conkerman wrote:Deceleration is merely acceleration in the opposite direction
I can be such a pedant sometimes...
You are right though.
You're right to bring up the bearing friction. But I don't think they qualify as "transmitted torque". If you buy into what I'm saying, it then begs the question what exactly is causing the bike to want to spin on the crankshaft axis? A reaction to crank/clutch mass. But how?
It's at this point I start to take on a demeanour akin to the little man in herb's avatar.
Think helicopter without a tail rotor or a bike doing a wheelie, just the forces are much smaller. Every action has an equal and opposite and all that.
conkerman wrote:Think helicopter without a tail rotor or a bike doing a wheelie, just the forces are much smaller. Every action has an equal and opposite and all that.
I learnt that early on, if I said to the girlfriend in the heat of the moment "no we're not going shopping" the equal and opposite reaction was usually a vast change in temperature and a denial of bedroom gymnastics
--
Steve Parry
Current fleet: '14 F800GS, '87 R80RS, '03 R1100S BoxerCup, '15 R1200RT LE Dynamic, '90 K1, '05 K1200S
conkerman wrote:Think helicopter without a tail rotor or a bike doing a wheelie, just the forces are much smaller. Every action has an equal and opposite and all that.
I can see where you're coming from. But I can see (what i think are) differences.
The helicopter blades are demanding a transmitted torque. So the tail rotor is needed even in steady state, as well as accelerating the rotors. There is a definite torque reaction, created by the gearbox trying to turn the helicopter fuselage around. The torque reaction (reaction to transmitted torque, that is) on our boxer is resolved within its own engine/gearbox housing. It becomes "unresolved" at the rear wheel, the axis of which acts at right angles to the crankshaft. That's how I'm presently seeing things.
Going back to the helicopter scenario, we'd have to remove any form of lift from the blades and then consider if the fuselage would still spin during steady state rpm. Bearing friction would be the only force left, apart from the accelerating of masses. Don't know if that's utter garbage or not?
Tapio wrote:Angular acceleration works the same way as straight acceleration.
Straight: F = m*a where:
F: force [N]
m: mass [kg]
a: acceleration [m/s^2]
Angular: M = I*phi where
M: moment [Nm]
I: mass inertia [(Nms^2)/Rad]
Phi: angular acceleration [Rad/s^2]
Bearing friction has nothing to do with this.
//T
P.S. the action and reaction is in Newton’s 3rd law. But the above falls under Newton’s 2nd. ds
Yes.
So the pistons are asked to accelerate the things to which they are attached. They don't care whether they spin the "flywheel" or the engine housing. It's just easier to spin the flywheel. But they're having a damn good try at spinning the engine housing (and frame). The reaction counter force is the wheels as they contact the road (or the side stand, or centre stand). If you are travelling along and the "flywheel" is rapidly accelerated, because there is some inertia involved in the "flywheel", the pistons have a go at spinning the entire machine instead. Because the reaction point is the tyres on the road the bike tries to lean over. An amount of countersteer will be needed to remain on course.
What is not quite so easy to get ones head around is why the torque input to accelerate the "flywheel" causes this reaction but the torque imput to propel the bike doesn't.
Try this - think fixed wing aircraft; the 3 axes of movement are pitch, roll and yaw (elevators, ailerons and rudder).
Blipping the BM throttle while stationary gives the torque reaction of rolling the bike to the right (ailerons)
The steering wander to the right that Er-Minio had is like yaw (rudder) and was wheel mis-alignment.
It will have a couple affecting it when the throttle is blipped and revs change as the front wheel is turning when at speed and it is now more difficult to input a steering change (gyroscopic effect) hence the use of countersteering but thats another can of worms to explain.
Pitch is the result of weight transfer under acceleration or braking.
Not forgetting the built in assymetry of the boxer (well 1100S at anyrate as per page 46.18 in the service manual) of 4.5mm which will also make them pull more to the right.
In the end the OP took it to Steve Jordan for a suspension setup and a bit of a general check up and they found the steering plate wasn't quite straight and that was causing the issues. Not sure where that happened but all I'll say is that it was fine before the Ohlins were fitted so I'm under the assumption the people that fitted that messed it up (they certainly messed up other things while it was being done).
The bike was on a trackday yesterday and handles beautifully now and most important, goes straight!
metropolis2k wrote:Not quite sure where this thread has ended up
In the end the OP took it to Steve Jordan for a suspension setup and a bit of a general check up and they found the steering plate wasn't quite straight and that was causing the issues. Not sure where that happened but all I'll say is that it was fine before the Ohlins were fitted so I'm under the assumption the people that fitted that messed it up (they certainly messed up other things while it was being done).
The bike was on a trackday yesterday and handles beautifully now and most important, goes straight!
We (ok I) veered off onto torque steer, although to be fair it was prompted by a comment made by someone in relation to the, then unknown to us, answer to the problem in the OP.
