WELCOME TO ALIGNMENT 101!
(this is a good reference for each term used and what each one means. before you shell out $100+ for an aligment, learn what the kid is doing to your steering system. http://www.familycar.com/alignment.htm)
Intro: we have a solid rear alxe and independent front suspension on every 4runner and truck since 1986. you do
NOT need a full 4-wheel alignment on these vehicles since there are
NO ADJUSTMENTS for the rear. the only adjustments on them are one the front, and therefore if a "2-wheel alignment" is cheaper at the shop than a 4-wheel alignment, by all means, save your money. below are the basics of any decent "2-wheel alignment" that should be followed to the "T" for every alignment on our toyotas.
"what is involved in an alignment?" three things are the basis for a good alignment:
camber is the "tilt" of the wheel. it either tilts in at the top or tilts in at the bottom. slight tilt in at the top is desirable.
http://www.familycar.com/classroom/I...ign_Camber.gif
caster is what makes it drive straight on the freeway and keeps the steering tight. notice on a shopping cart how the front wheels will turn in whatever direction you turn the buggy? that's because the contact patch of the wheels trails the pivot point of the steering axis.
http://www.familycar.com/classroom/I...ign_Caster.gifhttp://www.familycar.com/classroom/I...gn_Caster2.gif
[the following commentary was contributed by GOLDS]
Quote:
Originally Posted by GOLDS
The benefit of neg caster is less steering effort, this is used in vehicles with a very heavy front end IE my buddy's big block chevelle or often on vehicles without power steering.
Positive caster give you stability at higher speeds. I work at a mercedes benz dealer, and all of our cars have at least 10 degrees pos caster. some of the fast cars, IE SLR Mercedes Mclaren have around 13 degrees. These cars are built for the autobahn and are designed to cruise at 200kmh plus.
The best example I have for this principle is to picture a shopping cart (extreme neg caster) travelling at high speeds. The wheels will shimmy from side to side because they have no directional stability.
A expert alignment technician will ask you if you spend most of your time on the highway or in the city. They can tailor you alignment based on your response. Mostly city driving, aim for less caster, more
highway driving aim for more caster. look for a shop that specializes in front end work, they are more likely to know what they are doing. Also it is in your best interests if the tech is not payed on
piecework (like me). A tech will be much more likely to spend more time on your truck if it does not affect his paycheck.
Lastly, I do not remember if you mentioned scrub radius in your article. I have a theory on the proper matching of overall tire diameter to offset of rim. scrub radius is the intersection of SAI and centerline of the tire. The SAI should hit the ground slightly inside of the centerline of the tire. If manufacturer intended scrub radius
is not matched then you will get strange problems, hard steering, vibrations in steering wheel at certain speeds. In order to calculate the necessary offset for your rims you need to use the overall tire diameter with the SAI in a formula with SINE law.....
This is very difficult to explain in text, if you have any pictures of SAI and scrub radius it might make more sense. let me know if you have any questions. hope this is what you were looking for.
Chris
toe - think of it as pigeon toed or crows feet... its the angle of relation of the two front wheels when looking from above (with the top of the lines being the front of the vehicle - a bird's-eye view). if they are like / \, then the toe is negative or it's sometimes called "Toe-In". if they are like \ /, then the toe is positive and that is sometimes called "Toe-Out".
too much of either is bad and will cause VIBRATIONS - no matter what someone else may tell you - BAD TOE CAN AND WILL CAUSE VIBRATIONS LIKE AN OUT-OF-BALANCE WHEEL.
http://www.familycar.com/classroom/I...lign_Toein.gif
most shops don't care to do it correctly, and that's why you get drift, poor highway feel, and vibrations. our 3rd gens are very sensitive to alignment issues, so if it doesn't feel good, then it's out of alignment. when a 3rd gen is done properly, then it feels
AWESOME on the road.
The one thing you want to
ALWAYS request up-front
BEFORE an alignment is done are initial and final printouts of the specs that the alignment machine are reporting. Use this printout as a reference for reviewing the work that was done and make sure that all adjustments are within the recommended TOYOTA specs.
