Brake problems with 2014 CX5

[pbesong]

My car has 50K miles on it and i'm going to need to replace the front rotors AGAIN! what the heck? at about 25k miles the rotors started vibrating on braking. took it to the dealer thinking it was still under warranty and they said no, that's brake parts - not covered. they said the rotors were "visibly warped" and wanted an arm and a leg to replace them. i instead got new rotors for $30 less apiece at NAPA, thinking there was something wrong with the original equipment, but about 10k miles later i'm in the same boat. they're vibrating again. I know i should have replaced the brake pads when I did the rotors, but somehow thought they would just break in to the new rotors, which they seemed to do at least at first. I saved the original rotors and am going to see if they can be resurfaced. they don't look warped at all to me. seem to lie flat on an ultra flat surface. If i can get them resurfaced i will and i'll go ahead and get the new pads as well. could the calipers be causing this? would they be covered under warranty? I got the extended warranty to 60k. I also notice that when i back up in the morning my rear brakes squeak almost like they're down to the wear indicator, so I'm going to have a look at those too. very disappointed. i never had to replace any parts on my old 93 miata till the calipers seized at 125k miles.

 

[GAXIBM]

Brake rotors don't actually visibly warp. What happens is under heavy braking the pads get very hot and melt the pad and rotor under the pad which generates gas and liguid material. In a hard stop to a dead standstill the material is melted onto the rotor where the pad stops. This leaves a high spot on the rotor where the pad stopped that can be measured by a thicker spot on the rotor. This high spot creates additional friction in future stops when it goes under the pad giving the uneven braking jerk. Turning the rotors grinds off the high spots and makes them smooth again. There are reports of people getting the rotor & pad very hot again under heavy braking and melting the spot off but it is difficult. Chances are you have done panic stops to a dead standstill which is causing the "warp". When braking heavy try to take the pressure off the brake as much as possible before the wheels stop turning so the material is spread or cooled and not deposited. Of course it is better to risk brake damage rather than hitting something.

 

[madar]

Are you using a torque wrench on the lug nuts?

 

[jjw6455]

Make sure it is the front rotors, the back rotors can give the same symptoms. Don't resurface the rotors, they will warp quicker because they are thinner. NAPA's Ultra Premium rotors have a lifetime warranty. They still warp over time but you can exchange them for new ones at no charge. Get the lifetime pads at the same time and do your own brake jobs for free.

 

[madar]

Make sure it is the front rotors, the back rotors can give the same symptoms. Don't resurface the rotors, they will warp quicker because they are thinner. NAPA's Ultra Premium rotors have a lifetime warranty. They still warp over time but you can exchange them for new ones at no charge. Get the lifetime pads at the same time and do your own brake jobs for free.

I never agreed with cutting rotors either. They have enough heat to dissipate originally, and when you cut them there’s more heat to get rid of with less area. Two things I never skimp on is tires and brake components. You can’t check rotors accurately on a flat surface by eyeballing them, you should be using a dial indicator while they’re mounted on the car.

 

[tibimakai]

They remove a couple of thousands, I would not worry about that. Just don't exceed the minimum thickness.

 

[piotrek91]

OP, you should read this.
It's a long, techincal read, but IMO the guy really knows what he's talking about.
http://stoptech.com/technical-support/technical-white-papers/-warped-brake-disc-and-other-myths

especially interesting quotes are:

In fact every case of "warped brake disc" that I have investigated, whether on a racing car or a street car, has turned out to be friction pad material transferred unevenly to the surface of the disc.

and:

There is only one way to prevent this sort of thing - following proper break in procedures for both pad and disc and use the correct pad for your driving style and conditions.

 

[madar]

OP, you should read this.
It's a long, techincal read, but IMO the guy really knows what he's talking about.
http://stoptech.com/technical-support/technical-white-papers/-warped-brake-disc-and-other-myths

especially interesting quotes are:


and:

Yeah, good info here. The Bendix website has similar info about pad break-in. Of course, none of this means anything if the lug nuts aren't being torqued correctly by the OP, mechanics who remove/reinstall wheels, tire rotators, etc....

 

[edhchoe]

Rotors don't warp. Pad material sticks when it gets ultra hot like in racing or lapping on track. Cutting rotor is fine but it is odd why the OP's brakes keep getting so hot.

 

[Kedis82ZE8]

I wonder if the caliper slider pins aren't properly lubed?

 

[Surfsup]

I wonder if the caliper slider pins aren't properly lubed?

Or a brake caliper/piston might be seized on one side...? This happened to one of my cars. This would cause premature brake replacement and hot brakes as well as possible rotor damage due to excessive wear. If the OP replaced rotors recently and now already has a new bad rotor, there is a strong plausibility there is something wrong with the function of the caliper itself. Suggest either doing research to evaluate and remedy that situation or take it to someone the OP can trust and tell them the full situation and ask them to properly install a new rotor/pad and make sure the caliper is functioning properly.