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  #1  
Old 11-17-2004, 07:40 PM
wielder of thor's hammer
 
Join Date: Jul 2003
Location: Long Island, NY
Posts: 321
squeaking brakes, but pads good, 87 300e

My brakes have begun to squeak fairly consistently, but the wear warning light has not come on, and The pads look pretty good (about half inch left) upon inspection. what could cause this sqeaking? Is there some sort of wear indicator in the pads that makes them sqeak when they become worn? Another thing I noted was that the discs were very shiny, like chrome. I know they are not supposed to be, so could this have anything to do with the squeaking? Unfortunately, I have been riding the brakes a bit lately because the noise is so irritating and it is not as bad if I brake gradually. So this could theoretically be the cause of the shininess I have described, but I have only been doing this for a week and a half (I will not do it anymore). Any thoughts on this?

p.s. I Never realized how funny the word shininess looks until just now. English must be a B#%@! to learn.

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  #2  
Old 11-18-2004, 12:30 AM
wielder of thor's hammer
 
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Location: Long Island, NY
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I had always thought the paste was something you put on only with new pads, like they had a break-in period that required the paste. Did not know that the paste can stay there for a significant amount of time. Does it soak into the pad or something?

I'll coat pads with paste and see if this is the fix. thanks for your time.
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  #3  
Old 11-18-2004, 12:38 AM
wielder of thor's hammer
 
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Can either of the two pastes available for purchase in fastlane under "Brake anti-squeal paste" be used? They seem the same, but only one says MB on it... I'd rather just buy the good stuff, if there is in fact a difference.
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  #4  
Old 11-18-2004, 08:25 AM
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hope that you are not putting this paste to the brake pads itself... this has to go at the back of the pads ...to eliminate squeaking ...
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  #5  
Old 11-18-2004, 08:52 PM
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Location: Southern California
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I've had excellent results with PBR DeLuxe (NOT Metalmaster) pads. Since they have a slightly lower Cf than the OE pads, pedal effort is a little higher, but they:

1. Don't dust

2. Don't squeak or squeal, and

3. Don't chew up the rotors.

They are also very long lived. I estimate their service life on my 190 at 75K miles based on regular measurements in the 60K miles they've been installed.

Duke
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  #6  
Old 11-19-2004, 08:58 AM
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Location: New York, Long Island
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Quote:
Originally Posted by Duke2.6
I've had excellent results with PBR DeLuxe (NOT Metalmaster) pads. Since they have a slightly lower Cf than the OE pads, pedal effort is a little higher, but they:

1. Don't dust

2. Don't squeak or squeal, and

3. Don't chew up the rotors.

They are also very long lived. I estimate their service life on my 190 at 75K miles based on regular measurements in the 60K miles they've been installed.

Duke
So have I and the price can't be beat. Duke if you want a little more bite try the deluxe PLUS pads next time. There is a little more dust still no where near the OE pads but the bite is a little better.
www.brakewarehouse.com has them.
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  #7  
Old 11-21-2004, 03:18 AM
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Location: Canada
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Squeak vs Squeal

I know it may be interesting to try to describe sound in writing, but what's the difference between brakes 'squeak' vs 'squeal'?

Is 'squeak' more like grinding/friction, and 'squeal' more like vibration/tuning-fork?

Just want to learn the proper term to communicate with the service advisor. Thanks.
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  #8  
Old 11-21-2004, 12:06 PM
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I consider them to be essentially the same. Which one you use depends on your point of view. The noise typically occurs on light to moderate braking, less so on heavy braking. It's caused by pad vibration, which is induced by a little "stick-slip" friction between the fiction material and rotor that causes the pad to vibrate and the noise is usually generated at the contact points between the pad backing plate and caliper. That's why "brake paste" between the pad backing plate and caliper will usually stop or mitigate the noise because it creates a little damping.

I didn't use any when I installed the PBR (Repco back then) DeLuxe pads and they've never uttered a peep.

yal - Thanks for the tip on the PBR Plus. I recall looking at the PBR web site and they have a very good matrix on brake pad characteristics. (don't remember the URL, but a Google search should find it quickly.)

I'm so happy with the DeLuxe that I will probably install another set when they are due for a change. I don't mind the slightly higher pedal effort - got accustomed to it very quickly.

