Mysterious pulsing issue.

®win · Feb 7, 2019

Explanation from a former BMW Motorrad dealer on the Dutch GS forum:
“The buzzing sound that becomes harder and softer in a low frequency is the result of a resonance in gearbox, cardan shaft and c arda n. It performs at speeds of around 60 to 70 km per hour. Below and above in general not or much less. This phenomenon has occurred since the R 1150GS Adv entu re. It can not do any harm and you can prevent it by choosing a different gear, going a little slower or faster, or simply not paying attention to it.
The noise increases with the suspension of the suspension behind (cardan shaft couplings then create a larger angle), therefore this sound is generally perceived more clearly with Adventures.”

My previous GSA’s had it and my current MY ‘18 has it also.

CPJS · Feb 7, 2019

If BMW have known about this issue since the 1150 why have they not engieered it out?

®win · Feb 7, 2019

Because it is not a defect, it’s a feature.

spoonz · Feb 7, 2019

Not convinced that is the source. If it’s inherent in the design why only some bikes and why does it appear on some from new and some much later.

Morety · Feb 7, 2019

spoonz said:
Not convinced that is the source. If it’s inherent in the design why only some bikes and why does it appear on some from new and some much later.

I'm with you on that one. On mine it feels more than just slight gearbox resonance. The coupled vibration is very easy to feel and it's rational to be concerned what this might be doing to the life of bearings in the transmission path.

CPJS · Feb 7, 2019

On my '14 GS the thrumming did not start until about 6000mls and progressively got worse, I traded the bike in at 21,000mls by which time it was quite intrusive and could be felt right through the bike, I thought the gearbox might fail.

roamer · Feb 7, 2019

My 2014 gs did it,
i swapped the alloys for spoked wheels ,
Many different makes of tyres,
Took the drive shaft out checked joints, while greasing splines,
It was noticeable but not a worry,
just enough to check stuff during maintenance etc,
I dont have an lc now,

Stahlgewittern · Feb 7, 2019

Had same problem with my 2013 LC the symptoms disappeared when I traded it in for a Tenere.

boatman · Feb 7, 2019

My 13 TC does not have any of this :thumb2

SPCK111 · Feb 8, 2019

My 16 plate doesn’t do this at all.

squibb34 · Feb 8, 2019

Stahlgewittern said:
Had same problem with my 2013 LC the symptoms disappeared when I traded it in for a Tenere.

Many will know already, but the simple fact is that the BMW R1200GS/A has 2 UJs in the shaft, to accomodate the complexity of the single sided swing arm/rear drive articulation, whereas the Super Tenere runs a simple double sided swing arm with a fixed pumpkin & just one UJ in the shaft. Any slight stiction in the UJs or the slider splines on a GS will throw up a slight imbalance as the shaft spins up - it's an inherent feature of the design. Then, when it comes to lubing these things from the get-go, all the factories are extremely frugal with the lube - every little saved helps the bottom line.

CPJS · Feb 8, 2019

squibb34 said:
Many will know already, but the simple fact is that the BMW R1200GS/A has 2 UJs in the shaft, to accomodate the complexity of the single sided swing arm/rear drive articulation, whereas the Super Tenere runs a simple double sided swing arm with a fixed pumpkin & just one UJ in the shaft. Any slight stiction in the UJs or the slider splines on a GS will throw up a slight imbalance as the shaft spins up - it's an inherent feature of the design. Then, when it comes to lubing these things from the get-go, all the factories are extremely frugal with the lube - every little saved helps the bottom line.

It is not the drive shaft as the pulsing is engine speed related not wheel speed, it comes from the gearbox.

spoonz · Feb 8, 2019

The op also had a new shaft and it didn’t solve the issue.

squibb34 · Feb 8, 2019

spoonz said:
The op also had a new shaft and it didn’t solve the issue.

No. The OP was given to understand the dealer had changed out the shaft. Given that warranty had allegedly covered wheels & gearbox, both of which seemed far too costly & hence unlikely, I fancy there is a disparity between what the dealer says has been done & the actuality. He needs to eyeball the dealers screen to be sure, or better still take the whole issue to BMW UK Customer Service. The complaints procedure is perfectly clear on the UK website.

squibb34 · Feb 8, 2019

CPJS said:
It is not the drive shaft as the pulsing is engine speed related not wheel speed, it comes from the gearbox.

Shall we just say I beg to differ. What is there in a gearbox that can possibly do this - it's just gear sets in constant mesh. Anyway it was replaced allegedly?

ChazzyB · Feb 9, 2019

I think it's gearbox AND something else with setting up a beat frequency.

CPJS · Feb 10, 2019

squibb34 said:
Shall we just say I beg to differ. What is there in a gearbox that can possibly do this - it's just gear sets in constant mesh. Anyway it was replaced allegedly?

Not the shaft as mine did it 3rd and 4th at the same engine speed/different road speeds, just because you don't think it is the gearbox doesn't mean it is not.
Does your bike have this vibration ?

roamer · Feb 10, 2019

Interesting to hear it ran through from the earlier 1150 1200 models,
only experienced it myself on the lc light throttle mainly 4th gear, it did feel engine speed related opposed to road,
it just added that agricultural unrefined rugged workhorse feel , more character than a worry,

spoonz · Feb 10, 2019

I read on another site someone saying that their dealer found it to be the exhaust valve pulsing as the Revs just hover at the open/close point. He fitted an aftermarket exhaust and problem went away.?

So many theories but someone must have a definitive answer given the number of affected bikes.

CPJS · Feb 10, 2019

spoonz said:
I read on another site someone saying that their dealer found it to be the exhaust valve pulsing as the Revs just hover at the open/close point. He fitted an aftermarket exhaust and problem went away.?

So many theories but someone must have a definitive answer given the number of affected bikes.

Not that either, my bike/s both had full a system and both had the pulsing.

Mysterious pulsing issue.

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