How to Install Differential Assembly on HS181/HM181 RC Car

By BEZGAR | Published: 2026-10-28

Category: How-to Guides

Learn how to replace the differential assembly on your HS181 or HM181 RC car. Step-by-step guide for installing the PX9300-07 diff, with common mistakes to avoid.

Quick Answer

To install the differential assembly on your HS181 or HM181 RC car, remove the old diff, insert the new PX9300-07 unit into the gearbox, align the gears, and secure it with the housing screws.

Why the PX9300-07 Differential Fits These Models

The BEZGAR Differential Assembly (PX9300-07) is an original spare part designed specifically for HS181 and HM181 RC car models. This means it matches the gear pitch, shaft diameter, and housing dimensions exactly, so you won't need to modify the gearbox or shim the gears. Using a generic differential could cause binding or poor mesh, leading to premature wear.

Tools You Will Need

Have a small Phillips-head screwdriver, a pair of tweezers or needle-nose pliers, and a clean workspace. You may also want a small amount of lithium grease for the gear teeth, though it is not required.

Installation Steps

Remove the Gearbox Cover: Unscrew the four screws holding the gearbox cover on the rear of the chassis. Lift the cover off carefully—there may be small shims or washers that can fall out. Common mistake: Losing the shims. Place them in a labeled container or note their positions.
Take Out the Old Differential: Lift the old differential assembly out of the gearbox. Note the orientation of the gear teeth and any spacers. If the old diff is stuck, gently pry it up with a flat screwdriver from the side. Checkpoint: Inspect the gearbox housing for broken teeth or debris before installing the new diff.
Install the New PX9300-07 Differential: Place the new differential into the gearbox with the gear teeth facing the pinion gear. Ensure it sits flush and the axle shafts align with the output cups. Do not force it. Common mistake: Installing the diff upside down. The larger gear should mesh with the pinion, not the smaller one.
Check Gear Mesh: Rotate the pinion gear by hand. The diff gear should turn smoothly with a slight resistance. If it binds or feels too loose, reposition the diff or add/remove a shim. Checkpoint: Proper mesh means the gears turn without grinding or skipping. Adjust shims if needed.
Reattach the Gearbox Cover: Place the cover back on and tighten the four screws evenly in a cross pattern. Do not overtighten, as this can warp the plastic housing and cause binding. Common mistake: Overtightening screws. Stop when you feel resistance; the cover should be snug, not compressed.
Test the Drivetrain: Spin the wheels by hand or run the car at low speed on a stand. Listen for grinding noises and check that both wheels rotate freely. If the car pulls to one side, recheck the diff installation. Checkpoint: A smooth, quiet drivetrain confirms the installation is correct. If you hear clicking, the gear mesh may need adjustment.

Product Details

Differential Assembly(PX9300-07) for HS181/HM181: This BEZGAR Differential Assembly (part number PX9300-07) is an original spare part designed specifically for HS181 and HM181 RC car models. It guarantees a perfect fit without modification, saving you time and avoiding drivetrain binding issues.
Differential Assembly(PX9300-07) for HS181/HM181