superangrypenguin

Synopsis: Brought vehicle into dealer for rattling sound in rear of vehicle.
Repair: Installed clips to repair a dangling wire for the parking brake

Issue today: Reversed out of garage, disengaged parking brake, and massive squeal

Confirmed actions:

1)Sound remains when vehicle is in neutral rolling down a hill.
2) Sound remains while vehicle is in motion while neutral and applying slight brake.
3) Sound changes if I apply parking brake. (sound becomes louder, same type of scraping sound)

Suspected issue: Parking brake isn't fully 'releasing'

If I slam on the parking brake FULL/HARD while the vehicle is moving, and disengage it, the sound goes away. If I press the parking brake a few notches so it partially engages it, and then I release it, sometimes the sound comes back. When it does come back, it varies from a slight "hum"..."hum...."hum".... to a "scratch"..."scratch"..."scratch"....or if it doesn't come back, I hear nothing at all it and it appears to just go away.

Here's the interesting bit

After I messed around with the parking brake for a solid 20 minutes of testing (for the above), the issue is now "gone". [wtf?]

What should I do now? When I leave the vehicle in neutral with the parking brake disengaged and I jack up the wheel in the back which I think has the parking brake problems, I can't turn the wheel either (I suspect due to 4matic).

What should I do next?

This video is taken when the issue first started, before my testing and effing around of the parking brake.

Thanks!

http://sendvid.com/7za3d83y

superangrypenguin

Ugh I lost a bunch of skin on my finger today. hurts like a ****. (accident)

Anyways I jacked up the car in the rear and indeed could hear a scraping sound when turning the left rear wheel. I tried loosening the parking brake cable to no avail.

I give up. Going to the dealer tomorrow.

I HATE CARS. MAD!!

Carsy

Interested to know of the cure.

superangrypenguin

Thanks. Will do

I just took it out again...

Sometimes it comes back and sometimes its quiet as a whistle. I hate intermittent issues!!

Anyways ill report back tomm

Cheers!

superangrypenguin

Fresh from the dealer

*yawn* it's early.

Car's just coming off the hoist now. Turns out the anti rattle clip they installed came loose. Oh well. #fwp

superangrypenguin

Ok, so the original sound/problem is back. (not the squeal - that is now gone as per the fix above).

Here's the scenario, I went back to the dusty crappy dirt/rock filled road I was driving on which caused me to first notice this issue.

Sure enough, I hear the same noise. It's a light 'tapping' sound coming from the rear left of the vehicle. So yet again, it must have something to do with this parking brake cable.

Here's the thing though - on any regular road - whether or not that'd be driving over bumps, storm drain grills etc, I can't get the noise to occur.

Next time you're driving on a crappy gravel road can you please let me know if you hear something similar? The sound is a pretty loud metallic tap that happens every so often from the rear.

If I partly engage the parking brake, the sound goes away

Sigh. FWP

Carsy

I have had problems on gravel roads. A small stone lodges between the disc & the stone guard causing a harsh noise. Simple to fix, remove the wheel & flick out with a screwdriver.

superangrypenguin

It sounds to me like what you are referring to is a constant noise. Mind is intermittent. Can you kindly confirm sir?

Thanks

Carsy

It can be intermittent.

Sir John.

superangrypenguin

Thanks I'll give it a shot this weekend and report back. Thanks Sir John! (that sounds like a naughty **** screen name but i'll go with it )

Carsy

I worry about what you do after hours !

dieseldoc

Scary thought

superangrypenguin

So the original issue of a metallic tapping sound over small manhole covers is back.

Back at the dealer for the 3rd time and I have to fight for this to get covered under warranty.

Apparently what happens is over time the springs that are in the parking brake assembly in the rotors gets weakened and so as one drives over bumps, the parking brake shoes end up rattling a bit, hitting the rotor.

It's a nuisance but apparently not a safety concern. The shop foreman told me that most likely it's because the springs wear out (I do use the parking brake everytime I park), and because the slack isn't at tight over time now it rattles when the parking brake is not engaged.

The argument right now is that the parking brake shoes are a wearable item so this isn't covered, but my point is that the shoes are not worn, it's the springs, and what do I care that the springs are only part of an entire kit?

It's being escalated to the service manager and the warranty clerk at MB Corporate. I'm going to raise hell until I get this covered under warranty.

Anyways, this is apparently a common concern among people who use the parking brake. It's not normally an issue for people who don't use the parking brake but it's asinine that people don't do this (as discussed with the foreman).

