Brake rotors unsusal wear, metal falling off!!!! 1

[gary505]

I have different brake rotors from 2 vehicles that show strange wear only on the insidie of the rotor. 2006 nissan sentra 54,000 miles original brakes and rotors, 1996 saturn aftermarket rotors with 2 year guarantee, they ran for 4 years and no trouble then got noisy and this is what they looked like, inside only. outside was normal. even the inside pads looked normal but look at the rotor surface, did metal fall off and leave something else exposed?????
Caliper slides were checked and were free moving, pistons were free, calipers bleed several times, brakes feel normal but make noise. It looks like the inside pads were not even touching rotor but they would clamp had and after cleanup of rotor thy looked like this again in several weeks.
Are these rotors compound metal or plated?????
next 2 posts show detailed pictures

 

[gary505]

second piture

 

[gary505]

third picture
again, brakes felt normal and cars were used almost every day.
In 35 years I have never seen this happen before unless there was a mechanical problem, stuck slides or pistons, NO SO in these cases!!!

 

[swall]

Except for some high end car lines, brake rotors are cast iron, not plated or coated.

 

[metman]

It looks like it could be case hardened surface flaking off because of some anomaly at the case/core interface. A microscopic analysis would help.

 

[gary505]

Heat treating makes more sense, but why is the surface not polished by the brakepad once the harder material is flaked off. I was unable to contact the manf. of the after market brake rotor to find out if this is the case.
see closeup picture?????

 

[redpicker]

It's hard to tell from the pictures, but it looks to me like these rotors have been heavily corroded, then used. Is the material that is flaking off iron oxide? There is just too much oxidation on the entire rotor to let me believe these rotors have been used regularly for the past 4 years and then got noisy.

How were these vehicles stored? Maybe they both were flooded up to the axles for extended period, which froze the calipers. When the brakes were applied, only the outside pad moved (is the piston on the outside?) while the claiper stayed? After repeated braking applications, the calipers finally broke free, making the noise and making the rust flake off? Best guess from the limited information.

rp

 

[swall]

I have worked in the automotive brake industry as well as doing my own brake jobs and see nothing unusual in the photos, just the typical rust spalling scenario. Many of the lining compounds today are high iron content, and of course, that material rusts as well and some will transfer to the rotor. Rotors are not case hardened as metman suggests.

 

[gary505]

OK now I begin to understand what my be happening. These 2 cars were daily driver, never stored or exposed to water other than normal driving, we live in Kentucky, so no salt water. This is the first time I have seen such transfer, any idea about why the outboard pads did not do the same thing?????
I was not able to correct the situation even after resurfacing pads and sanding rotors with 40 grit paper. The transfer continued and happened within a few weeks again. Why did they last 4 years before doing this, are the pads to blame??? Perhaps the compound changes brakepad material as it gets near the metal backingplate.???
We have never seen this in other brakes over the years.

 

[macmet]

I have seen heavy spalling on my brake rotors before when one of my calipers was not functioning properly. If the caliper is not functioning properly (i.e. only one side works) you will have a rotor that is generating heat from friction and oxide forms. And when the caliper is not working, the oxide does not get worn off next time you're driving and you will eventually seeings spalling.

Brakes that are operating properly will have a shiny metal surface on both sides of the rotor after use.

 

[macmet]

... I should have added that even if the brakes are working properly, if the car is not used frequently, the shiny surface will begin to oxide. But, if they are working, this oxide will be worn off the next time the car is used.

 

[btrueblood]

Have to agree with macmet. Lack of wear on inside rotor face (with outer face looking clean and polished) means something is not functioning properly, either inner piston is stuck or caliper slide is stuck, or....

 

[looslib]

Disc brakes either have 1 or 2 pistons per side pushing the pads against the rotor or 1 piston and a sliding housing. If you get scaling and flaking on one side, that side is not being utilized during the braking process. Disc rotors will be smooth and shiny from the wearing of the pads against the rotors.

Have you noticed any increase in stopping distances recently?

You may get some braking action, but it isn't optimal since you are only getting a rubbing action on one side of the rotor. The wheels would never lock up as you can't get enough friction without the clamping action of both pads against the rotor between them.


"Wildfires are dangerous, hard to control, and economically catastrophic."

Ben Loosli

 

[gary505]

Hey read the first posts, these cars are daily drivers, one piston on the inside pad, the side that shows the rust and pad transfer.
I have 35 years automotive experience and these pistons, slides and hardware are working OK. Both cars showed same type of inside rotor transfer. I drove both cars and brakes seemed normal, I go down a very steep mile long hill and the braking effort and stopping power did not seem to be effected. I can not explain the inside rotor surface not being polished but the car would lock up the front brakes without pulling. Whatever is happening is still allowing the brakes to do their job but the inside rotors show this awful surface. So far, transfer from material on the inside brakepad to the rotor surface seems to be the explaination. Perhaps the pad material is different as it comes close to the metal backing plate. Hi iron content transfered to the rotor under heat and pressure may be causing this type of rotor surface problem??????

 

[Wrenchbender]

From looking at the pictures the inboard side of the rotors have rust exfoliation indicating that the inboard pads are inactive for reason(s) yet to be determined. (BTW heating would be asymmetric.)

I don't think it’s a materials problem, and occurrence on two different vehicles rules out a brake design deficiency. Check the operation of the assembled unit with prussian blue on the inboard surface. It’s a long shot, but could the wheel nuts be over torked, and cause just enough warpage to bind things?