C5 Ride Height vs. Toe Changes
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Team Owner
Joined: Aug 2005
Posts: 22,142
Likes: 76
From: North East
C5 Ride Height vs. Toe Changes
Follow me here.. who's who on C5 front alignment adjustments 
If the car ride height is increased, then this causes toe-in.
If the car ride height is decreased, then this causes toe-out
The tie rods are located towards the front of the car in front of the wheel bearing.
All of this because the lower a-arm stays static when adjusting ride height, the pivot point with the least amount of change is the lower ball joint nearest the spring perch (as compared to the frame connection points)
And, when changing ride height you're effectively adjusting the distance between the upper and lower a-arms by adjusting the height of the spring perch.
When the distance between the upper and lower a-arm is increased (raised ride height) this causes the tie-rod end to pull in for "toe-in" (+ toe)
Oppositely, decreasing the distance between the two arms by lowering the spring perch causes the tie rod to push out causing toe-out (negative).
What parts of this is right/wrong?
You decide
If the car ride height is increased, then this causes toe-in.
If the car ride height is decreased, then this causes toe-out
The tie rods are located towards the front of the car in front of the wheel bearing.
All of this because the lower a-arm stays static when adjusting ride height, the pivot point with the least amount of change is the lower ball joint nearest the spring perch (as compared to the frame connection points)
And, when changing ride height you're effectively adjusting the distance between the upper and lower a-arms by adjusting the height of the spring perch.
When the distance between the upper and lower a-arm is increased (raised ride height) this causes the tie-rod end to pull in for "toe-in" (+ toe)
Oppositely, decreasing the distance between the two arms by lowering the spring perch causes the tie rod to push out causing toe-out (negative).
What parts of this is right/wrong?
You decide
Melting Slicks
Joined: Jun 2002
Posts: 3,070
Likes: 5
From: Charleston South Carolina
Follow me here.. who's who on C5 front alignment adjustments
If the car ride height is increased, then this causes toe-in.
If the car ride height is decreased, then this causes toe-out
The tie rods are located towards the front of the car in front of the wheel bearing.
All of this because the lower a-arm stays static when adjusting ride height, the pivot point with the least amount of change is the lower ball joint nearest the spring perch (as compared to the frame connection points)
And, when changing ride height you're effectively adjusting the distance between the upper and lower a-arms by adjusting the height of the spring perch.
When the distance between the upper and lower a-arm is increased (raised ride height) this causes the tie-rod end to pull in for "toe-in" (+ toe)
Oppositely, decreasing the distance between the two arms by lowering the spring perch causes the tie rod to push out causing toe-out (negative).
What parts of this is right/wrong?
You decide
If the car ride height is increased, then this causes toe-in.
If the car ride height is decreased, then this causes toe-out
The tie rods are located towards the front of the car in front of the wheel bearing.
All of this because the lower a-arm stays static when adjusting ride height, the pivot point with the least amount of change is the lower ball joint nearest the spring perch (as compared to the frame connection points)
And, when changing ride height you're effectively adjusting the distance between the upper and lower a-arms by adjusting the height of the spring perch.
When the distance between the upper and lower a-arm is increased (raised ride height) this causes the tie-rod end to pull in for "toe-in" (+ toe)
Oppositely, decreasing the distance between the two arms by lowering the spring perch causes the tie rod to push out causing toe-out (negative).
What parts of this is right/wrong?
You decide
1) In Autocross you want toe-out in the front and toe-in in the rear.
2) When you lower the car you get the exact opposite of what you want for autox. The car toes-in in the front and toes-out in the rear.
3) Raising the car causes the opposite to occur.
That's the most my brain can handle...good luck.
Safety Car
Joined: Mar 2000
Posts: 3,581
Likes: 1
From: Springfield VA
Toe is controlled by the combined length of the inner and outer tie rods in relation to the rack and the ball joint. The rack sits higher than the lower control arms and the combined length of the tie rods is longer than the control arm.
As the car is lowered the point where the rack and inner tie rod connect becomes lower moving the angle of the tie rod closer to 90 deg (parallel to the ground). As the angle moves closer to 90 deg, the distance between the rack and the ball joint increases (toe-out). As the angle moves away from 90 deg, the distance between the rack and the ball joint decreases (toe-in).
As the car is lowered the point where the rack and inner tie rod connect becomes lower moving the angle of the tie rod closer to 90 deg (parallel to the ground). As the angle moves closer to 90 deg, the distance between the rack and the ball joint increases (toe-out). As the angle moves away from 90 deg, the distance between the rack and the ball joint decreases (toe-in).
Safety Car
Joined: Jul 2001
Posts: 3,667
Likes: 0
From: TurtleCreek Twp Ohio
Cruise-In III Veteran
The best handleing Vette I have ever seen both on a road course (near record lap at Mid-Ohio)and a skidpad (highest recorded skidpad number at the TireRack) is also one of the lowest Vette's I have seen.
And he'll tell you he's not a great driver, his car is just that good.
And he'll tell you he's not a great driver, his car is just that good.
Race Director
Joined: Sep 1999
Posts: 12,430
Likes: 914
From: CONCORD NC
bump steer is what you are talking about dynamically, of course for a static ride height change, you only need to set it once and you are done. If the rack is lower than the tie-rod mount, lowering the car will cause toe "out" in the front until you reach the point where they are at equal heights.. If the rack is higher than the tie-rod mount, lowering will cause to "in" in the front.
I don't know if you are asking a rhetorical question, or seeking real knowledge, but the bottom line is that a small ride height only barely changes toe. Just lower as wanted, re-set the toe once, and forget about it. Toe takes me about 10minutes to set on most cars (unles the thurst angle if F-d up severely), so no need to spend too much time analyzing. Quicker just to fix it with tools instead of calculators!
I don't know if you are asking a rhetorical question, or seeking real knowledge, but the bottom line is that a small ride height only barely changes toe. Just lower as wanted, re-set the toe once, and forget about it. Toe takes me about 10minutes to set on most cars (unles the thurst angle if F-d up severely), so no need to spend too much time analyzing. Quicker just to fix it with tools instead of calculators!
Race Director
Joined: Sep 1999
Posts: 12,430
Likes: 914
From: CONCORD NC
for the record, and because I happen to have a stock C6Z06 sitting in the shop:
the front rack is just barely/slightly higher than the tie-rod mounts, so lowering will toe "out" a tiny bit at first, then toe back "in" if you lower a lot. In reality, probably won't change toe at all in real world lowering amounts (1/2-1")
In the rear, the toe links mount much higher, so lowering will cause toe "in" no matter how far you go.
Again it is all related to the relative height of the steering/toe link to the spindle mounting location. Bottom line, measure and re-set the toe after any changes. It is easy and quick to correct with a straight edge, tape measure, a jack and 2 wrenches.
the front rack is just barely/slightly higher than the tie-rod mounts, so lowering will toe "out" a tiny bit at first, then toe back "in" if you lower a lot. In reality, probably won't change toe at all in real world lowering amounts (1/2-1")
In the rear, the toe links mount much higher, so lowering will cause toe "in" no matter how far you go.
Again it is all related to the relative height of the steering/toe link to the spindle mounting location. Bottom line, measure and re-set the toe after any changes. It is easy and quick to correct with a straight edge, tape measure, a jack and 2 wrenches.
