Zen & The Art of BMW Motorcycle Maintenance: ‘02 R1150RT Clutch Slave Cylinder and Gear Position Switch Replacement

[Lendog]

the wedge bikes do use a blue mineral oil in the clutch slave cylinder circuit

I as well have a 09 k1300gt

 

[AntonLargiader]

The fluid in the clutch circuit is not under high pressure and you won't feel any difference with a different hose. The only time I have ever replaced a clutch hose is when one got damaged, either by excessive rust at the bottom fitting or by excessive heat applied to the top to try to free a stuck bleeder. Cut the neoprene sheath away at the bottom to allow inspection and to reduce the likelihood of further rust. Water pools inside that sheath. The Spiegler hose has a thicker banjo fitting and there is no corresponding longer banjo bolt for it... at least, that is how it was when I tried one years ago. Stick with stock if at all possible.

If you want to inspect for leakage, remove the starter motor and look into the bellhousing with a flashlight. If everything looks dry, you are probably OK. You can also turn the rear wheel back and forth in gear and see any movement in the clutch spline - there should be none.

 

[Lendog]

The fluid in the clutch circuit is not under high pressure and you won't feel any difference with a different hose. The only time I have ever replaced a clutch hose is when one got damaged, either by excessive rust at the bottom fitting or by excessive heat applied to the top to try to free a stuck bleeder. Cut the neoprene sheath away at the bottom to allow inspection and to reduce the likelihood of further rust. Water pools inside that sheath. The Spiegler hose has a thicker banjo fitting and there is no corresponding longer banjo bolt for it... at least, that is how it was when I tried one years ago. Stick with stock if at all possible.

If you want to inspect for leakage, remove the starter motor and look into the bellhousing with a flashlight. If everything looks dry, you are probably OK. You can also turn the rear wheel back and forth in gear and see any movement in the clutch spline - there should be none.

The issue is there is not enough room to use a longer banjo bolt if the banjo is thicker resulting in stripped threads in the slave cylinder

 

[Lendog]

Well…well…well, it’s been quite a weekend for me and my beloved Der Beemer. Since I just got my bike titled/registered in Texas on Friday and it’s all cleaned up and looking spiffy, I had hoped that I would be able to enjoy a short ride over the weekend.

As I had mentioned in my prior post the bike has been sitting since moving to Texas a year ago, so I wanted to flush the old gas out. Fortunately, I did use a fuel stabilizer and I have have been going out to the garage every couple of weeks to start the bike and let it warm up until I get 1 or 2 bars on the RID display. The bike has sat while on a battery tender so the battery is still in good shape and start ups haven’t posed any problems. So, I took a ride down the street to fill up my tank with premium and that is when I observed (twice) while stopped that the bike didn’t shift from N to 1st when prompted with the clutch lever in. After releasing the clutch lever and reattempting, the bike then shifted from N to 1st gear. Upon returning to my garage, I checked the clutch fluid level by peering through the sight window. That’s when I observed that my “clutch fluid” (also known as DOT 4 Brake Fluid to the rest of the motorcycle riding public) was low.

This of course, led to a discussion here on the forum about why my fluid level dropped and the likely cause being a clutch slave cylinder that needs replacing ASAP. At this point, I ordered a Speed Bleeder to replace the factory grub screw since I’m obviously going to be flushing out the entire system when replacing that slave cylinder. So at this point, now with a full tank of gas and a slave cylinder replacement on my list, I decided I’ll just top off the fluid to the correct level and take a quick spin to see if there’s any difference when shifting from N to 1st. After riding about 20 miles, I noticed a new problem develop.

When riding, I noticed that as I was downshifting in to 3rd gear my RID Display showed E (6th gear). On the ‘02 RT, BMW decided to program the RID to show 6th gear as “E” for economy. As in fuel economy. Because….well, why not? They’re BMW after all and they just had to be different. As I continued to downshift, the RID registered 3rd gear as I clicked in to 1st gear. The green N light is illuminated correctly when in neutral, but it seems that 1st gear and 3rd gears are reading incorrectly on the RID display. So it appears that Der Beemer has learned a new trick! Lucky me. This happened for the rest of the ride home. Besides a faulty gear position indicator switch, I cannot think of anything else that would be causing this.

I decided to consult my service manual and check YouTube for a helpful video on replacing the gear position indicator switch and found a video posted by another Oilhead RT owner who demonstrated how to do exactly that. The video began with “After removing the swing arm……” -heavy sigh-

So, it would appear that either way, l’m going to be removing that swingarm and disassembling half the bike to replace BOTH the clutch slave cylinder and gear position indicator switch. Desperately looking to turn a negative in to a positive, the only plus that I can see is that I discovered the faulty gear position switch now, so that I can replace it at the same time as the slave cylinder while the bike will be torn down.