The only problem is that with time they became less effective - almost to the point where the ABS would not engage on dry pavement. They had become glazed, which is not uncommon with light brake useage. I solved the problem on a road trip over a twisty two lane mountain road that I drove hard using moderate braking to slow down for the corners. This broke the glaze and the brakes became much more effective.

Duke
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  #9  
Old 11-21-2004, 02:50 PM
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Pull all the pads and take a small wire brush and remove all the crud in the slots where the pads fit. Get them shiny clean.

Apply a SMALL amount of antiseize (any brand) to the sides of the backing plate and the back of the pad where the piston contacts mbefore re-isntalling. OEM pads will have a ring or a coating of dense plastic here, aftermarkets are usually plain steel (hint hint).

Remove brake fluid reservior cap and push the brake pistons back in each caliper a bit. If they don't move smoothly with minimal pressure, you need to rebuild them. If they do, open the bleeder valve, attach a hose, and press them all they way back, then close the bleeder. Use an old turkey baster and remove all the old brake fluid from the master cylinder, replace with fresh, and flush the old stuff out by bleeding after you re-install the pads.

The leading causes of brake squeal on an 80's MB are 1) aftermarket pads with no brake paste (or in some cases with), 2) dirty calipers so the pads sit crooked or bind, and 3) sticking calipers.

By this time, it's likely the piston seals in the calipers are rock hard, meaning high hard pedal, squeals, drag, etc. Rebuilds are easy, and it's most likely time for new brake fluid anyway.

Break in new pads with very gentle use until the "fur" wears off and you have full pad to rotor contact, and sandpaper new rotors to remove machining marks, else they groan.

Peter
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  #10  
Old 11-24-2004, 09:37 PM
wielder of thor's hammer
 
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Location: Long Island, NY
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Now my abs is coming on whenever I brake hard. My tires are good. It happens more in the rain, but the conditions are not bad enough that it should come on. What could cause this?
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  #11  
Old 11-24-2004, 10:53 PM
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Probably bad ABS sensors - which are surprisingly pricey - over $100 for each of the front wheels. I have an clever way of eliminating this cost, by pulling the ABS control unit and ABS warning light - but I live in Phoenix, where I could drive a hundred years and never need ABS. On Long Island you probably need to make the investment. You might also try cleaning them first. BTW - I agree with all said about PBR Deluxe - can't understand why anyone would use anything else. But the paste on the back will probably solve your problem. The MB paste works well - comes in little ketchup packets for about $3.00.
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  #12  
Old 11-28-2004, 01:04 PM
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Location: Evansville, Indiana
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Most likely a bad sensor, but a sticking caliper will do the same thing as one wheel will slow down faster than the other. You may be braking harder than you think, though!

clean everything, pull pads, and check it all out.

Note that you NEVER apply anything to the actual friction material, your brakes would then be completely ineffective and you will need mucho body work from hitting things....

Peter
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1987 300D Turbo killed 9/25/07, 275,000 miles
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  #13  
Old 02-12-2005, 04:18 AM
wielder of thor's hammer
 
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can somebody just clear up exactly where the brake pad paste goes by pointing it out in this attached pic? Will be trying to fix this over the weekend. The noise went away for a long while but has returned.
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squeaking brakes, but pads good, 87 300e-195.gif  
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  #14  
Old 02-12-2005, 09:22 AM
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The pad paste goes on the back plate of the pad, where the metal pad housing touches the caliper piston, get some brake cleaner- spray can $2 and spray the housing and caliper before installation. It evaporates quickly and should dissolve the caked up brake dust.
Also use the brake cleaner to spray the plate behind the rotor and clean things up. The ABS sensor is around there and if cleaned should work ok. They mostly just need cleaning... in my experience.
Dont spray the brake pad with cleaner.... just everything else.
Clean the slide pins that hold the pad with emory cloth, sand paper.... or something, and apply a small amount of wheel bearing grease to the pins.
If you are still running semimetalic pads .... you will get an occasional squeek.
If the rotors have any grooves worn into them the squeek will be more frequent.
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  #15  
Old 02-12-2005, 11:20 AM
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Maybe this will help (Red NO, Green YES)

Haasman
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squeaking brakes, but pads good, 87 300e-brake-pads-anti-squeak-areas.jpg  

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