I had new OEM pads and rotors put on my 86 420sel 1,000 miles ago. The squeal happened whenever the brakes got hot, I took it back to the mechanic and he "Hazed" the finish on the rotors, this reduced the noise but now the car does not stop as smoothly as it did. Is that s.o.p? Will this wear the pads faster? Should I demand new pads? It still squeaks(not as much)!

I don't know what Hazing is, but I had new front rotors and pads put on my 1986 420SEL three months ago. They squeeled for the first two weeks, then stopped. No problems, great stopping power. If the "hazing" has noticeably decreased the braking ability of your car make them fix it.



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Jason Priest
1986 420SEL

I suppose that brake squeal is very objectionable to somek, it bothers my wife quite alot. As long as there is no metal to metal contact, it doesn't hurt anything.

When it happens on my car I don't even hear it. Metal to metal contact on the other hand grabs my attention.

Typically it won't last very long.

Good luck



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Larry Bible
'01 C Class, Six Speed
'84 Euro 240D, manual, 533K miles
'88 300E 5 Speed
'81 300D Daughter's Car
Over 800,000 miles in
Mercedes automobiles

Hmm maybe they did not properly affix the brake squeak stop in the right places. If I remember reading in the DIY section, they said the pads need to be coated on the back, and a couple of other areas, though not on the pad surface itself, to aid in the squeal going away.

Sometimes with new pads they will squeal a bit until they are broken in. If I remmeber correctly.

As far as the hazing is concerned, what the hell is that? I would rather have better stopping and a squeak than worse stopping without a squeak.

Though usually my stereo is on so loud I cant hear the brakes squeal.

Alon

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'92 300CE
Metallic Black (Blue Flaked) on Parchment
Clear Corners
Black Grille Insert
78k Miles

Future Upgrades:
Sportline Suspension
17" AMG Monoblocks or EVO II's
94-95 Tail Lights
Euro Headlights
Chip
AMG Exhaust

Click here to Go To My 300CE Page

The only effective anti-squeal that you should use on Mercedes pads is the original blue paste that comes from Mercedes. Try to peek at the back of the pads and make sure they didn't use the silver Permatex or copper Wurth paste. Neither is effective at absorbing the vibrations.


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Rgds,
Aaron Greenberg
MB technician
Mercedes-Benz of Cincinnati
'67 250SE Cabriolet
'77 450SL
'80 300SD
'85 380SE
'86 420SEL
'89 420SEL
'93 300E 2.8
'74 Jensen Interceptor Mk.III
'81 DeLorean DMC12
'84 BMW 745i Turbo

Sounds like Ashman has the best cure for this particular problem. If you know that there is no metal to metal contact, simply turn up the radio<g>.

Good luck,

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Larry Bible
'01 C Class, Six Speed
'84 Euro 240D, manual, 533K miles
'88 300E 5 Speed
'81 300D Daughter's Car
Over 800,000 miles in
Mercedes automobiles

The hazing he is referring to sounds like what is sometimes called "deglazing" the rotor surface. The theory is that as the surface of the rotor wears, and this would depend on the pad composition, it acquires a very smooth surface. The undesirably smooth surface can cause high pitched squealing on some cars. The hazing dulls the shiny surface. Also, the purpose of the blue goo, or any other of the pastes behind the pad, is to change the natural frequency of the vibration away from the one that creates the squeal. Sort of like a dampening agent. The hazing means the mechanic would remove the shiny surface, leaving a "hazy" sort of dull appearance. I used to do this with about 400 grit paper. Same reason when you put new piston rings in, you "deglaze" the cylinder walls. Provides a new surface for the new pads (or rings) to wear on.

Deglazing (making dull) the surface, and using the paste, should stop the squeal, assuming the pads are in proper position and no other foreign material is caught in the rotor/pad (like a pebble or something...have seen this too)

Hope this helps. Dave

hehe LOL Larry. I'm still smiling at your response.

My brakes in my car don't squeal, but if they did, I'd work to no end to rid the car of it. I hate that damn squeal noise with a passion. hehe

Alon

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'92 300CE
Metallic Black (Blue Flaked) on Parchment
Clear Corners
94-95 Tail-Lights
Black Grille Insert
78.5k Miles

Future Upgrades:
Sportline Suspension
17" AMG Monoblocks or EVO II's
Euro Headlights
Performance Chip
AMG Exhaust

Click here to Go To My 300CE Page

The squeal is a buildup of resin binder on the surface of the pads. Two solutions. Go to a softer pad, or try a couple of heavy "panic" stops to burn the glaze off. This is most noticeable with new pads, especially MBZ OEM's The Blue paste on the back of the pads is to lubricate the contact surface between the pad and the caliper piston. will eliminate noise associated with the pads "creeping" across the piston face and creating noises until they stop moving. The real troublemaker is on the other side of the pads..

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Jeff Lawrence
1989 300e
2000 Dodge Grand Caravan SE