Wasserboxer-why did the silencer and swingarm swap sides?

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As there aren't many threads about the NEW water cooled 1200GS I thought I'd start one..........:blast

For those that don't read More Crap than News.....
(I bought it today for the 1st time this year-honest Guv.....)

On the newly released 1200GS both the swing arm and exhaust silencer have "swapped sides", exhaust traditionally on the left is now on the right hand side, paralever swingarm traditionally on the right is now on the left hand side-why?

The 1200GS' "Project leader" Antonius Rhue states the reason the exhaust swopped sides.......
So that when offroad riding, riders who dismount and push/walk alongside the bike have less chance of burning their legs.

And the reason the swingarm swapped sides?
So the bike looks better when parked on the side stand.

The swingarm one....... o.k. I'm with him on that one to a degree and as long as it didn't add to the budget too much I can't see the BMW beancounters getting too upset.

The exhaust one?
:roll
 
Ah- ha. Think about it:

If the drive shaft is moved to the opposite side, it has to rotate in the opposite direction to propel the bike forward.
It is therefore obvious that the change of sides is neccessitated by the new transmission arrangement. The alternative would be another set of meshing gears, with approx 5% losses in them, or to make the engine rotate in the opposite direction to previously. Only Honda and Simca seem to have have ever been happy with engines which rotate anticlockwise when viewed from the non clutch end. ( I am, of course referring to car engines here, but - what the hell, this is a 2 cylinder car engine anyway)
Myke
 
riders who dismount and push/walk alongside the bike have less chance of burning their legs. when its broken down.
 
Myke Rocks said:
If the drive shaft is moved to the opposite side, it has to rotate in the opposite direction to propel the bike forward.
Click to expand...

I think you could swap sides for the same shaft rotation by simply cutting the teeth the other way (i.e. as mirror image). If my spatial reasoning is working I think you could even keep the same shaft rotation direction and teeth cutting and just change whether the shaft engages at the top or bottom of the gear fixed to the back wheel.

Darren
 
Not as easy as that.

dazlewis said:
I think you could swap sides for the same shaft rotation by simply cutting the teeth the other way (i.e. as mirror image). If my spatial reasoning is working I think you could even keep the same shaft rotation direction and teeth cutting and just change whether the shaft engages at the top or bottom of the gear fixed to the back wheel.

Darren
Click to expand...

Your thought may be rationalised as follows:
I screw a nut off a bolt by turning it counterclockwise.
Having unscrewed it, one turns it through 180 degrees, but it still screws on again in the same direction as before.

One must move the crownwheel to the opposite side to reverse direction, and this is not practical on a motorcycle.
Myke
 
Myke Rocks said:
Your thought may be rationalised as follows:
I screw a nut off a bolt by turning it counterclockwise.
Having unscrewed it, one turns it through 180 degrees, but it still screws on again in the same direction as before.
Myke
Click to expand...

I don't think this is a good analogy and it is not strictly true (unless you also rotate your frame of reference along with the bolt - which for the bike would mean getting the drive shaft to switch sides by simply pointing the whole bike in the opposite direction). Think about it this way - you unscrew a nut by turning it counterclockwise only when you look from the threaded end of the bolt. If you look from the head-end of a bolt you unscrew the nut by turning it clockwise (put another way, a "normal" clock runs anti-clockwise when viewed from behind).

In any case, I wasn't saying I rotate the drive shaft 180 degrees, I was proposing the equivilent of a reversed-hand thread on an otherwise mirror image of the drive shaft. A straight mirror image of the whole bike does indeed require the drive shaft to rotate the opposite way, but this can be undone by reversing the gear cutting (in the same way a left hand thread changes whether a bolt is pulled or pushed along a bolt's thread for a given rotation direction.)

Instead of mirroring you can get also the drive shaft to switch sides while still moving the bike forwards with the same drive shaft rotation direction by putting it on the other side upside down - this is basically the other suggesion of changing whether the shaft engages with the top or bottom of the crown wheel.

I am 99.999% confident I am right, but also slightly wary that I have been caught out by such things before!!

Darren
 
OK, then:

dazlewis said:
I don't think this is a good analogy and it is not strictly true (unless you also rotate your frame of reference along with the bolt - which for the bike would mean getting the drive shaft to switch sides by simply pointing the whole bike in the opposite direction). Think about it this way - you unscrew a nut by turning it counterclockwise only when you look from the threaded end of the bolt. If you look from the head-end of a bolt you unscrew the nut by turning it clockwise (put another way, a "normal" clock runs anti-clockwise when viewed from behind).

In any case, I wasn't saying I rotate the drive shaft 180 degrees, I was proposing the equivilent of a reversed-hand thread on an otherwise mirror image of the drive shaft. A straight mirror image of the whole bike does indeed require the drive shaft to rotate the opposite way, but this can be undone by reversing the gear cutting (in the same way a left hand thread changes whether a bolt is pulled or pushed along a bolt's thread for a given rotation direction.)

