PROBLEM AFTER REPLACING FRONT ROTORS AND PADS

[August Forster]

Gentlemen,
Need help to diagnose the problem. I have replaced front and rear brake rotors and pads (all parts from MB) because didn't pass the state inspection at MB. And now noise is coming from the front wheels while driving. The noise is constant low rumble. I noticed the noise is more pronounced when turning the wheels.
Need help in this situation because I really won't be able to find it out myself!
Thank you!
Car : E320 / 1994

 

[gsxr]

A constant rumble/roaring noise is usually wheel bearings, not brakes. Does the noise change at all when you apply the brakes? If you jack up each front wheel, do both rotate easily when spun by hand?

 

[August Forster]

A constant rumble/roaring noise is usually wheel bearings, not brakes. Does the noise change at all when you apply the brakes? If you jack up each front wheel, do both rotate easily when spun by hand?

Thank you immensely for the fast response!
No, the noise does not change with braking at all.
The driver side rotor did not spin at all after installing the pads. I thought this is normal since all parts are new and are not worn. I do not remember if I tried to spin the passenger side rotor after installing the pads. But I think the passenger side rotor spun freely ... really don't remember for 100%

 

[August Forster]

A constant rumble/roaring noise is usually wheel bearings, not brakes. Does the noise change at all when you apply the brakes? If you jack up each front wheel, do both rotate easily when spun by hand?

I also noticed that the noise is beating the steering wheel and with very slow speed when coming to a stall these beats are becoming more define and discriminate.

 

[emerydc8]

If you remove the pads and rotor, you can rule out the brakes as a possible cause. If the hub still doesn't turn, I would suspect a bad wheel bearing. Did you have the rotor off when you did the brakes? Maybe something stuck inside the rotor hub when you installed the rotor.

 

[luckymike]

Maybe you got some grease on the pads? That might cause the beating you’re feeling.

 

[August Forster]

If you remove the pads and rotor, you can rule out the brakes as a possible cause. If the hub still doesn't turn, I would suspect a bad wheel bearing. Did you have the rotor off when you did the brakes? Maybe something stuck inside the rotor hub when you installed the rotor.

First I removed old pads, then unmounted the calipers from the knuckle, and then removed the rotors. The assembly was in reverse order. The only thing that potentially could be displaced is the flat O-ring around the piston. I usually manage to keep it in it's place when do pad change. The new rotor was spinning freely (without new pads installed), however I felt that it did not spin swiftly and quietly unlike the old rotor. Some resistance was noticed. But how is it possible that old rotor spins perfectly and when you put a new rotor on the same hub it does not spin the same way?

 

[August Forster]

Maybe you got some grease on the pads? That might cause the beating you’re feeling.

How much grease? Gloves that I worked with could have some engine oil traces but generally I don't think pad surfaces were spoiled significantly.

 

[emerydc8]

But how is it possible that old rotor spins perfectly and when you put a new rotor on the same hub it does not spin the same way?

Can you measure the thickness of the old rotors versus the new, and compare the thickness of both new rotors. Maybe they gave you a wrong rotor and one is thicker than the other. When I change pads, I always have to use the Mercedes tool to push the piston back into the caliper.. As the pads wear the piston pushes out., so it would require more than just keeping the pistons in place when the old pads are removed. The piston would have to be pushed back into the caliper. Do you think it might be that the piston isn't traveling freely? There are kits to rebuild the piston, but I've never had to do it.

 

[JC220]

I have noticed this problem with new MB parts recently. More so on newer cars is where I get only from the dealer but with new discs and pads they leave zero space for movement and typically bind for a first few hundred miles. Not good for the new brake disc but that is how they are and do free off after a few hundred miles.

Haven't had it really bad on a w124 before however.

 

[gsxr]

Thank you immensely for the fast response!
No, the noise does not change with braking at all.
The driver side rotor did not spin at all after installing the pads. I thought this is normal since all parts are new and are not worn. I do not remember if I tried to spin the passenger side rotor after installing the pads. But I think the passenger side rotor spun freely ... really don't remember for 100%

If the rotor did not spin freely after installing the new pads, you must have had to use force to insert the pads. They should slide in easily. This may have been due to the pistons not being fully retracted, and isn't a big deal.

