Builder Tools
Free tools and calculators for gearheads, builders, and wrenchers.
Showing 49 of 49 tools
OBD-II Code Lookup
Decode any check engine light code. Search P, B, C, and U codes by number or symptom — with causes, fixes, and safe-to-drive ratings.
Maintenance Schedule
Factory-recommended service intervals by year/make/model — oil type, timing belt, fluids, and more. Log directly to your service log.
Engine Swap Database
Curated compatibility guide for engine swaps — donor engines, required parts, cost estimates, and builder tips. Community submissions welcome.
Common Problems Database
Browse community-confirmed known issues by year/make/model — symptoms, causes, and fixes. Upvote issues you've seen. Submit problems not yet listed.
VIN Decoder
Decode any 17-character VIN to reveal manufacturer, model year, country of origin, and check digit validation.
Fender Tag Decoder
Decode factory build codes from Mopar broadcast sheets, GM cowl tags, Ford door jamb plates, AMC data plates, and VW M-code plates.
Bolt Pattern Guide
Look up wheel bolt patterns, lug nut sizes, and hub bore specs by year, make, and model.
Paint Code Lookup
Find factory paint codes, color names, and matching touch-up paint by VIN or year/make/model.
Torque Spec Reference
Common torque specifications for lug nuts, head bolts, intake manifolds, and other critical fasteners.
Tire Size Calculator
Compare tire sizes side-by-side — see diameter, width, sidewall height, speedometer difference, and clearance impact.
Gear Ratio Calculator
Calculate final drive ratios, RPM at speed, and optimal gear combinations for your drivetrain setup.
Engine Displacement Calculator
Calculate engine displacement from bore and stroke. Convert between cubic inches, liters, and cubic centimeters.
Compression Ratio Calculator
Calculate static compression ratio from bore, stroke, deck clearance, head gasket, piston dish/dome, and combustion chamber volume.
Quarter Mile ET Estimator
Estimate 1/4 mile elapsed time and trap speed from horsepower and weight, or work backwards from a timeslip to find implied HP.
Wheel Offset / Backspacing
Convert between offset (ET in mm) and backspacing (inches), and see how much the wheel protrudes from the hub face.
Carburetor CFM Calculator
Calculate the required carburetor airflow (CFM) for your engine and get the recommended Holley/Edelbrock size.
Ethanol Blend Calculator
Mix pump gas and E85 to hit a target ethanol percentage, or calculate the blend from a known mix. Shows estimated octane.
Wiring Color Reference
Common OEM wire color codes for GM, Ford, Mopar, Toyota, and Honda — searchable by system and function.
Automotive Unit Converter
Convert power, torque, pressure, length, speed, temperature, volume, and weight — type in any field to convert all at once.
RPM / Speed Calculator
Calculate vehicle speed across all gears from engine RPM — or find RPM at a given speed. Includes 18 transmission presets and tire size parsing.
HP / Torque Calculator
Convert between horsepower and torque at any RPM. HP = TQ × RPM ÷ 5252. Includes crossover RPM table and known engine references.
Boost / FI HP Estimator
Estimate horsepower from boost pressure and base HP. Includes intercooler efficiency, octane requirements, and safe compression ratio limits.
Wire Gauge / Ampacity
Find the minimum wire gauge for any circuit from current draw and wire length. Checks both ampacity and voltage drop limits. Full AWG reference table.
EFI Injector Sizing
Calculate required injector size in lb/hr and cc/min from HP target and fuel type. Shows duty cycle and the next standard injector size up.
Fuel Pump / System Sizing
Size your fuel pump and lines for any HP target on gas or E85. Shows LPH/GPH requirements, common pump ratings, and minimum AN fuel line size.
Transmission Ratio Reference
Complete gear ratio tables for 35 transmissions — GM, Ford, Mopar, and Import. Filter by brand and type, click any row to expand all gear details.
