Closed Loop Racing
Spindle Mount Caster Tool - Image 1
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SPINDLE MOUNT CASTER TOOL

Part # CLR-AE-007

$35.00

Read caster directly on the car. Sits in the pocket on top of a Speedway 3-piece spindle; set a digital level on it and read. Recommended level: Intercomp 102144. Repeats within about 0.1° on reseat and agrees with a bubble gauge to within its quarter degree. Instructions and test data below.

Specifications

MaterialPETG
FitsSpeedway 3-piece spindles
RepeatabilityAbout 0.1° on reseat
Print to printWithin 0.2°
vs bubble gaugeAgrees within 0.25°
Weight6 oz
1

Free shipping on orders over $150.00.

INSTRUCTIONS

  1. 1
    Set the car at ride height on a flat, level surface.
  2. 2
    Point the tire you are measuring straight ahead, parallel to the frame rail. Check the tire, not the steering wheel.Why the steering wheel isn't good enough↓
  3. 3
    Set the fixture in the pocket on top of the spindle. Make sure it is fully seated.
    Caster fixture seated in the pocket on top of a Speedway three-piece spindle
  4. 4
    Set the level on the fixture and read caster.
  5. 5
    Recommended level: Intercomp 102144. It reads the same both ways, so one reading is enough.How the levels compared on my car↓
    Intercomp 102144 digital angle gauge
  6. 6
    Using a different digital level? Some carry an offset, like my DXL360 did. Either read it, turn the level around, read again, and average the two, or find the offset once against a bubble level on a flat surface and subtract it.
    DXL360 dual axis digital protractor
  7. 7
    Lift the fixture off and seat it again. The reading should repeat within about a tenth of a degree.

REAL WORLD MEASUREMENTS

Real readings, one row per tool. The bubble gauge is the ground truth, drawn as a band because a bubble only resolves about a quarter degree. Anything inside the band agrees with it as well as it can.

Bubble gaugeIntercompDXL, both ways3.2°3.4°3.6°3.8°4.0°4.2°4.4°4.6°

Tap a row to see what that reading is.

Bubble gauge, with its quarter-degree band. Intercomp. DXL each way, with a dark tick at the midpoint.

My DXL360 was off by about 0.3° on a flat table, so I read it both ways and used the middle. The Intercomp reads the same both ways, so one reading is enough. Pulled off and put back on, the fixture repeats within about a tenth of a degree, and it lands inside what the bubble gauge can see.

THE WHEEL HAS TO BE STRAIGHT

The steering axis leans back (caster) and also leans sideways. With the wheel straight, the level only sees the lean back. Turn the wheel and the level swings around the axis and starts reading part of the sideways lean as caster. Drag the wheel off straight and watch the red bar grow.

Straight ahead / chassisAngle drawn 3 times largerReal casterSideways lean picked upWhat the level shows
Level shows
Error from steering

With the wheel turned a few degrees, my left front read 1.60°. Straightened out, it read under 1°. The level swings around the steering axis and starts reading part of the axis's sideways lean as caster. Get the wheel dead straight before you read it.

9° steering axis inclination is a typical figure, not measured on this spindle. Which direction adds and which subtracts depends on the side of the car.