Or, you could jack up the car and rest it on blocks under the lower control arms so the tires are just barely off the ground. Take Juniors sidewalk chalk and hold it against the tire tread and rotate the tire to make a chalk stripe all the way around. Middle of the tire is nice but either side of middle works too. Then take a nail, ball point pen, or something like it and brace it against the floor and the tire. Again, rotate the tire to make a line all the way around. The ends should meet exactly, if not, start over. I used to do this with just a pen line, but then I used to see without bifocals too.
Now take the $5.95 spring loaded shower curtain rod and adjust the length to fit firmly in between the tires. If you adjust the length so you push hard and grunt when inserting it between the tires, that is exactly 25 pounds. Rotate the tires so the rod is in front, and use a small wedge to hold the tires from rotating back down. Take your tape measure and measure carefully from one line to the other in front and in back. The difference between the two is the toe. If you adjust the tie rod ends to give about 1/16 inch closer in front than in back, you're golden. Just as our friend says below, you need to keep the steering wheel straight and adjust whichever side is out. Simply sighting down the outside of each front tire to the rear tire will give you the side which is out. Sometimes both are, generally the right/passenger side is the one out of whack. If you find that the wheel is just a fraction off center after this process, and you don't want to go through all the marking again, just pull the steering wheel off and move it one or two notches in the direction needed. Not nearly as involved as the below method but it works real well. Ken In a message dated 7/17/2005 2:49:02 PM Pacific Daylight Time, [EMAIL PROTECTED] writes: From: Fmiser <[EMAIL PROTECTED]> Subject: [MBZ] Weekend, shade-tree wheel alignment (long) To: Mercedes mailing list <[EMAIL PROTECTED]> Message-ID: <[EMAIL PROTECTED]> Content-Type: text/plain; charset=US-ASCII The tire wear on Helga was getting bad. I didn't want to spend money on tires without at least improving the chassis 'cause I don't like to throw money away... But Helga is a rusty, old beater. I bought it as a parts car - mainly for the engine. I've now been driving it for 8 months... So I decided I needed to at least _improve_ the alignment, even if I couldn't make it "right". Oh, and I did it in the garage, not under a shade tree. Do I need to change the subject? *smile* I have a caster/camber measurement tool. I used it to set both the caster and the camber on both wheels. Any adjustments to caster or camber will alter the toe in! Once I had both the caster and the camber where I wanted it, I started to check the toe-in. Well, the way I used to do it worked, but it was hard to get the steering wheel straight and it took a lot of effort. I figured I could improve the process. I decided to try a Jim Cathey approch. (This is a complement, Jim. You seem to have a talent for achieving high-tech results with common tools and materials.) First, I built a spreader bar. The manual says that 20 - 24 lbs of force needs to be applied outward to the leading edge of the wheels. Here's how I made my speader bar. I took a threaded rod, a couple of nuts, a short piece of 1.5-inch angle iron, and a 2x2x6ft to build it. I took the angle iron, marked it for 2 pieces each 1.5 inches long, but I did not cut it yet because I wanted to drill the holes while it was big and easy to hold on to. Each of the 2 pieces are identical. On one side of the angle I drilled a hole big enough for easy clearance for the threaded rod. On the other angle, I drill two small holes for dry wall screws to attach the angle iron to the 2x2. Once finish, one of the angle iron pieces was attached to one end of the 2x2. This one is for guidance. I put the threaded rod through the big hole, positioned the second angle iron so there would be a reasonable compromise between far-apart-for-better-guidance and close-together-for-long-adjustment-travel. One nut is on the (inside) end to keep the rod from falling out and the other one presses against the second angle iron pieces to apply outward force. (It would be better if I had a long spring between the nut and the angle iron - but I didn't have one on hand) To determine how long the 2x2 needed to be, I held the whole assembly under the car and said "About here." I cut off the extra wood and then use a 3-inch piece to act as a foot on the outer end of the threaded rod. To do this, I simply drilled a hole that's just a bit smaller than the rod and threaded the wood block onto the end of the rod. To use the spreader, I put the wood-only end of the 2x2 against the inside of a front tire and the other end (2x2 block on the end of the