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Myths of the Braking System | Brakes-shop.com

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You can "warp" rotors in one session if you really want to. Get them checked or look at them, if it's bad you will see the pad deposits or uneven wear.

 

"Warped rotors" is definitely the common term for a pulsating brake pedal, but the rotors are almost never actually warped from what I've read. It's an undeven deposition of pad material onto the rotor surface. Proper lugnut torque seems to be the best way to prevent it. That means fastening your wheels on with a torque wrench and re-checking torque after 100 miles of driving.

Once they're pulsating you can sand the rotors and pads, or have them turned, or replace them.

 

"Warped rotors" is definitely the common term for a pulsating brake pedal, but the rotors are almost never actually warped from what I've read. It's an undeven deposition of pad material onto the rotor surface. Proper lugnut torque seems to be the best way to prevent it. That means fastening your wheels on with a torque wrench and re-checking torque after 100 miles of driving.

Once they're pulsating you can sand the rotors and pads, or have them turned, or replace them.

Which driving habits cause differential thickness in rotors?

Who said anything about thickness in rotors? You yourself mentioned that it was uneven deposition of pat material onto the rotor surface. This could certainly be due to driving habits.
Uneven torque would be most likely to actually warp rotors, not somehow make them thicker in some areas than others.

 

My opinion is lug torque is kind of a myth. Most people go to shops who likely over torque
Driving habits is the most likely culprit of "warped" rotors

 

This is a very silly thing to believe. Proper torque-to-spec or at least uniformly torqued (be that over or under-torqued) means uniform clamping force is distributed across the lugs. This is absolutely critical to avoid runout, especially on a part of the vehicle which can be subjected to upwards of 2000+ lbs of force at any given time. That's incredibly important to torque down properly.

 

I'm not sure you guys read the above scholarly-quality article... Did you read about conversion of some of the cast iron disk surface to cementite, for example? What about the proper bedding-in procedure?... It's an informative article!

 

"Scholarly-quality article... " ?

How do you feel about this statement?

As the braking system in [sic] not quite airtight, a significant amount of water can be absorbed from the atmosphere in the course of a year. A 3% water content in brake fluid drops the boiling point as much as 170 degrees F. Brake fluid should be completely replaced annually.

 

Carroll Smith is a Racing engineer. If you research him you would similarly conclude. If you read that article, in its entirety, I believe you would conclude that much- if not all of what was said has merit.

Unless of course, you too, have similar credentials...

 

Annual brake fluid replacement though... Otherwise, yeah. Decent info there. Probably is news to some people for sure. No doubt the average schmo buying "performance" brakes for their DD has had problems with deposition induced pulsation. So it's great that a site selling such things can point to an article like that when dealing with return authorization requests.

As for Mr. Smith... he should be downgraded to "was" a racing engineer as of 2003. RIP

 

I agree that 1 x / year brake fluid changeout is excessive. But 1 x / 2 years seems reasonable. Few practise that.

Having said that, if it IS done, I imagine that caliper piston problems and master cylinder problems are fewer, perhaps by quite a bit.

Also, it bears saying that the clutch master and clutch slave should be included in the flushing.

Yeah, Carroll Smith WAS a Racing Engineer... hehe.

 

I mean in the sense people would rather believe someone torqued their wheels wrong than learn/admit their driving habits may not be ideal.

 

Which driving habits cause differential thickness in rotors?

 

I have had different issues with my old rotors and pads. From a vibration to severely rust on the rotors. This is not an endorsement but 18 months ago I changed to Power stops on my 2015 madza 3 and all my issues have stopped. Plus they are like $142 with pads per axle.

 

I put power stop rotors and pads on all 4 corners and within 2 months I had SEVERE pulsation from the front brakes. The rotors looked like hot garbage. Rockauto replaced them for free under warranty. The current ones are starting to show signs of pulsation but it hasn't gotten severe yet.

No effing clue, very frustrating.

 

In the original article 'way-up in the thread, Carroll Smith (an engineer with the Shelby program... now deceased) speaks of (in extreme situations, presumably) the cast iron of the brake rotors being metallurgically-changed to cementite - which is harder than the surrounding matrix of cast iron. Unless the layer of cementite is removed (by the special grinding-process Smith talks about) - well, the pulsation comes back - I think - 'real soon. So it is NOT just the differential deposition of brake lining material that is the issue, but the varyining / differential surface hardness that is ALSO causing an issue...

 

Extreme cases to be sure, mostly in racing applications. You would have to heat the rotor to at least 1300°F to begin the transformation to cementite. That would destroy most street car pads.....
The usual culprit here is run-out caused by poor installation. If the mating surfaces are not clean the rotor will have axial run-out, it will wobble side-to-side. Excessive run-out causes the rotor to come into contact with the pad at the spot where the run-out is at its maximum even when not using the brakes. Most common street car pads have pad material that is adhesive, that is it transfers to the rotor forming a layer of friction material on the rotor surface. Normally when the rotor is installed properly the pad transfers a nice even layer (proper bedding). However, if the pad is rubbing on one single spot on the rotor all the time due to run-out, that spot will develop an ever increasing layer of pad material and sooner or later you'll start to feel the brakes start to vibrate.

 

Wasn't expecting so many replies. Thank you all.
I showed it to two mechanics both said it's due to warped rotors. I took it to a third local mechanic and he replaced all four pads and front rotors.
I got Riley's Premium Rotors. ~$120. I drive normally and brake from a far away distance. Let's see how many miles these rotors are useful I drive 120mi a day.

