Brake System Flush | 48K Mile Service - Part 3

[Grumpy Goat]

[Duckbubbles]

Surprised at the amount of air bubbles that came out of your calipers initially. I don't have speed bleeders and I removed the wheels and front fender for a tire change when I did my brake flush. With some wedges to hold the pads apart on the front I was able to reach the bleeders easily, especially the left side. Didn't need the wedges on the rear, but reaching the caliper bleeder isn't a problem. Nice video.

Frank

[Duccrazydave]

Thanks for the video, Wayne. Let us know if your brake lever firms up as a result of the bleeding.

[Lee]

. Let us know if your brake lever firms up as a result of the bleeding.

Don't forget the Wetheads have a little softer feel compared to earlier boxers and Kbikes.

[Grumpy Goat]

Surprised at the amount of air bubbles that came out of your calipers initially. I don't have speed bleeders and I removed the wheels and front fender for a tire change when I did my brake flush. With some wedges to hold the pads apart on the front I was able to reach the bleeders easily, especially the left side. Didn't need the wedges on the rear, but reaching the caliper bleeder isn't a problem. Nice video.

Frank

Thanks Frank. I too was surprised at the bubbles that came out and expected that after it was all done the front brake lever would be much harder than it is, but it was not (as hard as on the S1000R). It appears slightly harder than before the bleed while difference in the rear brake seemed a little greater. Either way the bike stops just as good as it always did.

[Grumpy Goat]

Thanks for the video, Wayne. Let us know if your brake lever firms up as a result of the bleeding.

As noted above, it did firm up a bit but not a whole lot. The RS's brakes are more progressive than on the S1000R, which some say is "grabby". So that does call for a slight "re-learning" every time I switch bikes, but I tend to expect it now.

[Grumpy Goat]

Don't forget the Wetheads have a little softer feel compared to earlier boxers and Kbikes.

Having had no experience with either I have to take your word for it, Lee, although I am sure you're right. Never had the feeling that the RS would do a "stoppie" but there is no question that the S1000R can (even has anti-stoppie control).

[Lee]

Don't forget the Wetheads have a little softer feel compared to earlier boxers and Kbikes.

Having had no experience with either I have to take your word for it, Lee, although I am sure you're right. Never had the feeling that the RS would do a "stoppie" but there is no question that the S1000R can (even has anti-stoppie control).

As you noticed on your S1000, other BMWs have a better feeling initial brake feel.
The Wetheads feel great when braking hard but that first little bit feels soft.

[Lee]

I don't have speed bleeders and I removed the wheels and front fender for a tire change when I did my brake flush. With some wedges to hold the pads apart on the front I was able to reach the bleeders easily, especially the left side.

Frank

Good idea.
Why didn't you tell me that last week when the wheels were off
As for air bubbles I usually see a few and figure some of it is air seeping past the nipple and hose.

[Lee]

At one point Wayne mentioned the fluid burped up a little.
To avoid fluid burping up out of the reservoir, place a quarter or something similar over the hole in the bottom of the reservoir. This keeps the fluid from squirting out.

The first time I did a brake flush the manual way I had Debbie pump the lever while I opened and closed the bleeder. The first pull she shot fluid out of the reservoir. We both learned a soft pull was good enough. Luckily I had the tank covered.
I usually cover the tank and back part of the fairing because shit can happen.

To cover the tank I have a vinyl coated fender cover I won at a car show.
Towels are wrapped around the back of the fairing and dash.
   

[Grumpy Goat]

As for air bubbles I usually see a few and figure some of it is air seeping past the nipple and hose.

In my case my bleed house was tight so I doubt it was air leaking past.


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[Grumpy Goat]

At one point Wayne mentioned the fluid burped up a little.
To avoid fluid burping up out of the reservoir, place a quarter or something similar over the hole in the bottom of the reservoir. This keeps the fluid from squirting out.