threaded rod) on the other tire. That puts the 2x2 itself practically touching the oil pan. I turned the nut until I figured there was probably about 24 lbs force on the tire. Here's where the spring would help. Before putting it under the car, I could use a 25lb weight and note how far the spring compressed. Then with the rig under the car I could turn the nut until the spring showed the same deflection and it would be much more accurate than my guess! Now I needed a way to see the angle of the front wheels. I happen to have a level with a laser pointer in it. Straight edge, laser point - I had an inspiration. First try - I pressed the level against the outer edge of the rim. No good. The level was too long and ran into the tire itself when I positioned it so it would not run into the center cap. That meant I needed spacers that could be attached to the bottom edge of the level. I found two precision spacers - commonly called 3 inch pieces of 1/2inch EMT conduit. I attached these to the level with gaffers tape 'cause I have some on hand. (gaffers tape is a lot like duct tape but it doesn't leave goo behind when it's removed) I positioned the tape so the conduit - er, spacer - would be bare where it rested against the rim. The spacers were also tall enough that I could use the "ledge" just in from the outer edge of the rim. This "ledge" should be more accurate because it is much less prone to curb damage - but it also requires more precise positioning. All right. I could now accurately project the angle of the front wheel toward the back wheel. But how to spot if the angle is correct? I used a couple business cards. (don't tell my boss... *grin*) I have a spreadsheet to determine where on the card the laser targets needed to be. If any of you want it, let me know and I'll send it off list. On my W123, the distance from the front wheel center hub to the leading edge of the back wheel (where the business card turned laser target was mounted) is 2580 mm. Approximately. >From the alignment manual, I got the toe-in angle to be 25 minutes of a degree, with a tolerance of plus or minus 10 minutes. Using basic trig, I computed the "desired distance" - that is, how much out from straight back it needed to be. ( The math is Tangent of toe-in angle in degrees x length ) Since I did this in a spreadsheet, it was easy to also figure what that distance would be at the tolerance limits. Then, I needed to account for the fact that the laser dot is not against the levels straigh edge. On mine, with the spacers installed, if I set the level on a table, the laser would exit 41mm above the table top. I added this to the numbers from the middle section. I used these numbers to mark a target box on the back of my business card. The idea is that the card will be attached to the wheel with tape (probably gaffers tape) so that one edge of the card is touching the rim ledge and the rest of the card is sticking out like a flag. The data, in mm: desired distance 18.76 minimum 11.26 maximum 26.27 laser offset 41 desired distance - with offset 59.76 minimum - with offset 52.26 maximum - with offset 67.27 Enough time spend building tools - I was ready to _use_ them! I set the steering wheel straight ahead. I didn't have a bolt the right size to lock the steering gearbox. Note: if you don't lock the steering - either with the gear box bolt or column lock - it will probably move and mess you up! I though I was done at one point, but the steering wheel had moved, so I had to start again... You've been warned! I used the column lock to keep the wheel close to center, and then checked it often, and wiggled it as needed to keep it straight ahead. I attached the targets cards to the back wheels, installed the spreader, set the level against the front wheel, observed the location of the spot, and adjusted the tie rod ends. (The tie rod ends were easy to adjust because I had removed them from the car the day before to free them from the strangle-hold of rust. I was generous with the grease as I put them back together.) Left side, right side, check steering wheel, left, right, left right, steering wheel, right, left, etc. until I was happy with the position of the laser dot and the position of the steering wheel. Since this car isn't worth spending money for new parts, I also took a few short cuts doing the alignment. (guess at the 24 lbs spreader force, no steering gearbox lock, stoping at "close enough", etc.) However, this method seems to be fairly accurate. I'm eager to try it on one of my good cars - but not so eager that I won't wait until one of them needs it... The final result? I can't say if the tire wear is better - but the driving is _much_ better. Even with all the loose and worn parts. And it may not be good enough to truly be called a "Jim Cathey", it's close enough I feel like strut'n'!