 

It's an absolute nightmare. The OEM fronts had extreme pulsation at around 80k miles, very bad when braking from highway speeds, shook the wheel. Jerked a lot when coming to a stop, pretty obviously grabbing on a high spot every revolution on one or more disks.

I did all 4 corners, rotors and pads, with Powerstop OEM-style rotors and pads from Rockauto. I greased the pins, replaced the hardware, bled the brake fluid, bedded the brakes, even took them up into the mountains on the Tail of the Dragon to really break them in, whole 9 yards. Within a few months and only a few thousand miles, the fronts pulsed severely again. Rockauto replaced them under warranty for me, I installed the new rotors and sanded the pads flat. Plenty of life left, never really needed to replace pads front or rear from OEM, but the pulsation was impossible to ignore and extremely annoying.

2nd set of new rotors on the front started pulsing again shortly after. No amount of hard braking to re-bed them fixes it. I drive a flat commute to work everyday, no hard stops, nothing crazy, I brake like a grandma coming to a stop, and they are pulsing severely AGAIN. I did a ton of hard hard stops coming down the mountains, rode the brakes to get them hot, lots of 45-5 stops, they just keep getting a pulsation. Sometimes its the fronts, sometimes it seems to be the rears, sometimes the steering wheel shakes, sometimes not. It comes and goes in intensity, but the shuddering is always there after just a few thousand miles on new rotors and pads.


What gives? I don't drive my car hard 95% of the time, but my brakes keep pulsing even with tons of life left, on OEM rotors at 80k miles, and on Powerstop replacements after just 5k miles.

2014 Mazda 3 Base (iTouring) w/6MT. Living in Florida. 98k miles.

 

It's an absolute nightmare. The OEM fronts had extreme pulsation at around 80k miles, very bad when braking from highway speeds, shook the wheel. Jerked a lot when coming to a stop, pretty obviously grabbing on a high spot every revolution on one or more disks.

I did all 4 corners, rotors and pads, with Powerstop OEM-style rotors and pads from Rockauto. I greased the pins, replaced the hardware, bled the brake fluid, bedded the brakes, even took them up into the mountains on the Tail of the Dragon to really break them in, whole 9 yards. Within a few months and only a few thousand miles, the fronts pulsed severely again. Rockauto replaced them under warranty for me, I installed the new rotors and sanded the pads flat. Plenty of life left, never really needed to replace pads front or rear from OEM, but the pulsation was impossible to ignore and extremely annoying.

2nd set of new rotors on the front started pulsing again shortly after. No amount of hard braking to re-bed them fixes it. I drive a flat commute to work everyday, no hard stops, nothing crazy, I brake like a grandma coming to a stop, and they are pulsing severely AGAIN. I did a ton of hard hard stops coming down the mountains, rode the brakes to get them hot, lots of 45-5 stops, they just keep getting a pulsation. Sometimes its the fronts, sometimes it seems to be the rears, sometimes the steering wheel shakes, sometimes not. It comes and goes in intensity, but the shuddering is always there after just a few thousand miles on new rotors and pads.


What gives? I don't drive my car hard 95% of the time, but my brakes keep pulsing even with tons of life left, on OEM rotors at 80k miles, and on Powerstop replacements after just 5k miles.

2014 Mazda 3 Base (iTouring) w/6MT. Living in Florida. 98k miles.

Do you clean and sand the hub face and sides before mounting the rotor?

 

My theories on the sources of my reocurring problems:

-the caliper pistons are stuck since they're 6 years old and have never moved their full stroke in the life of the car. (neither front nor rear pads ever wore down to the squealers)

potential solution - unstick them by compressing and extending them a few times, or install rebuilt calipers



-the slide pins are sticking since I likely over-greased them with brake parts grease when I did the brakes, and they likelgot sticky around 80k miles on the OEM install

potential solution - pull them and clean them and the slide pin bores out completely, regrease with a very light application of Moly paste (I have some Honda M77 Molybdenium disulfide paste on hand already)



in addition I plan to block sand the rotors and pads again while I've got everything apart


Let me know your thoughts, and I'll repost here after I attempt these fixes once I can get down to my dad's garage some weekend soon.

 

Cleaned the rotors, installed new pads, polished the slide pins, greased them, flushed the brake fluid and bedded the brakes.

Still had pedal pulsation, intermittent steering wheel shake, and a new problem popped up where the clearance of the slide pins in the bores was too much (too loose) and the caliper would rattle on the brake assembly, clunking over speed bumps or rattling over washboard roads. Mexican brakes, nobody sells just the slide pins, only the ENTIRE caliper assembly. The slide pin clearance may have been an issue from the factory, or they wore out really early, because the pads were tapered after only about 10k miles of driving.

I got tired of all the messing around for a car that I wasn't really excited about anymore, and pretty disappointed with the quality of the Mexican brake assemblies and the integrated parking brake mechanism, and was looking for excuses to sell the car in favor of a pickup.

2014 Mazda 3 6MT w/98k miles got $4,000 trade-in value. I got a good 80k miles out of it, and it was a pretty reliable commuter, but the heart wants what the heart wants, and now I own a Nissan Frontier 4x4.


Goodbye forum, goodbye Mazda.

 

Good luck with the Nissan. Thank you for sharing all the while. Will miss an articulate Forum member...

 

Yes. I hope you enjoy the 4x4 life.

I am actively searching for a way to replace my rear Mexican made brake setup. The fronts are easy, but there is almost nothing out there for the rear.

The only BBK kits I've seen installed were with Brembos using a Chinese adapter.
CK

 

Yeah the Mexican rear brakes are ass. I did figure out how to mitigate the pads seizing but if you want an upgrade there's not a lot out there.