Alignment basics
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This is a discussion on Alignment basics within the Suspension & Wheels forums, part of the Tech & Modifying & General Repairs category; I frequently get pm's/emails w/ ?'s on alignment so I thought I'd put together a a alignment basics thread. We'll ...

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    Moderating on the run! Big Sky WRX's Avatar
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    Alignment basics

    I frequently get pm's/emails w/ ?'s on alignment so I thought I'd put together a a alignment basics thread. We'll look at camber/caster/toe, do's and don't for alignments and a few other bits and pieces along the way.

    Camber- what is it: measurement in degrees of the tire/wheel from the front




    What does it do for us- negative static (car not moving) camber can help us gain grip in turns, when our cars turn the outside tire wants to go positive, by having neg camber this positive change is negated and we optimally get a flat, wide contact patch.

    Excessive neg camber can degrade straightline braking (less contact patch) and can cause excessive tire wear (not as much as you'd think though- ore on that w/ toe).

    The oe spec for front camber on the WRX is -0.25- that's not a lot, especially for a performance orientated car. The WRX's upper strut bolt is eccentric and allows for adj, w/ the stock bolt- it's common to be able to get close to -1.4 degrees w/ the oem bolt. Camber plates (or caster camber plates) can increase this to close to -2.5 - -3.0. Some have also combined a camber bolt in the lower hole w/ the oem bolt to increase camber.

    The oem spec for rear camber is -1.3, there is no adjustment in the rear oem, many use camber bolts in the rear to provide adjustment.

    The oem specs provide for limited performance and help promote understeer- by increasing front neg camber you dial out some understeer, by adding positive camber to the rear you do the same. With camber bolts in the rear you can add some positive camber and dial out some understeer- you don't want to dial out too much though as you still want static neg camber for improved grip in corners.

    Cross camber- the difference between left and right camber settings, you want this as close to zero as possible.

    Caster

    what is it: Caster is the angle of the steering pivot, measured in degrees, when viewed from the side of the vehicle



    Caster also expresed in degrees, can help w/ performance as it goes more positive (ALK or caster/camber plate) it has the same effect as adding static negative camber. It also provides for straight line stability. It is not adj oem.

    The oe specs for the WRX are ~ 3.5 degrees, the ALK adds ~ .5 degrees, caster/camber plates ~ to 1.5 degrees.

    Most feel there are no negatives to increased positive caster (a little heavier steering effort), some cars run w/ as much 8 degrees.

    With caster plates you are able to control cross caster as well.

    Toe

    what is it: The toe measurement is the difference in the distance between the front of the tires and the back of the tires

    this example shows toe in



    Toe is adjustable both front and rear, the oem specs are 0 (+/- 3mm)- toe is adjusted in the front via the tie rods in the rear via the rear lateral links.

    Toe contributes more to tire wear than camber, thus most reccomend near 0 toe. Toe can also effect performance, toe out in front will help w/ turn in, toe out in the rear w/ rotation, toe in front and rear w/ high speed stability. People play w/ toe for performance gains, but make sure you know what you are doing befoer considering something other than very near 0 toe.

    Cross toe is important as well, again as close to 0 as possible.


    Alignment do's and dont's

    -do request a before and after printout
    -do tell them you want cross toe and camber as close to 0 as possible!
    -it's better to give them specific specs vs just getting it to "spec"- spec can range from positive camber on one side to neg on the other, toe in one side- toe out on the other- the factory specs are pretty wide (too wide!)
    -some shops won't do "custom" alignments- know that before going in
    -if your shop is having trouble getting front neg camber approaching -1.0+ tell them the lower strut bolt needs to be loosened as well to achieve this- you won't belive the # of shops that don't know this

    These are basics, I reccomend to everyone to learn more- your alignment is one of the biggest contributors (ditractors) of suspenion performance.

    WARNING this has not been thoroughly proofed, if there are glaring errors please let me know- thanks.

    Big Sky

    Here are the oem specs
    Attached Thumbnails Attached Thumbnails alignmentspecs.jpg  
    Last edited by Big Sky WRX; 03-01-2006 at 07:58 PM.

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    Registered User qoncept's Avatar
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    Wow, this is exactly what I needed to see. ::] Thanks, man.

    Can you recommend some starting points? Looks like when I get my coilovers on next month I'll be getting everything set to the recommended specs you mentioned except camber, which I'll probably go as low as I can in the front and about -1.0 in the rear.

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    Moderating on the run! Big Sky WRX's Avatar
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    For a good "street" setup, camber in the front from -1.0 - -1.5 (achieved w/ the oem bolts) and camber in the rear from-1.0 (must have camber bolts/plates to achieve this) to oem -1.3, w/ 0 toe is a very good all-around setup.

    If autox/track days start entering the mix then increasing front camber via plates should be considered, as increasing caster.

