anyone know how to align cars with the string method?

Messages
219
Location
milpitas
yo what up guys. i got an alignment yesterday because my ****en Toe was way off. my tires wore down badly. i just thought of making a new topic on this board. does anyone know how to do this method? i heard of it, but just like to know what its like. thanks
 
Messages
1,183
Location
Vermont
I'd have to go book hunting in the basement to get the information on alignment by string method. One method that I've used on level ground to get a ballpark toe measurement on the front end is by... Raising each front wheel so that you can rotate it by hand. Take a crayon/chalk piece with a fine point and hold it steady against the tire as you rotate the wheel. You could also hold a square on the pavement close to a tread line that runs the circumference of the tire to see if it is unchanging in position as the tire rotates. If unchanging, than use it as a reference point. Having let the tires back down, get in the car and drive forward and back once or twice to get the suspension to settle and the vehicle driving in a straight line. Shut the car down and put on the ebrake. With a friend, have them hold one end of measuring tape centered against the line on one tire, while you take the measurement on yours, from both front and back - as if the tire is rolling towards and then away from you. Compare the measurements. If the front measurement is larger then the rear, you have "toe-out". If the rear measurement is larger than the front, you have "toe-in". In place of a friends helping hand, you can make a simple templet out of three pieces of plywood. I noted this from the same book I believe that discusses string alignment. You need a main board length that is as long as your overall wheel track minus 1/2 tread width. You then need to securely affix a pointer board that's say as tall as the tire's radius. On the other end of this long board you need to securely affix a flat piece that again is as tall as the tire's radius, but also as wide as the tire tread. Paint the ends of both the pointer and recorder board white so that markings show up clearly. Mark a line on the pointer board for which alignment will be set, and leave the recorder piece for marking the positions of the scribe or noted identifier on the tire, with pencil. Using this board, one can simply lean it up against the tire so it doesn't move, set the pointer end, and walk over to the other side and mark the recorder board face, making a notation of "F" or "R" to identify from where the measurement was taken. Repeat for both the front and rear of the tire. A quick glance will easily tell you the toe condition, and you can quickly measure the difference with a short ruler.
 
Messages
3,775
Location
Houston, Tex
Rather than using something as wide as chalk, use an ice pick, or the edge of a screwdriver turned vertically. Rest this against some kind of base, like a brick or wood block, and have someone turn the tire into your scribe. If the scribes match at the end of the circle you have a valid line to go by, if not, try again. The problem, though, with any type of scribing, is that, as alluded earlier, the suspension is not in the fully loaded position, and driving any to get it in that position erases your scribe marks. It will get you very, very close however.
 