You need to test again, jack up each side and spin the wheel. Let us know if both sides spin freely, AND if both sound the same... should be very quiet. If one side has a roaring noise and the other does not, it could be bearings. And, if one side is roaring, the next test is to press the pads away from the rotor so there's no drag between the pads/rotor... this only leaves the bearings as the contact point.

BTW, what MB part number pads/rotors did you install up front?

 

[August Forster]

If the rotor did not spin freely after installing the new pads, you must have had to use force to insert the pads. They should slide in easily. This may have been due to the pistons not being fully retracted, and isn't a big deal.

You need to test again, jack up each side and spin the wheel. Let us know if both sides spin freely, AND if both sound the same... should be very quiet. If one side has a roaring noise and the other does not, it could be bearings. And, if one side is roaring, the next test is to press the pads away from the rotor so there's no drag between the pads/rotor... this only leaves the bearings as the contact point.

BTW, what MB part number pads/rotors did you install up front?

I will test both sides as described and will reply with the results and part numbers.
Thank you!

 

[August Forster]

One thing I forgot to mention and which I believe is worth to mention is that the car doesn't accelerate as good as it use to before brake change.

 

[August Forster]

Can you measure the thickness of the old rotors versus the new, and compare the thickness of both new rotors. Maybe they gave you a wrong rotor and one is thicker than the other. When I change pads, I always have to use the Mercedes tool to push the piston back into the caliper.. As the pads wear the piston pushes out., so it would require more than just keeping the pistons in place when the old pads are removed. The piston would have to be pushed back into the caliper. Do you think it might be that the piston isn't traveling freely? There are kits to rebuild the piston, but I've never had to do it.

I will measure the thicknesses to compare. The calipers were in my hands, so I was able to retract all 4 pistons maximally using a C-clamp.
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Quote: "Do you think it might be that the piston isn't traveling freely?"
=================================================
I really don't think so.

 

[August Forster]

Gentlemen,
I did a a stupid mistake - forgot to torque the lug bolts on driver side wheel. Thankfully I ended up with one lost lug bolt. Both rotors spin freely without any noise. After properly torqueing wheel bolts all noises were gone. I took pictures of part numbers of both rotors and brake pads as promised, and measured the thicknesses of the rotor and pads+rotor as well:

Passenger rotor: A 124 421 241 2 MIN TH 22.4 mm EGA 1R090717M
Driver rotor: A 124 421 241 2 MIN TH 22.4 mm EGA 1R090717M
Brake pads: A 005 420 0120

Thank you so much to all of you for the quick and prompt responses!

 

[luckymike]

Well, I sure didn’t see that one coming! A good reminder to all of us to always check the basics.

 

[August Forster]

Well, I sure didn’t see that one coming! A good reminder to all of us to always check the basics.

I couldn't believe my eyes when I saw a missing bolt and four loose ones. The conclusion is that one should never work on a car when he is excessively tired.

 

[Duh_Vinci]

The conclusion is that one should never work on the car when he is excessively tired.

Glad you sorted it out, though I would have never guessed the cause, glad you caught it before anything drastic took place! You also make very good point, too tired - saved that car work for another day for sure!

Regards,
D

 

[August Forster]

Glad you sorted it out, though I would have never guessed the cause, glad you caught it before anything drastic took place! You also make very good point, too tired - saved that car work for another day for sure!

Regards,
D

Thank you very much for the kind words!

 

[nocfn]

Glad you were not hurt or anyone else. We all have had some dummo moves so you are in good company. As you stated, details matter. Do something to remind you to do this in the future like mark the jack handle with pink tape or day-glow orange as a personal, silent reminder.

 

[August Forster]

Glad you were not hurt or anyone else. We all have had some dummo moves so you are in good company. As you stated, details matter. Do something to remind you to do this in the future like mark the jack handle with pink tape or day-glow orange as a personal, silent reminder.

Thank you! Very much appreciate it. I think after this episode I have had such a good lesson that I will remember it for a long time

 

[nocfn]

yep, typically one does not get a second chance. The environs are in your favor, buy a lottery ticket. -

 

[tomer]

So glad nothing drastic happened, and good job finding the issue... Good Karma!