Front end not level

[krazykuda]

You should bounce the front end or take it for a spin after adjusting the torsion bars to see where it settles in...

 

[famous bob]

Yes. but if one side is screwed all the way in and the other side is all the way out on the torsion bar adjusters, you've got bigger issues. Worn out suspension or torsion bars, or both. Or even worse yet, tweaked/bent frame rails or K frame.

-----------------------------------or a weak rear spring ---------------

 

[72bluNblu]

Start by eliminating stuff to find out where the problem is first;

- Jack up the car under the rear axle center. Now look at the car from the front; does it still sit uneven?

- Do the same at the front, jack it up at the K-member from the front, now look at the car from the rear. Is it level there?

If you’ve got a bad leaf spring jacking it up by the axle won’t help, the weight is still on the springs. Gotta support the car from the frame to take the rear suspension out of the picture.

 

[1969383S]

Geometry is the angle between the upper and lower ball joints. It does not change with bias or radial tires, the car does not know the difference.This is the whole reason for setting the ride height!

Like said using stock components follow the FSM, and if you replace it all with stock type stuff after you set the initial ride height with the nuts loose, future minor changes to ride height do not require you loosen them again. If you need to make 1” changes you have other issues.

 

[1969383S]

This whole FSM ride height adjustment procedure is to align the studs of the ball joints in an imaginary line so they are both in the center of travel posistion. If they are not in line then travel in each joint will reach different points in time. Tire type does not influence this but height does.

 

[72bluNblu]

Geometry is the angle between the upper and lower ball joints. It does not change with bias or radial tires, the car does not know the difference.This is the whole reason for setting the ride height!

Like said using stock components follow the FSM, and if you replace it all with stock type stuff after you set the initial ride height with the nuts loose, future minor changes to ride height do not require you loosen them again. If you need to make 1” changes you have other issues.

This whole FSM ride height adjustment procedure is to align the studs of the ball joints in an imaginary line so they are both in the center of travel posistion. If they are not in line then travel in each joint will reach different points in time. Tire type does not influence this but height does.

Man I don't even know where to start. They don't make red X's big enough for those comments, they're simply false. I hate to totally blow up this thread, but there's no way I can let that go uncorrected.

These cars have unequal length upper and lower control arms. That means the ball joints travel in separate and different arcs, because they're moving on different length arms. The geometry is constantly changing, regardless of where you set the ride height or what you set your static alignment at. This is also the reason why you need an alignment if you change the ride height. As soon as there's compression or extension, or a change in ride height, those geometry numbers- camber, caster, toe- they all change. How they change is actually more important than just the static numbers, and where you set the ride height can change how the camber gain and bump steer curves effect your handling. This article was about A-body spindles vs. the FMJ spindles and those geometry differences, but they also did full suspension geometry plots for a car lowered 1" from factory. You can see in those charts how much the geometry changes with travel, and what that means for handling if you think about what your suspension is doing as you go around a corner... Swapping Disc-Brake Spindles - Mopar Muscle Magazine

If you go further, and say, plot all the suspension points into a suspension analysis program, you can run a computer simulation on what ride heights and alignment settings give the best handling. I've seen this done for these cars, and if handling is your goal the FSM specs are wrong. The best camber gain and bump steer curves happen when the control arms are nearly parallel to the ground. For the FSM, that means when "A" and "B" are equal, otherwise known as a 1-7/8" ride height drop from the factory numbers for an A-body. That's a big drop, and requires a bunch of aftermarket parts to make it work. But that's where the best geometry occurs if you're running radial tires, and it's totally different than what the FSM says.

Why is it different? Radial and bias ply tires have completely different suspension geometry needs. How the tires handle camber and caster is totally different, which is why the factory alignment specs are terrible for radials. The car might not care, but the tires DO. Hence, the skosh chart most people use for their alignment specs on these cars instead of the specs in the FSM (which are for bias ply's). Radials want negative camber and positive caster, bias ply's can't handle negative camber and won't take very much positive caster either. Which is why we all need offset UCA bushings or tubular UCA's to get a decent alignment for radial tires, because the factory designed the UCA's for bias ply's and very little caster. Compare these numbers to the FSM, they start to diverge pretty quickly. And this chart is actually pretty conservative on caster, +5* or more for caster works great especially on power steering cars. Or on manual cars if you don't mind the increased steering effort. The chart pre-dates a big aftermarket supply for tubular UCA's, so you couldn't really get numbers like that.

