RetroArms CNC Low Profile Bushing 4mm Gear Shaft Axis (9 mm)

RetroArms CNC low-profile 9 mm bushings for 4 mm gear shafts

RetroArms CNC low-profile bushings are designed for mechanically demanding AEG builds and primarily for gears with 4 mm diameter shafts, such as reinforced RetroArms PandoRA gears. Please note that standard AEG gears generally use 3 mm shafts and are not compatible with this bushing version. The bushings are precision CNC turned from high-quality 1.2842 tool steel (90MnCrV8 / grade 19 313) and subsequently hardened to 58 HRC, making them suitable for high mechanical loads, including builds with powerful springs. The low-profile design was developed primarily for V2 gearboxes, where conventional protruding bushings may extend into the selector plate area and interfere with its movement. These bushings do not protrude unnecessarily from the gearbox and do not come into contact with the selector plate. They are designed for cylindrical gearbox holes with a diameter of 9 mm. The outer diameter of the bushing is intentionally approximately 0.04 mm larger than the nominal hole diameter to ensure a secure fit after installation, so the bushings must be carefully press-fitted or gently tapped into place. The bearing surface must be adequately lubricated with grease during operation.

Key features

Technical specifications

• Type: Low-profile bushings
• Material: 1.2842 steel (90MnCrV8 / grade 19 313)
• Manufacturing: CNC turning
• Hardness: 58 HRC
• Inner diameter: 4 mm
• Gear shaft diameter: 4 mm
• Gearbox hole diameter: 9 mm
• Installation interference: approx. 0.04 mm
• Design: Low-profile
• Lubrication: Grease

Package contents

• 6× RetroArms CNC low-profile bushing for 4 mm gear shaft (9 mm)

Frequently asked questions (FAQ)

Do these bushings fit standard AEG gears?

No. This version has an inner diameter of 4 mm and is designed exclusively for gears with 4 mm shafts, such as corresponding reinforced RetroArms gears. Standard AEG gears with 3 mm shafts require bushings with a 3 mm inner diameter.

Why do the bushings have a low-profile design?

The low-profile design is particularly useful in V2 gearboxes. The bushing does not protrude unnecessarily from the gearbox, so it does not extend into the selector plate area or interfere with its movement.

Why can't the bushings be inserted freely into the gearbox?

This is intentional. The bushings have an approximately 0.04 mm interference fit so that they remain firmly in place after installation and do not fall out. They therefore need to be precisely aligned and carefully press-fitted or gently tapped into place using a suitable tool. If necessary, they can additionally be secured with a suitable removable threadlocker.

Do the bushings need to be lubricated?

Yes. The manufacturer recommends adequately lubricating the bushings with grease. Proper lubrication reduces friction between the gear shaft and the bearing surface of the bushing.