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93' W124 E36 AMG ; 71' Cadillac Eldorado ; 07' S211 280 CDI
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Discussion Starter #1 (Edited)
I attempted to replace rear brakes on my 250D today.

I bought all the parts, but discovered that the parking brake shoes are actually OK, but there is something wrong with adjustment. It just doesn't work as it should.

Anyway...

After installing everything on the left wheel I started to install new disc on the right side.

I could not press one of the pads in and then, when I turned the disc by hand I noticed that the distance between the disc and the caliper changes and for 1/3 of the turn the caliper actually scrapes the disc!

I tried to sit the disc differently several times, but it's still the same.

I wonder - is the hub warped? :(

Any suggestions?

Take a look at the discs (new - OEM; old - Ate):


 

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About a dozen 1988, 1989, 1990, and 1991 sedans, wagons, 4Matics and 1 coupe
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A new disc can be warped if it was stored improperly, had something stacked on it, was dropped, etc. Definitely check the disc first because other causes will be harder and more expensive to fix.
 

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About a dozen 1988, 1989, 1990, and 1991 sedans, wagons, 4Matics and 1 coupe
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I meant to say that the calipers look like sh&%. They shoul dbe replaced.
Caliper rust is a real problem here in SE PA as well. They rust horribly at the areas where the pad edges rest. Even if the caliper pistons retract (aren't stuck) the pads can remain forced against the rotor becasue they can't move in the caliper slot. Reman calipers are scarce because good cores are hard to find (says my usual parts source).

When I bought my TE#1 the rear calipers were so rusted that only 1 piston of 4 was doing anything. New calipers were the only way to solve the problem. Look how 1 pad is worn down to metal while the other is still pretty thick.
 

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'92 300TE 4matic 280,000miles, '92 300TE 4Matic 'Ice Blue Metalic' 101,000miles
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I meant to say that the calipers look like sh&%. They shoul dbe replaced.
Caliper rust is a real problem here in SE PA as well. They rust horribly at the areas where the pad edges rest. Even if the caliper pistons retract (aren't stuck) the pads can remain forced against the rotor becasue they can't move in the caliper slot. Reman calipers are scarce because good cores are hard to find (says my usual parts source).

When I bought my TE#1 the rear calipers were so rusted that only 1 piston of 4 was doing anything. New calipers were the only way to solve the problem. Look how 1 pad is worn down to metal while the other is still pretty thick.
That is an unbelievable pic(!)...viewed from someone who lives in an arid climate. I just finished doing all my brakes and have nothing but minor surface rust-even the pins are clean. We never see anything like that here. That's why I always advocate buying cars, equipment & machinery from dry, arid regions.:thumbsup:

Kevin
 

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2013 E350 sedan, 2013 E350 cab, 1993 400E sold,1999 ML320
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Also those rotors dont look trued or turned, even new they can need prep for surface finish. That would be a couple hundred thousands that could make the difference.
 

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93' W124 E36 AMG ; 71' Cadillac Eldorado ; 07' S211 280 CDI
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Discussion Starter #12
I think I may have found the culprit.

Right now I am giving some chemical anti-rust treatment to the hub and caliper and in the morning I'll try to show - what I think - is the problem.

The disc is straight and true. It's an out-of-the-box original Mercedes-Benz part obtained from my most trusted dealership. I checked the disc just in case, but it's OK.

macdrone - I don't understand Your post. I think it's beyond my technical English capabilities. Can You rephrase it in simpler words? I'd like to know Your opinion.

Thanks for all the input!
 

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'87 300TD/'90 300D/'94 Quattro/'89 Vanagon TDI/'01 EV Weekender VR6
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That's why I always advocate buying cars, equipment & machinery from dry, arid regions.:thumbsup:

Kevin
I live on the wet side of the same state, and can say that we never ever see anything like that sort of rust on chassis and brake parts over here. I think the culprit here is copious amounts of road salt.
 

