Alignment for street cars

[C M Smith <cmsmith@domain.elided>]

To understand alignment for street cars one needs to remember how much 
rubber there is between the suspension arms and the bodywork.

Alignment is done "static" i with the car stationary and with only vertical 
weight loads. Loading secs for the alignment are now pretty well 
standardized. They used to involve weighting the car but since that's a 
nuisance most if not all modern cars are aligned with only normal unladen 
curb (or kerb for those who know how to spell) weight, no driver. Obviously 
in NA most cars should be aligned with the weight of only the driver on 
board,in the driver's seat, but they aren't.

Actual alignment is dynamic. When the car is being driven all the 
suspension bushings change shape allowing the suspension alignment to be 
"out of spec". It is this movement that the static alignment has to allow 
for. Most fwd cars are set up with zero toe or toe out. This is in 
anticipation of the drive wheels pulling forward and moving into a toe in 
position. Unfortunately, under hard braking the drive wheels move backwards 
and sometimes return to toe out. The 164 is very sensitive to this effect. 
I follow recommendations of others on this board and ask the alignment guys 
to forget about tolerances and set front to zero. This seems to prevent the 
front wheels from toeing out under heavy braking, which is good, but also 
slightly dulls the steering feel and turn in response, which is not good. 
However, the real kicker is that the front tires wear like gum eraser with 
toe out, due to the negative camber setting, which is not adjustable 
officially and darned difficult to adjust unofficially. I prefer to just 
buy tires rather than fiddle with going outside the fixed factory camber. 
Besides 2.4 degrees negative really sticks the front end down in hard 
cornering, which wears out tires anyway, regardless of camber!

Bottom line, fiddling with alignment is critical only for racing machines 
with hard suspension connections, or modified performance cars with non 
stock bushings (harder and say urethane or some such) and making slight 
changes can work wonders for handling. Street cars are so sloppy anyway 
that you really need to just experiment to find the best setting for your 
car at the state it currently is in(worn bushings can make even the best 
alignment a very iffy proposition for example) and stick with it. 
Invariably this will be within the tolerances specified by the factory and 
the trick is to find an alignment shop that will actually listen to you and 
do what you say. I find a prompt return visit after a botched alignment 
with a specific complaint, which they then verify on their machine at their 
expense, leads most good shops to say to themselves "oh it's THIS guy 
again, let's do it right first time shall we?" I have the same experience 
with wheel balance. After I casually mentioned that the tire was fine up to 
110 km/hr but the imbalance at 190 km/hr was really intolerable I have 
always got a first rate balance job every time (the balance machines, like 
alignment machines, are automatic and basically foolproof, it's just a lazy 
operator that won't do the work necessary to get the EXACT amount of lead 
in the EXACTLY correct location for a perfect balance, or alignment as the 
case may be.)

For my 150,000 km 164 with original bushings and Pirelli P6000 (round 
shouldered) tires I prefer zero front toe, and half the allowable spec for 
rear toe in. The front camber is, and always has been, just beyond the 
maximum allowable negative camber and the rear camber varies so much with 
loading that it's probably just as well it is non adjustable. Best i can 
figure rear camber goes from a tiny bit positive or zero to nearly 2 
degrees negative when heavily loaded or cornering hard.

BTW, I have yet to drive a 164 that doesn't drift slightly left or right 
when driving straight down an uncambered road and the steering wheel is 
always off one side or the other. I prefer a drift to the right, away from 
oncoming traffic!

Cheers


Michael Smith
White 1991 164L
Original owner
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