Here's an article that gives a quick breakdown on some of the differences between radial and bias ply tires, and why that affects the suspension geometry that you want to set Tire Tech

I apologize for the thread jack, but it's not all the same, and the FSM is not where you should get your alignment specs if you run radial tires.

 

[famous bob]

Man I don't even know where to start. They don't make red X's big enough for those comments, they're simply false. I hate to totally blow up this thread, but there's no way I can let that go uncorrected.

These cars have unequal length upper and lower control arms. That means the ball joints travel in separate and different arcs, because they're moving on different length arms. The geometry is constantly changing, regardless of where you set the ride height or what you set your static alignment at. This is also the reason why you need an alignment if you change the ride height. As soon as there's compression or extension, or a change in ride height, those geometry numbers- camber, caster, toe- they all change. How they change is actually more important than just the static numbers, and where you set the ride height can change how the camber gain and bump steer curves effect your handling. This article was about A-body spindles vs. the FMJ spindles and those geometry differences, but they also did full suspension geometry plots for a car lowered 1" from factory. You can see in those charts how much the geometry changes with travel, and what that means for handling if you think about what your suspension is doing as you go around a corner... Swapping Disc-Brake Spindles - Mopar Muscle Magazine

If you go further, and say, plot all the suspension points into a suspension analysis program, you can run a computer simulation on what ride heights and alignment settings give the best handling. I've seen this done for these cars, and if handling is your goal the FSM specs are wrong. The best camber gain and bump steer curves happen when the control arms are nearly parallel to the ground. For the FSM, that means when "A" and "B" are equal, otherwise known as a 1-7/8" ride height drop from the factory numbers for an A-body. That's a big drop, and requires a bunch of aftermarket parts to make it work. But that's where the best geometry occurs if you're running radial tires, and it's totally different than what the FSM says.

Why is it different? Radial and bias ply tires have completely different suspension geometry needs. How the tires handle camber and caster is totally different, which is why the factory alignment specs are terrible for radials. The car might not care, but the tires DO. Hence, the skosh chart most people use for their alignment specs on these cars instead of the specs in the FSM (which are for bias ply's). Radials want negative camber and positive caster, bias ply's can't handle negative camber and won't take very much positive caster either. Which is why we all need offset UCA bushings or tubular UCA's to get a decent alignment for radial tires, because the factory designed the UCA's for bias ply's and very little caster. Compare these numbers to the FSM, they start to diverge pretty quickly. And this chart is actually pretty conservative on caster, +5* or more for caster works great especially on power steering cars. Or on manual cars if you don't mind the increased steering effort. The chart pre-dates a big aftermarket supply for tubular UCA's, so you couldn't really get numbers like that.
View attachment 1715167775

Here's an article that gives a quick breakdown on some of the differences between radial and bias ply tires, and why that affects the suspension geometry that you want to set Tire Tech

I apologize for the thread jack, but it's not all the same, and the FSM is not where you should get your alignment specs if you run radial tires.

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
My front end man said about the same thing as this. I think he is as good as I`ve used .

 

[dukeboy440]

Geometry is the angle between the upper and lower ball joints. It does not change with bias or radial tires, the car does not know the difference.This is the whole reason for setting the ride height!

Like said using stock components follow the FSM, and if you replace it all with stock type stuff after you set the initial ride height with the nuts loose, future minor changes to ride height do not require you loosen them again. If you need to make 1” changes you have other issues.

This whole FSM ride height adjustment procedure is to align the studs of the ball joints in an imaginary line so they are both in the center of travel posistion. If they are not in line then travel in each joint will reach different points in time. Tire type does not influence this but height does.

Yeah... wrong. There's actually a service bulletin from Mopar to their techs about the requirementns for different adjustments when going from bias to radial tires back when. It is a scan that's been floating around the web for years, I'll see if I can find it

 

[1969383S]

Yeah... wrong. There's actually a service bulletin from Mopar to their techs about the requirementns for different adjustments when going from bias to radial tires back when. It is a scan that's been floating around the web for years, I'll see if I can find it

Would love to see it.

I certainly understand the difference in caster/camber/toe involved in the bias vs radial. Ride height sets geometry only. I will stick with that until otherwise proven. The measurement is taken in two locations and tire type or height makes no difference in this. Hell you can put a wagon wheel on it and still is what it is, and sets the relationship between upper and lower arms. If you decide to crank the height way up, do you not now sit on the bump stops of the upper A. I never mentioned anything other that stock components and went to point of mentioning it every post. This is not a discussion about over all alignment but the factory method for setting initial ride height.