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1993 300E, 2003 996 Turbo X50
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It's definitely road salt. I was in Nova Scotia visiting family a month ago and helped my dad do a front axle on his volvo. The damn thing was rusted so solid into the spindle that even in a press with 70 tons on it the thing didn't budge. We use salt on the roads here and my car has no rust underneath to speak of.
 

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'92 300TE 4matic 280,000miles, '92 300TE 4Matic 'Ice Blue Metalic' 101,000miles
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In reality it's actually a combination of things. For example, I used to live in MO. The weather changes very rapidly there and there is a fair amount of humidity. Troubled equipment I had on the farm never saw road chemicals and or caustic chemicals from animal waste. However, there was often rust and moisture inside axles, transaxles, transmissions, sealed distributors etc....stuff that wasn't used frequently.

By comparison, I had a farm over in Chehalis, WA (with the same equipment) where it rained nine months out of the yr (kind of another hell, but that's a personal opinion) and I never had any rust/moisture or equipment degradation like in MO.

Kevin
 

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'92 300TE 4matic 280,000miles, '92 300TE 4Matic 'Ice Blue Metalic' 101,000miles
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I think I may have found the culprit.

Right now I am giving some chemical anti-rust treatment to the hub and caliper and in the morning I'll try to show - what I think - is the problem.

The disc is straight and true. It's an out-of-the-box original Mercedes-Benz part obtained from my most trusted dealership. I checked the disc just in case, but it's OK.

macdrone - I don't understand Your post. I think it's beyond my technical English capabilities. Can You rephrase it in simpler words? I'd like to know Your opinion.

Thanks for all the input!
I think you're onto something...probably corrosion crap on the caliper itself. I don't agree about OEM or quality aftermarket discs not being true etc. That's part of the finish process in making the damn things. True they could have been damaged in shipping, but that would be more obvious than not.

I just finished a complete brake job front to back and other than scratching my head on one of the tiny springs holding the E brake shoes together, it was a pleasant experience overall and the new discs are magnificent compared to the old ones.

Kevin
 

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2013 SL550 Grey/ Red/Black Ash wood with every option
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Defective Rotor?

Max, I had a defective front rotor when I replaced all four on my wagon years ago. They were Balo brand. Got the driver side all done and rotated it by hand and it was out about a 1/2 inch. Took it all apart and installed it again, and the same thing. Moved the rotor to the passenger side and sure enough, the same thing. So it could possibly be a defective rotor. Also check the mating surfaces, and try fastening the wheel. Yours is out slightly, mine was out big time. Let us know what you find..........Thor
 

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'92 300TE 4matic 280,000miles, '92 300TE 4Matic 'Ice Blue Metalic' 101,000miles
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Even though you could get a warped new rotor, I'm betting his rotor was fine and it's the caliper itself encrusted with rust 'growth', for lack of a better term. Dry land barnacles?

Kevin
 

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93' W124 E36 AMG ; 71' Cadillac Eldorado ; 07' S211 280 CDI
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Discussion Starter #19
Problem solved. :)

I wanted to take pictures of it, but I didn't believe it would actually work and when I assembled everything to test the brakes and everything went fine, I was just to tired and relieved to take it apart.

First - I couldn't believe that vinegar is such a good anti-rust solution. I soaked some paper towels in vinegar and sticked them to the hub and caliper.

In the morning - the towels were all rusty and hub was 80% clean shiny metal...

When I cleaned the hub, my problem became clear. The hub was knocked in two places on its outer edge - the metal surface bent and it was no longer even on the edge. I didn't believe it would be so simple, but I filed the hub to get rid of the "bumps".
After that I greased it with Cu paste and after installing the disc I was very happy to see that the problem is gone - rotor now goes straight.

I had to deal with one more little problem - the dust cap ring around one of the pistons was dislocated due to rust underneath it. I cleaned it and put it in position.

Installed EBC GreenStuff pads. Test drive went great. No more knocking sound when braking. Pads cleaned the discs from the grey protective layer and the system works perfect.

I adjusted the E-brake, but it's still quite weak - barely holding the car on a hill, even though the shoes are in good condition.

Overall - a very productive day and a lot of $$$ saved on labor. :)

Thanks for all the input.
 
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