Quick question about adjusting toe on a C5
04-08-2007, 10:51 AM
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St. Jude Donor '08-'12, '14-'15
Quick question about adjusting toe on a C5
Had my car realigned at a local shop back in December for the upcoming race season. Although this is not a 100% dedicated race car I use a pretty aggressive set-up for street and track. Majority of my races are SCCA and NCCC Autocross with maybe one HPDE this year. After my first race I noticed the car wants to go all over the place. Had it up in the air recently at a more profession shop (dealership I trust actually) and while the Camber and castor numbers were right on the the Toe numbers seemed way out of wack.
I'm used to reading in terms of inches...so I have some pretty simple questions just to make sure I'm understanding properly:
The toe reading were as follows:
FRONT: -.20 and -.21 = -.41 total toe (the negative number is toe out correct?)
Based on my quick calculations that would be ~ 1/4" toe out on EACH tie rod....for a total of ~ 1/2" toe out
REAR: .25 and .26 = .51 total toe (the positve number is toe in correct?)
Looks like the rear is even more off at more that 1/2" toe in
QUESTIONS:
#1) Am I understanding the numbers correctly?
#2) Are my calculations converting to inches from degrees correct?
#3) Am I correct to assume that I have currently WAY too much toe out in the front and toe in the rear.
#4) Trying to get 1/16th total toe out in front and 1/8th total toe in for the rear...this would be ~ -.06 for the front and ~.12 for the rear is that correct?
#5) When adjusting toe how much to turn the tie rod end to get a 1/32" change in toe?....
It's been awhile since I adjusted the toe at the track so I have a question about the adjustments...kind of simple I just want to get some qualified opinions. In other words in simple terms if all of my calculations are right the it looks like I would need to take ~ .17 out of each front tie rod to get the car to handle the way it should. After loosing the jam nut how much should I have to turn the tie rod (Counter Clockwise to add toe in up front if I remeber correctly) to get to the -.03 or 1/32" of toe out in the front (per wheel)?
This will be a simple question for many of you so thank-you in advance for the help
I'm used to reading in terms of inches...so I have some pretty simple questions just to make sure I'm understanding properly:
The toe reading were as follows:
FRONT: -.20 and -.21 = -.41 total toe (the negative number is toe out correct?)
Based on my quick calculations that would be ~ 1/4" toe out on EACH tie rod....for a total of ~ 1/2" toe out
REAR: .25 and .26 = .51 total toe (the positve number is toe in correct?)
Looks like the rear is even more off at more that 1/2" toe in
QUESTIONS:
#1) Am I understanding the numbers correctly?
#2) Are my calculations converting to inches from degrees correct?
#3) Am I correct to assume that I have currently WAY too much toe out in the front and toe in the rear.
#4) Trying to get 1/16th total toe out in front and 1/8th total toe in for the rear...this would be ~ -.06 for the front and ~.12 for the rear is that correct?
#5) When adjusting toe how much to turn the tie rod end to get a 1/32" change in toe?....
It's been awhile since I adjusted the toe at the track so I have a question about the adjustments...kind of simple I just want to get some qualified opinions. In other words in simple terms if all of my calculations are right the it looks like I would need to take ~ .17 out of each front tie rod to get the car to handle the way it should. After loosing the jam nut how much should I have to turn the tie rod (Counter Clockwise to add toe in up front if I remeber correctly) to get to the -.03 or 1/32" of toe out in the front (per wheel)?
This will be a simple question for many of you so thank-you in advance for the help
04-08-2007, 03:35 PM
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Factory service allowable front toe settings are .14 to -.06 with .04 being service preferred. Front Sum Toe readings can be 0.28° to -0.12°
with 0.08° being service preferred.
Factory allowable rear toe settings are 0.09° to -0.11° with -.01 being Service preferred. Rear Sum Toe settings can be 0.18° to -0.22° with
-0.02° being service preferred.
A Hunter Engineering document I saw says you can convert degrees to inches by dividing degrees by 2 to get inches. Using that rationale .2 degrees would equal .1 inches or a little less than an 1/8 of an inch. This rational may only hold for measurements taken on their machines as a degree can cover a lot more distance than a half inch depending where you measure the distance from one side of the angle to the other side.
If your car was set up on a Hunter machine (likely) then you probably have about a 1/4 inch total toe out in the front and very close to a 1/4 inch toe in in the rear.
Bill
with 0.08° being service preferred.
Factory allowable rear toe settings are 0.09° to -0.11° with -.01 being Service preferred. Rear Sum Toe settings can be 0.18° to -0.22° with
-0.02° being service preferred.
A Hunter Engineering document I saw says you can convert degrees to inches by dividing degrees by 2 to get inches. Using that rationale .2 degrees would equal .1 inches or a little less than an 1/8 of an inch. This rational may only hold for measurements taken on their machines as a degree can cover a lot more distance than a half inch depending where you measure the distance from one side of the angle to the other side.
If your car was set up on a Hunter machine (likely) then you probably have about a 1/4 inch total toe out in the front and very close to a 1/4 inch toe in in the rear.
Bill
04-08-2007, 05:46 PM
#3
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Factory service allowable front toe settings are .14 to -.06 with .04 being service preferred. Front Sum Toe readings can be 0.28° to -0.12°
with 0.08° being service preferred.
