Alignment Numbers for Radial Tires on a '69 GS

No, the big switch to radials started in 1974 or so. Maybe after that, alignment specs changed, I'd have to look at maybe a 75 or 76 Chassis manual.

 

Negative camber tilts the top of the tire in at the top, positive camber tilts it out at the top. This is looking at the tire from the front of the car.

Caster tilts the top ball joint backwards (+ caster) or forwards (- caster) in relation to the lower ball joint.

Camber changes in the front tires as you go from full suspension extension to full compression. In our 64-72 A body cars, the camber goes positive as the suspension compresses. This is a big reason why our cars under steer when pushed hard into a corner. Think of a car turning hard into a corner. look at this GS,

In a hard left turn, the outside tire (R/S) suspension compresses, the inside suspension extends. Wheel camber goes positive on the outside tire, negative on the inside tire. The positive camber tilts the tire out at the top causing the tire to roll over onto the edge of the tread and sidewall. That causes the tire to slide, and the car to under steer. The A body cars had positive camber gain built into them. Sway bars improve handling in part by limiting that body roll (suspension compression and extension) and the resultant camber change. Later cars had negative camber gain in the front end. That outside tire camber went negative instead of positive. That caused the tire to stand up straighter and not roll over onto its edge. There are ways to convert our cars to negative camber gain, think taller spindles or taller ball joints.

Caster improves straight line stability. It makes the wheels want to go straight. Think of casters on a piece of furniture. You can push that piece of furniture in any direction and the wheels line up in that direction. The axis of rotation of the wheel is offset forwards or backwards from it's attachment point. Caster is a big reason why your steering wheel returns to straight away if you let go of it in a turn. Caster increases steering effort, not a big deal with power steering. Caster also causes a camber change as you turn the tires from lock to lock. Ever see a Mercedes Benz parked with the wheels turned to full lock? You'll notice the inside tire camber noticeably positive. The outside tire will have negative camber although this will not be as noticeable because the inside tire always turns sharper than the outside tire. That is one reason why MB's have a reputation for handling, they use something like 10* of positive caster.

Unfortunately, our A body suspensions do not lend themselves to large amounts of positive caster. You can put some negative camber into our front ends to help handling. Offset upper control arm shafts can help as well.

In our front ends, adding shims to both upper control arm bolts will increase negative camber. If you remove a shim from one bolt and put it into the other shim pack, you can tilt the spindle backwards or forwards increasing caster, negative or positive. Positive caster, as much as you can get, is the way to go. The more shims you have on a bolt, the less stable it becomes, one reason that limits our adjustment range. In the aftermarket, there are solutions to all of this. As mentioned before, taller spindles, taller ball joints, revised tubular upper and lower control arms. From the 1971 Buick Chassis Manual,

 

Radial tires also help handling as well. The radial tire construction allows the tread to stay in better contact with the road in part because the sidewalls allow it to.

 

The Buick Chassis Manual, in this case 1971.

 

I think radials go back to 1948. That isn't the question though. The question, your question is were there optional alignment specs in the Chassis Manuals for radials. Not that I know of, but I am going to see if I can find any.

 

Took a look at the 1974 and 75 Chassis manuals. I don't see any optional alignment specs for radials. They do list them in the tire sections of the manuals.