2006 R1200RT Rear Brake question

[Roy in SC]

Every two years I bleed the rear then the front Master Cylinders, then bleed the ABS Control Unit rear first, then front.

The Dot 4 brake fluid always comes out pretty clean but I still use about 1 quart of fluid each time to make sure everything gets flushed properly.

I finished the process yesterday and put the tank back on to go for a quick test ride.

The front brakes work well, but the rear brake hardly slows the bike down.  During the bleeding process, I get a good volume of fluid out while bleeding the Master Cylinder, as well as a good flow when flushing the ABS Control Unit.  I use the ABS Funnel and make sure I do not suck air into the system when bleeding.

Brake lines look good, pads are good, I pushed the cylinders back into the calipers again, then pumped the brake to get the pedal back.

When bleeding the ABS Control Unit, I pull the calipers and insert shims to ensure the pistons are pushed into the calipers.

2006 BMW R1200RT with 68,000 miles.   Any thoughts on what I need to check next?  Thanks for any help.

[dirtrider]

17 minutes ago, Roy in SC said:

Every two years I bleed the rear then the front Master Cylinders, then bleed the ABS Control Unit rear first, then front.

The Dot 4 brake fluid always comes out pretty clean but I still use about 1 quart of fluid each time to make sure everything gets flushed properly.

I finished the process yesterday and put the tank back on to go for a quick test ride.

The front brakes work well, but the rear brake hardly slows the bike down.  During the bleeding process, I get a good volume of fluid out while bleeding the Master Cylinder, as well as a good flow when flushing the ABS Control Unit.  I use the ABS Funnel and make sure I do not suck air into the system when bleeding.

Brake lines look good, pads are good, I pushed the cylinders back into the calipers again, then pumped the brake to get the pedal back.

When bleeding the ABS Control Unit, I pull the calipers and insert shims to ensure the pistons are pushed into the calipers.

2006 BMW R1200RT with 68,000 miles.   Any thoughts on what I need to check next?  Thanks for any help.

 

Morning Roy

 

Can you hear the servo pump come on when you use the rear brake pedal with the key on? (this is an important observation)

 

You didn't get brake fluid on the rear brake pads during the service did you? 

 

Do you have firm rear brake pedal with normal amount of travel before getting firm?  

 

Do you know if the rear brake worked correctly before your service? 

 

We really could use some more detailed information on your problem to help you in a more specific way.

 

 

 

 

 

 

[Roy in SC]

Thanks for replying DR.

The Servo Pump energizes when I turn on the Key, then cycles when I depress the brake pedal or the font brake lever.

The Brake Pedal is at its normal height after bleeding the Master Cylinder, pumping the pedal once or twice, then topping of the reservoir.  After bleeding the ABS, I removed the Shims, installed the Rear or Front Brake Calipers, then made sure the ABS Control Unit was topped off to ensure I had enough fluid.

[dirtrider]

6 minutes ago, Roy in SC said:

Thanks for replying DR.

The Servo Pump energizes when I turn on the Key, then cycles when I depress the brake pedal or the font brake lever.

The Brake Pedal is at its normal height after bleeding the Master Cylinder, pumping the pedal once or twice, then topping of the reservoir.  After bleeding the ABS, I removed the Shims, installed the Rear or Front Brake Calipers, then made sure the ABS Control Unit was topped off to ensure I had enough fluid.

 

Morning Roy

 

The Brake Pedal is at its normal height after bleeding the Master Cylinder, pumping the pedal once or twice.--  Are you saying that you need to pump the pedal once or twice to get proper pedal height.

 

Or is the hight OK now?  ALWAYS good even  on the first apply? 

 

Did you get brake fluid on the rear brake pads??????????

[Roy in SC]

After bleeding and putting the calipers back on, it takes one or two pumps to recover the pedal height.

Then it stays at the proper position.

[dirtrider]

5 minutes ago, Roy in SC said:

After bleeding and putting the calipers back on, it takes one or two pumps to recover the pedal height.

Then it stays at the proper position.

 

Morning Roy

 

Well, difficult to tell anything for sure over the internet, but IF you have good rear pedal height, have good rear pedal firmness, & the  rear servo pump is coming on then it is sort of pointing to a rear brake pad friction issue.

 

Any chance that you got brake fluid on the rear brake pads or on the brake rotor????? That will ruin the brake friction for a while. Did you use a hose on the rear caliper bleed nipple to divert the fluid away from the brake area while bleeding??????? 

[Roy in SC]

No brake fluid got onto the rear pads, as I use a Mighty Vac container (not the pump - just the container) with a long clear hose attached to the bleeder valve. After the process is completed, I use Brake Cleaner on all components to eliminate any brake fluid residue.  That is mostly on the bleeder valve.

In the BMW RepROM DVD, there is a paragraph that describes a Bleeding Test with the BMW Motorrad diagnostics system.

I suspect this is used to verify pressure, but it seems that I have pressure.

Based on your reply, I will pull the rear pads again and inspect them.  

 

[dirtrider]

27 minutes ago, Roy in SC said:

No brake fluid got onto the rear pads, as I use a Mighty Vac container (not the pump - just the container) with a long clear hose attached to the bleeder valve. After the process is completed, I use Brake Cleaner on all components to eliminate any brake fluid residue.  That is mostly on the bleeder valve.

In the BMW RepROM DVD, there is a paragraph that describes a Bleeding Test with the BMW Motorrad diagnostics system.

I suspect this is used to verify pressure, but it seems that I have pressure.

Based on your reply, I will pull the rear pads again and inspect them.  

 

 

Morning Roy

 

You can run the bleed test using a GS-911 but it is very difficult to get a lot of the I-ABS brake BMW's to pass that test (even on a perfectly functioning system).

 

If your pads & brake rotor are clean & fluid/oil free, AND you have good pedal pressure, AND  your servo pump is operating then try riding the motorcycle for while using the brakes as normal.  This might re-bed the brake pads to the rotor.  

 

Do not abuse or overuse the rear brake if it isn't stopping good as you can easily glaze the brake pads to the point that they will be difficult to recover.  

 

If you can't find anything else wrong with the rear brake then maybe remove the brake pads, then lightly sand them on a flat surface, then clean the brake rotor using a Scotch pad & brake clean.

 

Did you bleed the wheel circuit side with the key-on using the servos to push the fluid through?????????