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I want to nail down whats a good setting, but its a little confusing cause the measurement can mean multiple things... for example:
- if measuring with strings you are referencing front to rear of wheel which measurement from center would be 1/2 this
- alignment rack in degrees or inches is from wheel center.
So when peeps say 1/16" is it string or rack value and is it 1 side or total.
So, my settings which feel pretty good on track
- 3mm diff in string measurement each side (taken at outer wheel flat)
- meaning 1.5mm from wheel center and 3mm total toe in
- sin = 1.5mm / 229mm (18" wheel) = 0.38deg 1 side and 0.75deg total toe in
What do you all run and please specify type of measurement. Thanks!
I want to nail down whats a good setting, but its a little confusing cause the measurement can mean multiple things... for example:
- if measuring with strings you are referencing front to rear of wheel which measurement from center would be 1/2 this
- alignment rack in degrees or inches is from wheel center.
So when peeps say 1/16" is it string or rack value and is it 1 side or total.
So, my settings which feel pretty good on track
- 3mm diff in string measurement each side (taken at outer wheel flat)
- meaning 1.5mm from wheel center and 3mm total toe in
- sin = 1.5mm / 229mm (18" wheel) = 0.38deg 1 side and 0.75deg total toe in
What do you all run and please specify type of measurement. Thanks!
I consider 'TOE' as the difference from straight ahead, or "zero toe". Measure from your string (at zero) to the front of the tire (in or out) REAR:
I would recommend that you measure toe "IN" at the front of the rear tire. If that is not possible because it is not accessible, then measure toe "OUT' at the rear of the rear tire (on a machine).
I would recommend one eighth inch toe-in TOTAL: or one sixteenth inch per side. FRONT:
I recommend nearly zero toe for the front wheels. Some people use toe-OUT, but I do not use that. (You "might" want to use toe-OUT if you autocross only....not track days or HPDE)
A C2 Corvette pushes or understeers, so I use a LOT of negative camber at the front: negative 3 degrees for front tire traction or bite..
At the rear, you need the rear tires more upright in order to accelerate out of turns, so I run only negative 1 to 1.5 degrees.
Thanks for the feedback, that's about where I'm at in the rear. Front i set to just barely toe in at about 1mm total. C5 BTW.
Yes, toe "should" be as you state diff from 0. But many track people take their own measurements with either strings or toe plates, which require actual measurements between front and rear of tire... so to match an alignment rack reading you'd have to 1/2 this measurement. Plus can take the measurements at various points on tire or wheel or plates so measurement means less without distance from center. Degrees is best but still have to 1/2 your string/plate measurement to get from 0 value. Anyway, just curious.
I agree, but sorry that I jumped to the conclusion that you were talking about a C2. I race a C2, and had just come from the C2 board, and just got confused?
I consider 'TOE' as the difference from straight ahead, or "zero toe". Measure from your string (at zero) to the front of the tire (in or out) REAR:
I would recommend that you measure toe "IN" at the front of the rear tire. If that is not possible because it is not accessible, then measure toe "OUT' at the rear of the rear tire (on a machine).
I would recommend one eighth inch toe-in TOTAL: or one sixteenth inch per side. FRONT:
I recommend nearly zero toe for the front wheels. Some people use toe-OUT, but I do not use that. (You "might" want to use toe-OUT if you autocross only....not track days or HPDE)
A C2 Corvette pushes or understeers, so I use a LOT of negative camber at the front: negative 3 degrees for front tire traction or bite..
At the rear, you need the rear tires more upright in order to accelerate out of turns, so I run only negative 1 to 1.5 degrees.
Hi Garrett,
I was curious to why you dont recommend toe out in the front the front for road race use? I am still learning in this sport but I currently have my c5z toed out an 1/8 total on the front, 1/8 toe in rear, with -1.5 camber front with caster near +9 and -1.2 camber rear. The car feels great and the tire wear is perfectly even. This is on a track only car. Would you recommend changing this?
Most of us run toe out in the front, you need it in the corners or the inside and outside tires fight each other. Zero toe is not recommended by many of us, but this thread was about the rear so I didn’t comment . Even stock alignment recommended toe out.
My 04 Z06 is a different animal from my C2. I personally don't like the "wiggle" that I get under braking when I use toe-OUT at the front of my 63. I have no problem with toe-out on the C5. As mentioned above, I misunderstood the OP question as being about a C2 rear end.
I do run at CoTA often, but will not be there this weekend (I am at MSR Cresson).
Most of us run toe out in the front, you need it in the corners or the inside and outside tires fight each other. Zero toe is not recommended by many of us, but this thread was about the rear so I didn’t comment . Even stock alignment recommended toe out.
Can you say more? To me, non-zero toe (in either direction) is the definition of the inside and outside tires fighting each other.
Can you say more? To me, non-zero toe (in either direction) is the definition of the inside and outside tires fighting each other.
When going around a corner, the inside tire is cutting a slightly smaller arc then the outside tire. Therefore, you need toe out in front to get the front tires to not fight against each other. The best way I can explain visually is to take your hands and hold them in an exaggerated toe in position, like you are looking down on your car. Now turn them equally and you will see your hands are pointing towards each other. Now do the same with your hands in an exaggerated toe out position and turn them equally. You will see that the inside hand is making a tighter arc then the outside hand.
Robert Finlayson
I use the smart strings chart to convert between inches and degrees. The chart shows using wheel diameter Vs the tire diameter. As long as you know the distance between the two points that you use to measure toe it really doesn't matter where you make the measurement if you convert to degrees. The chart gives figures for toe at a single wheel.
OP: I think your calculation is in error. You shouldn't use half of the mm measurement as the value for the opposite side. You should use the complete 3mm as the angle you are measuring is based on a right triangle that has its hypotenuse the diameter of the wheel, the apex of the angle is located at the point where the shortest distance to the wheel which means the opposite side is equal to the difference between the two measurements not half of the difference. The adjacent side is equal to the distance between the two measuring points on the string.
Bill
Last edited by Bill Dearborn; 08-30-2018 at 08:12 AM.
Hey Bill, thanks for the post. If taking front and rear of wheel, you are taking total + and - measurements from the centerline... hypotenuse in this case is the full wheel diameter. So in your diagram x2 458mm, instead of 229. Math works the same but actual toe is from centerline, thus the 1/2.
Check 3mm in your chart at 18" spacing, which matches my calc of 0.38deg each wheel... the actual distance from center or toe in is 1.5mm each wheel.
08-21-2018, 05:13 PM
Rear Toe In Settings
