Hi Everyone,
Back in August I replaced all of my brake pads and rotors and ever since I haven’t been able to get rid of juddering and shaking above 55mph when using them. Below is the timeline.
1.7/21/10 Replaced all 4 pads and rotors with Hawk HPS pads and Centric rotors from tirerack.com parts $358.00 100 dollars labor to have neighbor who is a mechanic put them on. Total Cost 458.00
2. Realize something is off as it is shaking on braking and bring the car back to my neighbor who says it feels like the problem is shimmying in the rear. He makes me buy two cheap rotors for 40 dollars for the rear and takes the Centrics for 40 bucks tirerack.com supplies new Hawk pads for the rear under warranty.
3. Car still doesn’t feel right and shimmy’s, I try getting all four tires balanced and flushing the brake fluid total cost 100.00. No dice.
4. Next I try a full four wheel alignment car tracks nice and straight but shaking above 55 on braking is still bad as ever. Cost 90.00.
5. Today on 10/1 at wits end with car shaking I bring it to a local mechanic who test drives it “says I think you have a problem with your rears” I say do what you have to do to fix it, but I think its from the front since the rears are new again. He test drives it and says its definitely rears and replaces the rotors with Brembos and cleans the calipers and hub mounts and puts the Hawk pads back on total cost 310.00. I immediately drive the car straight to the highway it still shakes!!! above 55mph I call the mechanic back he says next step is to cut the fronts and to come back next week.
Please help i’m going broke and have spent over 1000 to fix this mess :(.
Why not just use the OEM brake rotors and pads? Until August when they wore out, they were just fine. I’ve had mixed results with aftermarket brakes, cheap and expensive. The factory OEM parts have never given me any issues.
It is not in today’s world you can turn the rotors a few times. A scratch coat to make sure the rotors are true might help, but I am afraid you have warped cheap rotors, quality parts for quality repairs.
Take the car out on a deserted road and run it up to about 50 MPH. Now slowly brake the car using the handbrake only.
If you feel a shudder it’s the rear. If you do not, it’s in the front.
Keep in mind that a brake shudder is not always caused by the brakes. A loose wheel bearing, worn suspension component, etc. can also cause this.
In every instance you mention that the vibration occurs while braking except one, step number 3, at which time the “Car still doesn’t feel right and shimmy’s, I try getting all four tires balanced and flushing the brake fluid total cost 100.00. No dice.”
How good are the tires on this car? Have they been rotated? Is each tire at the correct tire pressure? Tires (front tires especially) make a huge difference in how a car feels and drives and how safe the car is under even normal driving. Under extreme driving and stopping conditions, the difference can be life or death. I’m not trying to be dramatic. It just is.
Fot what it’s worth, if you have four good new tires inflated correctly, I think you are being jerked around by at least one mechanic. Vibration during high speed braking almost always means warped front rotors, but yours are allegedly brand-new. You replaced the rear pads, no new rotors but that should be okay for the rear brakes. If you have four good new properly inflated tires and new rear pads, the front brakes repair was substandard. And I’d bet the original rotors are still on the car, a lot thinner and even more subject to warping. Get the car to another shop for another look at at what’s going on.
Thanks for the help everyone and I really appreciate it a lot! A little more background on the car and situation may help. Its a 2008 Mazda 6i with 55k on it, with new General Exclaim tires put on at 42k . Back in August I did have all the pads and rotors replaced front and rear with what I thought were quality parts Hawk pads, Centric rotors from tirerack.com done by a neighbor “mechanic” who is friends with my dad (little worried on his mechanical ability.) Since the install it hasn’t braked right and shimmied over 55mph while braking, so now its on its third set of rear rotors after 300 dollars spent today and it still isn’t the same should I have the fronts turned or start looking at suspension issues? I know for sure I will stick to OEM and a certified mechanic next time, cause this is tapping into my engagement ring fund 
This car has been to four different mechanics for a brake pulsation, and nobody has put a runout gauge on it to figure out where it is coming from??? For some reason, this astonishes me, but so does doing an alignment and brake fluid flush to try to get rid of a brake pulsation. Checking the rotors for runout will tell you exactly which one or ones are causing the pulsation, and your mechanic can investigate from there. Another thought is the probability that whomever has been replacing your brake rotors has not checked for rust and scale on your hubs before installing the parts. Rust and scale will cause a runout problem and, therefore, a pulsation.
Are you sure this would test the rears? Some rears have a brake drum and shoes just for the parking brake. It wouldn’t test the rotors. If I’m wrong about the Mazda system, I apologize.
Thank you for the advice, I will have someone put a dial gauge to each of the rotors and hopefully I can put this 1,000 mistake behind me.
Like Mark, I too find it odd that nobody has done any proper diagnostic. This sounds like you either have residue on the discs (from lack of cleaning during installation) or a warped disc. As Mark said, a lateral runout measurement is in order.
There’s also a very simple way to check for residue and for parallellism of the disc surfaces simultaneously…while the car is on the rack, one can spin each wheel by hand while the brakes are slowly applied. If there’s inconsistant friction or poor parallellism of the surfaces (which can happen with vented discs) the bad disc will be felt as inconsistant resistance during spinning.
