I'm looking to perfect the alignment on my 69 FB convertable. It has Global West upper a-arms and springs. The tubular upper A-arms were suppose to provide +5 degrees caster. I'm only getting +3. Has anyone else tried new upper A-arms and been able to get 5? How did you do it?
Camber on the passenger wheel was -0.8. That resulted in the outer edge of the tire wearing out rapidly only on that side. Looking to go -0.5 degrees in the future. What are you guys running and how do you know?
Wish I could find the numbers for my 67. A knowledgeable shop did mine about 15 years ago and it has been perfect to this day. I will look and see if I saved it somewhere.
I have done all these modifications to customer cars that the owners wanted their first gen cars to do some corner carving. After spending thousands of dollars on suspension parts and big brakes they still are a first gen F body and will never handle like a modern car. They are a little better but still body roll and push thru the corners. I have been able to get 3 degrees of caster with stock control arms using offset upper shafts. at this point you should be installing solid body bushings.
Ok, answering my on question hoping it helps others going forward:
Global West says shoot for 5 degrees caster drivers side, 5.5 passenger side; Camber -.5 both sides. Toe 1/16".
Added two 1/8" alignment shims to the rear bolt on the passenger side to bring the castor up from 3.5 degrees to 5.5 degrees on that side. Really easy. This is on a 1969 Firebird convertible with global west upper A arms, stock lower arms, and Global Wests coil spring.
Running 15 x 8 wheels with 215/60/R15 radials up front.
Determined prior "Alignment experts" never adjusted caster/camber! Count your shims before you take it to get aligned. It they do not change in thickness and/or number, caster/camber was not changed and only a toe adjustment was made. If the caster/camber was correct, then the shims would remain the same BUT i find most shops too lazy or unwilling to do the work to adjust the camber/caster in my area (DFW).
In my example, I had 2 shops do an alignment, neither changed a shim, and the rt tire wore out on its outer edge quickly. My check found the caster/camber way off. Everyone I speak with "has a guy" that does old cars and does it "right". I ask how do you know without checking yourself? Most hobby cars have very low miles and a car can track perfectly straight and have a poor alignment eating tires. (just like mine did)
I also have 'a guy' that is tops. He uses a Hunter computerized alignment machine and shows before and after specs on a printout. The machine even saves prior info on my cars. He learned from the 'old guy' that owned the shop since the 1950's. No matter what I did to the suspension of my 1968 hardtop Firebird, he got it to track perfectly and my tires did not wear out. The shop told me they once had hired a guy that had worked at a local MAVIS tire shop. He never went farther than the toe-in, and they laughingly referred to a MAVIS alignment as 'Toe and go'. They fired him. So I wholehearted agree that you need to find a competent alignment guy that knows old cars too. The $100 cost is small potatoes compared to replacing $250 tires because they wore out too soon.
I have done hundreds of alignments using various makes of 4 wheel computer alignment machines and can tell you they are 100x better and accurate than the old plates and bubble gauges. The other advantage is get get all 4 wheels done telling you if the rear track is off.
I’ve been fiddling with the front end alignment on my 69 GTO. It was too difficult trying to schedule something with a place that knows what they’re doing. I bought a caster/camber gauge with a pretty delicate digital level. Then scoured the internet for info on what numbers work well. I’ve got many hours of trial and error getting to the point where it tracks pretty well. I’ve had fun and learned a lot. I’m not sure the alignment specs are all that critical for a driver. A few degrees of positive caster, about zero camber, and set the toe in 1/16 to 1/8. The racers and auto crossers like to dial it in a certain way and there is a science to that.
