How to Distinguish Fast and Slow Gearboxes in FAST?
4 Answers
The gearbox with an 'A' after the serial number is a fast one, while those without the 'A' are slow gearboxes. Rotate the front intermediate shaft and mark it. If the front rotates one turn and the rear output coupling plate also rotates one turn, it indicates a slow gearbox.
I often work on repairing transmissions for trucks. Fast and slow transmissions from FAST Gear are mainly distinguished by gear ratios and model numbers. Fast transmissions have smaller gear ratios, making it easier to reach higher speeds and save fuel, which is ideal for long-distance highway driving. Slow transmissions have larger gear ratios, providing more torque and better performance for climbing hills and hauling heavy loads. Specific models like the RT11509C have an 'H' indicating a high-speed type, while 'R' stands for low-speed. Once, a truck owner realized something was wrong only after changing the transmission—the speed wouldn't pick up after shifting gears. Checking the nameplate or user manual makes it clear. Pay attention to the difference in shifting feel while driving—low-speed transmissions have tighter gear engagement in low-speed ranges, providing stable acceleration but limiting top speed. If unsure, consult a professional repair shop to avoid damaging the vehicle or delaying work. Remember to verify information during regular maintenance to prevent confusion.
Veteran drivers often say the difference between Fast and Slow gearboxes from Fast Gear is quite noticeable. The Slow gearbox provides strong starting power and climbs steep slopes steadily like an ox pulling a cart, making it less prone to stalling. The Fast gearbox, on the other hand, zooms smoothly on flat roads but has weaker low-end torque. Once during a delivery, I noticed sluggish acceleration in low gear—turned out it was an R-type Slow gearbox. Normally, the shift lever feels different too; the Fast gearbox shifts more smoothly. Don’t guess the model—check the manual or snap a photo of the nameplate for reference when buying new. Mixing them up not only spikes fuel consumption but also risks skidding on mountain roads with heavy loads. Two decades of driving wisdom: a quick test drive tells all, and remind mechanics during maintenance to avoid wrong parts—cutting corners leads to mistakes.
Quick and straightforward, check the Fast Gear Transmission model codes. High-speed gearboxes often bear H, F, or High markings; low-speed ones have R, L, or Low. If unsure, refer to the vehicle's user manual or visit a repair shop to verify the nameplate. Incorrect shifting can cause jamming and abnormal noises, affecting safety and lifespan. It's recommended to verify during each maintenance to avoid confusion from modifications. Contact the service point immediately if the model doesn't match.
