Bosch eBike drive unit extension sleeves M8 - Classic

The Bosch expansion sleeves M8, T40 must be replaced after disassembly of the Classic-Line drive unit.

What is the Bosch expansion sleeve M8 (PU=3) used for:

• The Bosch Classic motor expansion sleeve M8 (motor screws  sleeve) is required to attach the Bosch ClassicLine motor to an eBike frame together with the Bosch mounting plate.
• The Bosch Classic motor has 3 stud bolts for this purpose, which are firmly connected to the motor housing and therefore cannot be replaced.
• These original expansion sleeves are needed to create a backlashfree connection between the drill hole and the screw connection on the one hand.
• On the other hand, during deformation, the thread is enclosed more tightly, thus preventing the connection from loosening on its own.
• It is essential to use the original expansion sleeve, as the original product is specially designed by Bosch for this application and only this ensures a secure connection between the different materials (steel, aluminum).

Why does the Bosch expansion sleeve M8 have to be replaced after every engine change? What torque do I need to pay attention to?

• Each expansion sleeve on the Bosch Classic engine can be used only once, because a "deformation" of the sleeve already occurs during the correct assembly process, while maintaining the required torque of 2530 Nm.
• A reused old Bosch Classic M8 expansion sleeve can break or loosen by itself and thus lead to a fall.

Important safety note:

• When reusing used expansion sleeves, there is an acute risk of breakage and thus an increased risk of accidents.
• If the sleeve is stretched, it is not possible to tell visually.
• If correctly installed, however, it must be assumed that the expansion sleeve is "used up" in any case when installed and must be compulsorily replaced after loosening this screw connection.

Further mounting instructions:
Please note that the drive unit mounting bracket consists of 3 parts.
1x Bosch mounting plate
2x Bosch M6x20 T30 Torx screws
3x Bosch M8 expansion sleeves Torx T40