Also, while I’m in there performing surgery, I might as well add lubing the final drive gear spline to that list. Is there anything else that you can think of that I should address from a preventative maintenance standpoint, since I’m going in to the bowels of Der Beemer?

- Clutch slave cylinder replacement
- Gear position indicator switch replacement
- Lubricate final drive spine
- ?
- ?

might as well check the rear shock, all (4) swing arm pivot bearings, u-joints

 

[Lendog]

the issue could be that the clutch is not sliding on the transmission shaft

 

[Lendog]

might as well check the rear shock, all (4) swing arm pivot bearings, u-joints

I don’t spend any time looking at the gear indicator cause I’m watching where I’m going

 

[tangoalpha]

The fluid in the clutch circuit is not under high pressure and you won't feel any difference with a different hose. The only time I have ever replaced a clutch hose is when one got damaged, either by excessive rust at the bottom fitting or by excessive heat applied to the top to try to free a stuck bleeder. Cut the neoprene sheath away at the bottom to allow inspection and to reduce the likelihood of further rust. Water pools inside that sheath. The Spiegler hose has a thicker banjo fitting and there is no corresponding longer banjo bolt for it... at least, that is how it was when I tried one years ago. Stick with stock if at all possible.

If you want to inspect for leakage, remove the starter motor and look into the bellhousing with a flashlight. If everything looks dry, you are probably OK. You can also turn the rear wheel back and forth in gear and see any movement in the clutch spline - there should be none.

Excellent advice on removing the starter to inspect the bell housing interior for signs of leakage. Thank you very much for that. Great tip!

 

[tangoalpha]

I don’t spend any time looking at the gear indicator cause I’m watching where I’m going

Yes, well the issue isn’t that I’m unable to determine which gear I’m in without a properly functioning display. With over 40 years of riding, most of the bikes I’ve owned over the years didn’t even have a gear indicator and some didn’t have a tachometer either. Using your logic, I can communicate lane changes with hand signals too, so you could argue that turn signals aren’t really necessary either, but that’s not really the point. If something is broken, I don’t ignore it, I fix it.

Besides indicating the wrong gear, a malfunctioning gear position switch can also indicate a false neutral by activating the green neutral light when the bike is in gear.

 

[tangoalpha]

the issue could be that the clutch is not sliding on the transmission shaft

Exactly and the MOST likely cause of that? Answer: The hydraulic clutch slave cylinder. Anything is possible, certain things are more probable than others however.

 

[AntonLargiader]

What issue is it that could be from the clutch not sliding on the transmission shaft? I think a few things are being conflated here.

1) The slave cylinder compresses the spring which then stops pressing the pressure plate rearward against the clutch disk. If the pressure is not being taken off, the slave cylinder is not doing its job.

2) The clutch friction disk slides/floats slightly on the splines of the transmission input shaft. If it doesn't float (most likely because the splines are worn or dry) then the clutch may drag slightly, which typically presents as grinding during downshifting.

I don't see issue #2 presenting here. Given that the clutch fluid went low, I would think that the issue on that initial ride was #1. It's not clear if it persisted after refilling the reservoir.

 

[tangoalpha]

What issue is it that could be from the clutch not sliding on the transmission shaft? I think a few things are being conflated here.

1) The slave cylinder compresses the spring which then stops pressing the pressure plate rearward against the clutch disk. If the pressure is not being taken off, the slave cylinder is not doing its job.

2) The clutch friction disk slides/floats slightly on the splines of the transmission input shaft. If it doesn't float (most likely because the splines are worn or dry) then the clutch may drag slightly, which typically presents as grinding during downshifting.

I don't see issue #2 presenting here. Given that the clutch fluid went low, I would think that the issue on that initial ride was #1. It's not clear if it persisted after refilling the reservoir.

Thank you for sharing your insight on this. I really appreciate members like yourself, who are willing to take time from their day to offer their input.

With regard to refilling the reservoir, the issue has persisted since refilling. Though I haven’t seen any tell tale leaks on my garage floor, that really does concern me because that fluid is going somewhere. The advice to remove the starter and look inside the bell housing with a flashlight to look for signs of fluid leakage was spot on. Also drilling a weep hole as was suggested by Devern is great advice. What’s that old saying about an ounce of prevention? It’s worth a pound of cure. I’d rather discover drops of fluid on my floor to discover I have a problem with my slave cylinder than find out later, the hard way that my clutch has been soiled.