out of phase D/Shaft

[fanbelt]

All:

For those that know, what does an out of phase drive shaft feel like?

The bike, 96 R 1100gs.

Is it a thready roughness at the same rpm in all gears? Goes away when clutch is pulled/eng idle.

Fanbelt

[mcmxcivrs]

While its possible that an out of phase driveshaft might cause some noticable pulsing in the drive train, the biggest issue usually increased wear and tear on the driveshaft and other drivetrain components due to the induced oscillations from the out of phase shaft. There is usually enough isolation from the damper in the driveshaft, slack in the splines and FD and even dampening from the tire to make the pulses undetectable to the rider.

It seems that from your description, the issue may be with the engine or quite possibly the clutch and/or flywheel being out of balance. Has the clutch been replaced or worked on? It is important to ensure that the clutch components are properly aligned to ensure the poper balancing is maintained. There are usually markings on each component of the assembly that must be aligned at equal spacing. The marks indicate the heavy spot of each part and are to be spaced apart to ensure they counterbalnce each other. If all three or even two were assembled together, the result is an imbalance that could very well create a noticable vibration. Typically vibrations will show up at a particular frequency which fits with your descripotion of it always being at the same RPM range.

Its is also possible that you may simply have an issue with the engines state of tuning. Imbalanced throttle bodies at the high RPM range will cause uneveness between the two cylinders and thus a rough feel that could well be felt as what you describe. Balancing at idle is done by adjusting the air screws on the TBs but a sometimes missed step is to balance the high RPMs by adjusting the throttle cables.

[PGlaves]

If it goes away with the clutch pulled, engine idle, but coasting at speed, it is not driveline related. It is combustion imbalance in the engine.

If it persists while coasting at speed, engine at idle, it is driveline related.

UNLESS, it is a failing U joint which gets cocked slightly off center when torque is applied, in which case it will come and go as you roll on hard, and roll off gently.

[fanbelt]

A lot to think about. Thank you folks. I'm thinking. Hmmm.

Fanbelt

[sedanman]

If the driveshaft has not been removed from the bike it is NOT out of phase. It's not something that just happens, someone has to take it apart and put it back together improperly. Tight or failing u-joint is something that could be spontaneous.

[cardoctor]

had a similar problem with my r1150gs . right throttle body was way out of sync.
buy a twinmax start with that.

[PGlaves]

If the driveshaft has not been removed from the bike it is NOT out of phase. It's not something that just happens, someone has to take it apart and put it back together improperly. Tight or failing u-joint is something that could be spontaneous.

I have seen several driveshafts out of phase from the factory.

[sedanman]

I don't doubt it. But someone would have done something about the o/p's '06 by now don't you think.

[PGlaves]

I don't doubt it. But someone would have done something about the o/p's '06 by now don't you think.

Not necessarily. The acceleration/deceleration at a 15 degree deflection is 15% - as the output from a joint speeds and slows each revolution with the joints 90 degrees out of phase. It decreases when the joints are closer in phase. But as long as the joints stay centered it is probable that no noticeable vibration would be present.

The problem is the stresses on the joints and splines as shaft speed varies on opposite sides of a joint.