Alignment/toe...how many degrees is each rotation of the shaft?
 

I want to play with the toe alignment in my car... Want to make sure I can get back to the current setting if I don't like the new setting...

Is there a rule of thumb for how much toe each rotation of the spindle/shaft adds to the toe?

For example, if you are running no toe (0/0)... and rotate both steering shafts 1 full turn... will you now be +0.5/+0.5?

Is each rotation 1/2 a degree? a 1/3? 1 degree?

Anyone ever measure?

So if no one knows what the answer is you can figure it out yourself.
Measure the thread pitch of the tie rod end threads with a thread pitch gauge (handy tool to have if you ever have to replace a bolt). If the thread pitch is 1 mm, then one revolution of the tie rod arm will move the wheel 1 mm. They you can do some trig to come up with the angle, which will be fractional (think of a triangle with one leg being 16 inches or whatever the diameter of your wheel is and the other leg being 1/2 of your total toe measurement). Multiply that fraction by 60 (minutes in a degree) and you will have your toe measurement in the proper form to compare to the spec.

If you don't want to do that just do an A-B comparison of your toe.

Doesn't everyone talk about toe in units of length, rather than degrees? Either way can work, but I think conventionally you'll hear people say things like "I've got 1/16" total toe-in in the back". You might be better off thinking of it that way. No trig and no confused looks when you try to compare settings. Just measure the difference from front of wheel to rear of wheel and call it a day.

Good point. But when you take it to an alignment place, the printout is in degrees. So if you say I want "1/16" in, they will just look puzzled...

Just use this: https://robrobinette.com/ConvertToeInchesToDegrees.htm

Ray Scruggs says 1/4 turn of tie rod equals 1/8" of toe adjustment.

The only way to be consistent is to talk degrees, that weeds out any non-trig types. If you want 0, then no trig required. The amount of toe-in is usually 0 to a tiny amount so not such a big deal for a street car. I can't notice difference between 0 and a mm or two, measured at the rim vs using trig.

Yet most of us racers talk in inches. Like my race car has 1/8" front toe out measured with toe plates. When the car was setup using strings, I had a little less than 1/8" front toe out since the measurement points were a little closer together.

Thanks, that helps...

May need to get a protractor up to my wheel and see what that is in degrees...

I got a free wheel alignment check when my wheels were getting mounted at Tires Plus...

Car tracks really well, very slight drift to the left after a while...

Caster, camber equal up front.

Toe + 0.2 degrees left, +0.5 degrees right... Steering wheel sits straight

In back, slightly greater difference...

Tires wearing well, handles great even on the track. Wasn't going to mess with it, but figure might be worth adjusting the front toe a smitten...

Didn't want Tires Plus messing with it, as I didn't want it adjsuted to some basic default recommended setting...

Not sure its worth messing with... for all I know the steering wheel was tilted a fraction of a degree...

Correct unit of measurement.....
 

Toe measurement is in (°) and many has not practiced trigonometry or forgotten about it. While it is common for people to refer to linear measurements, the correct unit is degree (°). A good example is to read is Kaefer's above post. A car with 15" wheel will have a different toe value when you install a larger 18" wheel unless the toe is @ zero degree.

Tony

Anyone that is using strings is measuring in inches or millimeters. They may convert to degrees but they are measuring in inches or millimeters.

Again, at the race track, just about everyone talks inches. It's pretty easy to use tow plates at the track to check toe and to adjust toe.

Depends.
In my case, I was setting my car up to the factory spec for an RS. Spec in in degrees. So I had to convert degrees to millimeters and then perform the alignment.

Bpu699, if you plan on doing your own alignments, I recommend picking up a Longacre camber/caster gauge off of Ebay. It's saved me a lot of time and heartache to use it.

A little Trig.
 

So BPU699, I decided to do some easy trig at my desk. You say you have +.2 and +.5 degrees which is +.7 degrees total. If I'm doing it correctly, .7 degrees measured on a 16" rim would give you a "total" measured .19" (3/16") toe out or almost 5mm.
That would normally be considered a race car place to be as I've heard others say.
My owners manual says spec. on the front is .16 to .3 degrees Toe IN total. I can easily adjust to get 2 or 3mm "total" toe in measured on my 17" rims. I hate my steering wheel to not be centered so I've messed with toe to keep it centered. You're probably right in saying its barely or not noticeable in normal driving. Over a long time, you could have more tire wear but and you may actually like the way toe out works for how you drive.

Pretty sure I have toe in... The digital print out from the wheel place shows that on their machine a "+" is toe in...

I do appreciate the math help :). Will try to add some toe out on the right wheel, perhaps a 1/2 a twist of the tie rod... Probably will make no appreciable difference ;).

You are probably right then that its very close to spec. Like you say, try adjusting that right side in a tad but know that it may mess with your steering wheel center a little just have to drive it to know.

Correct me if I'm wrong but I believe that tie rod lengths should be kept close to equal on both sides and then the steering wheel would be indexed so that it is centered. This would allow for equal travel of system side to side

I think that if you don't change the relationship of the steering wheel to the rack itself then you mostly avoid any issue. As long as you're car is going straight down the road and alignement is close, small changes like we're talking about here at the front are not at issue. 1/4 or even full turns of a tie rod end thread won't get you in trouble. Now if you pulled the steering wheel and put it back a spline off, you might get caught chasing things way off center with less or too much travel in one direction.
Pretty sure that measuring or equalizing threads is not a good way to align. Might give you info that the steering wheel is on the right spline, maybe ?

Not suggesting that you use it as a way to set alignment but as a starting point for doing an alignment. That might mean adding a turn or two on one tie rod and removing an equal amount from the other side to get the rack centered before the actual setup is done.

Just wanted to follow up. I got an alignment today at a performance-oriented shop. The alignment was done with a Hunter Hawkeye. Camber/caster in degrees. Toe was in inches (hundredths), on the screen and the printout.

I brought my own desired specs and they immediately said they wanted toe in inches, and gave the usual fractions like 1/16" as an example.