Mazda5 brake rotors

Maintenance/Repairs
1

Good morning everyone,
When I am going between 55+ mph my car starts to shake when I use my brakes. The mechanic at the Mazda dealership told me that the brake rotors are warped and need replacing. I asked the mechanic how this happened when I have such low miieage on the car. He said that the rotors would warp if they overheated which could happen if I brake going downhill, doing a lot of city driving, or if carrying a heavy load.

My car has only about 11,600 miles on it. Monday-Friday I drive 5 miles to work each way. On weekends I drive about 50 miles on the highway. I do not ride the brakes and I can only think of two times in the 2 years I have had the car that I have had to slam the brakes on hard. Clearly, most of the brake use is during my drive to work, but that is only 5 miles one way.

I explained that I do not carry heavy loads since I normally drive by myself and maybe a dog or two. I also explained that the other situations he posited of braking when going downhill or doing a lot of city driving sound like normal driving situations, and not anything that should cause rotors to warp? The mechanic said that he could only tell me what would cause my rotors to warp, and that how I drive is “on me”… grrrr. Not happy with that response at all.

I bought an extended warranty when I bought the car new, and was at this time told that because the rotors are warped, as opposed to cracked, they aren’t covered by the extended warranty because warping is considered a result of routine use. The repair is also not covered because I am over 12 months on the normal warranty.

Does this scenario sound right in a car with this mileage? Could I possibly have warped the rotors during a 5 mile commute to work? If so, what do I need to do to prevent this from happening again, because I am not willing to pay $350+ every 12,000 miles to replace rotors. I have been driving for over 40 years and have never run into this problem before. This is my first Mazda though, and it very well may be my last.

Any guidance, advisement, suggestions would be appreciated! Thank you!

2

This is becoming an increasingly common problem on new cars as automakers try to find ways to reduce weight and, by doing so, increase gas mileage. Smaller, lighter brake parts is an easy way to do this, but since rotors are no longer two inches thick and weigh 50 pounds, they have become easier to warp. Hitting a puddle after shedding 20-30 mph can do it due to the rapid heat/cool cycle. There are some ways to deal with this issue and save some money. First, find a good brake shop and see if your factory rotors can be machined. This will probably save you a decent amount of money, although they will likely warp again within a similar time frame. This may not be possible because there is less margin on modern rotors for machining. You can also request premium parts during your routine brake job, once again done by a brake shop rather than the dealership (contrary to popular belief, having services done at other shops will NOT void your warranty). Premium parts will cost a little more initially, but you will probably be happier for longer with them as they tend to last longer and hold up better with fewer problems.

3

Thanks mark9207. I asked about machining the rotors but the mechanic also said that they are already so thin…
It sounds like my best bet would be to spend the money on good parts at a brake shop, but wouldn’t the weight of the better rotor hurt my gas mileage which isn’t great to begin with?
How long can I drive on the existing warped rotors? Is it a safety issue or will it just make the car shake?

4

Your mechanic is wrong, your problem is that you are not heating your rotors up enough to burn off residues from the binding agents of the pads. Just take the car up to a speed of 55+ and where it is safe to do so, hit the brakes hard, but not to the point of lock up, just short of that. When you get down to almost a stop, accelerate back to speed and repeat. By the second hard stop, your problem should clear up.

Best part about this procedure, its free (except for a little gas). BTW, this is not a safety issue.

BTW, your mechanic is right about not machining the rotors though. But the rotors are not warped, they just have an uneven grip due to the residues from the pads. There is nothing wrong with the pads either, its just they way they are.

5

Rotors certainly do warp or develop parallelism problems. Cylinder heads, engine blocks, intake/exhaust manifold flanges, throttle bodies, etc, etc can all warp too. There’s not a metal alive that’s not affected by heat and cooling cycles.

There’s also no guesswork involved in determining this. That’s what a dial indicator and micrometer are for; and in some cases warpage is bad enough that eyeballs work fine.

Rotors can be safely machined but that depends upon the amount to be removed. Most rotors have about .030 of an inch to play with at a minimum and if a dial indicator is used to check rotors one can generally tell from that if they will clean up or not.
The main factor in rotor replacement or machining is economics. It’s usually more cost effective to replace rather than cut them.

6

Thank you for all your suggestions and information. I am not a car savvy person, basically anything past putting fluids, oil, and gas is above my skill level, so I appreciate your input.

7

This is the Mazda Service Bulletin. They are calling it “Brake Judder”

Bulletin No: 04-007/11
Last Issued: 10/17/2011

Subject:

BRAKE NOISE, JUDDER AND DRAGGING DIAGNOSIS AND SERVICING

BULLETIN NOTE

APPLICABLE MODEL(S)/VINS

DESCRIPTION
Some vehicles exhibit brake related concerns such as brake noise, brake judder or brake dragging. If you encounter a customer complaint for any one of these symptoms, refer to the following information to understand why symptoms may occur, and to better assist the customer in resolving their specific brake concern.

