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Usually, I use turbophil's method to measure toe: http://www.lotustalk.com/forums/f91/little-diy-alignment-45655/ but after talking to Carl, I though I'd also try the method shown in this post: http://www.lotustalk.com/forums/f91/little-diy-alignment-45655/#post795972
I get very different results using the two methods
anic:
It's easy to explain... the two methods do not result in parallel strings, at least with the wheels that I'm using (RAC Monolites). In fact, there's a 0.62/0.64 (right/left) degree difference in the angle of the strings to each other... and that's a lot, since the range of rear toe settings is 0.16 to 0.24 degrees.
For example, using the first method, I get 0.20 degrees of toe in on the left rear, with the second method, I get 0.44 degrees of <b>toe out</b>!
I'm very confident that I'm doing the first method right, as I've compared measurements to those taken from a laser alignment rig. I'm not sure I'm doing the second method correctly...
Any thoughts anyone? Is there something about the offsets of the RACs that makes the angle greater than with other wheels? Or is it simply that the different front/rear track of the car makes the second method questionable?
EDIT: The front/rear track of the car is spec'd at 1457/1507mm (front/rear)... that's exactly the angle I'm measuring: arcsin((1507-1457)/2)/2300 = 0.623 degrees
EDIT2: xtn pointed out this potential problem in this post: http://www.lotustalk.com/forums/f91/little-diy-alignment-45655/#post795985... is it possible that Jack's car has spacers on the front wheels? If they were around 25mm it would completely neutralize the difference in track, and make the method accurate for his car.
Pics...
1) Sighting down the two strings, first method on the outside, second method on the inside. Even with the "vanishing effect", you can tell they are diverging...
2) Looking straight down on the left wheel... here it's easy to see the difference in angles
I get very different results using the two methods
It's easy to explain... the two methods do not result in parallel strings, at least with the wheels that I'm using (RAC Monolites). In fact, there's a 0.62/0.64 (right/left) degree difference in the angle of the strings to each other... and that's a lot, since the range of rear toe settings is 0.16 to 0.24 degrees.
For example, using the first method, I get 0.20 degrees of toe in on the left rear, with the second method, I get 0.44 degrees of <b>toe out</b>!
I'm very confident that I'm doing the first method right, as I've compared measurements to those taken from a laser alignment rig. I'm not sure I'm doing the second method correctly...
Any thoughts anyone? Is there something about the offsets of the RACs that makes the angle greater than with other wheels? Or is it simply that the different front/rear track of the car makes the second method questionable?
EDIT: The front/rear track of the car is spec'd at 1457/1507mm (front/rear)... that's exactly the angle I'm measuring: arcsin((1507-1457)/2)/2300 = 0.623 degrees
EDIT2: xtn pointed out this potential problem in this post: http://www.lotustalk.com/forums/f91/little-diy-alignment-45655/#post795985... is it possible that Jack's car has spacers on the front wheels? If they were around 25mm it would completely neutralize the difference in track, and make the method accurate for his car.
Pics...
1) Sighting down the two strings, first method on the outside, second method on the inside. Even with the "vanishing effect", you can tell they are diverging...
2) Looking straight down on the left wheel... here it's easy to see the difference in angles
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