s55sl55driver

I have a 2004 SL55 with the AMG factory multi spoke rims with Pirelli P Zeros that I have had for about 1 year.

I am experiencing what appears to be front wheel lock up during aggressive driving/braking. When driving fast and breaking hard before a turn the wheels seem to lock up and leave rubber skid marks on the pavement. It seems like the ABS is not modulating fast enough. I have gone back to look at the skid marks on the roads where I am braking from about 85 mph down to 60 mph or so, The car is leaving a full pattern tread and all.

In an attempt to re-create the situation for the dealer, I took the car out behind the dealership and got it up to about 45 mph and slammed on the brakes. In the summer the car left long skid marks about 10'. Recently in the colder weather a few weeks ago the car left a series of skid marks starting at about 5' then 3' then 2' then 1' then 6" all told about 10-12 feet of rubber was left on the pavement. At first glance it looks like one long skid mark. Closer look reveals where the patterns start and stop.

I am not a professional driver but I can say that the car does not feel right. I had an NSX and it never locked up like this. I did take the car to Pocono this summer and it was locking up the front tires all day long. For what it is worth the instructor I had said the car should not be doing what it was doing.

I have had the car in to the dealer several times and the MBUSA rep says their are no error codes and the car is behaving normally. They claim that as long as the car stops safely no pulling etc. it is doing its job. My contention is that front wheel lock up is not a characteristic of a "race Inspired supercar" and is in no way acceptable.

So, does any one else experience this characteristic in their SL55?

The wheels lock up if you get into it really hard before a turn and they do it when you try to squeeze em softly but firm. I can't believe that my car is normal.

Please help and offer feedback.

Other than the brakes this car is amazing and a blast to drive. When I was at Pocono the starter said it was the best sounding car on the track.

AMG_55

it shouldnt lock up, at least not for 5 ft or even 3ft. it should lock up momentarily.
i drive my car (clk55 03) very hard and have never had this problem.
sounds like the dealer is trying to brush u off. i hate it when something is wrong and u know its wrong but they tell u about their stupid *** fault codes.

get a different sl55 and drive it, c if it behaves the same way. if it doesnt try contacting some1 higher up.... mbusa customer service mayb.

good luck

Chris 45971

There is some kind of special breaking system that engages when the car senses an emergency situation. I looked in the glossary of the manual and it has this:

BAS (Brake Assist System) ~ System for potentially reducing braking distances in emergency situations. The system is activated when it senses an emergency based on how fast the brake is applied.

I would ask the dealer if they can disable the system. If they say no, keep calling around until you hopefully find one that will do it for you.

Good luck.

CASL55

BAS shouldn't overrride ABS. It sounds like the ABS isn't working right. Does it work on wet pavement (you should feel it pulsing)?

Jim

s55sl55driver

I was told that you will not feel ABS pulsation in the pedal because of the brake by wire system.

Chris 45971

If you are hitting the brakes hard and fast (percieved by the car as an emergency situation), BAS should override everything.

s55sl55driver

When I am driving hard on the twisting back roads I don't just stomp on the brakes. Having said that...... I thought driving hard means go as fast as you can for as long as you can brake as hard as you can before the turn and get on the gas as fast as you can again...... When you do that with this car the front wheels lock up and leave rubber in the race track or road.

I was reading an article about Mario A. earlier today where he drove an Sl55, a Ferrari, a bmw z8. I am sure that car wasn't doing what my car is doing that's for sure.

CASL55

I drive pretty hard, and I've never accidentally triggered BAS. In fact, the only time I have triggered it is when I tried to see if I could. You have the right idea about late braking, and braking to maximum before turn-in. You want to back off the brakes as you turn in (trail braking) so that, as the lateral forces build up, the longitudinal forces are dropping. I always drive as if the car didn't have ABS, and try to brake almost to the point where the wheel would start to skid, and the AbS would come on. ABS is to me a safety feature to be employed if I screw up, not something to routinely use.

Having said that, if you do get on the brakes too hard, the ABS should go to work and prevent those long skids, and, not incidentally, allow you to generate some lateral force, which is impossible if the wheel is locked. So, it sounds like your ABS in not working right. Does it work on wet roads? Does it ever work?

Jim

CASL55

Don't jump on the gas. Aim just inside of the apex and squeeze it on. You can apply more and more power as you unwind the wheel.

