Traxxas Slash Gearing Chart Explained

Gearing is the cheapest, most effective way to change how your Slash feels — more top speed, more low-end punch, or a safer setup for a hotter motor. Here's how to actually read a gearing chart instead of just guessing.

The Two Numbers That Matter

• Pinion gear — mounted on the motor shaft (small gear).
• Spur gear — mounted on the drivetrain (large gear).

Gear ratio = spur teeth ÷ pinion teeth. A higher ratio means more torque and acceleration but a lower top speed; a lower ratio means more top speed but less punch off the line and more motor heat under load.

Reading a Typical Chart

Most Slash gearing charts list pinion size (13T–23T is common) against spur size (weighted for stock 68T or 83T spurs) and show the resulting overall ratio. As a rough guide:

• Bashing / low-power brushed setups: Stick close to stock gearing (~19T pinion on a stock spur). Prioritizes reliability and motor life.
• Brushless upgrades: Bigger motors generate more heat, so you'll typically run a slightly smaller pinion than "max" to keep temps in check, then work up.
• Racing: Gearing gets tuned per track — tighter/technical tracks favor more torque (larger pinion-to-spur ratio); long straights favor speed (smaller ratio).

The Heat Rule

Whatever motor you run, the golden rule is: gear for temperature, not for top speed. After a run, feel the motor can (not the magnets) — if it's too hot to hold your finger on for more than a second or two, you're geared too aggressively. Drop a tooth or two on the pinion and re-test.

Quick Adjustment Guide

Symptom	Fix
Motor runs very hot	Smaller pinion (fewer teeth)
Sluggish acceleration	Larger pinion (more teeth), within heat limits
ESC cutting out / low top speed	Check gearing isn't over-loading the motor
Excess drivetrain noise/wear	Re-mesh gears properly, check spacing

Mesh Matters as Much as Ratio

Even the "right" gear ratio will wear out fast — and can damage the motor bearing — if the pinion and spur aren't meshed correctly. You should be able to slide a piece of paper between the teeth with a slight friction fit; too tight and it binds and overheats, too loose and it strips teeth.

Start conservative, run a pack, check temps, and adjust one tooth at a time. Small changes make a noticeably bigger difference than you'd expect.