Screws, 4x12mm button-head machine (hex drive) (6)

Button Head Screws 4x12 mm with Hex Drive: The Spare Part You Shouldn't Be Without in Your Workshop

When it comes to preventive maintenance on RC models, screws are one of the consumables that are often overlooked until they start causing problems. The reference TRX-3937 from Traxxas addresses precisely that: a pack of 6 M4x12 mm button head screws with internal hex drive, in original spare part format so you always have stock in your drawer.

Main Features

• Metric: M4 (4 mm diameter)
• Length: 12 mm
• Head Type: button (button-head), low profile and rounded
• Drive: internal hex (Allen key / hex drive)
• Quantity: 6 units per pack
• Official Traxxas Reference: TRX-3937

Function and Performance

The button head offers a lower profile and a larger bearing radius than the standard cylindrical head, which distributes the load better over the surface and reduces the risk of the head sinking or damaging plastic or composite parts. The internal hex drive allows for precise torque application, preventing the head from slipping during assembly or disassembly.

In Traxxas models, this type of screw frequently appears at body mounting points, electronics covers, servo mounts, and other assemblies where space is limited and the head should not protrude excessively.

Compatibility and Installation

This is an original Traxxas spare part. The specific compatibility depends on the model in which this screw comes from the factory; consult your vehicle's parts manual or the parts diagram on the official Traxxas website to verify the usage points before installing them. As a general rule, any position in your model that uses an M4x12 mm button-head screw with hex drive will accept this reference.

For tightening, use an Allen key of the appropriate size for the internal hex of the head (check your model's specifications). Proper tightening, without excessive torque, ensures that the screw does not deform the housing or become over-threaded.

Installation and Preparation

• Check the condition of the thread in the housing before installing new screws. If the thread is damaged, repair it before proceeding.
• Apply a small amount of lithium grease or low-strength thread-lock if the mounting point is exposed to intense vibrations.
• Do not overtighten: the button head has a generous bearing surface, but the plastic of the housings has its torque limit.
• Store any leftover screws in a labelled organiser; this way, you'll have them located for the next maintenance session.

Common Mistakes

• Confusing button head with cylindrical head (socket cap): although both use hex drive, the profile and height are different. Always check the type of head specified in your model's parts list.
• Using the wrong Allen key: a loose-fitting key wears out the internal hex of the head and makes future disassembly difficult.
• Reusing heavily worn screws: if the internal hex shows signs of rounding, replace it directly. An original spare pack like this is the simplest solution.

Frequently Asked Questions

How many screws are included in the TRX-3937 pack?

The pack includes 6 units of M4x12 mm button-head screws with internal hex drive.

Which Traxxas models are they intended for?

They are original Traxxas spare parts. Exact compatibility depends on the model and the mounting point. Check your vehicle's parts diagram on the Traxxas website or in the included manual to confirm which positions use this reference.

What is the difference between button head and cylindrical head (socket cap)?

The button head has a lower and rounded profile, with a larger bearing surface. The cylindrical head (socket cap) is taller and offers more torque. Both use Allen keys, but they are not interchangeable at all mounting points.

Do I need any special tools to install them?

Just an Allen key (hex key) of the size that corresponds to the internal hex of the head. Check your model's specifications for the exact size.

Can I use thread-lock on these screws?

Yes, at points exposed to strong vibrations, it is advisable to apply a small amount of low-strength thread-lock (blue type). Avoid high-strength ones if you will need to disassemble them frequently.

Traxxas TRX-3937 button-head machine screws 4x12mm hex drive, pack of 6 — genuine Traxxas spare parts for RC car maintenance and repair. Keep your Traxxas model running at its best with original replacement hardware. Compatible with multiple Traxxas vehicles wherever M4x12mm button-head hex screws are specified. Essential workshop stock for RC enthusiasts and club racers.