I'm about to swap out my front rotors again ( for the third time ) because they warped. I'm pretty sure that the cause of the warping is the spirited drives in the mountains I do with my friends every summer. Keep in mind I drive through the Canadian rockies, on any given drive we can see summer tempertures in the day and close to freezing in some areas by night. Would swapping over to C5 rotors help keep them cooler? I want to keep my stock wheels, and stock calipers. My brakes do the job, but I'm kind of annoyed at the warping.

 

Rotors don't warp....the unevenness is due to an uneven build up of brake pad material on the rotor. make sure you replace pads at the same time, bed them in properly and you should be good. If you're using junk pads that can cause issues.

 

I blast thought the mountains too all the time and my cheap brakemotive rotors are fine.

What rotors/pads are you using?

 

I love the brake motive stuff. I wouldn't run it on a road course but I beat the crap out of mine on the street and auto x when I get the chance. 0 problems.

 

I use my brakes really hard, rotors never warp and the pads last a long time. There are a few keys to long lasting brakes:

-Use good quality rotors/pads.
-Bed them in properly when new.
-Keep the sliding surfaces lubed.
-Let the brakes cool by driving fast without applying them.
-Don't drive through a deep puddle when the rotors are hot.
-When coming to a complete stop, don't let the entire weight of the car rock against the spindle ears.
-When at a red light, just apply enough brake to hold the car, don't hold it harder then that, especially when the rotors are hot.

 

Rotors don't warp?

I have a set of rears that were "warped" on a 4th gen Trans Am I used for my build...I had them turned and since they are drilled and slotted it's very easy to see that parts of the rotor had to have more material shaved to be true again.

Doesn't seem ceramic brake pads would have caused the uneven thickness. Can you further explain?

(legit question, not sarcasm...always looking to learn)

 

^^ Sure thing, peruse the articles I'm linking. I did a lot of reading from my engineering friends before I accepted this as fact. I'm linking to the raybestos article and one from stoptech since they are manufacturers. Just google "rotors don't warp". Basically it's a common misconception that it's even possible with steel brakes. You absolutely will see material removed when a rotor is turned, I think noticeable run-out by pedal feel is like .0003" so if you are removing pad material from the rotor you absolutely could remove some of the metal from the rotor, it's a very small tolerance.

http://www.hendonpub.com/resources/a...etails?id=1787

http://stoptech.com/technical-suppor...nd-other-myths

 

excellent information, thank you for posting

 

I had a bonneville some time back that was plagued with this problem. I worked at a shop at the time so tunring rotors were not a problem. I started out just turning rotors, pedal pulsing was back a week later. The second time I turned the rotors I bought new pads as well. The pedal pulsing was back after a couple weeks. The third time I bought new rotor (because at this point the stockers were getting thin) and new pads again as well as lubed all the slide points, and the pulsing was back after a few weeks.

After fighting this for a while, I spoke to an old tech who said I should replace calipers and hoses, that one or the other was likely hanging up. They didn't feel like they were but I replaced both anyway, resurfaced the recently new rotors, surfaced the recently new pads with sandpaper, bed them in and it totally fixed the problem. I drove that car for several more years and it never came back.

I guess you remember the lessons that cost so much to learn.

 

Replace the Rotors and Pads, get yourself a good torque wrench, make sure all lugs are torqed to specs, (even pressure from all lugs) Bed them in properly and this should fix the issue. Going forward use the torque wrench on the lugs each time you reattach the wheel and that should keep your rotors from warping.

 

NP, I think it's something that is good to know.

Dragging calipers, or uneven pressure will absolutely cause uneven pad material build up. I actually had a bad caliper once causing this problem.

