Weird vibration and then boom no brakes!!! - Page 2 - PeachParts Mercedes-Benz Forum

zu! · #16 11-26-2009, 01:36 PM

Quote:

Originally Posted by Craig

Well, if the brakes are dragging, they should be getting hot after a few miles. Carefully feel the wheel after the next drive, if one wheel is hotter its probably dragging. Does the master cylinder feel OK now?

The thumping does sound like a bad CV joint. Take a look at the boots and see if any of them are cracked. You might of had two separate issues.

Here's the thing...the funny vibes stop after awhile! So I don't know what it is. The CV boots are good, I checked already. I'm almost going with Yak there and his bad shock theory...only because I can feel it in my seat like going over a road with a million timy ruts running across it. But that would not explain the jerk-jerk dragging that happens when I slow down at the lights. That's almost surely the rotors.

#17 11-26-2009, 01:45 PM

The jerking motion under braking could be rotors, especially is the were dragging and heating up.

I'm not sure about the vibration when you're not braking.

zu! · #18 11-26-2009, 08:56 PM

Quote:

Originally Posted by Craig

The jerking motion under braking could be rotors, especially is the were dragging and heating up.

I'm not sure about the vibration when you're not braking.

OK finally, I think I know what's wrong!! The first dry afternoon in November coupled with bad traffic saw me taking the lonely farm roads home. Same thing, judder-judder, stopped on a wide shoulder and hopped out and checked the wheels. Both front as well as the offside rear were cool to the touch (that was the one with the crimped hose). The nearside rear though was hot to the touch!!

I could smell burning and when I got home, in the quiet of my garage, I could hear the tell-tale pinging of hot metal cooling down. So it appears that that caliper is somehow seizing off and on. Strangely enough, that was the caliper that was I changed together with the two front ones just last year.

It appears that the original caliper that was not changed (with the crimped brake hose) was just fine but the new (well, rebuilt) one has seized.

#19 11-26-2009, 09:15 PM

Sounds like you found it, I wouldn't be surprised if the rotor was warped from all the heat.

Yak · #20 11-26-2009, 09:20 PM

As for the shock supporting the wheel carrier: when you lift the car, the shock extends a bit, but then pulls the wheel carrier off the ground. If the shock is dead, really bad, then it won't pull it up but the brake line will be the next thing. The shock controls how far the wheel carrier drops when that tire is in the air.

You may have a dragging parking brake (along with some other undiagnosed problem for the vibration.) The parking brake is inside the rear rotor. The cable pulls it tight and two shoes expand to rub against the "hat" like drum-style brakes inside the disc. It might be an adjustment problem, or it might be a rust problem with a stuck pivot or a busted retraction spring. The parking brakes have nothing to do with the calipers.

It's easy enough to check. Chock the fronts, jack up the rear, release the park brake, put it in neutral and try to spin the wheel. The should be almost no friction. If it's sticking you can try adjusting it through a lug nut hole with a screwdriver.

If it's bad, it's a straightforward fix. If you really want to be more thorough, it's easy to check. Remove the tire and the caliper (don't let it hang by the hose) remove the rotor and look inside. You can also inspect the mechanism. USe Loc-tite when re-installing the caliper.

If the problem started when the weather got cold it may be water in the parking brake line that freezes and locks your brake in place. The germans do not recommend using the praking brake in the winter for this reason (believe it or not...).

zu! · #21 11-27-2009, 02:49 AM

Quote:

Originally Posted by Yak

As for the shock supporting the wheel carrier: when you lift the car, the shock extends a bit, but then pulls the wheel carrier off the ground. If the shock is dead, really bad, then it won't pull it up but the brake line will be the next thing. The shock controls how far the wheel carrier drops when that tire is in the air.

OK, I've never seen that happen with my car.

I lift up the car, the wheels hang down all the way, till they look like they're cambered inwards. I always thought it was supposed to be that way!

Quote:

Originally Posted by Yak

You may have a dragging parking brake (along with some other undiagnosed problem for the vibration.) The parking brake is inside the rear rotor. The cable pulls it tight and two shoes expand to rub against the "hat" like drum-style brakes inside the disc. It might be an adjustment problem, or it might be a rust problem with a stuck pivot or a busted retraction spring. The parking brakes have nothing to do with the calipers.

