Agricultural clunk

General discussion of the BMW R 1200/1250RT
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Beagle
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Re: Agricultural clunk

Post by Beagle »

OrangeOkie wrote: Just read where the new R1200RT has the 1st gear "clunk" fixed. Can anyone confirm?

Mine is 2018 and does it. Sometimes when cold I go to put it in the garage and I have to check its gone in gear its so silent but that is not the norm. Quite a loud crunch.
gogs01
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Re: Agricultural clunk

Post by gogs01 »

If the issue is the "clang" when engaging first gear from neutral, my answer is not to engage neutral.  I stop in first gear and stop the engine with the kill switch. This avoids either sitting for (occasionally) extended periods with the engine running at a standstill, which can be particularly bad for air cooled engines, or worse - sitting with the engine running and the bike in gear with the clutch also suffering.
Then, when it's good to go, pull in the clutch, hit the starter and go.  Works for me.  👍


I don't know about the very latest models, but my 2017MY clunks from neutral to first once everything is up to temperature.
My 4th R1200RT = 2016 (2017 MY) R1200RT LE
guest2360

Re: Agricultural clunk

Post by guest2360 »

BMWs have been doing that since 1923 and no doubt will still be doing it 2023.
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smileymiley
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Re: Agricultural clunk

Post by smileymiley »

RTman10 wrote: BMWs have been doing that since 1923 and no doubt will still be doing it 2023.
Doesn't mean that they have to do it, can't be beyond the BMW hierarchy to commission a quiet, clunk free  gearbox!
Vini, Vidi, Velcro....... I came, I saw, I stuck around.
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David.
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Re: Agricultural clunk

Post by David. »

My 2012 TC doesn't clunk when selecting first gear, are BMW making progress or going backwards.
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Beagle
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Re: Agricultural clunk

Post by Beagle »

Is it gearbox or wet multiplate clutch. Does one with a dry plate clutch do it?
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Re: Agricultural clunk

Post by guest2360 »

Wet clutch, dry clutch, makes no difference as it’s the gearbox that makes the noise not the clutch.  Those that say they don’t hear it need to visit Specsavers 🙀
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Beagle
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Re: Agricultural clunk

Post by Beagle »

RTman10 wrote: Wet clutch, dry clutch, makes no difference as it’s the gearbox that makes the noise not the clutch.  Those that say they don’t hear it need to visit Specsavers 🙀

"Clutch drag" can have an effect on gear selection. Wet clutches by virtue of runnng in oil have a certain drag like a torque converter and wet clutches in an auto gearbox creates "creep".
The question is does a bike with dry clutch do it?
Last edited by Beagle on Fri Jul 20, 2018 9:06 pm, edited 1 time in total.
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David.
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Re: Agricultural clunk

Post by David. »

Beagle wrote:The question is does a bike with dry clutch do it?
The answer is, a bike with a dry clutch doesn't do it.
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Re: Agricultural clunk

Post by Sullivj »

David. wrote: My 2012 TC doesn't clunk when selecting first gear, are BMW making progress or going backwards.

Whereas my 2012 clunks terribly into 1st.
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Blueboy
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Re: Agricultural clunk

Post by Blueboy »

Steve F wrote: Nah, my K13GT Beemer was equally clunky in the low gears, and that was an in-line 4 cyl engine.  :-X
Spur .v. helical gears comes to mind re the difference between car (synchromesh helical gears which are smoother and quieter in operation) and bike (spur gears which are tougher but noisier comparably in operation) gearboxes.
The RT gears are helical...


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Beagle
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Re: Agricultural clunk

Post by Beagle »

Blueboy wrote: The RT gears are helical...


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This is R1200GS





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Re: Agricultural clunk

Post by Steve F »

Blueboy wrote: The RT gears are helical...


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Yes, so I see from the Motorrad website that they have gone over to the integrated gearbox with helical gears. So now I am confused as to why this bike is seemingly plagued by a clunky 1st gear selection at idle??!!🤔
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Beagle
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Re: Agricultural clunk

Post by Beagle »

Steve F wrote: Yes, so I see from the Motorrad website that they have gone over to the integrated gearbox with helical gears. So now I am confused as to why this bike is seemingly plagued by a clunky 1st gear selection at idle??!!🤔

Maybe its not the gearbox but due to the clutch?
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Blueboy
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Re: Agricultural clunk

Post by Blueboy »

Beagle wrote:
Maybe its not the gearbox but due to the clutch?
I found this after a long research on this rainy day here in Montreal...a lot of it makes perfect sense to me...
1) Most motorcycle clutches use multiple plates, which do not free completely (and separate fully from the adjacent plate) because they are contained in an oil bath (the gearbox or engine/gearbox oil).

Consequently there will still be some spinning of the input shaft when the gear selectors select whichever gear is there.

Even dry clutches still do not completely free when pulled in, and you might have to wait for 10 or 20 seconds for the input shaft to slow or stop, before being able to make a noise-free selection.

You could also find, if you do that, that the gear will not actually engage because it has stopped at a point where the engagement "dog" cannot fit into its mating slot(s). That's a little bit like what happens (except in reverse) when you hold the clutch in too long while coasting to a stop, or stop in gear and are unable to select neutral.

The "clunk" is not a sign of a problem, nor is it a problem in itself.


Then changing from 1st to 2nd is also a little rough, but then each gear upwards is fine...
Whats the mechanical reason for this? and is it present in all bikes?
The difference in gear speeds between 1st and 2nd is usually greater at the bottom end of the gearbox, hence there can be more noise because the sliding "dog" has to mesh with another "dog" spinning at a different speed..

However, a skilled rider will compensate for this by preloading the gearchange lever slightly and experimenting until he (or she) finds the correct "speed of lever operation" to make a clean, noise-free change. It's possible.

But once again, this is not really a problem.

Most bikes have this issue, but most good riders learn to change to minimise it. It makes you look better...or sound better.  ;-)

The higher the gear the less difference in speed between components, so that there is less tendency to clunk. However, if you delay the change by holding in the clutch for a few seconds, you should be able to get quite a good clunk.  ;-)


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