Jim

AMG_55

i agree, if u use abs a lot then u r not driving as smooth as possible; meaning u r driving slower than what is possible on that given piece of road.

be as smooth as possible in braking, turn the wheel as u slowly come off the brakes and gently but surely roll on the gas pedal pressure..... use a flick of opposite lock on the exit if necessary... too much oversteer means ur pushing 2 hard and not maximizing forward drive.

s55sl55driver

I just read this on the 2006 sl55 site:

"Antilock Braking System (ABS) ABS senses impending wheel lockup under heavy braking and pumps the front brakes individually or the rear brakes together (to help maintain stability) as needed up to thirty times per second, to prevent lockup and maintain steering ability. Electrohydraulic braking system eliminates the pedal pulsation commonly associated with conventional brake systems and ABS." Pasted from 2006 MBUSA Website

The word "prevent" is clearly used. So if a consumer has the expectation that the car is designed to prevent wheel lock up wouldn't it then be a reasonable expectation that the car does not leave 5' long skid marks? A skid mark is evidence of wheel lock up right? If so then why is the MBUSA District rep saying this car is behaving as engineered?

CASL55

No!

E55 Rocket

Hey S55. I have an 04' E55, and the same thing happened to me. I actually had a FLAT SPOT on my tire, and MErcedes had to replace it. They spent a few days looking into the problem, and ended up fixing to defect. I would take it to the dealer ASAP for warranty work.

MB AMG

So you're saying BAS overrides ABS? If you are, I don't think so. All it does is give you maximum braking force, regardless of how hard you are hitting the brake pedal. When the wheels start to lock up, ABS still comes on.

Oh yeah, I think the MB website has a good model how BAS works.

CASL55

What would that be like?

Situation: car going around corner, cliff on outside of corner, driver sees object in road, and hits brakes hard, but not as hard as the car thinks he should hit them.

What the car does: slams on brakes enough to lock wheels.

What happens: Driver loses directional control (wheels are skidding). Car goes off road to outside of corner, and over cliff.

Nah, you want the ABS to work under those circumstances.

Jim

AMG_55

i agree

very nice way 2 put it.
wheel lockup in a car equipped w/ abs is only acceptable in off road conditions where it helps to "dig" into the surface.... some 4by4s have a button to change the parameters of abs and tc

s55sl55driver

So it seems pretty clear that we are in agreement that wheel lock up should NOT occur at least not in any measurable lengths.

So what to do next?

The car has been in four times for the problem.

The MBUSA district rep is involved and believes the car is performing as engineered.

Does any one have suggestions on how to proceed? Feels like David and Goliath.

Something that seems so obvious is turning out to be a nightmare.

CASL55

You can try to bound the problem. Does the ABS ever work? As I've suggested here twice, go out and find out if it works in a straight line on wet pavement. Try a panic stop from 30 mph. If that works, try one slower or faster. I say start with wet pavement, because doing these experiments on dry pavement is harder on your brakes and tires, and is potentially more dangerous, depending on your skill and the road conditions.

If the ABS doesn't work at all on wet pavement, then your situation with the dealer is pretty simple: hey, this thing never works; fix it.

If it does work on wet pavement, try it on dry pavement, in a stright line, at various speeds. Just brake until lockup or ABS action occurs, then back out of the brakes to save wear and tear on your car and tires. If it fails on wet pavement, and works on dry pavement, then you have a more complicated discussion with the dealer, but still one that should be managable.

If it works on dry pavement, but just not at corner entrances, you could try that on the dealer, but I wouldn't expect a wonderful outcome.

BTW, someone said that you won't feel the ABS through the brake pedal. That is correct, but you will hear and feel it through the car. Do the experiments with the top or windows down.

Let us know the results. Good luck.

Jim

Anduspeed

me thing and Dealer said it's normal

alx

this is not normal. wheel dragging is desirable only at very low speeds and very slippery conditions. actually below certain speed (i think 15 mph) abs does not and should not work.

your problem could be a couple of things...

1. bad/ dirty abs sensor. easy and cheap to replace/ clean (might throw a code)

2. sticking caliper

2.1 inspect brake lines for kinks/ collapses (somewhat tricky)

2.2 replace/ flush brake fluid - should be done every 5 years anyway

2.3 rebuild caliper- kits are available - i think

how to find a front sticking caliper - drive for a while on the highway - slow down naturally without the brake- downshift when necessary. at the end apply emergency brake to stop. get out at feel (carefully) the front disks- if all three are cold but the one in question is hot- you have a sticking caliper).

also in extreme cases the car might pull towards the sticking front caliper

3. bad abs actuator block - $$$$

thats about it

good luck and let us know

IngenereAMG

I think this thread is from '05! He probably fixed it or sold it by now!

..... and, the condition is definitely not normal!

alx

Oh crap... You are right... Nevertheless...

Anduspeed

it looks like my front left wheel will not lock up when is in dyno mode .... so it must be the electronics

jrgator

Too funny. I was reading the whole thread with interest, relating it to a defective ABS sensor I had with my GT2, and then I find out it a 6 year old thread. Nevertheless, still relevant.