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Cleverly Designed Toe-In Adjustment ?

Posted: Sun Dec 13, 2015 10:39 am
by kiev
i don't know if Mitsu did this on purpose, but i like to think that they did.

The steering tie-rod is M12 x 1.5mm threaded rod with 6 flats in the rod at 12mm across the flats, so you use a 12 mm wrench to adjust after loosening the 17mm jam nut.

The distance from the steering pivot to the tie rod is 4 inches, and the distance from the pivot to the rim (where the toe measurement is made) is 8 inches. So there is a 2:1 gain ratio between the adjustment point and the measurement point (e.g. 1mm of adjustment will change the toe-in by 2 mm).

As it works out, with the 1.5mm threads and the 2:1 gain, turning just 1 flat of the tie-rod will move the toe-in by 1 mm. 1 full turn would be 6 flats and that would change the toe-in by 6mm (that would be huge).

This design makes the adjustment so easy for a mechanic to figure--just take the measurement and determine the desired correction in mm, then turn the tie-rod that number of flats.

For example i recently measured 3.5mm on L and 2.5mm on R, so the total was 6mm, which is at the upper limit of the toe-in spec (3 +/-3mm). i wanted to adjust to 0 at the lower spec limit to reduce friction from scrubbing, so i only had to turn in 3.5 flats and 2.5 flats to reach the target.

Re: Cleverly Designed Toe-In Adjustment ?

Posted: Sun Dec 13, 2015 2:13 pm
by JoeS
Hi Kenny - that's brilliant!

I'm curious how you measure your toe-in?

Here's a reasonable video on the subject that is an alternative to measuring to a gap in the tire tread:

Re: Cleverly Designed Toe-In Adjustment ?

Posted: Sun Dec 13, 2015 2:58 pm
by kiev
i wrap a long string along the trailing edge of the rear tires and up along both sides to 2 jack stands about 20 feet in front of the car. i use 2 little wooden blocks (1" cubes) to space the string out 1" off the rear wheel and adjust the stands to establish parallel string lines along both sides of the car (or motorsickle), then measure the gap between the string and the wheel rims using a caliper. There are numerous videos of string methods, some quicker than others.

The toe-in is the difference between the string gap at the trailing edge and the leading edge of the front wheel rims.

On my car the distance between the parallel strings was 61-1/2", and the nominal gap at the rear wheel was 27mm and at the trailing edge of the front wheel about 15mm.