breyfogle
10-13-2004, 06:15 PM
Currently over on the R11xxRS bulletin board there is a thread about recomended clutch lever adjustment on cable actuated
clutches. While there seems to be a lot of opinions and anecdotal evidence, there does not seem to be a lot of real
knowledge. Clutch free play is something I have been curious about since I first bought my RS and began reading all the
opinions about "proper" clutch level free play. BMW originally spec'ed 2 mm for '94 RS's, same a K bikes of the time.
The BMW recommended gap seems to have grown over time from 2 mm to 4mm, 5mm and even 7mm (1/4 inch!!), supposedly
in order to prevent premature clutch disk failure.
Disk clutches are relatively simple devices and I thought I more or less understood them so it makes
no sense to me how increasing the free play tp more than "just enough" can make any difference what so ever. If
the free play is set to XXX mm in the garage and that gap never completely closes up during high RPM, or high temperature,
or during full lock turns in a parking lot etc, the clutch disk is always fully engaged and there can not be any load
on the throwout bearing. The clutch disk can not be more than fully engaged.
Any additional free play at the lever is just slop at the lever. At some point, excessive free play should
actually prevent complete disengagement which would also be bad !
I currently have my '94 RS set to 3-4mm. Because of other people's concerns about this issue, I do check the free play
while riding under varying conditions by just feeling the clutch level from time to time. The gap does tend to
close up a bit at high RPM but so far there has always been at least some free play. Seems good enough.
Can anyone provide some additional (knowledgabe) insight on this ?
clutches. While there seems to be a lot of opinions and anecdotal evidence, there does not seem to be a lot of real
knowledge. Clutch free play is something I have been curious about since I first bought my RS and began reading all the
opinions about "proper" clutch level free play. BMW originally spec'ed 2 mm for '94 RS's, same a K bikes of the time.
The BMW recommended gap seems to have grown over time from 2 mm to 4mm, 5mm and even 7mm (1/4 inch!!), supposedly
in order to prevent premature clutch disk failure.
Disk clutches are relatively simple devices and I thought I more or less understood them so it makes
no sense to me how increasing the free play tp more than "just enough" can make any difference what so ever. If
the free play is set to XXX mm in the garage and that gap never completely closes up during high RPM, or high temperature,
or during full lock turns in a parking lot etc, the clutch disk is always fully engaged and there can not be any load
on the throwout bearing. The clutch disk can not be more than fully engaged.
Any additional free play at the lever is just slop at the lever. At some point, excessive free play should
actually prevent complete disengagement which would also be bad !
I currently have my '94 RS set to 3-4mm. Because of other people's concerns about this issue, I do check the free play
while riding under varying conditions by just feeling the clutch level from time to time. The gap does tend to
close up a bit at high RPM but so far there has always been at least some free play. Seems good enough.
Can anyone provide some additional (knowledgabe) insight on this ?