Shift button coming loose on the Schlumpf Speed Drive

Hi all,

As mentioned in this topic, I lost 2 weeks ago one of the shift buttons of my Schlumpf Speed Drive.
I ordered a new one and received it. When I mounted it yesterday I understood why I am loosing it: I am unable to apply sufficient torque to it.

The figure below shows what is the issue:

For one or another reason, the threaded shifting shaft does not protrude enough out of the crank shaft, and the M3 Allen screw sits then quite deep in the shift button.
The 1.5 mm Allen bit being too short to engage properly in the Allen screw, it slips in the screw head so the applied torque is not high enough. :imp:
I see that the torque wrench Schlumpf/Haberstock is selling does have a longer head, which makes it possible to tighten the screw properly, I guess :confused:

The only solution I have now is to use a common L-shaped Allen key to tighten the screw or to buy the torque wrench (60Eur! :imp: ).

Has anybody encountered the same issue?

Dear Bietrume,

might it be possible that the small Allen screw is of the wrong length?
It should be 5 mm.
(Maybe you could use a longer screw i.e. M3x6 or M3x8 mm)

Are you sure that the button is adjusted correct?
The surface of the button should be (when engaged) plain with the surface of the cranks.

The right one is a little bit too much outboard.



(The installing instructions were moved from the above mentioned topic to here.)

(From the Manual-Sclumpf-Speed-Drive.pdf (17,7Mb), Chapter B-5, found here:

*[a pair of pliers]
That’s meant for the old non-slotted version of gear shift buttons (before October 2004).
Instead of the pair of pliers please use the special wrench (tool B of
this post).