Brake Rotors inside surface corrosion

[Spoolmak]

I've been keeping an eye on the inside surfaces of my front brake rotors. They have rusted and formed a rust crust over two thirds of the rotor surface. That crust has worn off the pads, so that only 3/4 of an inch of rotor surface is showing a clean friction surface.

I replaced my rear rotors and pads last year for the same reason and will be doing the fronts shortly.

The outer brake pads still show more than 50% life left. Why is this corrosion happening to the inside surfaces of the rotors???? Is it a design flaw? Quality of OEM rotors?? Solutions???

Thanks in advance for your thoughts on this.

Tor

[carco]

I believe part of it is road splash of salt etc. but mostly low brake usage due to excellent engine and transmission braking in the DA combo. Also a major factor is a problem with brake rotors today whether OEM or aftermarket and that is metal porosity. Small pores into the metal that salts and moisture are able to enter and cause rusting below the "shiny" surface until rust jacking shucks the surface up and off!
We also see this in other OEM's and models that have long pad life.

[cowboywildbill]

Some Dealer's call the rust on the rotors "Lot Rot". It is a common problem, road salt and moisture sure contribute to it's progress. A vehicle that isn't driven regularly and sit's for a few weeks at a time is really at risk. Sometimes the Dealers have to turn the rotors on a brand new vehicle if it's been sitting on a lot for quite a while and it get's sold and the owner experiences rotor pulse. I have heard on trucks that are a couple of years old and have a bad case of rust, that a good set of aftermarket rotors don't seem to have as much of a problem with it. Maybe it could be the composition of the metal in the rotors.

[Quack_Addict]

IMHO (and I work in the auto industry), the OEM rotors are junk. I don't know for sure, but suspect there was a design flaw, or flat out poor quality of material, for several years in the trucks. My truck is a 2006 - built right when times were getting tough for GM - and GM was (still is) squeezing suppliers for every last fraction of a penny that they could save to prop up the bottom line and eek out that last buck of profit on every vehicle. Reference intermediate steering shaft issue... transmission cooler line issue... I'm sure there are more. Those 2 issues were not issues so much in the 2000-2004 model years. A friend of mine has a 2004 DA truck with less miles on it than my 2006. He's never replaced an intermediate steering shaft (I'm on #5), he's never had a trans cooler line leak (had to replace my lines last year), he's still on his original brakes - I got way less miles out of mine than he has on his truck now and he tows with his truck more than I do with mine. My brother has a 2002 HD and his ISS is still original, no trans cooler line leaks either.

I replaced my OEM rotors a couple years ago with some aftermarket rotors from a local automotive parts chain store. NO problems since, and my truck sees the same usage as it did when the OEM rotors rotted out.

FWIW, I was unable to find a service shop that would turn my OEM rotors.

Here is what mine looked like when I pulled them off in `08 with 38k miles on them:
http://i441.photobucket.com/albums/qq135/QuackAddict/IM002760.jpg

http://i441.photobucket.com/albums/qq135/QuackAddict/IM002759.jpg

[carco]

Quack_,,,,,, we will mill OEM rotors, BUT, we measure first for thickness and look @ the surface for problems. The surface of several of your rotors will more than likely "chip out" a deep pocket and then be undersized good only for boat anchors. We would likely not turn those rotors as I see pictured.
Raybestos rep told me that most rotors today, OEM or aftermarket have been cheapened up w/ a new process, but this process has a porosity problem with the metal. The pores will allow h2o and salts to enter under the shiny surface rusting away under the surface. This allows rust jacking of the surface upward and deep pits when the surface is knocked away.

[JohnC]

I had the fronts cut with only 17000 miles due to pulsing brakes, then last year I replaced the rears. the inside was rusted about 80% and the outside 50%.

[Mark Rinker]

I totally concur with the LOT ROT diagnosis. I have replace 4 sets of OEM Duramax brakes, always when one set went metal-to-metal, and the other three were never far behind.

Never had corrosion problems, and I live in Minnesota, where our roads are white with salt 4 months of the year. The only issue that I have seen is stress/heat cracking on the surface of the rotors, but never failure.

Trucks years are 2001, 2002, 2005, (2) 2006s...

All trucks were towed heavy and constantly, and all 4 sets went well over 100K miles!!! We keep the rotors SHINY...

I consider the OEM brake rotors, pads, calipers to be the best OEM brakes I have ever seen, and have only been able to duplicate their performance with the BEST quality Raybestos rotors, and the BEST quality Okibono (sp?) ceramic pads. (Never have owned the trucks long enough to see the second set worn out, but wear was on track for 100K interval in all cases.)

