Transmission Noise when engine braking

[HMMMYA]

Hi, I'm hoping for some pointers


BMW R1200RTP 2008 65k
Transmission noises during engine braking with slight vibration felt under seat. Noticed it on my last 2 commutes to work.


I've had this bike for 2yrs and put on 15k so I'm familiar with the feel of it but less clued up with the mechanics.


This noise is not significant but I'm aware it is not normal and is new and consistent through all the gears when engine breaking. When excelerating and idling on the centre stand the is no unusual noise. Rear wheel doesnt have play in it and spins with out any noises. gear function as normal.


Any ideas?


Before dipping into it id like to make a plan since I'll be investigating it on the street where it's parked so comments would be appreciated.


I'm very familiar with k100s and replaced the gearbox on one a few years ago which resolved similar problems. In that case the gearbox seal failed and the gearbox ran dry and made a noise on engine braking whilst shifting was relatively normally. I am feeling maybe I have a similar problems here albeit the noise is less significant to date with the r1200rt. Does this type of scenerio happen with r1200rt's?


Any comment on this and/ or pointers would be appreciated.


Cheers


Duncan

[David.]

Transmission noises during engine braking with slight vibration felt under seat.

Just a thought, the driveshaft is fitted with a cushion drive, a torsional vibration damper is integrated into the cardan shaft for greater comfort. Plus, there is a UJ at each end of the shaft. I wonder if under load (acceleration) it's ok, whereas on the overrun during engine braking it makes a noise and vibrates.



The gearbox fill plug is magnetic, remove it and check for any metal swarf. At the same time, the oil level can be checked, it should be at the lower edge of the filler hole. The gearbox oil should be changed every 24K miles or two years.

[HMMMYA]

Thanks David,


I took it out this evening for a local potter about to try and assess, I'm always in a rush on the commute and 95% is fastish carriageway. It appears the noise and/vibration isn't noticeable in low gears or speed but is in 4/5/6 gear peaking at 4000rpm higher it disappears and/or isn't noticeable and likewise lower. I did wonder if leaving it on the side stand had made a difference as the first 5 mins I struggled to get the noise back but I was in city center so wasn't giving it any Welly so this can't be confirmed. I'll find a day to pluck the fairing or and check the oil, I'll tick the easy stuff of first. Regards!

[David.]

The noise/vibration now sounds very different from that described in the original post, I'm confused.com.

In the last 2 years and 15K miles, what has been the service history.

[HMMMYA]

Hi David, Nothing has been done service wise with the transmission or splines etc. I have been slack. Just standard oil changes, sparks, filters, pads, discs, calipers, tyres, wheel bearings etc. I did have to piss about with the throttle cables for the while since the splitter box was gubbed and had to deal with alot of corrosion around the throttle bodies causing me headaches but that was some time back now. I took the fairing of in a rush tonight but haven't spent much time. Cracked the gearbox oil plug open. It looks topped up and clean oil, the plug has no magnet on it so no evidence of anything. I'll drain and change tomo but suspect this isn't the culprit. Ill take it for a spin after just to be sure but will then park it up. I will likely move down the shaft drive over the coming wks to change oils, lube splines and inspect. Unless you have something cheerier to suggest??

[David.]

My confusion is how the noise/vibration is being described. Firstly under engine breaking which is why I suggested looking at the shaft drive.

The second description is not very clear. I was thinking of engine service history, no mention of valve clearances or throttle synchronisation due every 6K miles.

Before taking any drastic action, how about getting a second opinion from someone who can experience the problem for themselves, rather than your description and my interpretation of it.

[HMMMYA]

Hi David,


Apologies i forgot to mention I did valve clearances and throttle sync in november likely 6kish back, I'll check this over again as it is an easish one. That said maybe I'm not doing it right so will refresh my memory on it. I'm mechanically minded but tbh always learning and never really know what I'm doing until the next gremlin arrises. There is a chap who has been recommended in Ayrshire bricksnboxers so ill tap him up after I put some time into myself to be sure it's not something daft as well as a familiarity exercise for myself. The hassles of the fairing and police roll bars have got me lazy with this bike so I do need to get to understand it abit better. I got this bike mainly to get me through the Scottish winters but ended up being on it more and more. I've got a few mths to get it sussed and will hop on my old rather chilly naked brick for a while. Appreciate your comments.

[HMMMYA]

Oh just a note on the "not very clear description" sorry I forgot to try and clear it up. the noise/ vibration is only heard felt during engine braking (not neccesarly heavy engine braking just a slight dip of the throttle) and never heard whilst on the throttle. It's not noticeable during lower rpm or even it appears gears. It seems most prominent at 4000rpm when I dip the throttle.

[David.]

When accelerating and idling on the centre stand there is no unusual noise.

Have you tried pulling the clutch lever in and letting it out whilst the bike is idling and in neutral.

Found this video about the clutch pushrod rattling, https://www.youtube.com/watch?v=xKF2VPq0Y9U

[HMMMYA]

Interesting video. Thanks. Yes when clutch is out and neutral my bike sounds like a London cab, it has a distinct rattle which disappears with pulling the clutch home. The bike has always been like this and I thought it not much to worry about until the clutch needed replaced. Nice to know it could be a simple fix with the replacement of the damper material on the clutch rod. This is a very different noise to what I am hearing with my problem tho (more of a metallic whurr) I will try and pull the clutch in tho next time I'm rolling on at 4k rpm just out of curiousity tho, if stays then I'll have to question where I'm looking.