Brakes!

[Kerry in Mpls]

2016 R1200GS, bought in 2019 with about 3000 miles on it, it now has about 21000 miles.

 

The other day I was in the garage checking rear brake action with the foot pedal and also using the hand lever (integrated action).

With the bike up on the center stand I spun the rear wheel by hand. I pressed the foot pedal and the rear brake engaged.

Then I started the engine and put the bike in gear to spin the rear wheel.

I pulled the hand lever and -- nothing. The rear brake did not engage at all -- zero.

Is this normal?

Does the bike have to be moving in order for the hand lever and integrated brakes to activate the rear brake?

 

No warnings are indicated on the display.

I don't have access to a GS-911 at the moment, so can't check for logged messages.

 

Suggestions welcome.

 

Thanks,

Kerry

[dirtrider]

8 hours ago, Kerry in Mpls said:

2016 R1200GS, bought in 2019 with about 3000 miles on it, it now has about 21000 miles.

 

The other day I was in the garage checking rear brake action with the foot pedal and also using the hand lever (integrated action).

With the bike up on the center stand I spun the rear wheel by hand. I pressed the foot pedal and the rear brake engaged.

Then I started the engine and put the bike in gear to spin the rear wheel.

I pulled the hand lever and -- nothing. The rear brake did not engage at all -- zero.

Is this normal?

Does the bike have to be moving in order for the hand lever and integrated brakes to activate the rear brake?

 

No warnings are indicated on the display.

I don't have access to a GS-911 at the moment, so can't check for logged messages.

 

Suggestions welcome.

 

Morning  Kerry

 

These newer BMW ABS systems (especially the dynamic ones on the GS ) kind of have a mind of their own with one wheel stopped & one spinning. 

 

A few things to try__ 

 

First is to re-try your rear wheel spin test but try with only the key-on & spin the rear wheel with your foot instead of in-gear with engine spinning it. 

 

Next, try the above test again using a LOT of front brake lever pressure & hold until the count of 4. 

 

Next, try this test again with the ABS  turned off.

 

Then try with the engine spinning  the rear wheel again but this time apply a LOT or pressure to the front brake lever & hold it there for the count of 4. (see if this forces the system to react).

 

Next, try this test again with the ABS  turned off.

[Kerry in Mpls]

Ok I tried a couple of your suggestions, DR.

 

With the bike on center stand, key ON (was off in previous experiment), engine OFF, bike in neutral, spinning the rear wheel manually, squeezing the front brake lever immediately activates the rear brake. Did not need excessive pressure or duration, it worked immediately. I heard a few gentle clicks as the brake engaged - maybe some kind of servo, but only at the moment of engagement, no continuous humming like on my 06 RT with whizzy brakes.

 

With the bike on center stand, key ON, engine ON, bike in gear spinning rear wheel, squeezing the front brake lever does NOT activate the rear brake. I tried a lot of pressure for a long time, no engagement. Interesting - but I'm thinking it's probably normal.

 

I did not try any scenario with ABS disabled, if I do I'll report back with results.

The main outcome is all seems to be working properly. Yay!

 

Thanks!

[dirtrider]

16 minutes ago, Kerry in Mpls said:

Ok I tried a couple of your suggestions, DR.

 

With the bike on center stand, key ON (was off in previous experiment), engine OFF, bike in neutral, spinning the rear wheel manually, squeezing the front brake lever immediately activates the rear brake. Did not need excessive pressure or duration, it worked immediately. I heard a few gentle clicks as the brake engaged - maybe some kind of servo, but only at the moment of engagement, no continuous humming like on my 06 RT with whizzy brakes.

 

With the bike on center stand, key ON, engine ON, bike in gear spinning rear wheel, squeezing the front brake lever does NOT activate the rear brake. I tried a lot of pressure for a long time, no engagement. Interesting - but I'm thinking it's probably normal.

 

I did not try any scenario with ABS disabled, if I do I'll report back with results.

The main outcome is all seems to be working properly. Yay!

 

Thanks!

Afternoon  Kerry

 

You probably don't need to do any more testing as your test 1 (above) shows it is working same as the older 1200 hexhead/camhead systems worked.

 

The only way the front brake lever can activate the rear brake is with the rear servo pump motor so you will never see the rear brake apply from the front lever without the key on. 

 

 

[60Aviator]

Not a good idea to run bike in gear on center stand. Not good for the universal joints on the shaft due to the angles and lets you know with that racket it makes. 

[Kerry in Mpls]

14 hours ago, 60Aviator said:

Not a good idea to run bike in gear on center stand. Not good for the universal joints on the shaft due to the angles and lets you know with that racket it makes. 

 

Ooh, good point. Yeah it was kind of noisy; I thought it was because there was no load on the drive train. I didn't even think about the u-joint angles.

This was a really brief experiment after I misinterpreted the key-off behavior, and the little voice in my head started asking "have we been riding around with only a front brake?? eeek!"

 

 

 

[dirtrider]

11 hours ago, Kerry in Mpls said:

 

Ooh, good point. Yeah it was kind of noisy; I thought it was because there was no load on the drive train. I didn't even think about the u-joint angles.

This was a really brief experiment after I misinterpreted the key-off behavior, and the little voice in my head started asking "have we been riding around with only a front brake?? eeek!"

 

 

 

Morning Kerry

 

The NOISE  is because of no load on the drivetrain, it just gets started & continued because of the dissimilar U joint angles at full droop.

 

BMW would not design that swingarm travel to allow harmful U joint angles  (doesn't come close) but it does allow dissimilar U joint angles so the shaft goes through an accel/decel phase twice per revolution at full droop.