Technical How I set toe-in

I was setting the toe-in on the roadster and thought I would share how I do it. I have no idea how most people do it. I tried measuring from tire treads but gave that up and made this.
I am a slob.
I use a trammel that I made from scrap. I made it a long time ago.
It is a piece of pipe with two straps that can be moved and tightened in position. They have marks at the top. I put tape on the tires and mark lines on the tape by turning the tires. The trammel straps get lined up with the lines. The trammel is then moved to the other side. Repeat as much as required to get the toe in set. It is very sensitive to set. I figured that one turn of the tie rod changes the toe-end by about 5/8 in.

 

Of late I’ve been plumb bobbing the center line of the tires and marking the floor. Amazing how a tape measure behaves so much better on a flat surface. Oh, the plumb stores a lot easier as well.

 

I use the carpenter's framing square on the center tread and mark the corner on the floor.
Rear left, rear right.
Front left, front right.
Measure rear, measure front.
Adjust toe to spec.

 

My method , I didn’t really trust a pen line on tape. I rebuilt the whole running gear , but assumed the tie rod was correct . After a few hundred miles we got the dreaded death wobble. Ha the front end had 1 1/4” toe in . Somebody in the past just guessed it .

 

I set my toe and recheck for square-ness the first time after all the paint and powder coating is done and the chassis is a roller - using a tape or a couple dowel rods taped together. Much later when the body is on and everything is working properly, I drive it to the alignment shop.

 

Slick stuff. At the track with the stock cars, we marked the tires with a piece of 2 x 4 and a rusty nail... the rest was a tape measure job.

 

A friend passed this method on to me. Hang a straightedge above the tire bulge from both front tires (mine are bed frame angle) and measure across the front and back with a good 1" blade tape measure. Nice and simple.

Gary

 

I've done several hundred of them simply by lifting the tire off the surface, holding a pencil to the tread of the tire with something to steady my hand and slowly spinning the tire so I have a visible line around the center of the tread. do the other side the same, measure from the line on one side to the line on the otherside at the back and repeat at the front and calculate the difference. The only problem with that is that you have to have a helper who will hold tape exactly where they need to.

The setup that Kiwi 4d posted at least is used when you set the chassis up without tires on the hubs and works. That lets you get that part done on an I beam front end where the toe in isn't going to change when you set the car down on it's tires. It won't work on and independent front end.

That hanging the angle iron on the sidewalls again is cute but doesn't take in wheel or tire run out. it gets a ball park figure that may be up to a quarter inch off depending on wheel and tire runout. These setups are just amature hack setups that really aren't that accurate.

I bought a pair of turn table plates from a used too peddler a few years ago that came with the fasten on the wheels aparatus to check toe in and even has two tape measures.

Just don't overthing it guys, it isn't rocket science and you don't need some elaborate setup to do it. You just need a jack, pencil and tape measure.

SnapOn did make a tire scribe tool back in the 40's an 50's and maybe earlier to scribe the line on the tread but I have never got my hands on one.

 

My brother made his own "turn tables" using some flat stock steel, 2 per side with grease between them. It worked pretty well.

 

I’d thought of that, but then thought the plates may “pop up” a bit and change location when they settled down.
Do you recall any details?

 

I have used 4 1 foot square pieces of Masonite board Take one piece slick side up and apply grease put another piece slick side down on it for both sides it makes it easy to grab a wheel and turn it side to side I use it with an old TRI ang-u-liner it's amaizing how close you can come https://www.bing.com/images/search?view=detailV2&ccid=PH92lhE5&id=F48202A387E6286D4C11D342DEBA81F02D096D9E&thid=OIP.PH92lhE52RphDatl69V92gAAAA&mediaurl=https://i.ebayimg.com/images/g/PiEAAOSwQRNfIyCR/s-l500.jpg&cdnurl=https://th.bing.com/th/id/R.3c7f76961139d91a610dab65ebd57dda?rik=nm0JLfCBut5C0w&pid=ImgRaw&r=0&exph=500&expw=375&q=tri+ang-u-liner+alignment+gauge&simid=608051903732526736&FORM=IRPRST&ck=CEBF6B6F8AAA6CDA5711167C4DBF6B83&selectedIndex=0&idpp=overlayview&ajaxhist=0&ajaxserp=0

 

I was taught to roll the vehicle forward at least one or more tire revolutions to load the steering joints just as if it rolling down the road. One would mark the center of the tires with a scribe while spinning the tires, then after rolling forward, measure off those scribed lines.
Just hanging off jack stands doesn't give an accurate measurement.
Swivel plates or greased boards comes closer.

 

I guess measuring between 2 angle irons is good enough for me since I am an amature hack. 45k mi. on one and 16k on the other without terrible tire wear. A couple of sheets of wax paper on a clean floor works for turn plates but I don't usually use it since I run my cars back and forth a couple of car lengths before rechecking.

Gary

 

I was about to call you an amateur hack but I see they index on the wheel.

 

For many decades I've simply used a homemade jig using a stick of 1/2" EMT conduit, and some bases welded to sit on the floor. Once I'm done with setting up a solid axle I slide the EMT tubing out and put the tubing and the stands aside for next time. I made the stands up so it's easy to use on either side of the front wheels, and clear cars, regardless of stance.

 

My procedure is to leave the tires off the ground after scribing the center lines.
I could just rotate the tires and not have both sides taped. I am lazy and have to move the trammel to the other side so leaving the tires be saves a step.
I don’t need turntables or sliding plates or to move the car back and forth.
I don’t trust the wheels or tires to give a true surface to measure from. I have confidence doing it my way.

 

If the wheels & tires are not a true surface to measure from ,what are you measuring from ?

 

To really align accurately within a range of 1/8" or so the reference needs to be a bunch more accurate than that.

The sidewall and other manufactured features on tires can be a relative mile off, and of course wheel runout can add to that a lot..
Steel wheels are not far behind.
Machined alloy wheels might be OK, but a dial indicator sitting on the floor needs to be used to confirm axial runout before assuming they are.

Maybe the face of the brake or hub run pretty true, but tough to reference if the car is sitting on it's tires at ride height.

A scribed line on each tire can create a pretty accurate "plane" on true to the axis of rotation of the tire/wheel/hub assembly, which is the reference needed for a real alignment evaluation.

 

I don't follow the statement that the tires and wheels aren't a true surface to measure from either.

Sure tires aren't perfect in their dimensions, but they're what are in contact with the ground. Therefore when measuring for alignment, relationship of the wheels and tires with the ground/vehicle is very important.

 

So, let's try a question.
On a solid axle rod, if you swap out 28" tall front tires for 24" tall tires,
does the toe in change?

 

Yes and no.

 

Of course it does. Toe is the difference in width of the leading edge of the tire compared to the trailing edge. If you move the measurement point relative to the tie rod (changing tire diameter), then the measurement changes.

 

I bought my front end setup from the local So-Cal dealer. He assured me all the parts were correct. When I assembled it all, the tie rod was 2" too long.

It was easy to see with the axle on the bench, though.

 

This is where that “weird” thing of degrees comes into play.

 

Yeah, for everyone who said they didn't need to understand geometry.

 

Or read a compass while flying half way around the world and can’t find your destination.

 

From what I've read ,industry standards is " within .060" " that's most ways you can measure . That's nearly 1/16" , not hard to get dubious measurements off a tire .
Pro alignment equipment attaches to the rim after wheel bearing runout & rim " trueness" is confirmed .

 

Been using this kit for years on on our Circle track car and my 56 Ford.