Rear brake bleeding

[bmwdenk]

Hey bretheren,

I'm wondering if there is a sure fire way to know if I have a bad ABS module?

Let me explain what I mean. Last season I lost my back brakes, they got very weak like air was in the system. I have changed my pads (never breaking any lines). Somehow air got in the system??? So I tried bleeding the air out (I got speed bleeders)- thanks Shawn -

Well that didn't seem to work, I checked the book and it says if air is being introduced into the system with no fluid leaking then change the slave cylinder. This weekend (fathers day).

Front brakes work fine and ABS system check at start up is good. I'm just running out of options.

So back to the original questions?

[philbytx]

Well, back brake bleeding CAN border on the Evil Arts, especially with the iABS ! However, you have the much simpler ABSII system.

 

Firstly, get yourself a large container of quality DOT4 fluid, such as Valvoline.

Now, did you bleed out the ABS unit? If not, do that first, then go to the rear brake caliper and do a GOOD bleed by JUST BARELY cracking open the bleeder valve, so it feels hard to bleed but fluid eases out. Sometimes air will creep past the bleed screw if you open it up too much. .

 

Once (and IF!!!!) the bubbles stop, check your brake lever.

If it still feels spongy, try the following.

 

After doing a couple of lever down/bleed/close bleeder/lever up's, put some clear tubing over the bleed screw and into a jar with some brake fluid in it. Crack open the bleed screw and let it sit and slowly "gravity bleed" for about 10 mins, ensuring you don't allow the reservoir to run dry. Then, do a couple of lever bleeds, tighten the bleed screw and check the rear brake lever.

Your pedal should feel firm now. If not, then you definitely have a hardware issue!

 

 

 

[bmwdenk]

Should I have the bike running when bleeding the ABS? Never done one before?

[Phil50]

No, you switch on the ignition, wait a few seconds and it will pump away. The full instructions are in the FAQ section of this site accessible from the home page. http://bmwsporttouring.com/faq.html I recommend you read them and follow those instructions. It is important that you have some sort of header funnel arrangement and don't let that run empty otherwise you'll make the job much, much harder.

 

 

[Danny caddyshack Noonan]

Denk

Your controller is fine if you aren't getting wig-wag flashing ABS lights on the dash.

For bleeding, no ignition, just pump it from the pedal. The 1100RT has a pretty dumb hydraulic system....aside from the POS PITA controller in the middle. The controller only moves during start up and during a locked wheel event. You may want to consider pulling the tupperware, tilting the tank forward and bleeding the nipple for the rear circuit at the ABS controller. It ain't terribly easy but can be done unless you have Andre the Giant hands. The rear circuit is on the left side of the bike.

 

Air going in is a concern. Have the same on mine just discovered yesterday. The lack of good rear braking and air points to the rear master cylinder, a bad hose or letting the reservoir run dry during pumping. My rear hose failed last year after the inner liner collapsed with the only symptom, initially, of spongy soft rear brake. The hose didn't rupture until the bleed I did, to fix the soft brakes, and flow halted making me push on the pedal very hard.

 

If you order parts, Chicago BMW still gives 20% off but, you don't get to see that discount until your card gets charged. It doesn't appear automatically on the website like one would expect. They do take about 2 weeks from order to arrival though.

[philbytx]

No.

 

You have ABSII without the power assistance of iABS.

 

 

[Phil50]

My mistake, should have read the sig!

[bmwdenk]

Just an update, changed my rear slave and used a vacuum pump to bleed system. Brakes are back and fine.

 

Thanks everyone.

[tpfeffer]

Is there a rebuild kit or did you have to replace the slave cylinder?