Phone-based front-end geometry — track trends, not laser-grade
Accuracy: Repeatability tool for pit deltas — typically ±0.5–1.5° camber vs a shop laser. Verify suspicious readings with a rim bubble gauge. Best for week-to-week changes, not certifying exact specs.
CASTER
CAMBER
TOE
POWERED BY CLAUDE · ANTHROPIC
Prerequisites
WHAT YOU NEED
🖨
PRINTED JIGS
One universal crown hook + checkerboard target — kart through IMCA
📱
YOUR PHONE
Any phone with rear camera
⬛
TARGETS
Checkerboard boards — print once, reuse every session
🏁
LEVEL SURFACE
Flat floor + driver weight in seat
ONE UNIVERSAL HOOK · KART → MICRO → SPRINT → IMCA · ONE TARGET BOARD
3D Print Files
START HERE — print the universal crown hook + checkerboard target. One clamp for kart 5" through modified/IMCA 15" — strap cinches any tire OD. Rim-specific arcs below are optional upgrades.
PRINT THE PARTS
01
REFERENCE TARGET BOARD
Embossed checkerboard + corner fiducials. Dovetail pocket on bottom — snaps onto clamp post.
One saddle for every division — kart 5" through IMCA/modified 15". Crown bar spans wide tread; inner + outer bites fit narrow kart and full-size. Strap cinches any OD.
Print universal crown hook + checkerboard target. That’s all you need for any car from kart to IMCA.
PLA or PETG — nothing exotic
Target board: use brim if bed warps
Universal hook: lay flat, long edge along bed X
Rim cups (#03–05) are optional — only if you want a dedicated lip fit
Inspect dovetail before race day — replace if cracked
02
SET UP THE CAR
~20 MIN
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Consistent setup is everything. Readings are useless if you change weight mid-session.
Level flat concrete or asphalt
Steering straight ahead
Turn plates under front wheels if available
Fuel at race weight
Driver in seat or 50 lb ballast at centerline
Let suspension settle 5 minutes
03
MOUNT THE JIGS
~5 MIN
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Drop the crown hook over the tire from outside, strap tight, snap the checkerboard target on.
Rim plane vs crown: universal hook mounts on the tire crown — shops measure the rim. Expect ~0.2–0.5° vs a rim bubble gauge. For rim-plane match, print optional rim cup (#03–05) for your wheel size.
Target must face square to the spindle — perpendicular to wheel face, not tilted with tread
Crown saddle spans tire width — outer bites for modified/IMCA, inner bites for kart/micro
Ratchet strap through plate slots — cinches any OD from kart 5" to 15" stock
Embossed squares give camera contrast — paint light squares white for extra pop
04
MEASURE CAMBER
~3 MIN/WHEEL
▼
Camber = tilt of wheel from vertical. Negative = top leans toward chassis.
Stand 4 feet from wheel at hub height, square to face
Select CAMBER mode, open camera
Freeze frame, tap 4 corners TL→TR→BR→BL
Do left front, then right front without moving car
05
MEASURE CASTER
~5 MIN/SIDE
▼
Caster = how camber changes as wheels steer. Use turn plates (#07) and steer exactly 20° each way.
Mark steering wheel center, then 20° left (chalk/tape or turn-plate sweep)
Steer 20° left → measure camber (CASTER L20)
Return center, steer 20° right → measure camber (CASTER R20)
Wrong steer angle is the #1 caster error — 20° not eyeball
CASTER = (L20 − R20) ÷ (2 × SIN 20°) SIN 20° = 0.342
06
MEASURE TOE
~10 MIN
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Why three ways? Toe is inches of front-wheel aim. No 3D printer yet? Start with MAT TOE (tabloid tiles at FedEx) or STRING TOE (tape + string). FACE TOE needs the printed target on the wheel — same jigs as camber.
MAT TOE (lowest barrier):Why — no jig, no string plane; bars OK. How — print tiles, scale-check, chalk + half turn, photo. What — inches on dashboard.
STRING TOE:Why — shop-style, no printer if you already string the car. How — front gap − rear gap per side. What — inches on dashboard.
FACE TOE:Why — fast once jigs are on the car (camber + toe same session). How — crown hook + target, front-quarter (~45°), LF then RF. Needs — 3D-printed hook + board.
MAT: chalk arc vs centerline STRING: front gap − rear gap FACE: wheel yaw ° (needs printed target)
07
HUNTER ANALYSIS
~1 MIN
▼
Once numbers are in the dashboard, Hunter reads cross values and calls adjustments.
Fill missing values manually if needed
Hit SEND TO HUNTER
Hunter calls which corner to adjust and by how much
Camera Tool
OPEN CAMERA
Position phone at wheel height, 4 ft back, square to wheel face. Level indicator must be green before save.
WHICH TOE METHOD?
MAT TOE
Start here if you don't have a 3D printer. Needs: tabloid tiles (FedEx) + chalk. Reads: inches from chalk arc. Bars OK.
STRING
Use when: you already string the car. Needs: string + tape (brackets optional). Reads: gap difference in inches.
FACE TOE
Use when: jigs are already on the wheels for camber. Needs: printed hook + target board. Reads: degrees → inches.
STRING GAP TOE — LF
String parallel to chassis. Measure gap string-to-tire at front and rear of same side. Front − rear = side toe in inches. Repeat LF and RF.
PIT MAT — HOW MAT TOE WORKS
Why the mat? No wheel jig needed for toe — chalk the tire, roll straight, photo the arc vs centerline. Bars and sight lines don't matter.
Get tiles:Order printed below (ships flat) · DIY tabloid at FedEx · free STL/SVG downloads.
ORDER PRINTED TILES
PETG 2-color, 11×17″ tabloid tiles — same grid the MAT TOE app expects. Flat-ship from Amarillo TX. Stripe checkout collects shipping.
Starter Kit
6× 11×17″ PETG tiles — ½″ grid, red centerline. Enough for micro/sprint pit MAT TOE.
Scale check distance = how many real inches between the two ticks you tap (count half-inch squares). Roll distance = how far the car moved (half tire turn ≈ 16" on a 10" micro wheel).
No scale check yet — run once each time you lay out the mat.
Downloads — tabloid SVG, 3D print STLs (base + centerline for color 2), or vinyl SVG:
