Verify first.....
Depends on the use of the car and it's set up, like everything suspension related.
Ride height changes the alignment numbers, and having a driver in the car will mean the car sits lower on that side. How much it changes depends on the weight of the driver and the wheel rate of the torsion bars, so a heavy driver with light torsion bars would have more of an effect. A light driver with heavy torsion bars would have less of an effect.
For a street car your loading situations are going to change more frequently (passengers, groceries, etc) so you may not spend enough time in one configuration to worry about setting the alignment a certain way. On the other hand, if the car is always loaded the same way, it would make sense to ballast the car that way for the alignment.
Why?
These cars only have a few degrees of adjustment with mostly factory components, so really there isn't much experimentation needed. Basic settings using the SKOSH chart for most people with a street car and radials would be more than good enough. You're not really going to change the toe more than 1/16" in either direction, it's unlikely you'd want to change the camber more than a .25° in either direction for most cars. And caster you likely won't be able to change more than .5° without giving up more than you want with factory UCA's.
Unless you have fully adjustable control arms I wouldn't see why more than half a dozen alignments would be necessary to find the perfect sweet spot for a given car. Hell I do have fully adjustable control arms, and even with multiple suspension component swaps/upgrades I'd have to say I'm still under a dozen different alignments on my Duster. And I can do them myself for free at home any time.
Bump steer on a mostly factory A-body is fairly minimal. Unless you have really extreme settings, or a lot of aftermarket suspension pieces, most folks wouldn't need a bump steer graph. Especially for a street car. For frequent road racing or autoX you'd want it done, but otherwise it's unlikely to reveal a problem. If you have symptoms of bump steer that's a different story.
Actually setting the scrub radius to zero is a bad idea. It's like setting 0 toe- your tires won't maintain that as they travel. If you're at 0 scrub at static you can get opposing scrub radius values from each wheel as the suspension travels since its independent, which causes the car to squirm. For a RWD car you generally want a small, positive scrub radius. But FWD street cars do better with a small negative scrub radius.
Completely disagree, especially with stock UCA's and bushings or even offset bushings. These cars have very little ability to get positive caster, and it makes a BIG difference in stability for both straight line and cornering. By comparison, unless you're really pushing your car in the corners almost no one would notice losing a little bit of camber, as long as it stayed slightly negative.
Nope. Depends entirely on what you do with the car. Sure, if you drive highways the majority of the time and don't push in the corners a smidge of negative camber is all you need.
But if you drive winding mountain roads, enjoy some spirited driving and have your car equipped with wide tires (more sensitive to camber changes), you may find that you get less tire wear at -1° camber than you do at -.25°. Tire wear will tell you what's right for you, if your tires are wearing evenly then your camber setting is fine. I manage to wear my tires evenly with -1° of camber, so it's not too much for the type of driving I'm doing.
Bump steer is a direct result from toe change, they are not separate things. Bump steer is what you feel when you have excessive toe change, simple as that. They are used interchangeably, but bump steer is the negative outcome of toe change.
And A-bodies do quite well over their entire travel range, which is close to 5" in factory configuration. Bill Reilly plotted it all out for his "debated usage" article for the FMJ spindles. Now, that suspension was basically entirely stock except for the 1" lower ride height compared to factory. It was run with 26" tires and a rake of 1.5". The toe-change is quite modest, you can read more about the range/effect in the article https://www.motortrend.com/how-to/mopp-0503-swapping-a-and-b-disc-brake-spindles/
Toe change is never going to be zero for any unequal length control arm suspension, but there's a fairly well defined acceptable range, and as long as you're in that it won't be a significant issue. Especially for a street car. I would almost never sacrifice suspension travel to reduce bump steer, there are far better ways to fix excessive toe change. Giving up travel makes it harder to keep the wheels planted on the ground.
Depends on the use of the car and it's set up, like everything suspension related.
Ride height changes the alignment numbers, and having a driver in the car will mean the car sits lower on that side. How much it changes depends on the weight of the driver and the wheel rate of the torsion bars, so a heavy driver with light torsion bars would have more of an effect. A light driver with heavy torsion bars would have less of an effect.
For a street car your loading situations are going to change more frequently (passengers, groceries, etc) so you may not spend enough time in one configuration to worry about setting the alignment a certain way. On the other hand, if the car is always loaded the same way, it would make sense to ballast the car that way for the alignment.
Why?
These cars only have a few degrees of adjustment with mostly factory components, so really there isn't much experimentation needed. Basic settings using the SKOSH chart for most people with a street car and radials would be more than good enough. You're not really going to change the toe more than 1/16" in either direction, it's unlikely you'd want to change the camber more than a .25° in either direction for most cars. And caster you likely won't be able to change more than .5° without giving up more than you want with factory UCA's.
Unless you have fully adjustable control arms I wouldn't see why more than half a dozen alignments would be necessary to find the perfect sweet spot for a given car. Hell I do have fully adjustable control arms, and even with multiple suspension component swaps/upgrades I'd have to say I'm still under a dozen different alignments on my Duster. And I can do them myself for free at home any time.
Bump steer on a mostly factory A-body is fairly minimal. Unless you have really extreme settings, or a lot of aftermarket suspension pieces, most folks wouldn't need a bump steer graph. Especially for a street car. For frequent road racing or autoX you'd want it done, but otherwise it's unlikely to reveal a problem. If you have symptoms of bump steer that's a different story.
Actually setting the scrub radius to zero is a bad idea. It's like setting 0 toe- your tires won't maintain that as they travel. If you're at 0 scrub at static you can get opposing scrub radius values from each wheel as the suspension travels since its independent, which causes the car to squirm. For a RWD car you generally want a small, positive scrub radius. But FWD street cars do better with a small negative scrub radius.
Completely disagree, especially with stock UCA's and bushings or even offset bushings. These cars have very little ability to get positive caster, and it makes a BIG difference in stability for both straight line and cornering. By comparison, unless you're really pushing your car in the corners almost no one would notice losing a little bit of camber, as long as it stayed slightly negative.
Nope. Depends entirely on what you do with the car. Sure, if you drive highways the majority of the time and don't push in the corners a smidge of negative camber is all you need.
But if you drive winding mountain roads, enjoy some spirited driving and have your car equipped with wide tires (more sensitive to camber changes), you may find that you get less tire wear at -1° camber than you do at -.25°. Tire wear will tell you what's right for you, if your tires are wearing evenly then your camber setting is fine. I manage to wear my tires evenly with -1° of camber, so it's not too much for the type of driving I'm doing.
Bump steer is a direct result from toe change, they are not separate things. Bump steer is what you feel when you have excessive toe change, simple as that. They are used interchangeably, but bump steer is the negative outcome of toe change.
And A-bodies do quite well over their entire travel range, which is close to 5" in factory configuration. Bill Reilly plotted it all out for his "debated usage" article for the FMJ spindles. Now, that suspension was basically entirely stock except for the 1" lower ride height compared to factory. It was run with 26" tires and a rake of 1.5". The toe-change is quite modest, you can read more about the range/effect in the article https://www.motortrend.com/how-to/mopp-0503-swapping-a-and-b-disc-brake-spindles/
Toe change is never going to be zero for any unequal length control arm suspension, but there's a fairly well defined acceptable range, and as long as you're in that it won't be a significant issue. Especially for a street car. I would almost never sacrifice suspension travel to reduce bump steer, there are far better ways to fix excessive toe change. Giving up travel makes it harder to keep the wheels planted on the ground.