it's me and my garage here.. i'm in the middle of setting up my front steering, and while waiting for the parts to rebuild my steering box i figured that i would set the toe adjustment.. i have tools and enough knowledge to get me in trouble.. Model A frame, 4 drop axle(ford), 40 box set up for side steer, 39 spindles(steering arms bent to run tierod under bones),16x4 steelies 500/550 tires... 7˚ caster.. i understand the reasoning behind an accurate toe adjustment.. and have researched how to do it, and yes i understand that ackraman plays a vital part in all of this.. what's puzzling me is how to set the tires perfectly straight forward..BEFORE the toe is adjusted??? perhaps it's a simple answer.. i do have a tendency to over complicate things... any suggestions??
Just get your rack to its center, or your pitman to its center and then find an accurate centerline to measure out to the wheels, front an back, just as if youaresetting each individual toe in adjustment with the centerline being the other tire... with all other things centered, your tie rod ends should be adjusted equally when finished. (same or similar amount of threads showing...)
The easiest way is with a peice of string?,take a long peice of old fashioned white string,tie it to the frame behind the rear wheel,now hold it up in the center of the rim area and move to the front with it,stretch it out and just touch the sides of the tires with it,iy should just touch the edges of the tires,move the wheel so it is flush with the string,you are using the string as a straight edge to get the wheels in line with each other,i really suck at directions,but you should be able to visualise what i mean,you can run the string around all 4 wheels and it should make a box?,you adjust the toe in with your tierod ends,you should be able to get it close enough this way so you can take it to a alignment shop,Im sure others will have a way to do it also,we use this in our shop on damaged vehicles so we can get them to the alignment shop. Harvey
Kneel down in front, look at the inside of each tire, 'gunsight' inside front and inside rear sidewall, line them up...note how much rear tire tread is visible past this visual line. Do the same on the other side, turn steering wheel a little 'til they're the same. Easy once you see it, but anything within 6 degrees won't be affected by Ackermann, caster, etc. You do know toe is measured at the tire tread, right? Reason I ask is that a 'known expert' argued with me that toe would have to be checked from between the backing plates. "You can't measure from rubber!" He was rigid. (guess what the quotient would be at the tires, with 1/8" backing plates difference!) I laughed.
Thanks Harvey I was actually visualizing a similar technique... Willy.. At the moment the box is out and apart..I needs ro be rebuilt(waiting for parts), and at the moment I don't have my drag link set up...I'm starting with the toe adjustment... Thanks!
You can sight down the inside walls of the front tire if the front and rear track are the same. On stock cars, we'd spin the front tires and mark a center line all the way around the tread. Measure at the back of the tire and then the front, the result is your tow in or out (my stock cars used a 1/4" out). It can be pretty accurate if you center the steering wheel and jam a wood block between the seat or steering wheel to keep the steering box centered. Bob
To make the ackerman work correctly, after the steering arms were heated and bent they need to be aligned as well. Put a sting across the top center of the spindle, then tie it to the center of the rear axle. The center of the tie rod hole should fall along this line. Sometimes a second heating and bending is needed. Let it cool slowly.
Measure between the tires in front, and in back. They should be 1/16 or 1/8 closer together in front. This will get you close enough to drive to an alignment rack. If you want to be real accurate and do it yourself here is how they aligned race cars in the 30s. Get 2 steel plates about a foot square and 3/8 thick. Put one on top of the other with grease in between. Line them up perfect. Push or drive the front wheel over them. If the car's alignment is perfect they will be undisturbed. If the alignment is off the top plate will twist. When you do this test it helps to have a 3/4" thick board in front and behind. The steering box should be exactly centered when the wheels are straight ahead. Check this by turning the steering all the way from left to right and count the turns. Then set it exactly in the middle. The steering wheel should be straight. Now adjust the tie rods so the tires are going straight and the steering wheel is centered.
It is hard to get a good measurement on the rear sides of the tires due to fan,engine, hoses, etc. Long ago, I made a toe in tool. It is plates welded to tubes that will side over some 1/8" pipe. I welded nuts to the tube sides and some cross bars to some 1/4" bolts. I jack up the wheels and spin them to scribe a centerline on them. Put a mark on the plates and line them up with the scribed lines. Compair front and back.You can get very accurate with this rig. The plates need to be 12-14" high to get to the center of the tires.
When my current coupe was ready for the road I aligned my tires "by eye" -- had bad death wobble. so I measured on the tires (yah on rubber) -- the tires were new, I measured the back of the tires and the same tread width on the front, adjusted it to 1/8" narrower at the front ... Death wobble gone, drives fine, I don't see how an alignment shop could do it better as far as the ride is concerned. To answer your specific question, just do what willy301 said.
This is the way big trucks are still done. You must scribe a line when working with 1/8" tolerance. Tires/wheels can easily be so far off, that your sidewall or tread groove measurement is useless. In other words, why do it, if it most likely is inaccurate. This is a real automotive alignment scribing tool, easy to copy, just a spring loaded needle:
Get two drywall squares ,Make extension bars bars.I did my backing plates ,I havent checked tires yet though
He wrote it out almost exactly like I was set to. Personally I would rather have the steering box on the car and hooked up before I set the toe in but on your car it can be done before you put it back if you want to. Do as BobSS396 said above and jack the car up and while spinning each tire scribe a line on the center of the tread with a pencil. It works best if you use something to steady your hand that holds the pencil. I can't remember what I used now but I did a lot of them that way 35 years ago. The line should circle the tire and come back on it's self when you get the tire spun 360 degrees. When you have both tires scribed lower the car to the ground with both tires point as straight ahead as you can get them. That is by sighting down the inside or outside of each tire to the back tire and getting the tires set so both site lines hit the back tires in the same spot. Now lower it to the floor, bounce the suspension a couple of times with your weight to settle it out and get the tape measure out and while having your helper hold the tip of the tape on the line on the back side of one tire up about as high as the tape will pass under the car in a straight line measure the center of the line on the other tire. Write that measurement down. Now measure the front side at the same height and at the same spot on the line as you did the back. write that down. If the front measurement is less than the back measurement you have toe in. If the front measurement is more than the back measurement you have toe out. Now once you know if it is toed in or out and if the toe in isn't what you desire to have you have to adjust it and measure again. Repeat until you get what you want for toe in and tighten the tie rod sleeve bolts and you are done.
Mr48.. the box is back in the car.. everything is marked and ready to be measured... that's tomorrows project.. thanks for the simplistic description... this is the way my instincts were telling me to approach this.. good to see that some instincts are good- cheers!
I would add one thing, after any change in the toe adjustment, roll the car backward for 10 feet or so, then roll it forward and re-check. The tires will take a set and sometimes you can see a change in toe.
Jack it up.Find exact center on steering wheel,the sweet spot on steering(neutral). Place a block in front of tire to steady your hand and use a piece of chalk on block and rotate tire,this gives you a broad white line around tire. Do the same thing this time use a pencil to make the line on chalk line.You will now have a line you can see, measure front than rear and adjust as required. Best to locate a center point on car to check if center of wheels are at the same distance from center of frame for your first measurement.
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