My car just received the VA state stamp of approval. As happy as I am, I was expecting to pay for some front brake work. I based this on a grinding, screeching, metal on metal sound coming from the front wheels when braking (usually under 20 mph), as well as an occasional series of STRONG vibrations when slowing down that seems to come from the front of the car. The mechanic said he was as suprised as I was that the car passed inspection without a hitch. He said, "your car is in great shape". Question. What could be causing these issues I am experiencing? I am grateful that my car passed but I am concerned thatthey may have missed something.

Thanks

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Rich B

1983 300D Turbo
205k

Excuses are crutches for the weak

Look for errant stones or other debris for the grinding. Do you feel vibration in the brake pdal and the steering wheel when braking? If so, check for warped rotors.

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RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

91 W124 300D Turbo replaced, Pressure W/G actuator installed. 210K

90 Dodge D250 5.9 Cummins/5 speed. 400K

Take a look at them first. The metal-on-metal usually means worn pads. The vibration on braking is almost always warped rotors. Using worn pads can generate a lot of heat, which in turn will warp the rotors so your problems may be connected. Sometimes the rotors have metallic defects in them which results in some scraping noise. When was the last time you replaced the rotors and/or pads? Sounds like you're due for a brake job.

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TC
Current stable:
- 2004 Mazda RALLYWANKEL
- 2007 Saturn sky redline
- 2004 Explorer...under surgery.

Past: 135i, GTI, 300E, 300SD, 300SD, Stealth

I just picked it up from the safety inspection five minutes ago. The mechanic said the pads and rotors look fine.

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Rich B

1983 300D Turbo
205k

Excuses are crutches for the weak

The only other thing I can think of that would make that ugly sound would be the wheel bearings, but they would not be under any stress while stopping in a straight line. There is something up with your brakes that the mechanic may have ignored, take the wheel off and have a look. While the tire is off, rotate the hub and look to see if there is any lateral motion (warping) to the rotor. See if there are deep grooves in the rotor too, which would indicate a small piece of metal debris being stuck between the pad and rotor making the noise. Strong vibrations during braking are due to rotor warpage or a loose caliper. You wouldn't have come close to passing the inspection with a loose caliper, and the bolts probably would have sheared off by now if loose anyways.

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TC
Current stable:
- 2004 Mazda RALLYWANKEL
- 2007 Saturn sky redline
- 2004 Explorer...under surgery.

Past: 135i, GTI, 300E, 300SD, 300SD, Stealth

Some brands of brake pads will squeal so loud that you will think it's metal on metal, even when the pads are nearly new. PBR Deluxe pads (aka Axxis Deluxe) have a reputation for being quiet and easy on the rotors.

Stupid question. Could being very dirty cuase any of this?

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Rich B

1983 300D Turbo
205k

Excuses are crutches for the weak

Maybe the squealing if you drive it very sparingly, not the vibration. Your rotor surface should be shiny.

__________________
TC
Current stable:
- 2004 Mazda RALLYWANKEL
- 2007 Saturn sky redline
- 2004 Explorer...under surgery.

Past: 135i, GTI, 300E, 300SD, 300SD, Stealth

Rotors are shiny and smooth. Both the noise and the vibration occur ramdomly, but only at lower speeds (35-40 and below). The car seems to stop fine, pedal feels ok. I will check the rotors for warping. I would think the shop would have checked that, if for no other reason they could have made some money had they found an issue.

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Rich B

1983 300D Turbo
205k

Excuses are crutches for the weak

Can you tell which side it is coming from? Does the steering wheel shake when the vibration occurs? Does it pull in one way or the other when the vibration occurs?

__________________
TC
Current stable:
- 2004 Mazda RALLYWANKEL
- 2007 Saturn sky redline
- 2004 Explorer...under surgery.

Past: 135i, GTI, 300E, 300SD, 300SD, Stealth

You may want to use anti squeal grease if you don't have any on there now. Check for shims between the back of the pads and the caliper piston.
Has it always been doing that?

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83 SD

84 CD

Here's a really wierd cause.. unlikely, but it happened to me. One of the sense wires from a front brake pad was bent outward and lightly rubbing on the insude of the wheel. No noise braking straight, but there'd be noise when turning right, none turning left that would change if braking. I'd also get an occasional, sometimes faint worn-pad warning light when driving in the rain. It didn't screech, but made me think it was a bad front wheel bearing. The fix was to bend the wire back down to toward the caliper so it didn't rub on the wheel anymore.

I've also had the pads stick to the caplier piston and cause a very high pitched squeal. Only heard when breaking at slow speeds -- anything faster and I was pressing hard enough on the brakes to prevent then from vibrating. It didn't sounds like metal-on-metal, but that may be related to the pad material. As I recall, Mercedes pads are soft. If someone put harder pads in so they'd wear longer, then maybe they make a higher pitch sound. Fix was easy -- remove the pads (sense wires stay attached to their pad as an inseparable unit), grease back with silicone brake grease (my squeal-reducer of choice) and reinstall.

Wheel bearings can cause vibration that changes during braking. I've only observed it to reduce when braking, but maybe sometimes you can get more vibration too.

Lift the suspect wheel, remove the tire, and give it a spin. If the noise is a consistent as you say, and happens at slower speeds, you'll probably hear something rubbing or grinding when you give it a spin. Could be as simple as the dust shield rubbing or a rock caught between it and the rotor.

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'83 300DTurbo http://badges.fuelly.com/images/smallsig-us/318559.png

Broadband: more lies faster.

It's been happening for about 2 or 3 months on and off.

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Rich B

1983 300D Turbo
205k

Excuses are crutches for the weak

How often do you drive it? I am beginning to suspect a sticking caliper. We can give you suggestions until we are blue in the face, but really you will have to go in there and give both front wheels a meticulous inspection for yourself or have somebody do this for you - simply the limitations of the internet. Look for any signs of wear on any of the braking components, grooves in the caliper, low pads, large specks in the pad friction surfaces, brake fluid anywhere, worn caliper seals, rotor clearance (they could be worn down below acceptable width), etc. Of course any anomolies like the wear sensor rubbing would raise a red flag too. I think the state inspection is more broad and a "once-over" type of look at things. If there isn't any glaring problem they will OK it. Any brake issue is not something you should ignore. I am concerned more about the vibration than the noise (though probably related) especially if it is as severe as you state. Good luck, I wish I could help you more.

Do you do your own work or usually bring it to a shop?

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TC
Current stable:
- 2004 Mazda RALLYWANKEL
- 2007 Saturn sky redline
- 2004 Explorer...under surgery.

Past: 135i, GTI, 300E, 300SD, 300SD, Stealth

Yeah, sounds like an up close inspection is needed.

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83 SD

84 CD