Messages
783
Location
Austin Texas
The bok you are looking for is "Tune to Win" by Carroll Smith (may he rest in peace). The link above shows the basics. Basically you need to construct two bars with notches at exactly the same place and the same distance apart positioined at mid axle on both ends. The car is positioned on level ground, and no, your driveway is not level enough unless you have done something 'special' to level it. You need it level with a handful of thousandths of an inch for best work. Small amounts of unlevelness (side to side) will change the weights on the tires which will change the set point of the suspension with changes the stationary alignments. Getting the pad level enough for suspension alignment is often harder than the alignment itself. Secondly, after any suspension adjustment, you need to roll the car forwards and backwards at least 8 feet to take any stress out of the bushings and tires. Set the steering wheel dead straight as you roll the car forward to the strings. Set the tires to operating pressures--not cold pressures! Reset tire pressure after alignment. To find out operating pressure, set tires to reconnended cold pressures, and go take a long drive at speeds you want the car to operate best at. Then get out and immediately measure the tire pressures and write these down. Average lefts and rights but keep fronts and rears separate. set the fronts to the average fron pressure and the rears to average rear pressures before alignment. A note about measurements: You are going to measure the various positions in inches (or mm). Often, the factory toe spec are written as if the measurement was taken at the rolling diameter of the tire. Since we are measuring at the bead we need to multiply the measurement differences by the ratio of rolling diameter to beed diameter. Toe is measured from the string to the inner bead on each wheel--since the inner bead is less likely to be out of whack due to curb damage and more consistent overall. The back-of-wheel to string measurement is subtracted from the front-to-string measurement to get the toe form that wheel. Left toe plus right toe is total toe. An important parameter is the thrust angle. This means that the driving wheels need to be toed evenly to the centerline of the car. For rear wheel cars, the rear toe must be set evenly. For front wheel drive cars, both the front toe and the front caster have to be set evenly (since they interact). Camber should be measured at the same time, either with a camber guage or by using a plumb bob as a vertical string and measureing top of wheel to bottom of wheel. To convert measurements from inches (or mm) to degrees: degrees = (top-bottom)/beed_diameter*57.3 To find out if the alignment settings are OK, take the car for a short drive. To find out if the alignments are appropriate for your driving style, you need to obtain a probe tipped pyrometer and take temperature measurements of each tire at 3 locations. Tire pressure is correct when the center of the tire is at the average temperature of the inside and eoutside deges. If the center is hotter than this, reduce pressure, if the center is cooler increase pressure. Camber is correct when the inside edge of the tire is slightly hotter than the outside edge of the tire (by about 10 degrees for street driving--and about 20 degrees for track driving). Toe is correct when the car drives straight down the road and it takes a little pressure on the steering wheel for the car to divert from straight. Lessening toe increases steering response, increasing toe increasees on-center deadness. moderate amounts of toe does not cause tire wear, excessive amount of toe does. Toe will interact with tire pressure and subtle amounts can be used to move the pressure around the contact patch to heat or releave heat buildup (depending upon what you want to happen). Cars that have been converted to spherical rod ends (e.g. no bushings) can run with just about exactly zero toe. But you always want to be toed out or in and not exactly zero. Urethane bushings can run less toe than rubber bushings for similar reasons. Race cars tend to like toe out as it makes the car turn in faster--toe out also makes the car dart (aka wander) across straight roads at the slightes provocation (and you can see this in race cars as they run down long straights when the TV camera is positioned at the braking zone.) Incorrect caster (after camber and toe and pressures are correct) will cause the car to drive in a big long arc and require some pressure on the steering wheel to remain straight. Get caster set very close to dead even.
 

tuong

Thread starter
Messages
219
Location
milpitas
WOW, i was shooting in the dark and i actually got response, u guys ever get any bad experience. I know one guy that **** up so bad, he drove about 100 miles and his tires were totally ruin.? is it easy. is it easy to mess up?
 
Messages
2,387
Location
Chicago area
Remember that when you change one setting, the others will change. Changing camber will affect toe in. Check and recheck. You can do an accurate alignment with home tools, care, and ingenuity. A common hand held laser can be useful, too.
 
Messages
12,385
Location
Northern CA
quote:
Originally posted by Steve S: For what is costs find a good alignment shop and use it , way less of a pain .
The difference is, if you actually understand what you are doing and check your work, when you are done you will know it's been done right. When you go to an alignment shop, all you know for sure is that your wallet is lighter. Have the last few days been warm enough for you Steve?
 
Messages
39,805
Location
Pottstown, PA
The difference is, if you actually understand what you are doing and check your work, when you are done you will know it's been done right. You're right. Alignment mechanics don't always go through all the steps. They can look at the tires ..see that nothing is wrong and just correct as needed for whatever wear patttern they see. For many it's "set the toe ..and let it go". The main thing an alignment rack does is generate revenue outside the alignment itself. It's a shock/strut/ball joint/tire work producer.
 
Messages
2,387
Location
Chicago area
If you do go to an alignment shop, they can do a very good job, and put things where you want them. Make sure you get a before and after printout, though, with all the specs on it. I wouldn't do it without a post alignment computer printout.
 
Messages
1,715
Location
Texas & BWI Area
Exactly, A good alignment tech will 1st road test after the tire install if applicable. The service writer before hand would have documented if there was toe out/in wear etc to give the tech something to look for. After the road test to find vibration, pulling etc the tech should shake down the front end/steering etc. This should weed out bad tie rods, struts, ball joints, CV Half Shafts, pitman/idler arms, camber bushings, etc. Any of these can turn your suspension and tires into toast. Most people do not even know what these components are let alone venture to repair them. So the key is to find a major but honest front end shop. Make sure they give you a before and after print out...the better shops will let you even watch the process. Hunter CAM machines are really sweet too [Smile]
 
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