It's easy enough to check. Chock the fronts, jack up the rear, release the park brake, put it in neutral and try to spin the wheel. The should be almost no friction. If it's sticking you can try adjusting it through a lug nut hole with a screwdriver.

This one freaks me out. There's a LOT of friction!!

That was one of the first things i tried. Lifted the car up and turned the rear wheels. Both sides were pretty hard to turn...ie one would need two hands to turn the wheel. The brakes seem to be engaged all the time, plus the drive shaft would turn too. All this in neutral, and I thought it was normal!

Quote:

Originally Posted by Yak

If it's bad, it's a straightforward fix. If you really want to be more thorough, it's easy to check. Remove the tire and the caliper (don't let it hang by the hose) remove the rotor and look inside. You can also inspect the mechanism. USe Loc-tite when re-installing the caliper.

If the problem started when the weather got cold it may be water in the parking brake line that freezes and locks your brake in place. The germans do not recommend using the praking brake in the winter for this reason (believe it or not...).

I've not used my parking brake ever since I did my disc brakes. The shoes were actually broken, so I left them alone. Could they have somehow 'grabbed' and engaged themselves? I've never really used them in over a year. Maybe for some reason, the brake seizes after a certain number of uses. Then, cos the rotors are warped, they oscillate and cause a vibration? Or maybe that vibration is caused by the shocks being bad and not damping the oscillation caused ...geez, my head is beginning to hurt.

OK first order of things would be to fix the brakes. I'm going to see about getting those wheels turning freely first.

Yak · #22 11-27-2009, 10:20 AM

If the hose had some slack when you swapped it you shouldn't be too freaked out. The wheels drop but they shouldn't 'stretch' the rubber brake line.

No offense intended to your mechanical or diagnostic skills - but it might be time to have a brake or suspension shop or experienced mechanic look things over. If you've got broken brake parts, weird vibrations, crimped lines, warped rotors, etc, then you're risking an awful lot.

Rotors and pads are cheap. Calipers are only a bit more. You can completely re-build your rear brakes for around $200-$250 US. ($75 /re-built caliper or $20 /caliper rebuild kit; $30 /rotor; $30 /park-brake kit).

Get a digital camera and post some pics of what you see when you're working on your car. There's a lot of expertise here that can better help to diagnose if they can see what's going on.

Bens lover · #23 11-27-2009, 10:22 PM

Get some pictures Mark!!
Yes the sun is great but we need rain too!

Cheers
From Down Under!!
Big Dan

RichC · #24 11-27-2009, 10:53 PM

I have a guess.

If this happened right after a rear tire change.

The roter may not be aligned.

There are six holes in the rotor.

Five of them are for the lug bolts.

And the sixth one is for the alignment pin.

It is possible to put the tire back onto the vehicle with that pin not in the hole in the rotor.

This would leave the rotor skewed from the 90 degree angle it should be from the center line of the rear suspension.

This would cause the rotor to push the brake caliper back and forth.

And would cause the tire to wobble while spinning.

Bens lover · #25 12-03-2009, 04:06 AM

Mark did u find the vibration problem on your car?

Big Dan
Down under!!

newtodiesel · #26 02-18-2010, 10:03 PM

Dag gonnit, read the whole thread and no solution...............

JimSmith · #27 02-18-2010, 10:31 PM

Seems like a CV joint or wheel bearing problem. Brake pedal going to the floor is either leakage (you say you don't have that) or, as others have noted, a case of heating of the brakes to the point of creating vapor bubbles. Try flushing the system. Water in the brake lines is the most common source of vapor. Good, clean brake fluid doesn't turn to vapor until well after the rotors and pads will smell noticeably if they are too hot.

Once the master cylinder goes to the floor because the seal, an O-ring is shot, it won't "heal" by itself. Water in the system will also cause more permanent damage - rust and caliper piston seal failures. Brake fluid is cheap. MB says change it every two years or so specifically to avoid rusting problems and vapor issues.

Jim

vstech · #28 02-19-2010, 09:02 AM

I do hope the OP logs in and posts what he/she found and how it got fixed...
missing/ broken parts in the E-brake... not good.
changing one side caliper, but not the other... not good.
hot dragging caliper/e-brake, not good...