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BMW GS/A: How to remove rear shock, replace clutch slave and fill/flush clutch line

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How to remove the rear shock, replace a clutch slave and fill/bleed a clutch line on a (2011) BMW GS Adventure

 

One of the cool things you may have found over the years of motorcycle ownership is first that you’re probably a decent judge after all of what’s really wrong with your bike and that you’re quite capable of fixing a lot of things by yourself.  At least that’s what I learned in this case.

 

It all started after completing the COBDR in July ’13.  After this gnarly water crossing where I was going too fast through some too-deep water and the engine sucked in some water requiring a trail side air filter, oil filter and oil change, I started to also have an issue with my clutch.  It was primarily on the way home.  I was riding through some pretty hot weather from Steamboat Springs headed back to Irvine and it was probably Grand Junction when I first noticed the problem.  I was coming off the freeway ramp and downshifting when I noticed there was almost no play in the clutch lever.  The bike stalled because I couldn’t get it into neutral or use the clutch lever to disengage the gearing.  I managed to park it at a Wendy’s, had lunch and then when I came back out and started it up again, the clutch was fine!  It was something about the warmer temps or when the engine was hot it would act up.

 

After I got home, I took it into the dealer to check it out and they said it was “just a bubble in the clutch line.”  They flushed and filled and it was working fine.  Well, it did work fine until the weather warmed up and it started to do the same thing.  I then took it to an independent mechanic (since I was now out of warranty) and he said it wasn’t clear to him what was wrong.  He did mention the push rod looked a bit worn and replaced that, but it’s only like a $9 part.  He did run the engine quite a long time in order to try and recreate the problem but it wasn’t happening.  Sure enough, when it warmed up again (WMRS ride in Aug ’13) the clutch went out again.

 

At this point I had learned quite a bit about what types of clutch problems tend to crop up and my #1 theory was that the clutch slave was bad and needed to be replaced.  I ordered a new clutch slave for about $155 (plus some new crush washers) and bought some special BMW clutch fluid ($26), although you can find a brand by Magura (Royal Blood Brake Fluid) at your local bicycle shop is essentially the same thing (Magura is the mfg of the clutch slave).  The replacement process was really a breeze!

 

So why did the slave fail in the first place?  Was it defective?  Was it normal wear and tear?  Poorly designed?  I think the most likely culprit is thermal shock, where the hot engine encounters cold water at a water crossing and that somehow compromised the slave.  There is no gasket where it attaches, so I’m thinking that’s the most likely reason.  We all like to blame the mechanics too, but I think the nature of this problem (only acts up when hot) makes it hard to diagnose.

 

I will lay out the basics here, but the more detailed instructions are in the attached video.  I figure not many of you will need to replace a clutch slave, but many more will need to take the rear shock off and perhaps bleed your own brake lines (every two years), so this should be helpful.

 

  1. Remove rear wheel

  2. Remove exhaust muffler

  3. Remove the top bolt of your rear shock under the seat.

  4. Using a strap to raise the swing arm high enough, remove the lower shock bolt and remove shock.  You may notice you can’t get in there with a torque bit unless you raise the swing harm high enough.

  5. Two screws will remove the clutch slave; clean out back of engine w/brake fluid and install new clutch slave.

  6. Before you re-attach the clutch line to the master cylinder up top and the new slave below, flush it out with brake cleaner, then air to dry.

  7. Reattach clutch line using new crush washers top (near master cylinder) and bottom (at slave).

  8. Refill the master cylinder reservoir and attach ¼” OD vinyl hose to the bleed valve at the bottom.  Using the process described in the video, pump the new fluid through until you see no bubbles.

  9. Tighten it back up, re-install rear shock (red loctite and proper torque specs) and exhaust and you’re ready to go!


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