Flushing/Bleeding the Brakes

[1000RR]

Well this was my first time at it... so if you have anything to add, feel free. BMW says to do this after your first year, then every other year after that.

So today I finally got out to do the brakes on my Race/Track Bike (R6) and the S1...

Per the recommendation of TJ as well as other racers, I changed both over to the Motul 600. Had never done the brakes before (on any bike), but checked out the Service CD and it seemed pretty straight forward. So I expected the worse but hoped for the best.

What makes the process VERY simple is one of these --> Mityvac Brake Bleeder Kits (2nd picture - the one that hooks to your air compressor). WOW, what a breeze.

FRONT BRAKES:

• Remove Reservoir Cap
• Suck out fluid from Reservoir
• Top off with new fluid
• Remove cover on bleeder nipple by master cylinder, suck out fluid
• As with any bleeding of any brakes, make sure that either while fluid is being sucked from the bleeder nipple or you are pressurizing the fluid in the line by pulling on the brake lever, that you tighten the nipple back down prior to unpressurizing the line or prior to turning off the vacuum... this will help ensure you don't get air bubbles sucked back up into the brake line at the nipple you're bleeding from.
• Keep topping off reservoir and ensure the fluid doesn't get below the drain on the bottom or you'll suck air in
• Bleed/suck fluid from the front left bleeder
• Between each time of draining the reservoir and filling, PUMP the brake lever (it'll be soft).. and get the pressure back in
• Top off again... I did this a few times on each bleeder valve to ensure that I got as much of the old fluid out as possible, the front fluid actually looked pretty good after a year... the rear was a bit darker
• Do the same to the front right bleeder valve.

BACK BRAKES:

• Remove/Move Reservoir out from under the bike
• Remove cap and suck out fluid from reservoir
• Top off just like you did for the front
• Bleed/suck fluid from the rear bleeder valve
• Top off and continue till you get nice new/clean fluid coming through the MityVac.

That's it... go ride and test. Worked great and took very minimal time.

The best part - for what I paid for the Mityvac, it's already more than paid for itself w/one service on the S1.. plus the track bike is done now too.

And a BIG THANK YOU to TJ from Rider's Discount!!!

[kevin_stevens]

Don't suck the fluid from the reservoir, just pull it through from the bleed valve until the level is low. Helps remove more small bubbles and grunge that way, and less chance of running it dry.

KeS

[viperclaw]

If you don't have a vacuum bleeder then just use the pump and bleed method.

-Have the drain line ready on the caliper bleeder
-Pull the brake lever in (or push down the foot brake lever depending on what you are doing).
-Loosen the bleeder with your wrench and once the lever comes back to the bar (or down to the bottom of travel for foot) close the bleeder. Doesn't have to be super tight just a light touch is enough to keep air from being sucked in when. . . .
-Let go of the lever and let it travel all the way back.
-Repeat until fluid is clear or probably 3 resevoirs full for the front and rear. The rear has less volume compared to the front but the brake line system and single piston rear caliper have less volume compared to the front.

At work I usually do pump and bleed because bleeding with the vacuum can actually take longer depending on how good your vacuum is and the size of the brake system. Then when done bleeding and before removing the hose I turn on the vacuum and suck up the fluid in the vacuum bleeder line and out of the nipple of the brake caliper.

[V8M3]

Do you need to bleed the brakes if you just remove the reservoir cap and add brake fluid?

[S1000RR ROB]

^^^^^^^^^^^^^^^^

NO

[1000RR]

Originally Posted by V8M3

Do you need to bleed the brakes if you just remove the reservoir cap and add brake fluid?

Quick answer = what Rob said...

But why your adding fluid would be of interest too... has it been low?

The maintenance schedule for the bike says to change/flush the fluid on the ABS bikes after the first year, and then every other year after that.

[viperclaw]

If it is getting low then check your brake pads for wear before simply topping it up. There is no real need to add any fluid as the reservoir is large enough to compensate for completely worn pads--the pads will wear out before the fluid level gets too low. Unless there is a leak but the brakes would feel spongy more than likely.

[kevin_stevens]

And if you *do* top it off, be careful the next time you pull your front wheel and have to push the pistons back to remove the calipers. Overflowing your MC reservoir isn't good for the paint...

KeS

[V8M3]

Originally Posted by 1000RR

Quick answer = what Rob said...

But why your adding fluid would be of interest too... has it been low?

No, I wanted to switch brake reservoirs to a smaller unit and didn't know if the smaller unit would require periodic top-offs.

[markjenn]

Originally Posted by kevin_stevens

Don't suck the fluid from the reservoir, just pull it through from the bleed valve until the level is low. Helps remove more small bubbles and grunge that way, and less chance of running it dry.

Pulling all the old fluid (with its grunge) through the system doesn't make sense to me when it can be removed at the reservoir. And it wastes more expensive fluid.

If you keep the reservoir topped off above the intake port, it is impossible to add air to the system during bleeding. And assuming you don't do something stupid like pump the lever, removing the old fluid from the reservoir (typically with a syringe or turkey baster) and refillng it with clean is not going to add any air to the system either.

Everything I've ever seen about brake bleeding recommends getting as much old fluid out at the reservoir before you start.

- Mark