rear brake rotors rusty?
04-24-2018, 09:33 PM
#1
rear brake rotors rusty?
Just purchased an 09 Z06. You know when your brake rotors get rusted from a car wash? Usually on all my other cars, the rust scrapes off after like 2 blocks of driving.
However, on the Z06, both the rears still have rust on them after driving a few days. The rust kinda just "smeared". its not super orange like fresh rust, but more of a darker color. The previous owner cleaned the car a lot, but didn't drive it much, so its possible that the rust is just much deeper than the pads can scrape. The rotor surface feels mostly smooth, so it can't be that bad. The front rotors feel like glass, whereas the rears kinda feel like 1000 grit sandpaper.
The fronts are squeaky clean as they should be. After some driving, all 4 rotors are warm/hot, so there is SOME clamping going on in the rear. The brake pedal is solid and feels great while braking, which indicates no air in the lines right?
I pulled the pads and had someone press the brake pedal as I watched the pistons, and they all come out smoothly. I pushed each one back with my thumbs, so pistons are not stuck.
The pads look smoother than they should be (glazed), so maybe this weekend I'll sand down the pads a bit and bleed the brakes. Anyone heard of this issue before?
However, on the Z06, both the rears still have rust on them after driving a few days. The rust kinda just "smeared". its not super orange like fresh rust, but more of a darker color. The previous owner cleaned the car a lot, but didn't drive it much, so its possible that the rust is just much deeper than the pads can scrape. The rotor surface feels mostly smooth, so it can't be that bad. The front rotors feel like glass, whereas the rears kinda feel like 1000 grit sandpaper.
The fronts are squeaky clean as they should be. After some driving, all 4 rotors are warm/hot, so there is SOME clamping going on in the rear. The brake pedal is solid and feels great while braking, which indicates no air in the lines right?
I pulled the pads and had someone press the brake pedal as I watched the pistons, and they all come out smoothly. I pushed each one back with my thumbs, so pistons are not stuck.
The pads look smoother than they should be (glazed), so maybe this weekend I'll sand down the pads a bit and bleed the brakes. Anyone heard of this issue before?
Last edited by damnbiker; 04-24-2018 at 09:35 PM.
04-25-2018, 12:48 AM
#2
Burning Brakes
Brake rotors rusting after a car wash IS normal. Just something about the steel in the rotors that lends itself to changing color right before your eyes right after a car wash.
Last edited by cheetah45; 04-25-2018 at 12:49 AM.
04-25-2018, 07:38 AM
#3
Bank that the fluid in the lines has not been power flushed since new, so start with power flushing the break lines with new fluid.
If you don't have a tech II to cycle the abs pump/valves to get the fluid out of them, then either get one, or take it to the dealer to do so.
As for the brake fluid, should be power flushed every to years. Hence even in 2 years, the fluid has absorb a great deal of moisture out of the air, and this water contaminates the fluid. Since the back brake lines are longer, this end up with back not correctly pressure grabbing the correct amount to the front brake pressure grabbing isntead.
As for what fluid, since it sounds like you are not racing the car, then even dot 3 would be fine.
As for the pads, pull them and get the numbers off them.
The oem pads are semi metallic for the Z06, and if someone installed cheap ceramic pads instead, than your losing initial bite, increased feed back and even temp ratings as well.
So correct pads, the lines fresh with new fluid, and the rotors should self clean in a few blocks of any surface rust build up from washing on the contact areas. Also, semi metallic pads are harder on the rotors, so if they do have slight surface rust pitting, then within a day of driving, the pads will remove that pitting to the point of getting the rotors smooth again.
Lastly, if the hats have not been painted (parts of the rotor that the pads are not going to make contact to), this would be a good time to pull and paint them as well.
This keeps the non pad contact areas from rusting.
Z51 option, HD oem pads, so the reason that you see so much dust on the barrels, and light rust on the rotor since the car had sat for about a week when the photos where taken.
Attachment 48339777
Attachment 48339776
To add, take a good look at the rotor surfaces, and if they look on the uneven side, they can be turned with a light facing it needed to not only clean the rotor surfaces, but to square the surfaces to each other as well. Hence the rotors wear out faster on the outer edges than the inner, so a light facing works well to square them back up as well. Plus, if the rear disc inner drum sections have a lip, they needs to be removed/turned so you can adjust the E brake pads correctly as well.
Hence if you can pull the E brake up more than 14 click from it lowered position, time to adjust the E brake pads.
If you don't have a tech II to cycle the abs pump/valves to get the fluid out of them, then either get one, or take it to the dealer to do so.
As for the brake fluid, should be power flushed every to years. Hence even in 2 years, the fluid has absorb a great deal of moisture out of the air, and this water contaminates the fluid. Since the back brake lines are longer, this end up with back not correctly pressure grabbing the correct amount to the front brake pressure grabbing isntead.
As for what fluid, since it sounds like you are not racing the car, then even dot 3 would be fine.
As for the pads, pull them and get the numbers off them.
The oem pads are semi metallic for the Z06, and if someone installed cheap ceramic pads instead, than your losing initial bite, increased feed back and even temp ratings as well.
So correct pads, the lines fresh with new fluid, and the rotors should self clean in a few blocks of any surface rust build up from washing on the contact areas. Also, semi metallic pads are harder on the rotors, so if they do have slight surface rust pitting, then within a day of driving, the pads will remove that pitting to the point of getting the rotors smooth again.
Lastly, if the hats have not been painted (parts of the rotor that the pads are not going to make contact to), this would be a good time to pull and paint them as well.
This keeps the non pad contact areas from rusting.
Z51 option, HD oem pads, so the reason that you see so much dust on the barrels, and light rust on the rotor since the car had sat for about a week when the photos where taken.
Attachment 48339777
Attachment 48339776
To add, take a good look at the rotor surfaces, and if they look on the uneven side, they can be turned with a light facing it needed to not only clean the rotor surfaces, but to square the surfaces to each other as well. Hence the rotors wear out faster on the outer edges than the inner, so a light facing works well to square them back up as well. Plus, if the rear disc inner drum sections have a lip, they needs to be removed/turned so you can adjust the E brake pads correctly as well.
Hence if you can pull the E brake up more than 14 click from it lowered position, time to adjust the E brake pads.