Custom Build - Quad Chassis Setup Guide

Overview

Looking to build out a high-performance electric quad chassis? We’ve got you covered.

Our go-to recommendation for most quad builds is the EMX QS 138 90H kit WITH v3 built in gear reduction— a powerful, streamlined setup designed for maximum performance with minimal complexity.

⚡ Recommended Powertrain Setup

EMX QS 138 90H with v3 built in gear reduction kit

• High torque, high efficiency motor platform
• Built in gear reduction motor:
  • 2.35:1 gear reduction
• Includes:
  • QS 138 90H Motor
  • Controller
  • Wiring harness

👉 Built for aggressive acceleration and consistent power delivery

• Select “E-Cable” for compatibility with a standard thumb throttle commonly used on quads
• V3 Gear reduction motors MUST be mounted with the driveline on the vehicle left as the motor can only spin counterclockwise at full power

🔋 Recommended Battery Options

To get the most out of the 90H setup, pair it with a high-output battery:

• High Power 76V 40Ah
• High Power “MX” 76V 48Ah or 60Ah
• High Power “Two Stroke” 76V 48Ah or 60Ah

👉 Higher capacity = longer run time + sustained performance

🎚️ Power Modes

The system supports a 3-mode power switch:

• 50% – Controlled power for tighter tracks or learning
• 75% – Balanced performance
• 100% – Full output, maximum acceleration

Alternative options for 3 mode switch (Request in customer notes at time of purchase): 

• Reverse / Low Power / High Power
• Reverse / Med Power / High Power

⚙️ Recommended Gearing

Since this is a direct drive setup, gearing is critical.

With a standard 22 inch quad tire

Typical starting point:

• Front sprocket: 12t 520 - Available HERE
• Rear sprocket: 35T 520 - Custom available HERE

Expected performance:

• Extremely fast acceleration
• 55+ MPH top speed (depending on setup and conditions)

👉 Quad setups vary heavily — gearing should be tuned per application

Due to the gearing requirements for a larger sized quad tire, it is NOT recommended to go with the direct drive variant. 

🔧 What You’ll Need to Handle

This is a custom install and will require fabrication.

You will need to:

• Fabricate motor mount plate / bracket
• Mount and secure the controller
• Design and secure battery placement
• Align drivetrain (chain + sprockets)

👉 We supply the powertrain — you handle chassis integration.

📐 Fitment & Dimensions

We’ve included:

• Motor dimensions
• Controller dimensions

Use these to:

• Mock up placement in your chassis
• Plan clearance for axle, chain line, and battery

⚠️ Important Notes

• This is a high-power setup — proper mounting is critical
• Chain alignment and tension must be dialed to prevent failure
• Ensure your axle, sprocket carrier, and chain can handle the load
• Expect significantly higher torque than typical gas kart setups

🚀 Need Help With Your Build?

If you’re unsure where to start, submit a ticket with:

• Your chassis type
• Tire Diameter
• Intended use (track, drift, etc.)

We’ll help you get your setup dialed.

Electro & Company
Ready to Rip.