Honda Car Forum

These are my current beliefs on this subject.
Please correct me if I'm wrong or if you have a good reference.

I have a Honda CRX HF 89 and 91 but I suppose this has other relevance.
I have service manuals from Helms, there might be more detailed manuals.

The only front end alignment that is easy it toe-in.
All the rest of the alignment (camber and caster)
is not supposed to be adjusted (but relies on intact bushings)
and can only be changed by bending heavy frame and suspension items,
something you can't do at home.

The inner lower control arm bushing has its axis a bolt in line front to back.
The bushing is two steel cylinders with rubber between.
The inner steel cylinder is longer than the outer.
The bolt pinches a frame bracket into contact with the inner cylinder.
The outer cylinder is press-fit into the control arm.
The rubber is glued between the cylinders and also the cylinders have grooves
that hold the rubber.

One way it fails is for the rubber to break loose from the inner cylinder.
If the bushing is not broken, there is equal distance front and back
between the outer cylinder and the frame bracket, say quarter inch.
When it is broken, the control arm rides back and there is no distance
between it and the rearward frame bracket.
Hard to explain, a picture would be better.

Why does the control arm ride back?
When the bushing is broke, the control arm pivots around the radius rod.
The front wheel when driven pulls the outer end of the arm forward,
the inner end of the arm is pivoted back.

I suppose if the bushing is bad enough, when you brake and accelerate,
the inner end of the arm moves back and forth, frontward and rearward.
But I suspect the inner end of the control arm comes to live,
more or less permanently, driven back as far as the frame bracket
(so the rear end of the outer cylinder is as far rearward
as the rear end of the longer inner cylinder).
I am guessing that the wheels are pulling more often than they are braked,
and over time the inner end of the control arm moves backward
and stays there unless you brake very hard several times is a row.

On my car a quarter inch movement on the inner end of the control arm
yields only an eighth inch on the outer end.
And that is only about one degree on a horizontal circle
around the pivot point where the radius arm meets the control arm.

That is significant with respect to toe-in, specced at 2mm or 0.08 inch.
(I think that is measured as difference of distance between fronts
distance between rear of tires.)
One degree of twist from a broken bushing yields a differnce of 0.2 inch
from front to back of a 13" wheel with tire.
Which is about twice the specced toe-in.

I suppose when the bushing fails, and IF the control arm does assume
a new stable position, that a toe-in adjustment would fix the symptoms
if not the cause.

As for caster, assume the eighth inch front to back movement
of the outer end of the control arm
is at a radius of 2 feet from the upper end of the McPherson strut,
which is the pivot for change in caster
(more or less, the geometry may be more complicated than that).
That eighth inch is only about one quarter degree of caster.
Which is not significant compared to the three degrees specced.

Should have no effect on camber.

If the bushing on one side breaks and not the other,
should the steering pull to one side or the other?
I would not think so,
since the wheel now out of kilter would just push
the other wheel to a new position.
The toe-in would be wrong but the steering should not pull.
Maybe the steering wheel would be pointing wrong,
but I doubt you would notice it.

I am currently trying a large plastic washer
between the frame bracket and the control arm.
In the miserly HF driving I do,
I don't want the possibility of an alignment change
under the heavy accerlating and braking that I don't do.
I am blaming the broken bushing on previous owners
hitting the curb when pushing the already phenomenal
turning radius.
I will see how long the plastic washer lasts.

I really think by current noise problems that I have
are just caused by cheap tires getting out of round.
One set has very noticeable set of waves
on the inner side, but only on one segment around the tire.
To my mind, that is probably a manufacturing defect,
and not caused by front-end alignment.
I really don't think new bushings are justified.

One of my cars WAS pulling right, but using a laser level
I adjusted the aim of the REAR wheels, which
seems to have fixed most of the pulling.

Other posts suggest that you live with broken bushings
unless you notice tire wear or steering problems or noise.
Other posts suggest that you can buy new bushings
and press them in with a large hydraulic press (rarely done),
or buy the control arm with bushings already in (usually done.)