1/2" Socket with TX Plus profile

The 1/2" drive socket for the motor mounting bolts on Bosch Gen4 e-bike drives. Torx Plus T40 profile, not standard Torx; the difference between the two is what stops the motor bolts from rounding under the torque those fasteners see.

Torx Plus is a Torx variant with a flatter contact angle on the recess flats. The geometry is similar enough to standard Torx that a standard Torx driver will engage a Torx Plus recess, but at the working-torque range Bosch's motor-mount bolts see, the standard Torx driver concentrates torque on a much smaller contact patch than the Torx Plus driver does. The result on the Bosch Gen4 hardware specifically: a rounded bolt head on the first or second removal, and a service issue that needs an extraction tool to recover.

This socket is the correct tool for those bolts. The Torx Plus T40 tip geometry engages the full Torx Plus recess flats; the 1/2" drive matches the torque-wrench size most workshops use for high-torque interface work. Pair it with a 1/2" drive torque wrench in the appropriate Nm band to hit the Bosch Gen4 motor-mount spec exactly.

Compatibility

• Bosch Gen4 e-bike motor units (motor mounting bolts on the Performance Line, Performance Line CX, and related Gen4 drive families)
• Works with any 1/2" drive: Unior's Pro Socket Handle, 1/2" torque wrenches in the appropriate band

Bosch is the largest installed-base e-bike motor manufacturer on US IBD-channel bikes, which is why a Torx Plus T40 socket is a workshop-level fitment requirement for shops servicing Bosch-equipped frames at any volume. Earlier Bosch generations (Gen 2, Gen 3) use different fastener interfaces and a different lockring; verify the motor generation before service.

Specs

• 1/2" square drive
• Torx Plus T40 tip profile (not standard Torx)
• Hardened, tempered steel
• Trivalent chrome plating to ISO 1456:2009
• Manufactured in Slovenia

Built in Zreče, Slovenia

Unior has been forging hand tools in Zreče since 1919, and is the official technical partner of multiple World Tour and downhill teams. The Gen4 e-bike motor-mount socket is one of the e-bike-specific tools Unior added to the line as motor-equipped bikes moved into the IBD channel; the construction is the same drop-forged, hardened, and tempered process the rest of the high-load 1/2" drive socket line uses.

Pro tip from our mechanics

Two failure modes drive the case for the Torx Plus T40 over a standard Torx: rounded Bosch motor-mount bolts on a service that you didn't intend to be a job, and an extraction process that risks the alloy threads in the motor housing. Using the correct Torx Plus driver from the first removal onward is the cheap way to never need the extraction process at all.

For why Torx Plus differs from standard Torx and when a workshop needs both formats in the bit drawer: Hex and Torx wrenches: how to pick the right tool for the job →.