Traxxas RTR Speed Run – Optional Gearing vs Stock Gearing
Traxxas RTR Speed Run
The 60+ mph on a Slash VXL box comes with a footnote. Traxxas ties that number to optional gearing and a 3S LiPo, and the gearing is the part thatโs easy to forget about. Some newer boxes have an extra pinion in the bag, so you may already own it without having thought much about it.
Iโm using the Slash VXL 2WD for the numbers here, since Traxxas publishes them clearly for that truck. Other VXL models are geared differently, so check your own manual before copying any tooth counts.
What the swap changes
The pinion sits on the motor shaft, and the spur gear sits on the drivetrain side. A bigger pinion gives you taller gearing: more top speed, and a motor that has to work harder to get the truck there.
| Setup | Pinion / Spur | Traxxas listed speed |
|---|---|---|
| Stock gearing | 23T / 86T | 35+ mph (a few listings say 40+, depending on battery) |
| Speed gearing | 31T / 76T | 60+ mph on 3S LiPo |
Look at those tooth counts again. The speed setup in those listings isnโt only a bigger pinion. The spur drops from 86T to 76T as well. If the bag only has a pinion in it, your truckโs manual will say what Traxxas wants paired with it.
Stock gearing is quicker off the line and more forgiving, and jumping and wheelies tend to feel better. Taller gearing feels lazy from a stop and wants a long straight to build speed.
Heat decides it
Taller gearing pulls more current, and the motor and ESC both warm up faster. On a 3S pack there isnโt much margin. Axialโs gearing guide puts the motor ceiling at 160ยฐF, measured at the endbell with an infrared gun after a few minutes of running. Motor makers differ a little, so your motorโs manual comes first, but 160ยฐF is a sensible place to start.
Loose dirt and grass add load, so speed gearing there will tend to cook a motor faster than the same gearing on smooth pavement. Gear mesh matters too. A strip of paper between the pinion and spur while you tighten the motor is the usual way to set it. Too tight adds heat, and too loose strips the spur.
Recommended Reading:
๐ What Does RTR Mean in RC? Ready-to-Run Explained
๐ Arrma XRT vs Traxxas X-Maxx โ My Honest Verdict After Months of Bashing
Do I leave the speed pinion on?
For general bashing, no. Stock gearing is easier on the motor and keeps the truck fun on grass, dirt and gravel.
Iโd treat the speed pinion as a part for one dedicated afternoon: empty pavement, a fully charged pack, a temp gun in your pocket. Make a pass or two, check the endbell, and let it cool. A motor fan helps, but I wouldnโt count on one to rescue gearing thatโs already too tall. Then put the stock pinion back.
The first pass is a decent time to find out how warm that motor gets, before you get to the second.