    Toe I would only change if you know exactly what you want and only after trying 0 first,

    Big Sky

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    Moderator fengshui's Avatar
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    The best way to visualize what Big Sky is talking about with caster/camber is to visualize the body of the car rolling when entering a high speed corner. During entry of the corner the weight shifts forward on the outside wheel. The goal of having a large neg. camber is that when the weights shifts onto the wheel, the tire would be close to parallel to the road surface (even though when standing still, it won't be parallel since it will lean inwards to the car - neg camber). Caster effects the car when turning as you can see it adds camber to the wheel when the wheel is turned when cornering. What looks like a slammed car standing still, will even out just right when entering high speed cornerers as long as the alignment is setup properly.

    EDIT: Toe is important to certain mid engine RWD cars like the Acura NSX and Toyota MR2. Imagine that these cars can be finicky, twitchy, and may spin out if not careful. To combat this the engineers dialed in some "toe in" in the rear so that the wheels actually spin on an inward to the car angle instead of parallel to the direction of travel of the car. What this in effect does is make it more difficult to get the back tires to slide because they are constantly fighting against it due to their direction of rotation.
    Last edited by fengshui; 12-20-2004 at 06:56 AM.
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    Registered User thechickencow's Avatar
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    Sticky this, or just add it to the tech reference?

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    Registered User MasiveMunkey's Avatar
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    Nice post. I was actually confused on lots of that stuff before reading it. Thanks.
    -Eric
    Originally posted by lanevoell
    stand up for yourself, painter!
    Wesome +1

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    Registered User Wrinkleboi's Avatar
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    good writeup, and i am guilty of PMing you asking all of this about a year ago .
    one question... is toe-in a positive or negative number?
    bryan

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    if you want to keep your front tires for more than a year i would not run -1.0 camber.

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    Registered User Wrinkleboi's Avatar
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    Quote Originally Posted by WRXSleeper
    if you want to keep your front tires for more than a year i would not run -1.0 camber.
    thats incorrect, -1.0 degree is really not all that much and you will have very minimal wear because of it. in fact you may have more wear on the outside of your front tires still, depending on how hard you push your car in the corners.
    there are many other factors that contribute to tire wear before you ever need to consider a moderate -1.0 degree of camber.
    bryan

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    Moderating on the run! Big Sky WRX's Avatar
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    Quote Originally Posted by WRXSleeper
    if you want to keep your front tires for more than a year i would not run -1.0 camber.
    I'd have to disagree w/ this- I've run as much as -2.2 camber w/ no ill effects- still out wearing my outers faster than inner. It's toe that will eat tires, 0 toe and you can run quite a lot of camber w/ no ill effects- especially as low as -1.0.

    I just retired a set of P Zero Nero's w/ four track days and probably close to 100 auotx runs, 20,000 miles and two years (spring->fall)- the minimum camber I ran w/ those tires was -1.5. I got just about the same out of my previous T1S's- same camber.

    Camber (neg that is) is your friend .

    Big Sky

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    i ran -.8 camber and approx 0 toe and it ate the inside of my tires up. i don't use my car at the track. i know negative camber upfront is good, i ran -1.3 on my honda and it didn't effect my tires that badly. i burned them off from driving hard before the inside wear was an issue.

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    Moderating on the run! Big Sky WRX's Avatar
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    Quote Originally Posted by WRXSleeper
    i ran -.8 camber and approx 0 toe and it ate the inside of my tires up. i don't use my car at the track. i know negative camber upfront is good, i ran -1.3 on my honda and it didn't effect my tires that badly. i burned them off from driving hard before the inside wear was an issue.
    It's defintiely in the realm of possibilities, but that's not the normal experience most have- it's possible the toe wasn't as close to 0 as it should have been????

    It's possible different tires will react differently to different camber too.

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    Registered User qoncept's Avatar
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    I guess I've got another question. Is there a cost effective way to play around with my alignment? With adjustable sway bars and struts and whatnot, it's as simple as turning this or readjusting that, but I'm sure I'm not the only one who can't afford to go get an alignment more than a couple times.

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    Quote Originally Posted by qoncept
    I guess I've got another question. Is there a cost effective way to play around with my alignment? With adjustable sway bars and struts and whatnot, it's as simple as turning this or readjusting that, but I'm sure I'm not the only one who can't afford to go get an alignment more than a couple times.
    get a friend who has a shop with an alignment rack.

    i think toe was at 1/16 toe out on both sides when you put it back on the rack.

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    Moderating on the run! Big Sky WRX's Avatar
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    Quote Originally Posted by qoncept
    I guess I've got another question. Is there a cost effective way to play around with my alignment? With adjustable sway bars and struts and whatnot, it's as simple as turning this or readjusting that, but I'm sure I'm not the only one who can't afford to go get an alignment more than a couple times.
    There are tools you can get and do your own alignments- you'll need something to measure camber and something to measure toe (toe will change when you change camber)- most of the bigger race parts outfits sell alignment bits. The actual changing of settings you can do w/ hand tools upper eccentric bolt on front strut for camber, front tie rod ends for front toe, rear lateral links for rear toe)- it's the accuracy of the measurements that are key.

    Big Sky

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