Did make one $800 misstep: The very first OEM set I replaced was done at a local tire shop, they got parts from NAPA, those junk parts lasted only <40K miles, :eek: when the pads separated, cracked, literally fell apart. The brake material looked like glue and sawdust from China - nothing like OEM. It was not a caliper problem, as all four corners were in similar state of falling apart.

[More Power]

Just a few years ago GM was on-track to replace all of the rear discs on pickups with drums because of what this thread is about. The early brochures even had it spec'ed out for rear drums. But... GM folded on the plan because surveys indicated owners expect 4-wheel discs these days.

This rotor rusting problem is worst, as you'd expect, in the rust-belt states. Salt and road de-icer are the biggest part of the problem, but I also think (like others here) that the alloy is also partly to blame. SS Brakes (www.ssbrakes.com (http://www.ssbrakes.com)) advertises better stuff, but they ain't necessarily cheap. ;)

Jim

[carco]

Mark, I agree, even with the rotor rust issues the GM OEM parts wear very good. Prob get better brake life w/harder use. My 04 with 76000+ the brakes are about 40-50% to go, but the rotors will prob not make it that far.

We like Raybestos best rotors.
We do not like NAPA brakes very much.

[Spoolmak]

I decided to replace the front rotors and pads now and bought the parts today. I expect I'll do the job next Monday or Tuesday in a friend's heated shop. It is winter up here!!

I did not buy OEM but went with Lordco branded rotors at $72 each, and a set of Wagner Thermo Quiet ceramic pads for $89.00.

I looked into getting better rotors, but the next step up was $220 each. The Lordco folks told me that the rotors I bought were significantly better than the OEM, for which the dealer wanted $125 per side.

I have 157,000km - or @100,000 miles on the truck and am still on the original front brakes with the pads showing very little wear, but the rotors inside surfaces way worse than the worst pictures shown above.

Take care all. Stay warm!!

Tor

[Heartbeat Hauler]

It may very well be the rotors as you all are talking about, but something else to consider is that maybe the pins that the pads ride on, or other aspect of pad operation, are corroded preventing the "entire" pad from making full contact with the rotor. This is not an uncommon problem. This might explain the development of rust on the outer portion of the rotors. It may also lead to a soft or spongy brake pedal. HTH.

[carco]

Heartbeat,,, your theory is correct and that can be a contributing factor. Yes a spongy pedal can result from the conditions you pointed out. I can say that on mine the rusty rotors are developing and it is not due to caliper pins or slides. Shortly after new and once since I cleaned and lubed wondering if that might help because usually one side is worse than the other.

[Mark Rinker]

Go hook that diesel on something BIG heavy once in awhile...like 18000# out back, and take it for a ride.

Use the brakes moderately...SHINE THINGS UP!!! :D:D:D



Also, we wash the trucks frequently to keep the salt off, spending a fair amount of time on each wheel and wheel well area, getting as much high pressure inside the wheels, and in from the backside as possible...

[Spoolmak]

Did the front brake job yesterday in friends heated auto workshop with hoist. Man, what a joy!!! It took just over one hour to replace both rotors and pads. Sweet!!!

The old rotors inside surfaces were incredibly bad - worse than I had thought. The clean working surface on driver's side was 1/2 inch wide, 5/8 inch wide on passenger side rotor.
The rust was so deep I'm sure neither rotor could be resurfaced.

I'm going to follow Mark's advice and use the brakes more, rather than the engine compression in the tow modes.

It's only minus 10 here today. Downright balmy!

Stay warm.

Tor

[JohnC]

It's only minus 10 here today. Downright balmy!


That's why I prefer Fahrenheit to Celsius. +14 beats -10 any day...

[Spoolmak]

That's why I prefer Fahrenheit to Celsius. +14 beats -10 any day...

John. That's especially true in degrees Celsius.....

Tor

[2tough2park]

Inside rust is the exact problem I posted about not long ago. The dealer who I had inspect them said it happened due to sitting for long periods. That could very well be true as I don't drive my truck every day. My rotors looked exactly like the ones pictured except much worse on the inside. I vowed to drive the truck more(put almost 8000 miles on this year so far) and put SSBC rotors on. I received a nice compliment from an NTB tech while putting on my new tires. He asked why I did it and then commented the same as in the other post that new car rotors just aren't as durable as they used to be.