First of all, thanks to Terry, Inlinesix for the inspiration. I took Terry’s idea for measuring toe and modified it a bit.
I assembled the measuring tool out of two sections of 2X6, 12" long. To the top 2X6 I attached a length of 1X1 of the same length. To this I attached a 29" piece of aluminum angle. The 1X1 allows the 2X6 base to stand out from the tire bulge
The black mark in the center of the angle marks the center that goes directly under the knockoff, the black marks at the two ends (one hidden under a piece of blue tape) mark the diameter of the tire The piece of I beam is my portable anvil, it’s sitting unattached to the thing to add weight so it doesn’t move around.
To measure toe, place a piece of tape on the floor under each of the two blackmarks at the end of the angle. Drop a plumb bob down to the tape and mark where it touches the tape. Do this at the front and rear of each side. You wind up with four marks on four pieces of tape. Next measure the distance between the two front marks and the two rear marks. The difference is total toe.
When I measure I put the 10 inch mark of the tape measure at the front mark and then place the I-beam on the tape measure to keep it from moving while I go around to the other side of the car to get the reading. Then I repeat that process on the marks at the rear of the tire.
It takes about 10 minutes max, you don’t have to move the car to measure anything, and it can be accomplished by one person using one tape measure.
I’ve checked the process by measuring, driving the car, pulling back in the garage and measuring again, about 4 times. I get the same measurements each time so I think it’s pretty dependable.
Help me out here because I always get wrapped around the axle (no pun intended) when thinking this through. How does this technique ensure that the toe is actually referenced to the center-line of the car as in this diagram?
IOW, is it possible that one wheel has zero toe and the other has toe-in such that elementary trigonometry would indicate on spec? Or, one could be toe out and the other toe in and show on spec?
The spec for toe is a dimension, e.g. 1/8", not degrees. The measurement of the distance between the front of the wheels (not tires) should be less than that at the rear of the wheels for toe-in. The car center line does not come into play. Start with the wheels in a straight-ahead position and both wheels move in or out at the same rate when you turn the tie rod tube since the ends are threaded one left, one right.
It doesn’t really matter. Worst case, you get done ,and fine with the steering wheel straight ahead, the car wants to go slightly left or right. If that happens, you simply SHORTEN one tie rod, and LENGTHEN the other by the same amount, until the car goes straight when the steering wheel is straight.
Don’t make this more complicated than it is. Toe is NOT a terribly critical adjustment.
I imagine it’s not difficult to determine the center line of the car, although I’ve never done it. Find two consistent points on each lower control arm in front and drop a plumb line down and mark the spot, Measure the distance between the two marks, divide by 2 and mark the spot under the car. Repeat with the rear dropping your plumb bob from somewhere on the rear suspension. Pop a chalk line between those two center marks and extend that line past the front tires. That’s the center line of the suspension.
From memory, I think the centerline is important when determining thrust angle, not so much when measuring front toe.
If you are able to make a straight run into your garage without turning the steering wheel you most likely have the front wheels straight enough to measure and set the toe. The manual says you want 1/16" to 1/8" total toe. So if you established, and are measuring from the center line, each side would be one half of that.
Odd, it seems like I posted to this thread before, but evidently not. Another senior moment.
Toe can be specified in degrees or inches/mm. The former is independent of tyre diameter, of course. The latter depends on tyre diameter. One purpose of toe is to compensate for “camber thrust” which is outward when camber is set positive.
Factory settings for camber and toe were based on fitment of factory tyres or equivalent. Compared to the sixties or seventies, newer tyres are likely to be stiffer, or lower aspect ratio, and maybe wider. Their slip angle, which determines camber thrust for a given amount of camber, is probably not as original, likely much less. Because of these factors, camber can be and often is reduced, even to zero or perhaps negative. This changes the amount of compensatory toe needed–to zero or, just guessing here, possibly negative as well.
So the original specs are based on factors no longer relevant. I think “slightly positive” toe is probably the best bet. You avoid the instability of too much negative toe, and avoid the scrubbing effect on tyre wear of too much toe. IMHO.
It will find its own center line when going down the road. If too far off it will pull left or right
The real trick is, if you’re as anal as I am, is to have the steering rack centered (same amount of turns to the left and right) once you achieve the correct toe in. In my case once I achieved the correct toe in I had to turn both tie rods the same amount (one to shorten and the other to lengthen ) to center the rack for travel while maintaining the toe in.
Once that was done I centered the steering wheel…
