Alignment Problems
Thread Starter
Safety Car
Joined: Jul 2002
Posts: 4,269
Likes: 3
From: St. Charles IL
Cruise-In 5-6-7-8-9-11-12 Veteran
A CI-6 Car Show Winner
Alignment Problems
My 75 is in the alignment shop, the guy is having real problems getting the settings right. GM calls for 2-1/4 degrees caster and +3/4 degree camber. Vette Brakes and Products recommend 2-3/4 degree caster and 0 degree + camber because of radial tires vs. the original bias ply tires.
The problem he's having is getting the Caster set. Left side best he could get is 1-3/4, right side 1-1/2. There are no shims on the forward upper control arm bolts at this point, and if he adds more rear shims the camber goes negative.
Hopefully some of you may have gone through a similar problem and can give some advice on what to try? I think the guy knows what he's doing. Could I have a frame issue or something along those lines?
The problem he's having is getting the Caster set. Left side best he could get is 1-3/4, right side 1-1/2. There are no shims on the forward upper control arm bolts at this point, and if he adds more rear shims the camber goes negative.
Hopefully some of you may have gone through a similar problem and can give some advice on what to try? I think the guy knows what he's doing. Could I have a frame issue or something along those lines?
Le Mans Master
Joined: Jan 2000
Posts: 8,918
Likes: 27
From: New Hill NC
You probably have some change in the front frame geometry. It is common if ever hit or driven hard over speed bumps or rough conditions. You have two choices, spread the upper control mounts, or use off set control arm shafts.
Drifting
Joined: Dec 2004
Posts: 1,345
Likes: 3
Your handling will be better with a little negative camber in the front end anyway. I have manual steering and had the front end set for a little more high speed stability as follows:
Camber Castor Toe
Left +0.4 deg +1.9 deg 0.22 degrees in
Right -0.3 deg +2.6 0.21 deg in
Total 0.43 degrees in
My car tracks great with these settings.
The factory toe setting is as follows:
Set Toe In at 3/16” to 5/16” (.19”-.31”)
(.20 to .33 deg per side) 215 or 225/70R15 Tire
I converted the inch specs to degrees using the tire sizes shown above.
Camber Castor Toe
Left +0.4 deg +1.9 deg 0.22 degrees in
Right -0.3 deg +2.6 0.21 deg in
Total 0.43 degrees in
My car tracks great with these settings.
The factory toe setting is as follows:
Set Toe In at 3/16” to 5/16” (.19”-.31”)
(.20 to .33 deg per side) 215 or 225/70R15 Tire
I converted the inch specs to degrees using the tire sizes shown above.
Race Director
Joined: Nov 2000
Posts: 11,872
Likes: 12
From: Waterloo ontario Canada
There are replacement cross shafts with more camber built into them. They are from TRW and I forget the other source. I have part numbers at work.
You can also remove the upper A arm without removing the spring and have the cross shafts machined with a 1/4 inch slot towards the front for about 5 degrees positive caster.While this sounds difficult it only takes about 5 minutes for anyone with a mill.
I did this years ago for increased caster.
Camber can only be fixed with offset arms.
This is a shot of a offset cross shaft compared to a stock one.
You can also remove the upper A arm without removing the spring and have the cross shafts machined with a 1/4 inch slot towards the front for about 5 degrees positive caster.While this sounds difficult it only takes about 5 minutes for anyone with a mill.
I did this years ago for increased caster.
Camber can only be fixed with offset arms.
This is a shot of a offset cross shaft compared to a stock one.
Thread Starter
Safety Car
Joined: Jul 2002
Posts: 4,269
Likes: 3
From: St. Charles IL
Cruise-In 5-6-7-8-9-11-12 Veteran
A CI-6 Car Show Winner
The car is now out of the shop. It does drive very well, but falls short of the specs by both GM and VB & P. This is what I wound up with:
Camber: Left: 0.0 Right: 0.7-
Caster: Left: 1.7- Right: 1.6-
Toe: Left: .17- Right: .16-
Looks like this is as good as it's going to get unless I replace the cross shafts like Norval recommends. The shop also recommended the offset shafts. I don't think I'm going to have any problems the way it is now, but I think I would like to do those shafts eventually. Probably a great project for next winter! Thank you everyone that responded, I really do appreciate all of your help.
Camber: Left: 0.0 Right: 0.7-
Caster: Left: 1.7- Right: 1.6-
Toe: Left: .17- Right: .16-
Looks like this is as good as it's going to get unless I replace the cross shafts like Norval recommends. The shop also recommended the offset shafts. I don't think I'm going to have any problems the way it is now, but I think I would like to do those shafts eventually. Probably a great project for next winter! Thank you everyone that responded, I really do appreciate all of your help.
