Highway Tractor Alignment

Axle Shim Calculator

Enter the laser readings and get the shim call for each axle.

Measurements

Enter left and right triangle readings for each axle.

Triangles are here
What Do These Words Mean?

Left Reading: The number the laser shows on the left steer-tire triangle.

Right Reading: The number the laser shows on the right steer-tire triangle.

Distance To Steer Axle: The distance from the steer axle to the drive axle you are measuring.

Bushing Spacing: The distance across the same axle from the left bushing shim point to the right bushing shim point.

If Left Reading Is Higher: Tells the app which side to shim when the left reading is bigger than the right. If testing shows it is backwards, flip this setting.

Difference: How far apart the left and right readings are.

Shim Needed: The theoretical shim thickness needed to straighten that axle.

Results

Ready to calculate Enter the readings to see what shim to use.
Axles 2
Biggest Shim 0.000 in

What To Install

No calculation yet Enter the measurements.

Status

Waiting for values.

  • Each axle is calculated from left and right laser readings.
  • Recheck after the shim change.
  • Use OEM procedure as final authority.

Formula

Shim needed = (reading difference / distance to steer axle) x bushing spacing