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steering center - first and foremost, the steering wheel should be rotated to the "center position", the key turned off and the steering wheel locked into position. this will assure that when you go down the road (assuming that everything else is correct) your steering wheel will be centered. this is an annoying pet peeve of mine that i can't STAND when left uncorrected...
http://www.familycar.com/classroom/I...ing_Center.gif
Another problem with steering center has to do with the type of roads that are driven on. Most roads are crowned to allow for water drainage you usually drive on the right side of the crown. This may cause the vehicle to drift to the right so that the steering wheel will appear to be off-center to the left on a straight road. The best way to compensate for this is as follows:
If there is a difference in caster, it should be that the left wheel is more negative than the right wheel, but not more than 1/2 degree. Check the specs for the specific recommendations on side-to-side differences.
If there is a difference in camber, then the left wheel should be more positive than the right wheel. Check the specs to see what the allowable difference is.
__________________________________________________ _____
now, on to the technical stuff:
caster is easily adjusted and should be done FIRST. on a 3rd gen, you do that by moving the front and rear lower cam adjustments until you create a situation where the contact patch of the tire is physically behind the axis of rotation created by the upper and lower ball joints.
from there, you adjust the camber. you get the camber set by moving front and rear adjustment cams the same amounts (inward or outward) to keep the caster set, so you have a ever-so-slight tilt inward at the top (1 degree or less usually), then you recheck your camber.
next, worry about the toe. you adjust the toe by turning the adjustment nuts on the steering links (tie end rods). this is a more tedious process and most techs that i have run across don't bother with toe adjustments, even though they are critical in getting a smooth, oscillation-free ride.
***VERY IMPORTANT STEP***
as a final "step" you then go back and check caster again, AND RE-ADJUST. then check camber again, AND RE-ADJUST. finally, check toe again, AND RE-ADJUST. repeat the process until all (3) are in-spec. a proper alignment is an iterative process - not a get-em-in-and-get-em-out job.
*****SUPER IMPORTANT FOR THOSE OF US WHO GO OFFROAD*****
finally, YOU RE-TORQUE EVERYTHING DOWN - especially the DRIVER FRONT and PASSENGER REAR CAMS along with the TIE END ROD LOCK DOWN NUTS- THESE ARE THE MOST CRITICAL. If you don't torque the snot out of these two cam lock-down bolts, every time you go over a heavy bump, the weight of the rig will want to "walk" these two cam lock-down bolts (the geometry tries to turn them to the left and loosen them) and torque the cam so that it spins to the outside, pushing the lower part of the tire farther out than the top. this will screw up all three aspects of the alignment, causing a negative caster, negative camber, and toe-in. alignment shops grease monkeys (more likely kids now-a-days) are NOT going to properly torque these cam lock-down bolts. after an alignment, i take my 18" socket breaker handle and put about 180+ ft-lbs on them to snug them down. not ONCE have they ever been properly tightened after an aligment.
one of my experiences recently: "last time i went in for an alignment, the runner was tracking OK, but had a slight pull to the right, and the steering wheel was off center - this was driving home from the freaking alignment shop! after about 300 miles, it was pulling severely to the right, felt loose on the highway and developed a BAD vibration that i felt throught the truck and in the steering wheel. i got underneath and looked - the rear passenger cam adjustment was completely pushed outboard while the front was almost centered. this pushed the caster for that side to the positive, pulled the toe WAY inward, and threw the camber severely inboard. NOT GOOD. it was OBVIOUSLY not properly aligned - not anymore. upon inspection, i found the driver front cam LOOSE. the idgit aligned the truck, but didn't do it properly due to the pull and the off-center steering wheel from the beginning, and to top it off he then didn't torque the cams down properly. the passenger rear and driver front have to be VERY, VERY TIGHT to keep them from self-loosening due to the force of the suspension trying to turn the bolt. on the opposite corners, the suspesion works to tighten the bolts. i use a 18" socket breaker bar to tighten them."
As far as
SAI and
Included Angle are concerned, you shouldn't have any issues with these as long as everything is installed properly and you don't have any bent or broken parts. If the alignment shop tells you that one of these are out of spec, then you have some serious issues that you need to look into.
http://www.familycar.com/classroom/Images/Align_SAI.gifhttp://www.familycar.com/classroom/I...n_Included.gif
i hate lazy idiots that charge $100 for 15 minutes of half-assed work and don't do a job right. be informed of what's going on and look over their shoulders when they are doing the work so that you know you're getting your money's worth. don't be just another sheep in the flock. know what's going on and what you are paying for. hell, even print this out and take it with you if you need some notes. maybe even share it with the kid doing the alignment and teach him a thing or two...
KEYWORD SEARCH TERMS
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