Losi 5IVE-T Gearing Guide — FDR, Pinion & Spur Chart

Losi 5IVE-T RC Gearing & Optimization Guide

Optimizing your gear ratio is one of the most effective ways to balance speed, torque, and electronics longevity in your Losi 5IVE-T 2.0 (1/5 Scale Large Basher / Racer). The relationship between your pinion gear (attached to the motor) and your spur gear (attached to the transmission) dictates how hard your motor has to work — and on a 1/5 basher & large scale racer platform with a 5.6 internal transmission ratio, even a single-tooth pinion change shifts your final drive ratio by 3-5%.

The Losi 5IVE-T 2.0 is a 1/5 scale short course truck designed for both large-scale racing and heavy-duty bashing. Its gasoline-powered stock configuration uses a 2-speed transmission and a mod-1.5 metric gear pack; brushless conversions are increasingly common but must respect the massive rotating mass of the truck when choosing gearing.

Basher & Monster Truck Durability Notes for the Losi 5IVE-T

Heavy landing impacts on a platform like the Losi 5IVE-T routinely bend motor mounts out of parallel with the spur, which is the single fastest way to strip a 48-pitch spur gear mid-session. After every big air session, sight down the pinion-to-spur mesh and confirm the motor plate has not shifted — a mount that has moved even half a millimeter will chew teeth within a pack. Just as importantly, check your center differential fluid thickness on a regular schedule; on high-power basher drivetrains the center diff is what manages extreme power distribution between the front and rear axles, and thin or contaminated fluid lets the light end spin up under throttle punch, spiking motor amp draw and cooking spur teeth from the inside out.

🛠️ Essential Tools Required for Gearing Changes

Hex drivers (1.5mm, 2.0mm, or 2.5mm depending on the Losi 5IVE-T variant)
Paper strip (for setting precise gear mesh)
Infrared temperature gun (crucial for monitoring motor heat after each run)
Threadlock (for the pinion gear grub screw)
Pinion gear puller (recommended when swapping gears on a hot motor shaft)

📋 Comprehensive Gearing & Temperature Guide

1. Understanding Pinion vs. Spur Gear Adjustment

Changing your gears alters your final drive ratio. Installing a larger pinion gear or a smaller spur gear increases top-end speed but increases the load on the motor, causing it to run hotter. Conversely, a smaller pinion or larger spur increases torque and acceleration while lowering top speeds and keeping your motor cool. On the Losi 5IVE-T, this trade-off is amplified by the fixed 5.6 internal ratio — small external changes have a direct thermal consequence.

2. How to Set a Perfect Gear Mesh

Improper gear mesh will quickly strip your spur gear or bind your drivetrain.

Loosen the motor mount screws slightly.
Place a small strip of standard notebook paper between the pinion and spur gear teeth.
Press the gears tightly together and tighten the motor mount screws.
Roll the paper out. The paper should have clean, crisp crinkles without ripping.

Recommended Pinion & Spur Chart

All combinations use a 57T 48-pitch spur. FDR is calculated as (spur ÷ pinion) × 5.6 internal ratio.

Pinion	Spur	FDR	Typical Use
14T	57T	22.8	High-bite carpet / tight indoor
16T	57T	19.95	High-bite carpet / tight indoor
18T	57T	17.73	High-bite carpet / tight indoor
20T	57T	15.96	High-bite carpet / tight indoor
22T	57T	14.51	High-bite carpet / tight indoor

Understanding Pinion & Spur Gears

Stock 5IVE-T 2.0 uses a 17T mod-1.5 pinion / 57T spur in the primary reduction. Brushless conversions typically use the same primary reduction and adjust the secondary gearset for their target top speed.

Rollout Targets

With 1/5 scale tires the rollout number is dramatic — well over 8 inches per motor revolution in high gear. Gearing decisions on a 5IVE-T are less about lap times and more about matching the powerband to the track layout.

Motor Temperature Management

Gasoline versions rely on head temperature rather than motor temp; keep the cylinder head under 250F (121C). Brushless conversions must respect the massive current draws that come with launching a 12+ pound truck — thermal shutdowns are common with under-sized ESCs.

⚠️ Critical Safety & Temperature Warning

Always use an infrared thermometer to check your motor and ESC temperatures during a run. RC electric brushless motors should never exceed 160°F (71°C). Exceeding 180°F (82°C) risks permanently demagnetizing your motor rotor and frying your Electronic Speed Controller. If your Losi 5IVE-T is running above these thresholds, you must "gear down" by installing a smaller pinion gear immediately, improve airflow with a larger motor fan, and inspect the drivetrain for binding.

Calculate a custom FDR for your Losi 5IVE-T

The link below opens the calculator with Custom / Other Chassis pre-selected, the Losi 5IVE-T's internal ratio of 5.6 and its recommended battery of 6S LiPo (22.2V) already set — just plug in your pinion, spur, motor, and tire to see top speed, runtime, and FDR for your exact setup.

Open calculator with 5.6 ratio + 6S LiPo (22.2V) preset →

Losi 5IVE-T 2.0 (1/5 Scale Large Basher / Racer) Gearing Guide