E220 2006 S211 Estate with SBC rear brake bleeding procedure

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e220estate

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Joined
Sep 16, 2015
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106
Location
Wiltshire
Car
E220 Estate 2006 S211 T model
Hi all - I think I may have just bitten off more than I can chew....Yesterday I replaced both rear callipers because the old ones were binding when I fitted new pads. Lost only a couple of tea spoons of fluid. Now all in place but now of course they need bleeding! I never touched the front brakes and deactivated the SBC and disconnected the batteries (did I really need to disconnect the Aux as well - just extra work if not?). I thought that if the ancient way of bleeding did not work then I could use the re-activated SBC to force fluid thought to the back callipers BUT I think I may be wrong in this? Is it absolutely essential to use STAR to bleed the rear brake system? Was about to start but thought I would ask the question to avoid muck-ups.
TIA as always, Brian
 
....been doing some more reading and my mind is working as follows.
I haven't tried to change the fluid. This was done a couple years ago by my indy when some corroded brake lines needed replacing.
Soooo...the whole SBC system was full before I removed the rear callipers. Each calliper was removed in turn and each flex brake line was re-attached immediately. There was no pressure-related ejection of fluid as I disconnected each calliper and only about 1-2 teaspoonfuls of fluid was lost on each side before I could re-attach the calliper.
Therefore, my reasoning goes, the whole system, except for the last couple of inches of flex hose and the new callipers, should be as full as when the old callipers were in place? That being the case 'normal' bleeding by re-activating the SBC pressure (not the brake pedal) should work, shouldn't it? None of the sensors, other than the pressure sensor for the SBC should have a hissy fit - or am I being too optimistic.
Brian
 
If you’ve only disturbed it at the calipers it’s possible to bleed it with a vacuum bleeder. I have Star myself, but if just a small repair I use the vacuum bleeder because it’s quicker than powering up the laptop. Pumping the pedal will not work, don’t waste your time with that
 
Thought I would first try without a vacuum bleeder - not in my current kit!

- I topped up the fluid reservoir to make sure there was enough to avoid air entering here
- car jacked/supported, right rear wheel off first
- connected Aux followed by main battery, key in ignition, opened drivers door, SBC ABS pump kicked in for the usual period.
- disconnected main battery again, left for several mins and did the above step again.
- did this 3 times (ie 3 SBC ABS primings) therefore there should be pressure in the system; left battery connected
- slowly backed off the bleed screw a little (expecting fluid to spurt out) - nothing. Then after perhaps 10+ secs fluid began to run out. Closed nipple and examined the pads - they had moved to take up some of the slack you get on the calliper sliders when you replace the pads and push the piston into its bore ie the pressure in the fluid was starting to get the new pads engaged with the rotor. A couple more SBC ABS primings and the pads were fully engaged with the rotor. Hub turned ok (ie not locked). Fluid came out of the bleed nipple.
- turned ignition on - no messages :thumb:
- wheel back on
- did the same with the left rear wheel with exactly the same result except that the pads were already engaged with the rotor before I opened the bleed screw to get the air out.
- started car, wife pressed brake and the hub was stopped - eased off and it revolved again ok therefore not locked
- wheel back on, turned on ignition - still no messages:thumb:
- just been for a short test - no dash messages and the same braking as before I changed the callipers.

To conclude, it looks as though I have managed to change the rear callipers without using any 'special' kit. Perhaps this worked because the whole system was already working ok and full of fluid (probably the main factor).
Game plan now is to use it locally for a few days 'on test' and ask my indy to do an MoT brake test to see how the brake forces stack up.
Brian
 

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