1st gear clunk
Posted: Fri Nov 11, 2016 10:02 am
Just found this on the BMW Club Forum...
That awful Bang when selecting 1st gear”
I am sure this is the cause of the problem, The tolerances and or damage in the clutch basket female to friction plate male plates do not allow the plates to disengage when the clutch is pulled in resulting the unit trying to send drive to the back wheel (I call this a ghost drive) When 1st gear is engaged from neutral the (ghost) drive is then forced to disengage as a result of the bikes weight now coming into play as a result this then shocks the plates to separate, Hence the leap forward and loud clashing of the gears, The leap forward is the delay in the (ghost) drive disengaging, Once this has happened the (ghost) drive will disengage and stay that way selecting other gears are also effected, When the power unit is cold this problem is not always evident but as the power unit warms the tolerances reduce and the crashing gear problem becomes much more evident. A second theory also has a place regarding this problem , the movement of the clutch mechanism when engaged to disengaged is very small and the oil has an effect acting like a torque converter and spinning the clutch assembly and thus the drive chain and as above would have the same results. However the problem should be at its worst when the oil is cold as the viscosity is at its thickest and as the oil warms and the viscosity reduces then the problem should reduce, but this is not the case the units that I have observed get worse as they get hotter thus leading me back to a tolerance problem. It has been noted that a large number of the R1200 water cooled units (but not all units) have this problem and when presented to BMW the answer (“Well they all do that Sir”) (“is this correct me thinks”)
OK we have dog gears in the gear train and by nature they have a tendency to crash but not to lurch the bike forward and should not grind. We as BMW owners have go used to owning machines with separate power units regarding engine /gearbox.
Thus any contamination in the gear train will have no effect on the engine and its oil. Now that the water cooled units have a combined engine / gearbox power unit any contamination generated within the gear train will have a consequence on engine oil contamination practical count, each time the gears bang and grind /crash this must be placing debris into the oil bath.
The engine oil samples taken from my bike and analysed by a professional business show a high particle count of Iron compared to other materials within the sampled oil. (see analysis report ),I do not as yet know where the iron has come from but I would suspect the gears, I have asked BMW to inform me regarding the gear material but this has not happened,
A little information regarding oil filters. Oil filters do not remove all the debris suspended in oil but take out a percentage this percentage depends on its rating known as the Beta ratio (along with other factors) which is given as a percentage and at best would take out 97% of the particle count.
The higher the particle count the higher the percentage that will pass and go around the engine unit thus generating even more debris. This iron will travel around the engine and act as a grinding paste, As the particles suspended in oil increase in numbers the amount of particles will pass the filter (beta ratio) of the filter and go around again thus raising the amount suspended in oil, Then it shall be only a matter of time before the engine unit fails and this could be well outside the warranty period.
The material count from the oil analysis =
Iron 110 parts/million, Chromium 15 parts/million, Copper 15 parts/million, Aluminium 15 parts/million, Silicon 15 part/million, Nickel 7 parts/million.
This particle count is normal for a power unit with only 3,600 miles except for one material.
I have had my clutch changed and the problem has gone away when tested in my workshop even after warming the power unit to correct operating temperature but due to an injury I shall not be able to take the bike out onto the open road until spring 2017 at best. In my opinion it is not just an annoying gear crash but a potential major fault waiting in the wings to come a bite you on the bum, but I may be wrong!
interesting :thinking:
That awful Bang when selecting 1st gear”
I am sure this is the cause of the problem, The tolerances and or damage in the clutch basket female to friction plate male plates do not allow the plates to disengage when the clutch is pulled in resulting the unit trying to send drive to the back wheel (I call this a ghost drive) When 1st gear is engaged from neutral the (ghost) drive is then forced to disengage as a result of the bikes weight now coming into play as a result this then shocks the plates to separate, Hence the leap forward and loud clashing of the gears, The leap forward is the delay in the (ghost) drive disengaging, Once this has happened the (ghost) drive will disengage and stay that way selecting other gears are also effected, When the power unit is cold this problem is not always evident but as the power unit warms the tolerances reduce and the crashing gear problem becomes much more evident. A second theory also has a place regarding this problem , the movement of the clutch mechanism when engaged to disengaged is very small and the oil has an effect acting like a torque converter and spinning the clutch assembly and thus the drive chain and as above would have the same results. However the problem should be at its worst when the oil is cold as the viscosity is at its thickest and as the oil warms and the viscosity reduces then the problem should reduce, but this is not the case the units that I have observed get worse as they get hotter thus leading me back to a tolerance problem. It has been noted that a large number of the R1200 water cooled units (but not all units) have this problem and when presented to BMW the answer (“Well they all do that Sir”) (“is this correct me thinks”)
OK we have dog gears in the gear train and by nature they have a tendency to crash but not to lurch the bike forward and should not grind. We as BMW owners have go used to owning machines with separate power units regarding engine /gearbox.
Thus any contamination in the gear train will have no effect on the engine and its oil. Now that the water cooled units have a combined engine / gearbox power unit any contamination generated within the gear train will have a consequence on engine oil contamination practical count, each time the gears bang and grind /crash this must be placing debris into the oil bath.
The engine oil samples taken from my bike and analysed by a professional business show a high particle count of Iron compared to other materials within the sampled oil. (see analysis report ),I do not as yet know where the iron has come from but I would suspect the gears, I have asked BMW to inform me regarding the gear material but this has not happened,
A little information regarding oil filters. Oil filters do not remove all the debris suspended in oil but take out a percentage this percentage depends on its rating known as the Beta ratio (along with other factors) which is given as a percentage and at best would take out 97% of the particle count.
The higher the particle count the higher the percentage that will pass and go around the engine unit thus generating even more debris. This iron will travel around the engine and act as a grinding paste, As the particles suspended in oil increase in numbers the amount of particles will pass the filter (beta ratio) of the filter and go around again thus raising the amount suspended in oil, Then it shall be only a matter of time before the engine unit fails and this could be well outside the warranty period.
The material count from the oil analysis =
Iron 110 parts/million, Chromium 15 parts/million, Copper 15 parts/million, Aluminium 15 parts/million, Silicon 15 part/million, Nickel 7 parts/million.
This particle count is normal for a power unit with only 3,600 miles except for one material.
I have had my clutch changed and the problem has gone away when tested in my workshop even after warming the power unit to correct operating temperature but due to an injury I shall not be able to take the bike out onto the open road until spring 2017 at best. In my opinion it is not just an annoying gear crash but a potential major fault waiting in the wings to come a bite you on the bum, but I may be wrong!
interesting :thinking:
