Unusual brake rotor wear/metal falling off in chunks
Unusual brake rotor wear/metal falling off in chunks
(OP)
OK you metalurgists, I have come across and unusual patter on front disc brake rotors. The metal on the inside of the front rotors is very rusty and falling off in chunks. The outside of the rotors looks normal. The cars will make a faint scraping sound but the brake performance seems normal although the rotor surface looks terrible.One vehicle had 54k miles original nissan rotors and the other was aftermarket premium rotors, lasted 4 years then all of a sudden started to show this same pattern. I have checked the slides and everything is free, pistons are free,calipers bleed multiplt times, both pads show same type of wear but the inners are wore much more. Look at the pictures and see if you can explain what is happening. I have a guess that the rotors may have been multiple layers of different metals and when the surface metal is gone the underlaying is soft and not up to the stress.





RE: Unusual brake rotor wear/metal falling off in chunks
I have tried resurfacing pads and rough sanding rotors but the problem returns in a few weeks again, even mixed pads side to side with same results. Both rotors, inside look the same.
RE: Unusual brake rotor wear/metal falling off in chunks
Can you test for hardness of good clean metal at various points on both inside and outside of the rotor and maybe the hat.
Regards
Pat
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RE: Unusual brake rotor wear/metal falling off in chunks
The heavy rust scabs look pretty typical of how iron and steel rust up here in the Massachusetts under car environment after a few years. The only surprising thing is how one side of the rotor could look "normal" and the other could have wide bands that have not been participating in braking activities.
I sure think you will find a matching stepped profile in the pads that ran on "odd" side.
Are the calipers fixed (pistons on both sides of the rotor) or floating (piston on one side)
RE: Unusual brake rotor wear/metal falling off in chunks
RE: Unusual brake rotor wear/metal falling off in chunks
RE: Unusual brake rotor wear/metal falling off in chunks
I am going to post to metalurgists on this site also
RE: Unusual brake rotor wear/metal falling off in chunks
RE: Unusual brake rotor wear/metal falling off in chunks
Regards
Pat
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RE: Unusual brake rotor wear/metal falling off in chunks
In picture ...011.jpg I think I know which pads were on the "bad" side of the rotor. If I had never seen the mating rotor surface I would not describe their wear as "almost normal."
i'd start over with new rotors and Warner or good NAPA pads.
RE: Unusual brake rotor wear/metal falling off in chunks
Pictures posted are from 2006 Nissan sentra, original brakes from factory 54,000 miles, daily driven also, never stored or been in deep water.
I replaced rotors and pads, lubed slides and tested movement, bleed brakes tested piston movement and burnished them in. Customer supplied new parts, O-reilly's Bosch rotors, pads I did not recognize name.
RE: Unusual brake rotor wear/metal falling off in chunks
2 cars, Southern UK.
2001 Focus, front pads less than 1/2 worn, outside looks absolutely fine, but a sudden heavy juddering on braking forced a more detailed inspection revealing rather similar to your photos on the inner side. A big flake had broken away leading to the juddering. The caliper pistons and slides were moving freely. These were replaced in March and so far seem fine.
1996 Audi A6, New Pagid branded discs and pads fitted last October. Caliper pistons and slides both working properly and the brakes were an absolute revelation after fitting. 15k later, the outsides look perfect and the pads barely worn but the inside surfaces are beginning to show the "rings of death" and a there is now a hint of judder under heavy braking.
Both cars are daily drivers. The Audi does far higher miles and gets driven harder.
I've not come across this before in this form. What I have seen quite frequently is a similar effect on the OUTSIDE of rear discs which is invariably a sign that the caliper slides have siezed.
We did have an exceptionally hard winter 2010/2011 with lots of salt so maybe that is a factor? The proximity of the sheet-metal inner shield may also be a factor. Would like to know as I hate replacing parts that are only a small part worn!
Regards
Nick
RE: Unusual brake rotor wear/metal falling off in chunks
This is what is happening here.
RE: Unusual brake rotor wear/metal falling off in chunks
making people scratch there heads for 40 years ..
RE: Unusual brake rotor wear/metal falling off in chunks
Curious that Bosch did not know what the problem was since it was their brake pads?????
Gary M&G Engineering
RE: Unusual brake rotor wear/metal falling off in chunks
I think all passenger car rotors will be some flavor of cast iron
RE: Unusual brake rotor wear/metal falling off in chunks
the mind set of the chinese when it comes to making products is horiable , as they can copy the looks of the product ,but not make the material of the product right . most of there philosphy is make as many as you can as cheaply as you can ,( kind of like the japanese in the early 70's)
one thing about driving ,is when I deliver containers to these places dist centers ( AX, AA, PB) I get to see the docks on the inside , and one company I will not name names , has gaylords of failed rotors and drums that they load outbound back to china , and most of them are new and never made it out of the dc or was returned from the store , they are cracked or have peices broken out of them from while in use, in transit or are like his ,spalled , and I have looked at some of them , you can see the grain layering in them from uneven cooling , on a average for the 5-6 containers of brake castings I return one full one, that says it all. But today people over look price vs safety ( Darwinism at its finest )
when I mean laminate its a layer, not a folding/hammerweld operation they use to make damascus steel
making people scratch there heads for 40 years and ask me why??? ..
RE: Unusual brake rotor wear/metal falling off in chunks
RE: Unusual brake rotor wear/metal falling off in chunks
Most rotors are made of J431 G3000 cast iron. This is pretty common stuff. Bad cooling can cause a lot of problems, and is usually caused by trying to cool things too fast to get more production.
I've had rotors such as seen in the pictures in this post analyzed by a metallurgical laboratory. There was no anomaly found in the metal and no laminating. I would have to say that the cause could very likely be corrosion due to the friction material.