Speed bleeders

[Ian J Hartley]

Ok. Finally convinced . Thanks all the input invaluable as ever.

One last question. Does it really matter which order the circuits are bled in? Wheel first, control second? Other way around? Annoyingly I don't know what goes on inside that lump of aluminium! And I haven't had time to research it!

By all accounts no! I did my control circuits first, then the power circuits. The book says to replace the power circuit fluid every year and the control circuits every two years.

There is no direct fluid connection between the control and the power circuits, the only physical connection is via piston in the servo unit.

Ian

 

[Ian J Hartley]

I used this as a guide. Read it through a couple of times until the principle gelled.

http://advwisdom.hogranch.com/Wisdom/service_abs3.pdf

I attempted it with some trepidation, but after I had completed the job, I found it was just as easy as conventional brakes, The Control circuit is the fiddliest because it is conventional open bleed nipple / pump lever / close nipple / release lever and repeat, and the access to the nipples is awkward. The power circuit bleed is a breeze.

Enjoy it.

Ian

 

[Slipperyeel]

By all accounts no! I did my control circuits first, then the power circuits. The book says to replace the power circuit fluid every year and the control circuits every two years.

There is no direct fluid connection between the control and the power circuits, the only physical connection is via piston in the servo unit.

Ian

Magic! I really wasn't clear on this detail. As an aside, does anyone know a good linky with a full explanation of how the Servo unit works?

 

[Ian J Hartley]

It seems that BMW issued a service bulletin back in 2006 that states:- It is no longer necessary to bleed the control circuit at the "metering circuit" and "integral circuit" bleed nipples. The control circuit bleed should be done at the "control circuit" bleed point only.

That is the tall vertical bleed nipple next to the electrical connector.

Ian

 

[Slipperyeel]

Interesting. I think I'll do the whole lot this time around but it's useful to know.

I would like to see a diagram of how the whole unit works or even pull apart an old one. I've grown to like the Servo brakes so kinda dreading a point when/if they give up. Has anyone ever fixed a 'failed' servo unit? Or is it like flippin watch inside there?!