SBC: How difficult to stop car once it goes out? - Page 2 - PeachParts Mercedes-Benz Forum

Stretch · #16 11-19-2015, 11:14 AM

Thanks for clearing that up Shertex.

I understand that you

Suspect Bit is Crap

and perhaps want to

Spend Before Crash

but perhaps it would be best to

Search Before Committing before you do so!

shertex · #17 11-19-2015, 11:16 AM

Quote:

Originally Posted by dieselbenz1

Well at least you will get the error message confirming you have no assisted brakes. The pump is only one component of the system, what about the wiring harnesses and SAM which can also have problems.

So once the error is annunciated it should be an immediate tow to the dealer! Lawyers may have a lot of fun discussing why someone knew his braking power was down significantly yet still chose to drive.

Wasn't implying that I'd continue to drive if it went out...simply wondering about the braking power to get me off the road to a safe spot.

leathermang · #18 11-19-2015, 11:26 AM

I wonder if there is a data base somewhere which shows accidents and or deaths attributed to the SBC going out ? NTSB ? or something like that ?

shertex · #19 11-19-2015, 11:36 AM

Quote:

Originally Posted by leathermang

I wonder if there is a data base somewhere which shows accidents and or deaths attributed to the SBC going out ? NTSB ? or something like that ?

There has been an effort to get people to file complaints with NTSB...but it's never reached the threshold of getting MB to do a recall. Not sure whether or not there are any accidents attributable to a failed SBC...that would be good information to have.

spark3542 · #20 11-19-2015, 11:44 AM

I'll reply first-hand...I'm probably the one most recent that this happened to.

I went 256k miles before the first hint that my SBC unit was about to fail. I don't know why mine failed, maybe it reached to predetermined number of brake applications, or something else.

I will say I always had significant "groan" whenever I opened a door, the SBC doing a self test. With the new unit there is much less groan.

My unit failed while I was moving and had no brake pressure applied. When I saw the red dash of death, I immediately applied the brake gently to see what I was up against. There was a gradual slowing, and any added slowing that I wanted took an enormous amount of foot pressure.

I immediately mentally switched to grandmother mode (admittedly I usually have a pretty heavy foot, but more so on the throttle than the brake). I would initiate my stop 1000 feet before I actually needed to be at zero mph, for the 5 miles of backroads home. I immediately parked it in the garage and didn't move it until I had the new SBC unit.

It was definitely an unsettling experience, but there's not much you can do about it. Hope it fails sometime other than when you're trying to panic stop.

The new unit has been flawless. About 5k miles on it so far.

leathermang · #21 11-19-2015, 11:51 AM

Some car companies clearly have NO 'threshold' .... witness Chrysler, Toyota , Honda, where even a decade after they know Deaths were caused... they continued to ignore the problem... or actively cover it up....

shertex · #22 11-19-2015, 12:16 PM

FYI reman pump from dealer can be had for about $780.

jcyuhn · #23 11-19-2015, 12:56 PM

Quote:

Originally Posted by leathermang

I wonder if there is a data base somewhere which shows accidents and or deaths attributed to the SBC going out ? NTSB ? or something like that ?

A while back I searched for incidents, data, or just anecdotal stories of injuries and crashes caused by SBC failure. I came up with nothing. Found zero reports of injuries or death and perhaps one small denting of the front bumper of a car. My conclusion is that it's not really all that dangerous. Even though any new car can generate 1G of braking force, how many old, neglected cars are in the 0.3G club? My guess is that you have plenty of company at that level of max deceleration...

barry12345 · #24 11-19-2015, 01:26 PM

If a person can remain in control of themselves there may be a couple of things. Put on the parking brake not letting it rachet lock so you can modulate it some.

In desperation we were told the automatic put into reverse is going to be damaging perhaps but a better option than nothing sometimes.

I once lost my brakes totally going down the down side of a very long bridge approach and exit ramp. This was in a 1951 chevy and the only thing I really did was drop a gear down and almost pray. Fortunately the traffic ahead cleared and I eventually got stopped. I was going to start rubbing the cars side along the edge to reduce momentum if the traffic ahead was not clearing.

I had a little time to think. Now how an individual reacts is going to be totally unknown until an episode is underway. Combined with the time and distance to a collision.

For example I could have easily panicked if the requirement to stop was absolutely minumin. Now the fellows that frequent auto wreckers may look at cars that use this unit. If it looks fairly recient check the cars vin with mercedes. Subtract that milage number with what you can get up on the cars odometer .

If low enough to satisfy you buy the junkyard part. Another approach that may not get you far but might work. Tell Mercedes you do not feel safe in a car with your family and a perhaps a known ticking time bomb in the braking system.

They might bite if for example they felt selling safety was part of their function. Or the dealer might consider it might result in another sale. He can quietly pull and replace the part and probably more than a few have already. Costs him nothing and he may respond to some form of incentive.

I did not make the business world out there myself. It just is what it is. Actually with a problem like this there should have been a mandatory recall for replacement either at a certain milage . Or if the replacements are better and far more durable than the originals right away.

If the car is in decent shape and the milage is at what some have failed at. One way or another I would get it changed out. The possibility of experiencing failure and getting through it with no harm or damage is just a roll of the dice.

leathermang · #25 11-19-2015, 01:52 PM

Quote:

Originally Posted by jcyuhn

A while back I searched for incidents, data, or just anecdotal stories .... My conclusion is that it's not really all that dangerous. ..

May be they are pretty much foolproof...
or it may be something having to do with no agency having ' failure of SBC' as a category in its data system. Or persons who know of such failures not knowing there is some agency keeping track of that situation.

shertex · #26 11-19-2015, 01:55 PM

I'd be interested in finding out the percentage that actually fail prior to, say, 300k miles. Perhaps the incidence is ultimately rather low.

barry12345 · #27 11-19-2015, 02:03 PM

Mercedes will unofficially have the statistics. They will not show them to anyone. Plus they might have been very careful on how they gathered them. Letting product remain on the road like this might result in some liability.

I was also wondering if not changing the brake fluid at the required intervals and proof of that might be a loophole they could use. Maybe unchanged brake fluid is a contributor for all I know. Depends what actually fails in them I guess.

BillGrissom · #28 11-19-2015, 02:30 PM

Another issue is driver training. Freeway lanes are actually wide enough for almost 2 cars per lane, plus emergency lanes. So, if the cars stagger as they brake, it is much easier to avoid a pile-up. That extra 15 ft can make all the difference between significant damage and nothing. I have noticed in Sacramento that in "sudden braking" scenarios on the freeway, many drivers pull half-way into the emergency lane as they brake, and they do it early before absolutely needed, as a "just in case" reaction. If you wait until the last 50 ft, no time for that. I don't know if they were trained in school or just figured it out from watching others, but makes sense and surely helps.

hangit · #29 11-19-2015, 02:38 PM

Quote:

Originally Posted by leathermang

I wonder if there is a data base somewhere which shows accidents and or deaths attributed to the SBC going out ? NTSB ? or something like that ?

SBC and NHTSA - Mercedes-Benz Forum

I also practice applying my emergency brake to stop/slow the car. You have to lift your left foot a lot higher than you think to reach it.

John

leathermang · #30 11-19-2015, 02:44 PM

Quote:

Originally Posted by hangit

.....I also practice applying my emergency brake to stop/slow the car. You have to lift your left foot a lot higher than you think to reach it.....

People should try that regularly in a parking lot.... keeping the ratchet button depressed...
they are likely to learn that the emergency or parking brake needs to be adjusted... both the resting position of the brake and the wires which connect to it...
and how much better hydraulic application of brakes is than mechanical...