This is a good point as well, too much torque or even uneven torque on the lug will cause the rotor to flex, this is another common issue that causes a pulse in the pedal. Still not "warping" due to heat or driving style though

 

brembo slotted with hawk hps pads. had this setup for 7 yrs and i love it, rotors hasn't warped on me once

 

i disagree about it being uneven pad buildup. it's uneven wearing away of the rotor. as the pads hit the rotor the pads wear away and get thinner... which is why you eventually have to replace pads there's none left. and the rotors also get thinner. it's the pads wearing the rotor away unevenly over time that is the problem.
the rotor needs to spin true on the front wheel hub or rear axle flange. if it doesn't then as the pads wear away at the rotor the "warping" gets worse over time. brake shops can turn rotors while on the car accounting for wheel hub runout, you might want to look into that and have runout on your front hubs checked. it can be as simple as rust on the front wheel hub when you put a new rotor on that causes runout from the start even though the new rotor is completely true. so i think your best path forward since you have a repeat problem is get new rotors and find a shop that can check and turn those new rotors while on the car. i'll bet that solves your "warping" problem. also, don't overlook how the wheel lugs are torqued, it's the clamping of the wheel onto the rotor onto the wheel hub that keeps things together. uneven lug nut torque can result in rotor warping, so it's to your benefit to use a hand torque wrench and get all lugs torqued as even as possible and as tight as possible.

 

Could you please link me to your source for this? Yes the pads get thinner, they deposit material onto the rotor. Some leaves as brake dust, some sticks on the rotor. You resurface to get rid of the pad material, because it is not an even distribution the resurface makes the rotor thinner.

 

It's all about the transfer layer, assuming the car doesn't have mechanical issues, like a sticking caliper, worn hub, unevenly torqued wheels, etc.

 

Wow.. I never even thought about the wheel torque being an issue. How did that not occur to me? I'll be sure to double check the lug nut torque on this next job. Also didn't consider the hubs, they are a bit rusty. I'm going to go ahead and replace both front hubs anyway as they are getting up there in mileage. I'll also switch over to C5 rotors since all I need is the adapter, this should give me a bit better cooling and extra braking. Should I go ahead and replace the calipers too just in case or stick with them?

 

Baer "Eradaspeed" rotors is the ticket.

 

the source is me, from experience.
you may get a very (very) thin layer of brake pad material embedded into the rotor surface, i'd say less than 0.0005".
the rotor and pad wear away and over time the pad is not going to push it's own material into the rotor surface, it's going to wear it away, as both the pads and rotors get thinner.
if you simply put a used rotor that is "warped" on a lathe to be turned and observe the cutter it is cutting away metal not brake pad material. as you measure various points of the rotor you'll observe high and low spots on the inside and outside face of the rotor.

for runout dimensions you can look up gm spec's, going from memory i think they claim anything under 0.003" runout is acceptable and "should" not cause pulsation. if you look up rotors on napa their premium rotors state maximum lateral runout of 0.004" when purchased, and their ultra premium rotors have a max runout of 0.002" with an "out of the box no turn guarantee".
I believe 0.007" and greater is the value that is considered definitely warped.

 

unless you drive in winter and have major rust under your car or have never changed your brake fluid then your calipers are probably fine. if you can compress the piston back into the caliper easily and the piston isn't hanging up then you won't gain much with new calipers other than a nice new look. i would undo the slide pins on the caliper and re-lubricate them.
without knowing the history of the car and who did the brake work it's hard to say if it was poor attention to detail causing your repeat problem.
if you have the money then if you went with new front hubs, new front rotors, and had those new rotors turned while on the car to verify there is no runout then i think you would get as good as it's gonna get. but don't let the shop then zip the wheel lugs on with an air tool, undo your lugs and retighten with a reliable tq wrench. for new hubs with new studs that are dry you can probably tighten to 110 lb-ft safely.

 

I used to think I was warping rotors on a few of my cars and over the years found a couple things to help.

First, if you are going to let hang on an off ramp to a light, stop short, then slowly roll up to the light letting the rotor cool more evenly and do not stop dead on a hot rotor allowing pad transfer in one spot. Never happened again on the Firebird when sticking to this rule.

I also now and then get a pulse on my stock Brembo system on my SRT8, if it persists, I go out to a country road and re bed the brakes. 4-5 65mph to 5 mph hard stops in a row. Then drive for a 1/2 mile or more with out touching the brakes. Same as I bed in new brakes.

90% or more of the time this works to fix up the problem, though once it happens it comes back sooner. No change of pads or rotors though.

Give it a try, it could save you money.