Another possibility is that your parking brakes were not properly readjusted during the brake job and are dragging. Mazda 6 uses the calipers as the parking brake mechanism rather than a small inner drum brake, so someone may want to review those.
The good news is that replacement of the discs on this vehicle does not require hub removal, so improper castle nut adjustment can be safely eliminated as a possible cause.
You’ve done everything right. You trusted your neighbor who’s a mechanic and you’ve brought it to a local shop for follow-up. Unfortunately, neither has done proper diagnostic work. Don’t let anyone cut anything until they’ve actually done the measurement(s) and the diagnostics. At this point you may even want to jack up each wheel and do the “spin by hand while slowly applying brakes” test yourself and see what you find.
Your post shows perfectly why people have extreme anxiety over having their cars worked on. It saddens me to realize that this stuff is going on.
Post back, whatever you decide. We care.
Rotate the tire and see if the shimmy moves. Belts can separate internally and the tread moves side to side causing the shimmy you feel.
When you replaced the rotors did you wash the coating off the new rotor before installing them?
You’re correct. I don’t think this car uses park brake shoes but if I’m wrong I apologize.
Rod Knox is also correct about washing rotors or drums before installation to remove any rust prevention film.
Sometimes that film is noticeable and sometimes it’s not. Even rotors and drums that are machined should be washed before installation to remove any oil and grime residue that is picked up from the road or the car they’re on.
First off, stop kicking yourself for buying those parts. Centric rotors are high quality - in fact, they’re often much higher quality than OEM.
Hawk pads are probably the second best pads out there, behind only Porterfield. I guarantee those are better than the comparative crap Mazda put on there from the factory.
I don’t think you should have the fronts turned. Turning rotors only makes them warp faster than they should. It’s pointless. I don’t think your rotors are warped.
Here’s the test for front vs. back shuddering - - Does the steering wheel shake, or do you just feel it in the brake pedal? If the steering wheel shakes, it’s the front. If not, it’s the back. That will tell you where to start looking.
Whichever it is, pop the wheels off and first look at the pads. I have seen people install them backwards. Not only does this chew up the rotor, but it causes all sorts of weird braking issues, up to and including a shuddering feeling. (it also makes a lot of strange noise, but some people don’t hear it). Next make sure the pads are where they should be - if they were installed at an angle, they could be binding and not contacting the rotor properly. That can definitely cause a pulsation in the brakes. If everything looks good, remove the caliper (hang it from a suspension part with a wire to avoid stressing the brake line) and then remove the rotor. Inspect the hub. Make sure it’s even, and there aren’t any blobs of rust on either the hub or the underside of the rotor that could cause the rotor to be off-level, which is another possible cause of your issues. Since this has happened on 2 sets of rotors now, you should pay very close attention to that hub, since the problem is more likely to be there than inside the rotor.
I know the mechanic has already looked at this stuff, but it’s Your car, and You care about it a lot more than he does. He might have missed something, and this is something you can do on a Sunday afternoon in your driveway with minimal equipment. Feel free to take photos and link to them here so that we can virtually look over your shoulder as you inspect this stuff.
Thank you for the very helpful posts everyone, so tomorrow morning I am going back to the local mechanic who says he is willing to make it right. I am going to ask him to throw it up on the lift and spin the wheels as stated to see if there is any friction when the rotor spins, secondly I am going to ask him to use a run out meter. His response last time was, nah that’s probably not the cause it’s those cheap rotors on the back. You are exactly right I am anxious as all heck to go for fear of just throwing more money at it. I am going to be firm with what I want checked and will let you all know the final outcome. Thank you for all the support.
I’ve often wondered how many mechanics even own any micrometers or a magnetic base/dial indicator setup to inspect rotors.
Faulty rotors (warped, parallelism issue, or whatever) is not a guessing game and for what it’s worth I doubt that cheap rotors are the problem.
I would hope that any mechanic who considers himself a professional would have these tools. I hear about some unscrupulous places and wonder if they even have a brake lathe due to the way they sell jobs. I had a shop manager who visited another shop once at the directive of the owner because she wanted him to watch them work “because they make a lot of money”. It’s almost needless to say that he hated the way they did things there. Every brake inspection was an automatic “calipers, pads, rotors, drums, hardware, shoes, wheel cylinders, brake flush” and the car never had a micrometer put to it. He said they did have a brake lathe, but it was sitting in a corner collecting dust, along with the micrometer, dial indicator, and spec book. They sounded like parts changers to me rather than mechanics.
I cannot in my worst dreams magine a shop that does brake jobs not having some form of dial indicator to measure runout. They aren’t expensive, and surface profile measurements are simply too much a part of the diagnostic process.
I can understand a shop’s choosing not to preferring not to “turn” and reuse discs and drums. Nobody wants to redo the job for free because the discs could not longer take the heat. I know there are min. readings, but I can understand a shop not wanting to fool with it.