Transmission or clutch?

[poodad]

I have an '11 R1200RT with 44K miles. Transmission oil was changed at 22K three years ago with full synthetic. The manual says replace at 24k miles. 

 

Last Friday I noticed that all of a sudden I couldn't down shift from 5th to 4th most of the time, and lower gears some of the time UNLESS I let out on the clutch between each gear and let the engine decelerate the bike. No problems from 6th to 5th.

 

In a car (from what I remember of the days when cars had clutches) this would typically indicate a throw-out bearing going bad such that the clutch was not completely disengaging  when shifting.

 

I'm going to change the transmission oil tonight and hope that the problem goes away, but I'm not optimistic.

 

Anyone seen this problem before?

[Pappy35]

Is the clutch fluid reservoir full? If yes, drain it 1/2 and go ride and see if it's better.

[poodad]

28 minutes ago, Pappy35 said:

Is the clutch fluid reservoir full? If yes, drain it 1/2 and go ride and see if it's better.

What will this accomplish?

[dirtrider]

40 minutes ago, poodad said:

I have an '11 R1200RT with 44K miles. Transmission oil was changed at 22K three years ago with full synthetic. The manual says replace at 24k miles. 

 

Last Friday I noticed that all of a sudden I couldn't down shift from 5th to 4th most of the time, and lower gears some of the time UNLESS I let out on the clutch between each gear and let the engine decelerate the bike. No problems from 6th to 5th.

 

In a car (from what I remember of the days when cars had clutches) this would typically indicate a throw-out bearing going bad such that the clutch was not completely disengaging  when shifting.

 

I'm going to change the transmission oil tonight and hope that the problem goes away, but I'm not optimistic.

 

Anyone seen this problem before?

 

Afternoon poodad

 

Difficult to tell much from just basic information over the internet. You can try a gear oil change but I doubt that will help (but worth a try anyhow).

 

Probably the place I would start it to verify the shift lever link is not binding that ball sockets & that the stub lever on the transmission (the one that the shift link hooks to) is tight on the stub shaft (pinch bolt tight). 

 

If you can get it into gear with engine running & sitting still without a fight or excessive noise then  it should have  enough clutch release to properly shift. (if you have doubts then adjust the clutch lever all the way out & see if that helps the shifting)

 

 

[Pappy35]

5 hours ago, poodad said:

What will this accomplish?

I hoping to save myself a bunch of typing by just asking the question and providing more detail if needed but I guess some people don't just take advise at face value...

 

The way the system works results in a hydraulic lock situation when the reservoir is full that presents exactly like a failing clutch, which is what your present predicament sounds like.

 

There is no "throw out bearing" per se in this bike's system, at least not exactly like you'll find in a car. In the RT there's a rod that runs from the slave cylinder on the back of trans housing forward through the center of the transmission to the clutch pressure plate. When you pull in the clutch lever, the master pumps fluid to the slave which pushes the rod forward. It pushes the pressure plate forward which unloads the clutch friction plate.

 

As the clutch wears, the engaged position of the pressure plate rests further and further aft, This pushes the slave cylinder aft causing the fluid to collect in the reservoir (exactly the opposite of how most hydraulic brake systems function). Eventually the reservoir will become completely full and then the fluid pressure will not allow the pressure plate to fully seat with the lever released. Symptom: slipping clutch and rough gear changes.

 

Search Youtube for "BMW R1200 Clutch Replacement" and you'll find a number of relevant videos showing how the assembly goes together.

[Pappy35]

Well, technically there is a throw out bearing but it's inside the clutch slave cylinder.

 

Here's a video, one of many, that show some of the details...

[beemer chuck]

+1 on lubing the shifter ball joints and checking for tight fasteners. This can cause shifting issue.

I believe that a full reservoir would hold the clutch open and cause slipping, not hard shifting.

Check the movement of the clutch lever with the bike off and in gear. Push on the tire or roll the bike back and forth. The clutch should engage about half travel. Tire should rotate easily with clutch pulled. Does it clunk or lurch going from neutral to first?

I would drain the trans into a clean container check the volume drained and have a good look for debris on the fill plug magnet. 

[Pappy35]

Yeah, you're probably right, I suggested the clutch reservoir as it's a quick visual and something that is kind of contra-intuitive.

[poodad]

54 minutes ago, Pappy35 said:

Yeah, you're probably right, I suggested the clutch reservoir as it's a quick visual and something that is kind of contra-intuitive.

I appreciate the explanation. 

 

I think I've eliminated the clutch as a potential problem:

 

1. Problem persists even with the engine off

2. I've adjusted the clutch lever adjustment such that there is still a huge range of travel to go after the clutch feels disengaged as tested by rocking the bike forward and back. 

 

[poodad]

I changed the transmission oil. I captured the old fluid in a clear container (at least what didn't end up on the floor). The magnet on the fill plug had very, very little crud on it. What little was there did not feel the slightest bit gritty.

 

Even after letting the old oil sit for 24 hours, there is no visible sediment.

 

I found this thread which sounds pretty scary. https://forums.bmwmoa.org/showthread.php?72143-11-R1200RT-will-not-Downshift-at-times

 

I have found a couple of threads where the shift linkage can cause this issue. I gave it a cursory look last night, but couldn't get a good close look because the exhaust was hot. I'll give it a better look tonight.

 

BTW, kudos to the BMW design engineers who figured out how to put the transmission drain plug in the exact worse position possible.

[poodad]

I may have caught a break on this problem. Last night, I found that the upper ball-socket gizmo of the shift linkage had unscrewed itself from the transmission shift arm almost all the way out. The back side of the socket was hitting the exhaust flap servo.

 

It wasn't catching - but I'm hoping that the inward horizontal force on the shift rod created by the interference is what was making the shift stepper mechanism misbehave. This is bolstered by the fact that the exhaust flap controller is mounted in rubber, and can move a bit. I figure that when the bike warms up, and the servo works the cables that move the flap, it moves inward slightly, worsening the horizontal pressure on the shift rod.

 

Unfortunately, I got interrupted by work problems last night before I could get the bike put back together (you have to remove several bits to get at the shift linkage - not to mention grind down a 13mm wrench to fit the slim open area on the socket).

 

I should have an update tomorrow.

[Pappy35]

That's great! I mean that it's great that you found something that it sounds like you can fix. 

[poodad]

Update: the shift linkage was indeed the problem. Apparently, even a slight bit of inward axial force on the shift rod will prevent the shift step mechanism from working properly.

 

I will be checking the linkage every oil change, and if it looks like it is unscrewing again, it's getting loctite.