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Hurrey's Caster / Pinion / Wheelbase Alignment Wizard

Hurrey's Caster · Pinion · Wheelbase Wizard

Technician-facing calculator for solid-axle Jeep / Bronco platforms using upper & lower control arm length. Auto-fills OE specs, tracks wheelbase shift, and shows live caster / pinion behavior. Print to attach this to the RO.

Vehicle & Customer

Select chassis, pre-fill OE specs, then override as needed.

FRONT + REAR · SOLID AXLE

Chassis Preset JK / JL / TJ / LJ / JT / Bronco

Preset Actions OE wheelbase, caster, pinion & arms

Tip: Use preset to establish stock reference, then adjust “New” arm lengths only.

Customer Name

VIN / Plate

Odometer (mi)

Technician

RO / Invoice #

Shop Lug Torque (ft-lb) Auto-filled where known

· Vehicle preset: JL 4-Door · Wheelbase 118.4" · OE caster 6.0°

Baseline Geometry & Tire Package

Wheelbase and alignment targets, plus tire diameter for ride height / length.

OE BASELINE

OE Wheelbase (in) Center-to-center

Resulting Wheelbase (in) Calc from arm change

Wheelbase delta 0.00" change

Front Caster Target (°)

Rear Pinion Target (°) Relative to driveshaft

Factory Front Pinion (°) For ref only

Front Caster Result (°) Calc · live

Caster vs OE target 0.0° offset

Front Pinion Result (°) Approx · live

Front pinion delta 0.0° change

Rear Pinion Result (°) Calc · live

Rear pinion vs target 0.0° offset

Tire diameter is used to approximate ride height gain and overall bumper-to-bumper length change. It does not change wheelbase.

Current Tire Size Metric / flotation presets

New Tire Size Can override preset

Tire diameter delta / ride height 0.00" dia change

Stacked tire visualization: inner ring = old diameter, outer ring = new diameter (scaled relative). Helps quickly communicate ride height and overall length change to the customer.

Control Arm Lengths

Enter OE (Old) and Adjusted (New) lengths for front & rear uppers/lowers. This drives caster, pinion, and wheelbase change.

OLD / NEW ON SEPARATE LINES

Front Axle – Driver side reference, passenger assumed matched.

Front Lower – OLD (in) OE reference

Autofilled from OE (stock reference).

Front Lower – NEW (in) Adj. length

Front Upper – OLD (in) OE reference

Autofilled from OE (stock reference).

Front Upper – NEW (in) Adj. length

Front Arm Brand (NEW)

Front Arm Part # (NEW)

Preset Helper

Rear Axle – Driver side reference, passenger assumed matched.

Rear Lower – OLD (in) OE reference

Autofilled from OE (stock reference).

Rear Lower – NEW (in) Adj. length

Rear Upper – OLD (in) OE reference

Autofilled from OE (stock reference).

Rear Upper – NEW (in) Adj. length

Rear Arm Brand (NEW)

Rear Arm Part # (NEW)

Preset Helper

Visual Axle Rotation & Pinion / Caster

Conceptual only – shows axle / pinion behavior based on arm length change. Not a replacement for an alignment rack.

REFERENCE ONLY

Rear Axle Rotation & Pinion

Pinion: 0.0°

Left: Axle tube rotation Right: Pinion vs driveshaft

Front Axle Caster & Pinion

Caster: 0.0° · Pinion: 0.0°

Left: Axle tube & caster rotation Right: Caster arrow at knuckle

Printable Alignment Summary

Mirrors the fitment tool style with wheelbase, caster / pinion, tire data and parts info. This is what you hand to the customer.

SUMMARY · RO ATTACHMENT

Shop Disclaimer: This calculator is an engineering aid only and does not replace a calibrated alignment rack, straight-edge verification, pinion angle measurement tools, or on-road validation. All values are approximations based on control arm length change and typical solid-axle geometry. Final caster, camber, toe, thrust angle and pinion angles must be verified and adjusted by a qualified technician. Modified vehicles, aftermarket components and tire sizes may require settings outside OE targets. Customer is responsible for re-torque of suspension fasteners and wheel lugs after 50–100 miles and routine inspection after off-road use.

Need help deciding what fits your build?

Use Hurrey's tools and reference pages to narrow down fitment, compare options, and talk to the shop before ordering.

Fitment Tools Offset, tire, and clearance calculators used to plan builds more confidently. Fitment Library Vehicle-specific wheel and tire reference data for faster research. Services Repair, diagnostics, suspension, diesel, fabrication, and local installation help. Contact the Shop Reach out if you want a second opinion before checking out or booking service.