Crawl Ratio Calculator
Calculate your total crawl ratio from transmission 1st gear, transfer case low range, and axle ratio. Includes presets for 16 transmissions and 17 transfer cases.
Approach & Departure Angles
Calculate approach, departure, and breakover angles from wheelbase, overhangs, and ground clearance. Presets for Jeep, Tacoma, 4Runner, Bronco, and more.
Lift & Tire Size Guide
Find the maximum tire size for your lift height by platform. Covers Jeep TJ/JK/JL, Tacoma, 4Runner, Bronco, F-150, and Silverado with required modifications.
Winch Sizing Calculator
Find the minimum winch rating for your GVW and terrain type. Includes snatch block calculations, drum layer pull reduction table, and wire vs synthetic rope comparison.
Recovery Gear Reference
Shackle, kinetic rope, and tow strap sizing by vehicle weight. Working load limits, minimum breaking strengths, and essential recovery equipment guide.
Axle Reference Guide
Dana, Ford, GM, Toyota, Chrysler, and AAM axle specs — ring gear diameters, spline counts, gear ratio options, max torque, and build notes. Filterable by manufacturer and position.
Transfer Case Reference
Low range ratios, shift types, input splines, and applications for Dana, NP/NV, BorgWarner, Toyota, and aftermarket T-cases. Includes Atlas and NP205 doubler builds.
Re-Gear Calculator
Find the ideal axle gear ratio after a tire size change. Shows closest standard ratios and RPM comparison at highway speed for old vs new tires.
Pinion Angle Calculator
Calculate driveshaft angle change after a suspension lift and find the correct pinion rotation to equalize U-joint working angles and eliminate vibration.
Air Down Guide
Recommended tire pressures by terrain — rock crawling, sand, mud, hard pack, and highway — scaled to your stock PSI and tire size.
On-Board Air Sizing
Calculate air volume and fill time to re-inflate tires from aired-down PSI. Compressor CFM reference table with common 12V and engine-driven units.
Locker & LSD Reference
Every differential type compared — open, clutch LSD, Torsen, lunchbox locker, Detroit Locker, ARB air locker, electric locker, and spool. Pros, cons, brands, and best use cases.
Suspension Lift Type Guide
Compare every lift type from leveling kits to custom 4-link systems. Covers range, cost, complexity, geometry impact, ground clearance, pros and cons for each approach.
Trail Rating Scale Reference
Decode trail difficulty across all major systems — 1–10 numeric scale, USFS road classification (1–6B), and color codes. Includes vehicle requirements and cross-reference table.
Chain & Sprocket Calculator
Calculate final drive ratio, top speed at redline, and cruising RPM. See the exact effect of going up or down a tooth before you buy sprockets.
Suspension Sag Setup
Check front and rear suspension sag against targets for your riding style. Step-by-step measurement guide and preload adjustment recommendations.
Carb Jetting Guide
Calculate main and pilot jet adjustments for altitude and temperature. Includes needle clip position reference and symptom diagnosis for rich/lean conditions.
Rake & Trail Calculator
Calculate steering trail from rake angle, fork offset, and tire size. Understand how custom triple clamps, tire changes, and rake modifications affect handling feel.
Motorcycle Tire Size Decoder
Decode metric motorcycle tire sizes, compare two sizes side by side, and calculate speedometer error and ride height change when fitting a different size.
Fork Oil Level Guide
Fork oil grade, volume, and level specs for popular sportbikes, adventure bikes, and MX machines. Viscosity guide and explanation of how oil level affects handling.
Brake Fluid Reference
DOT 3, 4, 5, and 5.1 specs compared — dry and wet boiling points, hygroscopicity, compatibility rules, flush intervals, and a brake symptom diagnosis guide.
Track & Venue Finder
Find drag strips, road courses, autocross venues, and karting tracks near you. Filter by type and state.
Motorcycle Power-to-Weight
Calculate HP/lb and kW/kg with or without rider weight. Compare to 25 production motorcycles from 600cc sportbikes to supercharged hyperbikes.