W211 with SBC H brake pad change - my positive experience

[anyweb]

ok to be sure i do it correctly, do i remove positive or negative ?

also, when i get around to doing the actual brakes do i have to leave the car in P or N or D ?

 

[television]

The car must be on level ground to safely remove the rear pads and paint the hubs, just slip it out of park and the parking brake off so that you can turn the rear hubs, put it back into P when painted.

Always remove the neg lead first for safety reasons. You remove the rear one first, then the Aux one. the reverse when connecting so Aux one first

On the teaching programs the instructors pull the large plug out of the SBC pump, but its all live and I do not think a good idea.

 

[anyweb]

just slip it out of park

so N is ok ?

 

[television]

Yes you can turn the hub in N but only put it in N after you have the rear pads out. it does no matter for the fronts and it can stay in P and brake on.

Chock the front wheels, of if using axle stands, then you should be safe

 

[anyweb]

ok i havnt done this yet as i'm a bit concerned about disconnecting the battery, dont want any new problems,

but i thought about it and was wondering if the SBC had a fuse that i could pull instead, does it and if so will pulling that out give the desired result ? (ie: that i can remove the brake pads etc...) ?

 

[television]

The 211 dies not have any battery disconnect problems at all, no fuse for SBC

 

[learn4life]

Hi
I need to change rear brake bads on my 2005 E220 W211.
As mentioned in this thread, do I need to change the two rear sensors too as I am only changing the rear brake pads?
Can someone please also advise if I only need to remove the -ve terminals from both batteries (first from the main battery in the boot and then small battery in the bonnet).
Do the +ve terminals not required to be removed?

Thanks

 

[learn4life]

"I've read SBC can be disabled by disconnecting both batteries and from then on its no different to a standard system apart from needing to be more attentive to fluid level when finished."

Is the above statement true?

 

[BertieBear]

I thought that I would share my experience of changing the front discs and pads on my 2005 W211 E280 Cdi. My vehicle does have SBC and therefore before starting, I read a great deal of posts about this procedure. As I do not have a SDS, I decided, that the best option for me was to unplug the Multiplug on the SBC pump. This was done after the car was locked and left to go into sleep mode for about 10 minutes. Contrary to some of the posts I read about the possibility of shorting pins when unplugging the multiplug, the plug has a latch/unlatch mechanism that ensures the plug pulls away cleanly and squarely with no risk of shorting. With it unplugged and secured, I replaced the discs and pads as per any normal vehicle.

I did not open the bleed nipples when pushing the pistons back into the calipers as I did not want to run the risk of air entering the system. Instead I siphoned a quantity of brake fluid out of the reservoir, ensuring not to go below the minimum level mark.

Once I had completed the pad/disc replacement, I refilled the brake fluid reservoir and replaced the SBC pump multiplug. The pump then pressurized the system once I unlocked and opened the drivers door.

No warning messages came up on the dash. I also checked for fault codes using my scanner, no fault codes were recorded.

I have to say that I was a bit apprehensive about taking on this task, mostly as a result of the conflicting information on various forums about what could go wrong with the SBC system. As long as you do not activate the SBC during the process, it is a simple job and no more difficult than a normal brake system.

Next job is to do the same on the rears.

Hope this helps someone thinking of taking on this task.

 

[John Laidlaw]

This is great to hear, well done!

 

[BertieBear]

Having completed the Front Disc/Pad change reported on previously, I decided to tackle the rears. As per the procedure used of the front, I disconnected the SBC Pump Multiplug connector after the car was left to shut down. However, the car was left in neutral to allow me to rotate the wheels so as to be able to check the adjustment of the parking brake shoes when the new discs were installed. It soon became apparent that the rear caliper pistons were sticking when being pushed all the way back to accommodate the new pads. Apparently this is a known problem with the ATE rear calipers on the W211. Many have suggested that a caliper change is the only option. However, I decided that I would undertake a caliper rebuild and determine whether the piston could be freed up by simply working it back and forth and lightly honing the piston bore with extra fine wire wool. I previously owned a CLS with the exact same issue and I was able to do exactly that, in effect lightly honing the bore of the caliper with extra fine wire wool.

Note, that all the parts need to be thoroughly cleaned following the honing procedure to remove any particles that could damage the piston, bore and seals.

In order to undertake the caliper rebuild it would be necessary to remove the calipers from the vehicle and this would require the rear calipers to be bled when reinstalled. Having studied the hydraulic system and read a lot of posts on the subject, I was sure that by applying a pressure bleeder at 2bar, (30psi) to the reservoir, it would force open the valves in the SBC pump, resulting in that pressure being applied directly to the rear calipers. I undertook a test prior to removing the rear calipers and was delighted to find exactly what I had expected. Brake fluid is pushed under pressure out of the rear calipers when the bleed nipples are opened.

Having confirmed that the rear calipers could be bled as described I completed the caliper rebuild, (new piston seals and dust seals), Disc and Pad changed and Parking brake shoes adjusted. The rear calipers were then bled using the pressure bleeder, passenger rear caliper first then driver side rear. The flexi hoses had been clamped before removing the calipers to avoid the system completely bleeding out and therefore avoiding too much air entering the system. Once all the air had been pushed out of both rear calipers, the reservoir was filled to the correct level and the multiplug reconnected.

I'm happy to report that having now completed a complete brake service on both the front and rear, the brakes feel epic with no fault codes logged.

I hope that my two "lengthy" posts will be of help to someone else thinking of doing the same. With the right tools, (essential pressure bleeder), and due care not to activate the SBC self test, (in my case disconnecting the multiplug connector was the only sure fire method of achieving this without the ability to deactivate the system with a diagnostic tool), then the brakes in the W211 can be treated in the same was as any other system.