Ride height setting confusion
Your setting is pretty close to factory, and yes, they looked like 4x4's. Even in the promotional pictures you can see a lot of the cars were almost nose high. So, you didn't do anything wrong at all. The 1/2" to the factory bump stop is also close to correct, these cars in stock trim used the lower bumpstop quite frequently. It's a progressive bump stop that helped to make up for the ridiculously soft factory torsion bars. Most people with stock set ups don't even realize that they're constantly all over the lower bump stops. A dab of grease on the top of the bump stop and a trip around town will pretty much always show contact with factory settings and bars.
I run my Duster at about 24 7/8" from ground to fender. It's lowered about 2" from factory. Following the factory method for measuring A-B to determine the ride height I'm pretty much at 0. I run an upper bumpstop that's about 2.75" tall, and a lower bump stop that's about 3/8" tall. But I also run the earlier style QA1 LCA's, which aren't as thick and therefore add more clearance. I end up with a little less than 1" of clearance at the bump stop. Which yeah, is probably a bit more than factory. But because I run a short, non-progressive polyurethane bumpstop, I don't want to be using it all the time. I want my suspension to stay off the bump stops, where the factory basically counted on using the bump stops.
The camber curves are available for a lowered car, they were published for a car lowered 1" from factory buy Bill Reilly. The curves were published in data form in this article, for both the factory 73+ A-body disk spindle and the FMJ spindles. Swapping Disc-Brake Spindles - Mopar Muscle Magazine
The best suspension geometry for the A-body suspension with radial tires comes very close to being when the LCA is parallel to the ground, or A-B = 0. You can actually see this in the tables published in that article. Because the length of the control arms doesn't change, the data points are not going to change substantially. Lowering the car doesn't change the data points, it just means that you're moving along the curve (through the data points) from a different starting spot. Which is important, because if you start from the LCA level to the ground all the upward travel of the suspension adds negative camber, which is exactly what you want for best handling with radial tires. Now, making static camber and caster adjustments does change those curves a little, but really, for the most part you can look at those curves and have a decent idea of what you'll get. If you're setting up for competition the devil is in the details and you'll want to measure your own car, but for most street cars, even ones set up for handling, the general idea of what the curve is doing is just fine.
Now, why is the factory ride heigh the way it is? Well, the factory ride height puts the control arms at an angle. From where the suspension starts at the factory ride height, you get positive camber gain initially, which is better for bias ply's. Which is why it was designed the way it is. But it's not good for radials, which do better for handling with negative camber gain. Fortunately, because torsion bar suspension is very ride height adjustable, we can literally correct for the factory setting the car up for bias ply's just by lowering the car and adjusting the bump stops around the new center point. The best handling for a radial tire equipped A-body ends up being lowered quite a bit from factory.
Your setting is pretty close to factory, and yes, they looked like 4x4's. Even in the promotional pictures you can see a lot of the cars were almost nose high. So, you didn't do anything wrong at all. The 1/2" to the factory bump stop is also close to correct, these cars in stock trim used the lower bumpstop quite frequently. It's a progressive bump stop that helped to make up for the ridiculously soft factory torsion bars. Most people with stock set ups don't even realize that they're constantly all over the lower bump stops. A dab of grease on the top of the bump stop and a trip around town will pretty much always show contact with factory settings and bars.
I run my Duster at about 24 7/8" from ground to fender. It's lowered about 2" from factory. Following the factory method for measuring A-B to determine the ride height I'm pretty much at 0. I run an upper bumpstop that's about 2.75" tall, and a lower bump stop that's about 3/8" tall. But I also run the earlier style QA1 LCA's, which aren't as thick and therefore add more clearance. I end up with a little less than 1" of clearance at the bump stop. Which yeah, is probably a bit more than factory. But because I run a short, non-progressive polyurethane bumpstop, I don't want to be using it all the time. I want my suspension to stay off the bump stops, where the factory basically counted on using the bump stops.
The camber curves are available for a lowered car, they were published for a car lowered 1" from factory buy Bill Reilly. The curves were published in data form in this article, for both the factory 73+ A-body disk spindle and the FMJ spindles. Swapping Disc-Brake Spindles - Mopar Muscle Magazine
The best suspension geometry for the A-body suspension with radial tires comes very close to being when the LCA is parallel to the ground, or A-B = 0. You can actually see this in the tables published in that article. Because the length of the control arms doesn't change, the data points are not going to change substantially. Lowering the car doesn't change the data points, it just means that you're moving along the curve (through the data points) from a different starting spot. Which is important, because if you start from the LCA level to the ground all the upward travel of the suspension adds negative camber, which is exactly what you want for best handling with radial tires. Now, making static camber and caster adjustments does change those curves a little, but really, for the most part you can look at those curves and have a decent idea of what you'll get. If you're setting up for competition the devil is in the details and you'll want to measure your own car, but for most street cars, even ones set up for handling, the general idea of what the curve is doing is just fine.
Now, why is the factory ride heigh the way it is? Well, the factory ride height puts the control arms at an angle. From where the suspension starts at the factory ride height, you get positive camber gain initially, which is better for bias ply's. Which is why it was designed the way it is. But it's not good for radials, which do better for handling with negative camber gain. Fortunately, because torsion bar suspension is very ride height adjustable, we can literally correct for the factory setting the car up for bias ply's just by lowering the car and adjusting the bump stops around the new center point. The best handling for a radial tire equipped A-body ends up being lowered quite a bit from factory.
