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  #1  
Old 05-09-2008, 10:48 AM
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400E declining brake service life

Hello All, I have a 1992 Mercedes 400E driven less than 8K annually by my retired schoolteacher wife (read that light use). Hereís the issue. Always serviced at local Mercedes dealer. Front pads and rotors at 53K, front pads and rotors at 73K, front pads and rotors at 91K, now front pads and rotors at 105K. See the trend ? Iím now getting 25 % less service life than at 53K. Local service manager unable to explain why this is occurring. Wife is not going to track days on weekend nor does she drive with her left foot on the brake. Any thoughts?

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Old 05-09-2008, 11:10 AM
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Are they replacing the rotors due to service life OR due to warpage?
Is the brake warning lamp comming on every time?
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  #3  
Old 05-09-2008, 11:25 AM
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400E declining brake service life Reply to Thread

No, there is no warpage, replacement occurring due to service life (pads worn out). I know this is a heavy car with soft pads and I thought 20K was poor but 14K is ridiculous. I know it will vary based on how the car is driven but the car is driven 50 % less than it was previously and I'm getting 25% less service life out of the components- doesn't make sense to me
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Old 05-09-2008, 11:37 AM
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A lot of it has to do with driving style. Did you physically see the pad degradation at each service interval, or just trust the dealer to be honest?

If the dealer is being honest, and the wife really isn't riding the brake--It is weird at the least to get such poor pad life...

With a 400E track days could be some fun

-GH
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  #5  
Old 05-09-2008, 12:10 PM
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Brakes

My '87 300E went to 160K before the rotors were changed out. Front Pads were changed every 40-50K. Rears were changed twice in 200K, and I drive like Kyle Busch.
My '95 E420 has 110K and the original rotors. Pads were changed once.
Anziani
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  #6  
Old 05-09-2008, 12:27 PM
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Brake rotors should last 2-3 brake pad changes. They have a service life that is marked as a minimun thickness on the DISC hat area. Sounds like they are replacing the rotors WAY too soon!!

Your brake pad life is short, but not terrible if you live & drive in a metro area with constant stop & go driving.
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  #7  
Old 05-09-2008, 12:47 PM
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try Bendix brand rotors and pads, price is a bit more....Bendix has been in the brake business a LONG time. Bendix is either made in USA or made in Canada, advance auto parts is a good place to find Bendix brake components.
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  #8  
Old 05-09-2008, 06:28 PM
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I get about a year out of front brake pads 15-20K miles, but I am one that does all the stopping at the very end of the off ramps. I am hard on brakes. i have never worn out a rotor though. I buy soft organic brake pads instead of metallics to preserve the rotors.
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Old 05-09-2008, 08:54 PM
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Bought my 400E in January 1998. FWIW, here's the service history for the front brake pads. By the way, my 1993 takes 1992 front pads:

90,200
101,488
112,900
129,289
148,500
166,763
179,607
195,075
210,493
228,947

I think it averages about 15,000-18,000 per change. I noticed that it has increased as I age and my driving habits have changed. I tried the non-factory pads initially (Performance Products), but they only lasted about 5,000 miles. I have consistently used only factory pads since. I change the rotors about every third or fourth pad change. Maybe one or two good hard stops could have contributed to your increased wear.
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  #10  
Old 05-09-2008, 11:10 PM
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Quote:
Originally Posted by emerydc8 View Post
Bought my 400E in January 1998. FWIW, here's the service history for the front brake pads. By the way, my 1993 takes 1992 front pads:

90,200
101,488
112,900
129,289
148,500
166,763
179,607
195,075
210,493
228,947

I think it averages about 15,000-18,000 per change. I noticed that it has increased as I age and my driving habits have changed. I tried the non-factory pads initially (Performance Products), but they only lasted about 5,000 miles. I have consistently used only factory pads since. I change the rotors about every third or fourth pad change. Maybe one or two good hard stops could have contributed to your increased wear.
Wow! I thought I was the only one that went through brakes this fast1
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  #11  
Old 05-09-2008, 11:19 PM
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I think the dealers just change discs a lot "because". Most owners know nothing, and don't bother actualy looking at the brakes. I remember looking at the bin that they throw old brake discs in, and they were all brand freaken new. MB discs are soft and it doesn't take long to get a lip, I couldn't feel a lip on most of them. Some were probably warped but that was a big bin.

I was actualy looking for W126 rotors I would have grabbed them.
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Old 05-09-2008, 11:31 PM
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The dealer is hosing you on the rotors. You should get 2-3 pad changes per rotor. I always do my own brakes and rotors as the job is too easy to pay someone lots of $$ to do it.
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  #13  
Old 05-10-2008, 08:49 AM
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So are all the front pads wearing evenly? If not, check for a seized caliper piston.

The rotors should either be scored or have a definite lip at their outside edge if they are really worn out.
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  #14  
Old 05-10-2008, 09:09 AM
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This is why I always change my own brake pads.

When to change pads and rotors is a judgment call. It is in the interest of any repair shop to be cautious on bad and rotor replacment.

it is in my interest to only change things when they are worn beyond what is safe in my own mind.

Tom W
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  #15  
Old 05-10-2008, 03:45 PM
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Are the pads truly worn out? Pull a wheel off and take a look for yourself. I had a 1993 400E that I put 135K miles on before trading it. Fronts would go about 50K while rears went 85K. I wonder if you are buying something you do not need.

I do a lot of track driving. The requirement for Porsche and BMW events is 3/16" pad remaining to pass tech inspection at beginning of weekend. For street use, I let mine go down pretty far. Besides grabbing the rotor to slow the vehicle, the pad provides resistance that impedes heat from getting into the caliper and possibly boiling the moisture in your brake fluid and making your pedal spongy.

Changing pads is very easy to do. Ditto for the rotors. You would save large dough doing it yourself.

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