Just wondering when or how often should an alignment be done to the front tires since I auto-x the car a lot? I just had one done about 4-5 months ago and the car feels like it needs another one. HELP!

Joey

 

If you've got a flat area of pavement to set up on, it isn't all that difficult to measure camber and toe yourself. Caster involves a little more work (and some math). Expensive, fancy equipment isn't necessary; that mostly makes the job go quicker so that a shop can actually make a little money doing them. If you're at all mechanically-minded, doing whatever available adjustments exist isn't that tough either.

What condition are your tires now in, relative to just after your car's last trip to the alignment rack? I'd start there.

Norm

 

The tires are in good shape so far, aside from the wear from auto-x'ing. I just feel the car pull to the right on freeway speeds, so that was my thinking that I needed another alignment. Do you have some steps that I can follow and list of equipment? I could do it if I had instructions on how to do the alignment.

 

I had it typed out and posted elsewhere, but it appears to have been lost. Sit tight while I see if I have it saved as a file (or reconstruct it if I don't).

Meanwhile, you might read this thread, particularly the posts by MFE. Some of the details in my method differ slightly from his, but it should give you some idea.

http://www.corral.net/forums/showthr...Home+Alignment

Norm

 

For a number of years, all I needed was a carpenter's 12" combination square with a bubble level in the handle, a small scale that measured in 0.01" increments (it was just something I had; 1/32" graduations are probably sufficient for most work), 4 jackstands, two lengths of black thread, a plumb bob (or something that'll work like one; a church key on a thread will do in a pinch), and a steel tape (or two). And a calculator that has trig functions.

Camber is measured by placing one end of the C-square against the wheel rim, moving the other end until there's "zero bubble" in the level, and measuring the gap at the other end. Since the wheel is somewhat larger, you'll be a few inches ahead of or behind the axle centerline. I normally took measurements at both locations as a check on my work. Be sure that the square is perpendicular to the pavement as seen in side view. Then a little math and use of either the arcsin or the arctan function (the difference is negligible at the magnitude of the angles you'll be working with) will give you the camber angle. Or, since it's close enough to 0.15* per 1/32" gap over the 12" length of the square's ruler, you can just use that conversion if you prefer.

Toe is measured from the strings, stretched over the jackstands and set to be parallel to the car centerline. If you're a little off, there won't be any problems with total toe, though if you were going to get into thrust angle measurement that would be off slightly. Anyway, this setup requires some patience. Set the strings to be the same distance off the wheel centers front and rear. Measure the distance between the strings with the plumb bob and the steel tape(s) in front of and behind the car. Adjust both strings equally until the distance is the same at both ends of the car.

Once the strings are parallel, you measure between the string and the wheel rim at the front and at the rear of each front wheel using the same little scale. Measure the distance between your measuring points on the wheel and you can now either calculate the toe as an angle or scale it up to the outside tire diameter to get a toe measurement in inches. That's toe per side, and may be either 'in' or 'out'. Total toe is the algebraic sum of these angles (or inches), considering toe-in to be of opposite sign to toe-out.

Caster is most easily determined by taking camber readings with the front wheels turned right, then again with the wheels turned left the same amount, taking the algebraic difference and applying a factor. This factor depends on the steer angle you use. If you can get 30* steer out of the front wheels, this factor is 1.00. At 14.5* (a much easier angle to obtain), it's 2.00. Mathematically, this factor is 0.5/[sin(steer angle)]

If you're way off where you want to be, it's probably easiest if you roughly set camber, set caster, go back to camber, and finally do toe. If you're reasonably close, just the caster, camber, toe sequence will suffice. Then go back and check everything. This does get easier with a little practice.

Norm

 

Shops local to me do the alignment checks for free. It's only the changes they charge for.

Anybody have a suggestion how to adjust caster on our cars?

 

You might be able to get up to about half a degree (you want it more +, I assume) by slotting the 3 bolt holes in the strut tower before you bottom out against the edge of the big hole in the middle. And I think you could move the ball joint forward with the right combination of eccentric LCA bushings. One caveat is, of course, whether these are legal mods for whatever class that you're running. Another is that there will be some effect on bumpsteer, since the outer tierod end will move vertically as caster is changed.

Norm

 

Thanks. Gotta look at how that would work with Stillen plates though. Ecentric & offset bushings aren't a problem but I can't change/open that center hole at all. I'm at +2.6deg now and would like to be around 3ish I think.