I haven't been in an alignment shop for over 30 years. I align all my cars with an inclinometer and tape measure. Alignment shops have wonderful equipment, but few of the techs really understand how it works and don't understand suspension geometry.

There are probably still shops that want to set camber or caster "lead" to compensate for road crown. Such advise dates from the 1920s when most roads were unpaved and highly crowned to promote rapid drainage. Modern paved roads have very little crown and don't need any "lead" in the aligment settings. Set everything as close to equal on both side as can be achieved within the accuracy of adjustments and measurements.

All my cars are set for maximum positive caster and maximum negative camber, EQUAL ON BOTH SIDES within the available adjustment range. This means that on a typical road that is cambered for drainage, they will usually drift VERY SLOWLY to the right. So if you fall asleep on a two lane road you won't drift into the oncoming lane and have a head on collision.

In the left lane(s) of an interstate, this might mean the car will drift left, but interstates typically have center barriers or wide median strips.

On my '88 190E 2.6 I was able to achieve +10.5 deg. caster and -0.75 deg. camber. These settings minimize understeer, which is greater on the front heavy 2.6 compared to the 2.3. The front weight distributions are 57/53 percent, respectively.

High positive caster promotes straight line stability and high self centering torque, but it can also cause shimmy, which is why Mercs have a front steering damper, and I can assure you that when this damper fails the front end can go into a violent shimmy, the likes of which I have never experienced in any car. High caster settings also generally require power steering because of the high self-centering torque, which would make for very high steering effort on a manual steering car. With manual steering 2-3 degrees positive caster is about the limit before effort becomes excessive.

High postive caster also yields negative camber gain on the outside front tire when you turn, and the combination of a little static negative camber and the negative camber gain compensates for body roll and keeps the outside front tire closer to vertical with the road. This is why my settings reduce understeer, but they do no cause excessive inside front tire wear.

I didn't use a spreader bar to set the toe, but merely set it about about 1/16" toe in. If the tie rods measure equal length the steering wheel should be centered when the car is going straight, but I usually have to tweak one tie rod once or twice to get the steering wheel dead centered, as even the slightlest off-center of the steering wheel when driving straight drives me nuts.

Duke