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Entries in SBC Brakes (2)

Tuesday
Mar102015

Sensotronic Brake Control

If you remember with the launch of the SL in 2002, and then the higher versions of the E Class, Mercedes-Benz introduced Sensotronic Brake Control (SBC). A revolutionnary braking system with a pump, and pressure reservoir to enhance braking, on the premise that most folks would never apply the level of pressure even with a power brake to shorten brake distances.

In 2003 the E500 had SBC brakes, and an air suspension. Neither of these are inexpensive systems to repair.

In the case of Walter, when lining up for an apex, SBC does a phenomenal job to scrub off speed in a short distance. Brake in a straight line and hit the apex...Walter never misses a beat.

The downside of SBC brakes is that they are complex to service, even performing a brake job (replacing pads) is an undertaking the brake system needs to be de activated with the DAS. Bleeding the brakes is an experience in its own. Not surprising Mercedes discontinued SBC brakes after a few years.

Some weeks ago Walter decides to get cranky, lights up the dash in red, yes the SBC pump is acting up. The car still brakes but in a different fashion that when the pump is working. If you have a car with SBC brakes and the dash lights up red, be very cautious, there is a reason its red and it does not go away.

Keep in mind that you are used to braking with increased pressure from the pump. The messages in the dash bluntly tell you what the car will do - reduced braking effect - longer braking distances. Not recommended to drive the car.

Its an older car, it fell in love with flat beds last year, to start 2015 its the SBC pump. A perfect OUCH moment of nothing will be inexpensive to repair.

Bring the car to a Mercedes-Benz dealer the warranty on the SBC system has been extended to 15 years, from the previous 10 years. In our case Walter is out of the 10 year time frame.

Yes...there is a silver lining in the SBC brake cloud.

 

 

Tuesday
Oct072014

Brake Lines

At times cars have this innate ability to totally irritate you. Walter as you can see from the latest posts is on a mission to become an irritant, starting with the suspension air pump, crank sensor, windshield, then the wheel alignment, and a few days ago a brake line.

Lets step back for a moment.

There was an hydraulic fluid leak in front of the left rear wheel. At first blush it could be the shock absorber which has hydraulic fluid, that started to leak.

Not a big deal, but a constant minor leak. 

Peaking under the car during the wheel alignment the left rear shock is very dry...oops does not seem to be the shock abosorber. 

If its not the shock abosorber, the other possibility is a brake line. It almost does not make sense that a brake line would leak (seep)...or does it?

Until the "brake fluid low visit workshop" comes on in the dash at the most inopportune time. A case of "I don't need this s$%t this morning" 

If you see some sort of hydraulic fluid leaking/seeping from the car, got to a workshop immediately and have the leak confirmed and repaired.

Been around Benzes for decades, we keep on driving Walter, even when it was not the shock we still drive Walter, even when the lights in the dash come on, we still drive Walter. 

Hydraulic leak, low brake fluid, how much is left in the master cylinder? 

Walter makes it on its own to the friendly mechanic. Yes...drove Walter in a very cautious fashion to minize brake applications.

The conversation goes as follows.

"A brake line is leaking in front of the left rear wheel" reply from the mechanic "You should not have driven the car...not safe"

"How could a brake line leak?" reply from the mechanic "SBC brakes generate very high line pressures the metal fatigues cracks, leaks". It all makes a ton of sense on a 12 year old car.

From the mechanic "You know that its a pain to bleed the lines with SBC brakes...you remember" the reply "Yes...and it consumes a ton of brake fluid too...I don't think its bad that too much air went in the system".

Fortunately we have other vehicles...and the patience to endure Walter's foibles.

Hopefully whoever engineered those weak brake lines from over a decade ago and saved a few pennies in the process got a promotion. 

Again...if you see hydraulic fluid on the ground best not to drive the car, if a leaking brake line bursts especially with SBC brakes it can turn into a dangerous situation in a nano second. 

Bottom Line:

Replaced the left and right brake line and bled the brakes. Absolutely not lingering on what could have happened if the brakes failed.