**
One of the ways to make this go away is to engage the parking brake a bit - this supports the theory that it's the springs.
Another is = if I pull the dust cover near the rotor assembly closer towards me, the sound of the springs rattling away if I bang the wheel with a rubber mallet goes away. This is because the springs are attached to the dust cover, so by bending it it increases tautness in the springs, so the issue goes away. If the springs are in full slack, then ultimately things rattle.

If it's not covered under warranty, it's about a $400 fix. I'm OK with spending $400, but if it's a rattle that I can only hear with the window down, then f*** it I say. Anyways, more news to come

I hate parking brakes, and right now I hate cars. Gak. #fwp

Carsy

Thanks for the follow up.

You say by engaging the hand brake puts a little load on the springs. I wonder if you adjusted the cables a little tighter whether that would do the job. Make sure that the shoes are not engaged when driving.

I reckon that the MB hand brake is the worst I have ever used. It seems to take an unusual amount of effort to hold the car on even a slight slope. No wonder things cables & springs stretch.I only use it when necessary to prolong its life.

superangrypenguin

Couple of things

1) I was told by the shop foreman that it's not only MB that has this design now. I mean, from a theory point of view, MB's design is very sound - it makes ton of sense and really does give the advantage of both old world parking brake technology (in the day of drums) in the new world of disk rotors/pads.

2) Yes, I have had the dealership do just that - they've tightened it to the point where there is a TINY bit of drag when you turn the wheel - however, the issue remains.

Personally, I don't know how I feel about the fact that there is a TINY bit of drag (in that setting). Doesn't that add unnecessary wear on the shoes anyways? But anyway, this didn't fix the problem either. Issue still comes and goes (more info below)

I did talk to him about tightening the slack on the parking brake cable where it splits into a Y. He had advised that there really isn't much there to tighten up, so it's really not worth looking into (according to him)

He's a smart guy and I appreciated his time with answering questions. I'm in no means doubting anything he has said, I just find fault with MB's initial response of..."well, the springs don't come as a separate part and since the shoes are a wearable item and since everything comes in a pack, it's not covered". *bite me.

The interesting fact is that I use the parking brake everytime I park my car. There are days like today where no matter what I do, I can't get it to give the same symptoms as I first saw (clack clack clack over pot holes). Then there are days where it's as prevalent as a seeing a skinny blond hottie in SoCal

What a weird issue, anyways I'll follow up once I have more news early next week.

Crni01

I had the same problem on my car, the sound heard at the rear right wheel only at low speeds and over rough bumps on road , the cause of my problem was diformed hole on dust shield in which brake spring hookes in , which caused brake pads hiting brake rotor due no tension from spring


Since I had to change all the disks and plates anyway, I replaced the dust shield and the parking brake set and after that i sometimes heard the whining sound of the parking brake which disappeared putting a little pressure on parking brake but after a thousand kilometers it disappeared, a suppose it just needed to settle down a bit

superangrypenguin

Dealer ended up covering the labour. They said it'll probably take 2 hours or so to do. They asked me to pay for the part, which I did and bought for $89. They'll replace all the shoes/springs next week. So $89 in the end to fix this problem, not a big deal.

There are NO safety concerns. Just a stupid clanking sound when driving over small bumps. Since it makes the car sound cheap... I figured I'd fix it given the small price tag.

tekfoc

It's actually plastic clips that are mounted to the emergency brake cable that goes into rotor housing.
I had the same issue a while back and made Mercedes replace the missing clips .
Noise over bumps gone.

superangrypenguin

In your case, if you bend and manipulate the dust shield, does that problem go away?

I don't believe it would in your case, and yet in mine it does. So I don't think we have the same issue.

tekfoc

Actually they also replaced brake pad springs first .
But in my situation the noise was still there when hitting bumps .
Made the shop Forman put my car on the lift
And physically showed him by hitting the rear tires with a rubber mallet.
Walla there's the noise .
Replaced plastic clips no noise for almost 2 yrs.

superangrypenguin

Thanks. In your particular case did the noise ever go away if you had the parking brake slightly engaged?

I have never been able to get the noise to....happen...if the parking brake was even slightly engaged. Thank you

I should have specified. All the shoes/springs that I have bought in the OEM kit are for the parking brake system only. Those are what will be replaced next week.

tekfoc

I never bothered to slightly engaged my parking brakes to see if noise would go away.
when they changed the shoe springs first their was a tsb on the springs to be replaced.
but like I said before turned out to be plastic clips that attach to rear brake cables that were missing .
replace your springs and check to see if plastic clips are broken or missing.

superangrypenguin

Just a quick update.

The dealership replaced all of the parking brake parts that come with the OEM parts for that entire system (springs, shoes etc)

Issue is now fixed.

tekfoc

Glad to hear