dklawson
Yoda
Offline
A bit of history on our GT6. It was raced by my father-in-law during the early 1970s. He lowered the car and I'm sure the camber, castor, and toe were changed. Years ago I put new bushings in the suspension when I restored the car. BUT, I only drove the car locally and since I didn't notice any driveability problems I never set the alignment.
The car has a brand new set of tires and my wife wants to drive it more frequently and on the highway. After her first trip she reported the car was smooth as glass up until 60 MPH and developed a shake in the steering wheel above that. I seem to remember similar behavior on the old tires the few times I had the car up to highway speed.
I've searched here and I've read my factory manual on the settings. However, since the car has been lowered I doubt I'll ever see the factory specs again. Therefore, I have the following questions.
The factory spec for an empty car is 1/16" to 1/8" of toe-in. The camber was something close to 2 degrees positive (out at the top). The castor was also specified but I can't figure out how I'd measure it. Are there any easy ways to measure castor?
I'm OK with checking and setting the toe. However, is the camber REALLY supposed to be POSITIVE? That's counter-intuitive to me I'm also very confident (without measuring yet) that the car currently has negative camber. However, if the car is supposed to have positive camber and if I remove enough shims to move it back into positive territory, what should I aim for? With the short front springs I doubt it will ever go to 2 degrees positive. If I ended up at something close to zero degrees would that be “good” or “bad”?
Should I just focus on the toe and leave the camber alone? The steering effort is a bit heavy but not too bad. It DOES make ugly tire squealing sounds when making low speed turns at near full steering lock.
Again, how exactly are you supposed to check castor? How critical to driveability and tire wear is castor? I understand that this is adjusted by removing and installing shims to "pivot" the lower A-arm forward or backward but I can't imagine how you measure this. Should I leave a sleeping dog alone?
Lastly, so I don't go around in circles, is there a logical order to make these adjustments so they don't "fight" each other?
Thanks in advance for the advice.
The car has a brand new set of tires and my wife wants to drive it more frequently and on the highway. After her first trip she reported the car was smooth as glass up until 60 MPH and developed a shake in the steering wheel above that. I seem to remember similar behavior on the old tires the few times I had the car up to highway speed.
I've searched here and I've read my factory manual on the settings. However, since the car has been lowered I doubt I'll ever see the factory specs again. Therefore, I have the following questions.
The factory spec for an empty car is 1/16" to 1/8" of toe-in. The camber was something close to 2 degrees positive (out at the top). The castor was also specified but I can't figure out how I'd measure it. Are there any easy ways to measure castor?
I'm OK with checking and setting the toe. However, is the camber REALLY supposed to be POSITIVE? That's counter-intuitive to me I'm also very confident (without measuring yet) that the car currently has negative camber. However, if the car is supposed to have positive camber and if I remove enough shims to move it back into positive territory, what should I aim for? With the short front springs I doubt it will ever go to 2 degrees positive. If I ended up at something close to zero degrees would that be “good” or “bad”?
Should I just focus on the toe and leave the camber alone? The steering effort is a bit heavy but not too bad. It DOES make ugly tire squealing sounds when making low speed turns at near full steering lock.
Again, how exactly are you supposed to check castor? How critical to driveability and tire wear is castor? I understand that this is adjusted by removing and installing shims to "pivot" the lower A-arm forward or backward but I can't imagine how you measure this. Should I leave a sleeping dog alone?
Lastly, so I don't go around in circles, is there a logical order to make these adjustments so they don't "fight" each other?
Thanks in advance for the advice.