For What Its Worth

Alignment specs with Rack and pinion and CPP lower A-arms

The alignment specs I used are 0-.25 degrees Camber, 1.5-2.5 degrees positive Castor.  and 1/16 toe in.   The Castor needs to stay close to equal on both sides.    How close they can get to 2.5 degrees Castor depends on the cars fit tolerances etc.   A savvy alignment mechanic knows how much difference to put between driver side Castor/Camber and passenger side to account for the driver in the car.

Finding someone that can align an older car correctly took a few tries.  Modifications should not be a problem to a good alignment shop.  I finally found Garland Safety Lane alignment in Garland TX.   Well seasoned mechanics and it took 15 minutes total to do the car correctly.

Definitions of what people are talking about when discussing front suspension

Toe In/Out

The amount the tires are turned in or out when going straight.  Too much either way wears tires. Too much toe out and tires wear on the inside.  Too much toe in and tires wear on the outside.  Toe out helps to make turning easier, but going straight harder, it wanders easier.  Toe in tends to keep the car from wandering. 


The amount the center of the wheel leads or trails the pivot center line made by drawing a line through the upper and lower ball joints.  When it trails the center line, positive caster, it is more stable.   Too much trailing and it gets hard to turn. When leading, negative caster, the suspension wants to help you turn but does not self center or stay straight by default.  O or even some negative caster is primarily for racing courses.  Positive caster is what is used on the street. 


The vertical angle of the wheel when looking down the side of the car.  As suspension goes up & down this can change.   When this is out of spec, one side or other of the tire gets too much wear.  Reference link

Front end alignment

Setting Camber, Caster and Toe to predetermined settings.  Done at normal height going straight.  Settings vary based on tires used and the geometry of the suspension.  Manufactures give recommended settings for ride, safety and tire wear concerns.


The turning radius of the front wheels when turning.  When you turn the wheels the linkage will cause a variance in the turning radius from one wheel to the other. The inside wheel in a turn is turning a smaller radius. A good setup has the wheels turning the "correct" radius based on the amount of turn.  If this is off, the car may not turn as well and you may hear squealing from the tires as one will push/pull through the turn a little.  Reference Link 

Bump steer

The amount the steering geometry changes when suspension travels.  When you hit a bump, how much the steering wants to change or turn right/left.  This also happens when going in a turn and one side drops lower than another.  Usually you want near 0 bump steer.  Parts need to be designed with the right geometry to avoid problems.  Reference link

Roll Center

The theoretical centerline down the length of the car that the car rolls about when going in a turn.  When it is high, we say a car is top heavy.  It is part of the basic design of the suspension.

Dropping a car with Drop Spindles vs. shorter springs

Drop spindles keep the normal geometry angles and action.  Just make sure the drop spindle design clears brake rotors etc.  Drop springs put the suspension in a constant bump mode.  Setting the alignment at the new height helps, but roll center and geometry changes during turning & bumps will act differently than what it was designed to do at stock height.

Ackerman, Toe In/out, caster and camber can all change during turning and suspension travel making the tires grab better or in some cases worse.  It can be a problem when the parts were made to fit the available area first and provide proper geometry second.  Changing geometry of parts will effect how the suspension works as a whole.

Happy Motoring, VHubbard.  May 2009

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