The perch wedge is the common name of an important part of the clutch and
throttle controls. It was used on all BMW motorcycles from 1956 till at
least the /7 and maybe longer. It's function is to keep the clutch and
throttle castings from twisting on the handle bars. It is inconvenient to
turn the throttle and have the whole throttle casting turn. The part is still
available and costs $12 in 2004. I do know that Vech has it. That
seems expensive, but it always was costly. If you suffer the consequence
of failing to have it, that price will seem very cheap indeed. Install one
in each side. Don't waste your time trying to find an alternative for the
The perch wedge is almost invisible when in place. One end of it can be
seen if one looks from the center of the bike outwards and under the casting.
In the gap, where the two parts of the casting almost come together to tighten,
is a small triangular space. In that space is the wedge. It is
common for grease and dirt to cover it up. I then use a thin wire to stick
in the greasy hole. If the wire goes in, then it has no wedge.
Many owners aren't even aware of its existence. The owner typically removes the
throttle or clutch casting and the wedge falls onto the floor. IF it is
found later, the owner has no clue what it is or where it came from. Check
your bike to see if you have them. If you don't have them installed and
the controls are tight, then you may have 7/8"
handlebars. That is really bad and often breaks the castings.
If you look closely, you can even see the teeth of the wedge.
The wedge seated in place in a casting.
The screw that tightens the casting squeezes the two parts together and
forces the wedge into the chrome of the handle bar. The slightly curved
part, that is against the bar, is made up of several lines, or serrations, that
"bite" into the bar. This keeps the control casting from rotating on the
This is the top view showing the groove that the tightening
screw "fits into." This keeps the wedge from moving sideways.
This view shows the serrated edges, or teeth that "bite" into the bar.
This shows the end view of a BMW motorcycle perch wedge.
More information on controls and cables