Factory allowable rear toe settings are 0.09° to -0.11° with -.01 being Service preferred. Rear Sum Toe settings can be 0.18° to -0.22° with
-0.02° being service preferred.
A Hunter Engineering document I saw says you can convert degrees to inches by dividing degrees by 2 to get inches. Using that rationale .2 degrees would equal .1 inches or a little less than an 1/8 of an inch. This rational may only hold for measurements taken on their machines as a degree can cover a lot more distance than a half inch depending where you measure the distance from one side of the angle to the other side.
If your car was set up on a Hunter machine (likely) then you probably have about a 1/4 inch total toe out in the front and very close to a 1/4 inch toe in in the rear.
Bill
with 0.08° being service preferred.
Factory allowable rear toe settings are 0.09° to -0.11° with -.01 being Service preferred. Rear Sum Toe settings can be 0.18° to -0.22° with
-0.02° being service preferred.
A Hunter Engineering document I saw says you can convert degrees to inches by dividing degrees by 2 to get inches. Using that rationale .2 degrees would equal .1 inches or a little less than an 1/8 of an inch. This rational may only hold for measurements taken on their machines as a degree can cover a lot more distance than a half inch depending where you measure the distance from one side of the angle to the other side.
If your car was set up on a Hunter machine (likely) then you probably have about a 1/4 inch total toe out in the front and very close to a 1/4 inch toe in in the rear.
Bill
Does anyone have an answer for the other questions. Since I know that both sets of tie rods are adjusted the same...I just need to make a equal adjustment to both sides which is pretty simple after marking the rods....so the other question...
Which way to turn the tie rods to take some of the Toe Out from the front and remove some of the Toe In from the rear?
...and how much much of a turn to take 1/16th" ...in other words 1/4 turn of the tie rod equals approximately what in terms of 1/16th of a inch??
I know I can get out camber plates and all of that, however since I already know where I'm starting from it should be an easy adjustment if I know how much the Toe per side will changer per 1/4 turn
04-08-2007, 06:41 PM
#4
Melting Slicks
From zero toe to "track setting" I have been using about 1/2 turn of toe out (turn to lengthen the tie rod) in the front. I forget what the ratio is from the tie rod to the edge of the tire, but the threads are about (it's metric, but "almost" 16 threads per inch, close enough) 1/16 of an inch of tie rod per turn, per side. I was thinking that this was a pretty modest amount (like 1/8 inches of total toe if you did 1/2 turn per side), but I haven't looked at the ratio between the tie rod and the outside of the tire in a year or so...
If the ratio from the tie rod to the edge of the tire is say 2:1 (I know it is smaller than that, but you can measure it with a tape measure and figure it out pretty quick), you will get about 1/4 of an inch of total toe per side for 1 turn of the tie rod. That is, the front edge of the tire will move out twice what you turn the tie rod (1/8 of an inch in this case)and the inside will move in the same amount, so you would get 1/4 inch per side of total toe for one full turn of the rod.
Mark you rods with something that won't come off in the rain, and you are cool.
If the ratio from the tie rod to the edge of the tire is say 2:1 (I know it is smaller than that, but you can measure it with a tape measure and figure it out pretty quick), you will get about 1/4 of an inch of total toe per side for 1 turn of the tie rod. That is, the front edge of the tire will move out twice what you turn the tie rod (1/8 of an inch in this case)and the inside will move in the same amount, so you would get 1/4 inch per side of total toe for one full turn of the rod.
Mark you rods with something that won't come off in the rain, and you are cool.
04-08-2007, 08:58 PM
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So your basically saying I would get a total of 1/4" of total toe with one full turn ON EACH tie rod end...if that correct? In other words I would get 1/8" of toe per side with one full complete turn of the tie rod on each side...is this correct?
04-08-2007, 09:34 PM
#6
Race Director
in my experience, 3 "flats" , or 1/2 turn, =1/16"
so for me, 1 turn on EACH side would be a total of 1/4". That pretty much confirms what you've said above.
if you haven't checked out my DIY alignment guide, do so. I'm going to update it with detailed instructions on actually adjusting the C5/C6 soon.
http://www.davidfarmerstuff.com/
so for me, 1 turn on EACH side would be a total of 1/4". That pretty much confirms what you've said above.
if you haven't checked out my DIY alignment guide, do so. I'm going to update it with detailed instructions on actually adjusting the C5/C6 soon.
http://www.davidfarmerstuff.com/
04-08-2007, 10:13 PM
#7
Melting Slicks
You need to measure and figure out the "linkage ratio" between the tie rod end and the tire diameter. I was just giving an example, if the linkage ratio is 2, then the calc is correct. Find out the correct linkage ratio, that is, the RADIUS of the tire divided by the distance between the tie rod end and the kingpin axis. That ratio times the thread pitch (1/16) times two (since the front of the tire is moving in as much as the rear is moving out) is the total toe change per side, and times two again since you will do two sides the same. That gives you the total toe change.
What David is saying is probably correct, the linkage ratio is probably around four, since I was shooting for 1/8" of total toe out (if I reacall correctly) with a half a turn of toe out per side. Just take a couple of minutes to measure it and you will have all you need.
What David is saying is probably correct, the linkage ratio is probably around four, since I was shooting for 1/8" of total toe out (if I reacall correctly) with a half a turn of toe out per side. Just take a couple of minutes to measure it and you will have all you need.
