Alignment Specifications

There is a slight difference in terminology between this information and the information found on most alignment equipment. The following text should be helpful in understanding the different terms used. The alignment specifications are shown on the opposing page:

• Front Toe  - The Total Toe specification represents the left and right toe specs added together. Toe is measured in degrees and minutes.
• Front Camber  - Camber is also measured in degrees and minutes. Camber is adjustable only a some vehicles. The maximum amount of Camber adjustment is approximately .5 +/- degrees.
• Track Differential Angle with 20° lock on inside wheel  - This angle is also known as "Toe Out on Turns". With the inside wheel turned to 20 degrees on the front turn plates, the difference in the toe angle should be as specified.
• Caster  - Caster must be measured by sweeping the wheel through an arc of 10-20 degrees. (Most alignment equipment requires at least 20 degrees). Ride height is crucial to this specification. If the vehicle is too high or low in the rear, the Caster measurement will be affected. Caster is NOT a "live angle", the wheels must be re-sweeped to check the measurement again. Although Caster is NOT adjustable, it should always  be checked to insure there is no "hidden damage".
• Front Wheel Displacement  - More commonly known as "Setback", this is a measurement of the angle formed between the front axle to the Geometric Axis. The front axle centerline should be at 90 degrees to the Geometric Axis. A quick check of setback is to look to see if the wheel is centered in the wheel opening. Setback is a good diagnostic angle, if the Caster is off, the Setback measurement could indicate the cause. Look for bent suspension components or damaged suspension carrier/subframe.
• Maximum Wheel Lock  - Also known as "Maximum Steering Angle". This is the maximum angle of the wheels when turned to the inward and outward lock position. When this measurement is out of specification, check to see if the steering rack or steering box is centered. This can cause a hazardous condition and premature tire wear.
• Rear Toe  - Just as with front toe, this is the combined measurement of the rear left and right toe. Rear Toe is also measured in Degrees and Minutes.
• Rear Camber  - Rear Camber is always negative on BMW vehicles. Rear Camber adjustable on some models.
• Geometrical Axis Deviation  - The Geometrical Axis Deviation is also known as the "Thrust Angle". The optimum angle is zero degrees. The Thrust Angle is the angle formed between the Geometric Centerline and the Thrust Line which is the imaginary line which bisects the rear toe angle. A Thrust Angle of Zero Degrees is Optimal.

Depending upon the type of alignment equipment used, the specifications can be expressed a number of ways. Whenever possible, set the alignment equipment to read in degrees and minutes. Some alignment equipment has this option, this is more desirable than trying to convert from inches to degrees etc.

The alignment angles are expressed in degrees and minutes. For example:

6° 30' is expressed as 6 degrees, 30 minutes. 

There are 360 degrees in a circle and 60 minutes to each degree. The are also 60 seconds to each minute, but adjustments this fine are rarely used.

32 M Wheel alignment E39 / US