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Old 05-21-2012, 08:07 AM   #1
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Default Front toe per turn?

I would like to know what the change in front toe (mm or angle) per one turn of the steering rods are. On my race car, I have made a tape “flag” on the steering rods so that I easily can turn half laps. But over the winter I lost my notes on how much change in toe one turn gives. Anyone who knows?

Thanks!
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Old 05-21-2012, 08:32 AM   #2
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Not sure, but that's a good idea!!!
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Old 05-22-2012, 03:21 PM   #3
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Nobody has this info?
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Old 05-22-2012, 11:02 PM   #4
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I know I've read it somewhere before. Try asking the autox guys on miata.net, they often adjust their toe at events.
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Old 05-23-2012, 03:29 AM   #5
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Good point. Of course, some searching found old threads on the theme om M.net.
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Old 05-25-2012, 08:48 AM   #6
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And the answer you found, for people searching in the future is...

Thanks.
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Old 05-25-2012, 12:04 PM   #7
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the answer is:

measure the perpendicular distance "d" from the axle centerline to the steering rod pivot (perpendicular to the axle and kingpin both--NOT the length of the arm at a funky angle)

measure the thread pitch "p" (distance between adjacent thread peaks)

take the arctan of p/d to get the angle change per full turn for one side of the car.

example (NOT MEASURED):

d is 200 mm
p is 1.25 mm
angle = arctan(1.25/200)
angle = 0.358 degrees.
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Old 05-25-2012, 02:47 PM   #8
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Haha, awesome. Someone paid attention in geometry class.
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Old 05-25-2012, 03:25 PM   #9
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I know that 1/4 turn is actually quite alot of toe.. but never memorized these notes.
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Old 05-31-2012, 08:07 AM   #10
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Maybe I should have returned to check this thread sooner...

Quote:
Originally Posted by Spookyfish View Post
I know that 1/4 turn is actually quite alot of toe.. but never memorized these notes.
Yes, I have found the same. Between 1mm and 1,5mm, according to the threads at M.net.

First race weekend is finished and the car is back in the garage again. On the 11th, I'll go back to my sponsor for an alignment again. I'll check then as the car is hooked up to the machine how much toe 1/4lap gives me and post back here.

To be continued...
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Old 05-31-2012, 10:24 AM   #11
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1 complete revolution of both sides will change toe by 7mm (source: 1999 workshop manual).
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Old 06-02-2012, 10:45 AM   #12
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Quote:
Originally Posted by Track View Post
1 complete revolution of both sides will change toe by 7mm (source: 1999 workshop manual).
Came in here to post this, left satisfied.

You can also do the rule of thumb "1 tie rod facet=1mm" if youre lazy. If Ive dicked around with the suspension and know its way off, I generally do that to get it close and then adjust from there.
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Old 06-02-2012, 09:41 PM   #13
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Quote:
Originally Posted by Spookyfish View Post
I know that 1/4 turn is actually quite alot of toe.. but never memorized these notes.
I've found on my car at various ride heights, centering around 4.0" pinch (from 3.5" pinch to 4.75") that roughly 1/4 revolution of the tie rod arm into/out of the tie rod end usually changes around 1/16" toe change per side.

(I measure my toe with toe plates, so I don't know the degree changes.)

Always wondered if anyone took note of the same/similar.
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Old 06-11-2012, 07:18 AM   #14
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Seams as my research is a bit redundant now, but as promised: I'm back from the sponsor with a fresh racing alignment. My cars ride height places the lower A-arms just horisontal. I found that 1/4 turns equals 0,1degrees, or 1,3mm toe per side.
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