
To recap, Caster is the angle forward or backward that the tires are, Camber
is the angle that the tires strike the ground, and Toe in/out is how
parallel the right and left side tires are to each other. A 4-wheel
alignment will also align the front and rear tires so they are on the same
track. You should have all three adjustments on the front tires, and have at
least caster and camber on the rear.
No, actually what he was told is correct. There is no means of
adjusting either caster or camber designed into these cars. That does
not mean that it can't be done. First, you put the car on an alignment
rack to see if it is out of tolerance. Then, only if needed, you would
have to add various shims or offset bushings or other doo-dads to allow
some adjustability. But in the stock form, there are no eccentrics or
other adjustments provided.
It's actually kind of nice that you can slap in all new suspension
components and the only alignment that really needs to be done is the
Wow! That's amazing that there are no adjustments for caster or camber in an
independent suspension. I guess I need to spend more time under my car so
I'd know this sort of stuff. I would have thunk that the adjustments would
be done by way of eccentrics as opposed to shims, but if you say there are
no adjustments, then I am not going to argue the point.
I did a pretty good job of explaining the adjustments thought, didn't I?
That's only for a check. And it may not show the reason for pulling to one
If you're certain the tyres are all worn the same and at the correct
pressures - don't laugh - then it's likely to be worn or damaged bushes or
other components which can only be replaced - not adjusted.
Have you had the car since the steering was ok and this fault has
developed - or have you just bought it?
*A cubicle is just a padded cell without a door.
Dave Plowman firstname.lastname@example.org London SW
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