Don’t Trust Your OEM | This Measurement Is CRITICAL

🚙 Building a fast car? Get $400 OFF the all-inclusive VIP online course package deal: https://hpcdmy.co/transvip1 ☀️ Put this knowledge into action and tune your own transmission. $50 USD off this online course: https://hpcdmy.co/transtt Is your tune only as good as this ONE measurement? Accurate tyre size and final drive ratio data are critical inputs for transmission tuning, and a common mistake is trusting the OEM's own measurements. Whether tuning a daily driver, track car, or drag build, bad data in this area can throw off the ENTIRE calibration and waste hours of work. This is just ONE of many modules from HPA’s Practical Transmission Tuning course showing how to measure rolling tyre circumference in the real world at the pressures and conditions that matter. You’ll also see how to calculate accurate tyre diameter and how to use that to improve your transmission logic. You'll also learn methods for confirming the final drive or axle ratio in different driveline layouts, including ring-and-pinion gear counting and the wheels-up rotation test. Whether you're working with a standard rear-wheel drive setup or a sealed transaxle, you'll discover what’s realistic, what’s approximate, and what’s definitive. These fundamentals are especially important when working with a secondhand vehicle, an unknown tune, or a modified driveline. It’s easy to make assumptions, but small errors here can throw converter lockup, shift scheduling and calculated load out of line. Our approach focuses on facts over guesses to help build a solid tuning foundation. ------------------------------------ TIMESTAMPS: 0:00 - Why Tyre Size and Final Drive Matter 0:35 - Don't Trust OEM 0:41 - Tyre Measurement Method 2:15 - Repeatability and Circumference Calculation 2:40 - Tyre Height/Diameter Calculation 3:37 - Adjusting for Operating Pressure 4:03 - Tyre Growth in Drag Racing 5:10 - GPS and Torque Converter Lockup Strategy 5:14 - Confirming Final Drive Ratio 6:00 - Counting Ring and Pinion Gear Teeth 6:54 - Visual Method for RWD Differentials 7:56 - Limitations of Approximation 8:47 - Transaxle Limitations 9:03 - When You Should Measure 9:16 - Summary and Use Cases 9:24 - Converter Lockup Speed Calculation 9:50 - Lesson Summary 10:47 - Transmission Tuning Is Not Magic 11:08 - Course Info and How to Start ------------------------------------ 🏆 Win FREE ECUs, engine components, wiring tools, alignment setups and more. Enter now, no purchase required: https://hpcdmy.co/giveaway 🏎 Free EFI tuning lesson: https://hpcdmy.co/EFI101y 💻 How to reflash tune your stock ECU: https://hpcdmy.co/hptly ⚠️ Motorsport wiring introduction: https://hpcdmy.co/wiringlessonyt 🧑‍💻 CAD & 3D scanning lesson: https://hpcdmy.co/learnCADnow 🧰 Performance engine building basic: https://hpcdmy.co/eby 🔧 DIY align your car for the track or street: https://hpcdmy.co/aljyt 🛻 Performance diesel engine tuning, 4 free lessons: https://hpcdmy.co/essential-diesel-knowledge 🕸️ Website and full course range: https://hpcdmy.co/hpa 🎤 HPA Tuned In podcast: https://hpcdmy.co/podcast 👙 Merch (HPA tees & hoodies): https://hpcdmy.co/merchy ------------------------------------ TAGS: #highperformanceacademy #buildtunedrive #learndriveoptimise #learntotune #enginebuilding101 #dontletthesmokeout #wiring101 #dieseltuning #datanerd #racecraft #cars #motorsport #racing #boost