Instead of mirroring you can get also the drive shaft to switch sides while still moving the bike forwards with the same drive shaft rotation direction by putting it on the other side upside down - this is basically the other suggesion of changing whether the shaft engages with the top or bottom of the crown wheel.

I am 99.999% confident I am right, but also slightly wary that I have been caught out by such things before!!

Darren
Click to expand...

Imagine your drive is by straight cut bevel gears (a horrible thought).
Now the same thing having no teeth at all on either gear, so it drives by friction.
OK. The teeth have no influence on the direction of rotation of the output shaft. All that happens is that the 2 shafts must, in any friction situation, turn in opposite directions. The teeth are only there to provide a little friction.
There is one exception to the above, and that is where the teeth are on the inside of the driven (large) gear. In that case, both shafts turn in the same direction. Think very old lawnmower wheel and cutting drum.
Myke
 
There was a section I read in all the BMW blurb (could have been somewhere else though) that said they swapped sides to rotate the shaft in the opposite direction of the engine therefore it acts as a further damper on the rotational forces of the crank. Makes sense to me and will enable them to reduce the mass and size of the counter shaft inside the engine. The only problem I have with the idea is that it isn't down the centre line of the crank so I am not sure how effective it would be.
 
Marki_GSA said:
There was a section I read in all the BMW blurb (could have been somewhere else though) that said they swapped sides to rotate the shaft in the opposite direction of the engine therefore it acts as a further damper on the rotational forces of the crank. Makes sense to me and will enable them to reduce the mass and size of the counter shaft inside the engine. The only problem I have with the idea is that it isn't down the centre line of the crank so I am not sure how effective it would be.
Click to expand...

I remember seeing that somewhere too.

Don't really see how that would make a difference either.
 
Myke Rocks said:
Imagine your drive is by straight cut bevel gears (a horrible thought).
Myke
Click to expand...

Ahh - I was envisaging a worm gear drive with the worm on the end of the drive shaft and reversing the thread on the worm or whether it engages at top or bottom of drive gear to swap rotation.. I hadn't really thought about it, but I guess bevel gears are probably a better solution than a worm gear and I agree for this the rotation direction can't be so easily reversed.*

Darren

Please ignore any asterisks. It is a random iPad thing.
 
I think moving the swingarm to the left side now gives countless more options for mounting the tax disc. Who now says BMW doesn't listen to the big issues of 1200 GS owners on this forum. :D
 
There may be a minor truth in this

Marki_GSA said:
There was a section I read in all the BMW blurb (could have been somewhere else though) that said they swapped sides to rotate the shaft in the opposite direction of the engine therefore it acts as a further damper on the rotational forces of the crank. Makes sense to me and will enable them to reduce the mass and size of the counter shaft inside the engine. The only problem I have with the idea is that it isn't down the centre line of the crank so I am not sure how effective it would be.
Click to expand...
But the inertial forces in the drive shaft will be ( relatively) very small compared to those of the crankshaft, so the effect will be very small.
The fact that it is not in line with the crank is irrelevant.
However, even if it were, it wouldn't concern BMW too much, given that they still don't bother with mounting the balance shaft correctly. (Currently below crankshaft). To mount it properly takes 2 balance shafts, one below the crankshaft, and one above. They would contra-rotate, and would kill the rocking couple completely. What they have installed quarters the amplitude of the vibration, and multiplies it's frequency by four. Yes, it's less worse than none at all, but not great either.
Myke
 
swingarm and exhaust swap

Its actually simpler than that...its so when i filter at slow pace, passed a wannabe twat lounging in their west side ride, with their window open and texting or talking on their mobile phone, I can pull the clutch in - give it some welly and deafen the f ..er...! even more now, before riding off!

Oh how I hate people on phones in cars! Are they really so important...right, off to the pub now! fsakes...:hide
 
Take a 1980 Honda CX500, rotate both cylinders until they are 180 degrees apart, sell it to BMW. Engine drives the clutch in front of the engine, the mass of the clutch rotating in the opp direction to the crank helps to cancel out torque rection without needing any fancy swingarm.

Take a drive shaft from the K range, very few problems there. Fit it with the new engine and name it the all new GS2100. This suits the required rotation without re designing anything. Shame they felt the need to make up silly excuses like looks better on the stand or stops you burning your leg while pushing it.

I do like most things they have done, its almost as if they have taken note of all owner suggestions. Shame they let journelists have a say, the three button indicators is the best system I have ever used. Gone to be replaced by the GT1600 silly fragile system.
 
Nippy Normans supply Touratech, Wunderlich, Desert Fox and many other makes of accessories.
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