Dragging R 1100 RT Rear Brakes

[mweiland2]

I don't know if this has been covered before or not but I have a great deal of brake dust on my rear wheel (I have 3K since that servicing). I just had the rear rotor and pads replaced on my 54K servicing but was wondering if this is normal.

I talked to the original owner and he mentioned that he noticed this as well. It seems that the rotor is really warm and I only rode the bike 5K miles from the time that I purchased the bike in November of '08 to when I was told my rear rotor/pads were toast!

I am very careful with the amount of rear brake I use and know that I am not riding the brake. I just don't want to replace the rear rotor again in the near future as my intitial introduction to having my "new" RT serviced was costly at best.

Any thoughts?

[genen8kua]

You'll find a lot of folks complaining about how the R1100 series chews up rear brake pads. One correctable cause for rapid wear is a little bit of rust on the pad pin. This can cause the pads to bind and stick a bit. Removing the pin and touching it up with some 600 grit or so emery paper and then lightly greasing it before reinstalling can help.

Pulling the caliper to check pad wear is one of the easiest jobs on the bike & recommended (IIRC) by BMW every 6K. Pulling and touching up the pin is only one step further (& looks like it maybe could be done with the caliper still on the rotor). The IBMWR.org website has a couple mentions of it in the technical article.

[mweiland2]

Thank you for your feedback. I will look at the pins while I am waiting for a new Moto-Techniques Oil Filler kit. But. . .that is another story in itself!

[Andy VH]

I have only replaced the rear brake pads on my 94 R1100RS twice in 141,000 miles. I regularly use the rear brake along with the front brake for almost all stops, so I keep my rear caliper active and moving all the time. That in itself may be one reason i never have a dragging rear brake.

The older Oilheads use a single acting rear caliper. That means when you apply the rear brake, pressure pushes out the caliper piston to push the outer brake pad to contact the brake disc, and then the increased travel of the piston and disc (via the mount buttons) "pushes" the disc into the inner brake pad. Greater rear inner brake pad wear, versus outer brake pad wear indicates a restriction on the brake pad pins.

If you don't actively/regularly use the rear brake, the "pins" that the inner brake pads move on, can get rusted/gummed/crapped up and actually "hold" the rear inner brake pad to the disc those few times you do use the rear brake. The pins must allow for easy motion of the inner brake pad. I use anti-sieze on the pins to make sure the inner pad is not restricted from retracting. Also, not regularly using the rear brake can cause the piston to hang up and cause brake drag, heat, and excessive pad wear. So, to reduce rear brake pad wear and heat, use the rear brake MORE often.

[TheRoss]

At around 60,000 I had to rebuild my rear caliper. It was sticking bad enough to really heat up the caliper. And then one day on the road it just locked up. I was moving slowly in a gas station parking lot, applied the rear brake and it locked up. To get home I had to open the bleeder screw slightly and tap on it to release pressure, which also dripped brake fluid on the outside of the caliper. I then rode home without touching the rear brakes at all. BMW sells a rebuild kit that includes 4 seals and 2 pistons (if I remember correctly). Or maybe the kit is just the seals. It was not a big repair, but watch where you insert the new seals, they are not all the same size.

More recently I replaced the rubber boots that cover the caliper pins discussed above. One of the boots had a tear in it, which allowed water and dirt inside, thus causing rust to build up on the pin preventing good smooth action. BMW sells the 2 boots together for something like $25. Use vasoline or litheum grease when installing the new boots or you'll tear them.

8 shows the seals. It is a kit that includes 4 seals. $38.

http://farm3.static.flickr.com/2464/3944964997_3f6b38a0de_o.png

Seals: #34212330311
Rubber boots: #34212330312