[TheJDMan]

Both my neighbor and I have 07 Duramax 2500HDs his is a GMC and has less miles then my truck at around 75,000. Recently his truck failed it's annual VA state safety inspection due to a ring of rust around the rotors outer diameter. The inspector said he failed the truck because the pads were not in full contact with the rotor. In trying to understand what the issue was we looked at my truck and it had the same rust ring on the OD of the rotors. We contacted a couple of other Dmax owners and found the same rusty brake rotor issue. In order for his truck to pass we ended up replacing pads and rotors front and rear. Since then I have heard from a ASE Master Mechanic friend that said he has seen the same thing in his shop and attributed it to poor quality rotor material. According to him there have been service bulletins referring to excessive brake rotor rust on GM light trucks. This is apparently not a pad wear issue since both of our trucks had at least 3/4 pad remaining. My inspection is not due for about six months but I have already purchased new pads and rotors and will be installing them come spring. I live just north of Richmond VA so we don't live in anything like a salty rusty area.



I'm just curious if others have seen excessive brake rotor rust issues as well.

 

[heymccall]

We covered that quite a bit, years ago.
The rotors develop a light rust layer while sitting unused. When everything works correctly, the pads scrub that rust off while in operation.
And I emphasize "works correctly".
One root cause is pad backing end plate rusting and/ or rusting of the caliper bracket, both resulting in the pad no longer floating.
The other root cause is corrosion of, or improper lubricant, on the slide pins upon which the semi floating caliper slides, also resulting in the caliper no longer floating.

If the pads or calipers are not free to "float ", mild brake application will not remove all of the overnight rust on the swept areas of the rotor.

 

[davester]

This does sound like an idiot inspector, as the pads don't go to the edge of the rotor, so there will be a narrow ring of rust around both the inside and outside edge of the rotor surface.


Now, if there is rust within the area that is swept by the pads, that doesn't go away with braking, that could be a problem.


I know for my truck, there isn't any rust within where the pads cover the rotor, but it's also a daily driver with mostly city driving, so the brakes get used a lot.

 

[heymccall]

I think he's referring to rotors like in this thread
https://www.dieselplace.com/forum/7...-drivetrain-2001-2010/971652-front-rotor.html

 

[TheJDMan]

You know I remember reading these threads and completely forgot them, shame on me. I also have your brake pad maintenance procedure in my mind so that the plan is to fit the new pads so they slide easily and I already have new AC Delco ceramic pads, AC Delco slotted rotors and all new hardware.