Front brake problems

[rigtec]

it doesn't sound like this guy is much of a friend, nor is he an honest mechanic. at 15,000 miles, the rotors were still pretty much new. the pulsation/vibration isn't from the rotor being warped, but instead uneven friction material buildup. there was plenty of meat left on your rotors. they could have easily been resurfaced.

I suggest a different shop next time.

Hi nevada,

...sorry to disagree, but I was with him when he mounted a FIXED caliper (wobble measuring tool) to the spindle to measure the distance the rotor was 'Un-true' and there was quite a bit of wobble, due to the heat created by the constant pressure against the rotors (both L & R).

The rotors traveled a good distance (in mm) from side-to-side during normal driving; I just didn't notice it until it got severe because I don't use the truck on the highway very much... hence the low mileage! Thanks for your reply and 'Best to you',

rig

 

[jhguth]

Hi nevada,

...sorry to disagree, but I was with him when he mounted a FIXED caliper (wobble measuring tool) to the spindle to measure the distance the rotor was 'Un-true' and there was quite a bit of wobble, due to the heat created by the constant pressure against the rotors (both L & R).

The rotors traveled a good distance (in mm) from side-to-side during normal driving; I just didn't notice it until it got severe because I don't use the truck on the highway very much... hence the low mileage! Thanks for your reply and 'Best to you',

rig

Rotors dont warp, pad material is transferred, so if they are low mileage there is still plenty of material and they can be turned

I think what they used is a runout gauge which just showed that the surface isn't flat

 

[adamsrotors]

^ well, yes they do warp, but you are right...they are prob. glazed. turning is also not the only solution...try re-bedding them and doing to HARD.

you can read more about this and the transfer of pad material to rotors, HERE in our FAQ's.

 

[progress4m]

... do not hold the vehicle still with hot brakes, which causes the transfer of pad material to the rotor, causing the "warped rotor" symptoms.

That and do not overtight your lug nuts… I strongly believe both of those are biggest contributors to vibration during baking ("warped rotor" symptoms).

It worked for my 3rd and 4th gen 4runner (4th gen was used a lot for towing,)… I have changed front pads and rotors on both when they were well past 100k mark…
Always used OEM brake pads for replacement -just do not get the cheaper one (dealer calls them "warranty replacement" parts), buy the one that is truly OEM part (made in Japan).

 

[jhguth]

^ well, yes they do warp, but you are right...they are prob. glazed. turning is also not the only solution...try re-bedding them and doing to HARD.

you can read more about this and the transfer of pad material to rotors, HERE in our FAQ's.

They dont, the temperature to warp the metal is well above the temperature of the rotor

They need to be rebedded but doing so without turning the rotor is a waste

Sent from my SM-G930V using Tapatalk

 

[rigtec]

Rotors dont warp, pad material is transferred, so if they are low mileage there is still plenty of material and they can be turned

I think what they used is a runout gauge which just showed that the surface isn't flat

Listen...

What's your point; 'I WAS THERE' (you were not)! And I saw the fatigued, overheated metal rotors starting to turn blue and wobbling badly, so "I authorized the work"! I also worked as an auto tech for many, many years, so just let it go! Don't EVER tell anyone that steel/metals don't warp or fatigue from extreme heat cuz it does! ...'Let it go'!

rigtec

 

[Jetboy]

They dont, the temperature to warp the metal is well above the temperature of the rotor

They need to be rebedded but doing so without turning the rotor is a waste

Sent from my SM-G930V using Tapatalk

Brakes experience combined heat and fairly extreme internal expansion forces. Not uncommon to exceed 50,000 psi of internal force due to thermal expansion. If they heat unevenly or heat more near the center they don't expand radially but expand laterally causing a run out. And can cause plastic deformation (not returning to straight). So, yes rotors absolutely do "warp". They also crack. And glaze. Lots of ways to fail.

 

[jhguth]

Listen...

What's your point; 'I WAS THERE' (you were not)! And I saw the fatigued, overheated metal rotors starting to turn blue and wobbling badly, so "I authorized the work"! I also worked as an auto tech for many, many years, so just let it go! Don't EVER tell anyone that steel/metals don't warp or fatigue from extreme heat cuz it does! ...'Let it go'!

rigtec

But that's a common myth, it looks wobbly from the uneven rotor. It's a common myth that the metal actually warps


http://www.stoptech.com/technical-support/technical-white-papers/-warped-brake-disc-and-other-myths

http://www.hendonpub.com/resources/article_archive/results/details?id=1787

https://alconkits.com/support/brake-pad-info/110-the-real-truth-about-warped-brake-rotors

http://www.brakeandfrontend.com/warped-rotors-myth/

Etc...

 

[Jetboy]

Use google scholar. Lots of actual science has been done. Or go use a brake lathe in a brake shop for a day. Or ride a mountain bike once. There's no question that rotors can be permanently deformed by thermal expansion forces.

 

[rigtec]

Brakes experience combined heat and fairly extreme internal expansion forces. Not uncommon to exceed 50,000 psi of internal force due to thermal expansion. If they heat unevenly or heat more near the center they don't expand radially but expand laterally causing a run out. And can cause plastic deformation (not returning to straight). "So, yes rotors absolutely do warp". They also crack. And glaze. Lots of ways to fail.

Thank you Jetboy...

for using your brain, a technical, theoretical approach to your point, and 'most of all'... just good ole' common sense! For a moment I thought that a cognitive rationale was a thing of the past (I'm getting tired of lies, folklore, B/S and hearsay being perpetuated here on this Tech-Support forum); kudos for restoring my faith! 'Best to you and yours',

rig!

 

[dade73]

I kept getting that shimmy. I would hit the rotors with a brush when washing and it would stop for a little while. then it would start up again.

Smoked through the TRD pads. rears only lasted 14k miles

Went and upgraded all 4 rotors to the Power Stop Z36. and the pads to the ceramic dustless pads. I haven't had an issue since. I figured I was going to be adding weight to her soon, I wanted to be able to stop.

Yes I have had to get on it partially a few times. almost ate the steering wheel she stopped hard and fast!

That has been 20k on them, no issues at all.

 

[1996_Valencia_Owen]

Most "warping" is from Chinese (or true oem-country) pig iron rotor castings being done crappily/cheaply/quickly.

Cold-treated rotors stuck in an oven and then left to sloooooowly cool do the best.

The "warping" is 99.999% the result of nonhomogenous pig iron TEMPORARILY deforming and heating unevenly, based on diff mixes of base metals in diff areas of the rotor. This makes pad glazing stick to the rotor differently in those spots. Also can make them wear unevenly.

The basic size and spec of the 4Runner rotors is awesome, tho.

For example, the Lexus GX460 which weighs 500 lbs more and has 30+ torque more, uses identical brakes. So even with that extra heft, theyre capable of meeting Lexus' high standards.