That’s a good safety technique. It also wouldn’t burp if the level is kept sufficiently away from the hole. I think I will ask Donna to make a bib for me. 😀


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[mspratz]

Nice video GG. Interestingly, the BMW Service manual for the R1200RS doesn't say anything about flushing the pump to clear air bubbles from the pressure modulator. After watching the video I connected my GS-911 to my bike to see the GS-911 instructions for myself. I'm a little mystified why the GS-911 people think this is necessary, and BMW does not. I remember reading about the complexity of bleeding the older BMW ABS systems, and I have to wonder if the GS-911 people are suggesting this be done only because their device has the capability.

[Duccrazydave]

. Let us know if your brake lever firms up as a result of the bleeding.

Don't forget the Wetheads have a little softer feel compared to earlier boxers and Kbikes.

That’s interesting. In most of the bikes I’ve worked on previously, changing/bleeding the system and replacing stock rubber lines with braided or Kevlar has been the solution for the lever feel issues. Since the RS already has braided lines, I guess it comes down to master cylinder bore size being the difference? When it comes time for pad replacements I’ll probably go for a slightly more aggressive compound for more initial bite.


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[Grumpy Goat]

Nice video GG. Interestingly, the BMW Service manual for the R1200RS doesn't say anything about flushing the pump to clear air bubbles from the pressure modulator. After watching the video I connected my GS-911 to my bike to see the GS-911 instructions for myself. I'm a little mystified why the GS-911 people think this is necessary, and BMW does not. I remember reading about the complexity of bleeding the older BMW ABS systems, and I have to wonder if the GS-911 people are suggesting this be done only because their device has the capability.

Yes, I too noticed that BMW made no mention of including the ABS pump in the flushing process and that always made me wonder that if only the 3 lines were bled / flushed then perhaps there is some old fluid that could remain in the ABS pump. Without knowing the plumbing I think I feel better knowing that per the GS-911 way all components are bled in some way. Maybe that is why I was seeing bubbles after the first flush.

[Duckbubbles]

Good idea.
Why didn't you tell me that last week when the wheels were off
As for air bubbles I usually see a few and figure some of it is air seeping past the nipple and hose.

I think my crystal ball has a case of Covid 19- it's been a little cloudy lately. I'll quarantine it for a while.

Remarked on the initial bubbles because I didn't get any bubbles out of any of the bleeders when I did mine. Just flushed enough fluid through to remove all old stuff. Sucked all the fluid out of the reservoirs, inserted paper towels to soak up any back flush and pushed the caliper pistons back into the housings. I have some wooden wedges that I placed into the calipers to keep the pistons retracted and proceeded with the bleed. I'm working by myself so getting to the left caliper is impossible without removing the wheel. Tire change is a convenient time.

Frank

[mspratz]

Yes, I too noticed that BMW made no mention of including the ABS pump in the flushing process and that always made me wonder that if only the 3 lines were bled / flushed then perhaps there is some old fluid that could remain in the ABS pump. Without knowing the plumbing I think I feel better knowing that per the GS-911 way all components are bled in some way. Maybe that is why I was seeing bubbles after the first flush.

Sure as heck can't do any harm to follow the steps recommended by the GS-911 people!

[Lee]

As for air bubbles I usually see a few and figure some of it is air seeping past the nipple and hose.

In my case my bleed house was tight so I doubt it was air leaking past.


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My hose is very tight.

[Lee]

Interestingly, the BMW Service manual for the R1200RS doesn't say anything about flushing the pump to clear air bubbles from the pressure modulator.

This was done on the older Servo ABS bikes. BMW does not call for it on the newer bikes but I still do it to exercise the ABS pump.
On the K1200RS service schedule it was called a Bleed Test.

[Duckbubbles]

This was done on the older Servo ABS bikes.

Could that be because the servo type brakes had separate systems, the wheel circuit and the actuating (?) circuit? The new system runs from master cylinder through the ABS unit and to the calipers (I am pretty sure).

Frank