BRAKE JUDDER
Brake judder (or warping) is caused by uneven thickness (runout) of the brake rotor. During braking, the clearance between the pads and rotor becomes wider and narrower. This causes force onto the pads and may create a vibration. Vibration is transferred through the brake hydraulic system and/or suspension and can be felt by the customer through the brake pedal, vehicle floor and/or steering wheel. Even micron-size unevenness may cause brake judder. Brake judder is more noticeable when slowing from a higher speed.

In most cases when brake judder is diagnosed, the rotors can be machined using an on-car lathe and the pads can be refinished using sandpaper to restore braking performance.

NOTE :DO NOT use an off-car lathe for warranty repair.

It is not necessary to replace the rotors and pads unless:

^ Excessive unevenness (runout) of the rotors is present that cannot be remedied by resurfacing without exceeding the minimum thickness of the rotor.

^ Excessive heat damage to the rotor (may include heat cracking).

^ Excessive heat damage to the pads.

When you encounter a customer complaint for brake judder, discuss the customer’s driving and storage habits of the vehicle. Identify which wheel is causing the judder and visually inspect the rotors and pads to identify the cause.

NOTE :Refer to MS3 online service information or Workshop Manual section 04-50 for lateral runout, minimum rotor, and minimum pad thickness specifications for the subject vehicle.

Rust:

^ If rust on the rotors and/or brake pads is identified as the cause of the unevenness, measure the lateral runout and machine the rotors using an on-car lathe; refinish the pads with sandpaper (grit #80). If machining the rotors does not correct the brake judder, replace the rotors.Excessive Heat Damage:

^ If the rotors have excessive heat damage or cracking, replace them.

NOTE :Signs of rotor heat damage include blue spots or hard spots.

^ If the rotors do not have excessive heat damage or cracking, measure the lateral runout and machine the rotors using an on-car lathe. If machining the rotors does not correct the brake judder, replace the rotors.

^ If the brake pads are heat damaged, replace them.

NOTE :Signs of brake pad heat damage include shiny surfaces or backing plate paint flaking.

^ If the brake pads are not heat damaged, refinish them with sandpaper (grit # 80).

Brake Pad Dragging:

A dragging brake pad will cause excessive heat and may warp the rotors. This may result in brake judder. Perform the inspection and repair for Excessive Heat Damage".

NOTE :During rotor replacement, ensure the hub is free from any foreign substances that may prevent the rotor from fitting flush against the hub. A rotor that does not fit flush against the hub may experience a reoccurrence of brake judder.

BRAKE DRAGGING

This procedure will assist in finding the cause and appropriate repair for the brake dragging.

Inspection:

  1. Safely raise the vehicle on a hoist.

  2. Determine which wheel the brake dragging is occurring from.

  3. Remove the wheel, then rotate the brake rotor by hand to confirm the brake dragging.

  4. Loosen, but do not remove the two (2) bolts securing the caliper to the bracket.

  5. With the brake pads still installed, remove the bottom bolt and rotate the caliper upwards.

  6. Rotate the rotor by hand again and confirm if brake dragging is still present.

  • If the brake dragging is still present, check for the following:

^ Brake pads seized in the mounting support/hardware.

^ Contact between the brake rotor and other components.

^ A seized wheel bearing.

^ Brake booster push rod out of adjustment.

  • If the brake dragging is not present, check for the following:

^ A seized or slow to return caliper piston.

^ A seized caliper slide pin(s). Lateral runout of the rotor exceeds specification.

Inspection Results & Repair:

^ If seized brake pads are found, clean the mounting support/hardware and brake pads before reinstalling.

^ If contact between the brake rotor and other components is found, repair as necessary.

^ If a seized wheel bearing is found, replace it according to MS3 online service information or the appropriate Workshop Manual.

^ If the brake booster push rod is out of adjustment, readjust according to MS3 online service information or the appropriate Workshop Manual.

^ If a problem is found with the caliper piston return, check for the possibility of water entry due to caliper piston boot breakage or poor sealing, etc. Review the vehicle’s maintenance and repair history before deciding on whether to rebuild or replace the caliper.

^ If seized caliper slide pin(s) are found, remove the pins. Clean and lubricate the pins, then reinstall.

^ If a brake rotor runout problem is found, machine the rotors using an on-car lathe and refinish the brake pads using sandpaper (grit # 80).

NOTE :DO NOT use an off-car lathe for warranty repair.

8

My remedy is still the cheapest and works most of the time. Try it first.

9

Improper torque on lugnuts is also a common cause for rotors warping.