View Full Version : 71 camaro steering geometry


dale68z
09-25-2012, 01:28:10 AM
My 71's right tie rod assy is 1/2" shorter than the left. I have always felt that unequal length tie rods will affect the tire turning radius... kinda like ackerman. I cannot rationalize why, but it is something I have felt is true.

True, or not? And why.

I also noticed my pitman arm does not point straight rearward. My idler and pitman are not parallel to each other.
My steering wheel is straight, also the upper shaft's center punch mark is straight up. The steering gear is centered.. I pulled off the pitman, the steering wheel turns 3 turns lock to lock. Turned the wheel back 1.5 turns, and steering wheel is now back to straight.

The pitman arm is not parallel to the frame, I think the idler was parallel to the frame. The pitman does not point straight back. It is probably off to the drivers side by 20 degrees?
Normally when a gear is centered the pitman will be directly pointed to the rear.

I did check if the steering arms were bent, both right and left arms were withing 1/16 of each other.

When measuring the drag link, it is, say... 24"'s. The sector shaft to idler pivot is about 23.5 " 's.

Measuring across the diagonals also do not add up. I expected both to be the same.

My question is why did GM do this? What were they thinking?

Have any of you measured, or modeled the geometry of your steering, or front suspension/ alignment.? ackerman, camber/ caster curves, bump steer, tire scrub, antidive.

I raced a dirt modified 12 years ago. I had a computer program that helped a ton on front suspension geometry. I spent a lot of time on my dirt car to make the steering and suspension work they way I needed it to with great success. I am now very interested in modeling this car.

ratpatrol71z28
09-25-2012, 01:46:00 AM
Yeah i need help to on this so i'll keep tuned, just did a steering switch and my turning radius isn't as good as it was stock :(

HyPer
09-25-2012, 03:53:54 AM
Same here, as far as I know, if there's different lengths between pitman and spindle, the wheels will be at different angles when turned to their own lock. If I were you, I'd look into getting equal length tie rods and straightening that pitman arm. Even if our suspicions are incorrect, it will certainly make you feel more at ease. This is something hard to wrap your mind around.

dale68z
09-25-2012, 06:55:50 PM
I just ordered the newest autoware steering geometry pro program.

http://www.auto-ware.com/software/asgp/asgp.htm

John just got back from the SCCA nationals, so he is behind on his phone calls.

The fun will begin.

BonzoHansen
09-25-2012, 09:05:00 PM
IRRC firebird & camaro idlers & pitmans are different in some cases, apparently to clear the poncho motors. maybe you have a mismatch?

dale68z
09-26-2012, 12:54:13 AM
IRRC firebird & camaro idlers & pitmans are different in some cases, apparently to clear the poncho motors. maybe you have a mismatch?

Could be, cannot rule out a mismatch, at this point.

I would assume by the time I am finished it will be a "Jonny Cash" car. But, it may be already a beutiful thing.

My modified used a 80 malibu frame, lower control arms and spindles. I used a camaro 3rd gen drag link, a "modified" b body idler arm, b body lower ball joint, chevy van upper ball joint, and a custom made by me, welded together pitman arm that fit a 605 (snap ring style) box. Oh yeah, tubular uppers (I made these also), and home grown custom frame mounts.
I had tried other stock parts on the car... 1st gen camaro lowers, crown vic lower ball joints, pinto spindles, multiple different idlers, pitmans and drag links, and ball joints.
I would go to wrecking yards and snag random front end parts to try out, or model with the computer.
I also bought into the idea that a nationally known chassis builder did their homework. I bought their bumpsteer correction kit. I checked my bumpsteer after installing... it was horrible on my car, like, you have to be kidding me horrible.

BonzoHansen
09-26-2012, 11:21:40 AM
look at that, someone just bumped this one: http://www.nastyz28.com/forum/showthread.php?p=2814608#post2814608

ratpatrol71z28
09-26-2012, 11:53:47 AM
Oh well what I found out is that my Tubular heidts lower arms are mainly for racing so it has a little stop, that's why it won't let me turn more than I can, I may just cut it off.

Todd80Z28
09-26-2012, 03:13:46 PM
I don't think the tie rod arm length would affect turning angle in a static state (no control arm movment), provided the pitman, idler and steering arms are the same length. The tie rod is just the ... well, tie.:)

HOWEVER, I would think unequal length is going to give you side-to-side bumpsteer variances as the suspension travels up and down.

I don't have any real hard data on the car with regard to all the above measurements, though, so this is all just hypothetical.

dale68z
09-27-2012, 01:29:28 AM
I don't think the tie rod arm length would affect turning angle in a static state (no control arm movment), provided the pitman, idler and steering arms are the same length. The tie rod is just the ... well, tie.:)

HOWEVER, I would think unequal length is going to give you side-to-side bumpsteer variances as the suspension travels up and down.

I don't have any real hard data on the car with regard to all the above measurements, though, so this is all just hypothetical.

I know I have checked this with turn plates. I am sure it made a difference that was not good. But, that was over 13-14 years ago so my memory is foggy. I just can't visualize it in my head.