Message text written by Michael Hargreave Mawson
>Front Camber
>^^^^^^^^^^^^
>Positive camber increased from less than one degree on each wheel to
>between two and two-and-a-half degrees in the fourteen months since I
>last had the wheel alignment done. In that time, I replaced the front
>springs and shocks. Cause and effect?
<snip>
As was pointed out earlier, the camber is constantly changing as the car
moves up and down due to the unequal lengths of the upper and lower A-arms.
This is why it is recommended to set the suspension with the car loaded as
normal. Setting the camber and then changing the springs will likely cause
the car to sit at a different height and cause the camber to change.
Camber differences can cause the car to pull to one side. So will caster
differences (side to side)
>Front Caster
>^^^^^^^^^^^^
>All the front suspension bushes (and, indeed, all the front suspension
>components) were replaced within the last month, so it seems that I
>would need to shim the A-arm mount to bring the front caster in line
>with spec. However, the consensus appears to be that this is
>unnecessary. That's good. :-)
I disagree with that. If the car was re-aligned recently (before the
bushing replacement) then the adjustments were made to compensate for the
bushes sagging and deformation. Replacing the bushings will put the
geometry back to niminal and the previous alignment is now incorrect and a
realignment is recommended.
>Front Toe
>^^^^^^^^^
>Fourteen months ago, my toe was set within the specified parameters at
>+11 mins. When the car went in for alignment this year, it was -18
>mins. What causes this? Pot-holes?
Changing the suspension bushings could cause this. Or even a little
settling in the bushings. Or the car setting a little higher or lower on
the springs could cause that. 28 minutes is not much.
>Rear Camber
>^^^^^^^^^^^
>This car had a new rear spring (from Rimmer Bros.) fitted in April, 2001
>(and it doesn't have a camber compensator). In December of that year,
>the Rear Camber was recorded as -44 min (L) and -1 deg 24 min (R). I
>have done nothing at all to affect the rear suspension since then
>(except that I probably altered the ride height by changing the front
>suspension, and I removed a whole heap of junk from the boot this time),
>and it is now reading +53 min (L) and +5 min (R). HOWEVER, looking at
>the back of the car after I've been for a drive, the wheels have visible
>negative camber. From what I have been told, it sounds as though the
>car wasn't allowed to settle before the readings were taken (on either
>occasion). Is that a logical deduction? In any case, if the camber
>is going to get more negative as the spring ages, I'm going to get
>closer and closer to spec over the next few years without actually doing
>anything! This is also good. :-)
Once again, the suspension should be checked with the normal expected load
in the car. Load the driver's seat with enough weight to simulate your
weight (or sit in it yourself) and be sure the tires are not bound up by
rolling the car fore and aft before measurement.
They don't call this a swing axle for nothing. If the car is raised off of
the ground and returned to the ground the tyres will contact the ground in
a stance that is narrower than normal and the forces applied to the tyres
will cause the suspension to set higher than normal. Rolling the car will
allow the tyres to find their desired position.
>Rear Toe
>^^^^^^^^
>Opinions seem divided on this one - so I deduce that the asymmetrical 11
>min of toe-out is only borderline problematic. Is that a fair
>assessment? If I did decide that I wanted to remove a shim from the
>left, how easy is it for a ham-fisted mechanical ignoramus such as I to
>do this?
Asymetrical rear toe will cause the car to "dog track" which is to say the
car will drive down the street a bit sideways. This is most common to live
axle cars with leaf springs where the axle has shifted on the spring on one
side. I'm not familiar with this suspension but isn't the adjustment for
this done with shims inserted in the U-joint attachments to the diff?
I hope this helps.
Dave Massey
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