Rotor warping yet again

I respectfully disagree.

The rotor itself isn’t “bent” or “twisted” although the surface could be uneven.

To each his own. Have a great day.

 

150000 still on the OEM rotors, almost 3/4 good. replaced the pads at 130 with OEM pads and no problems.

 

Exactly it’s uneven transfer of brake pad material.. from heat, improper break in, corrosion, improper torque.

 

How does improper lug nut torque cause pad material transfer?

As i mentioned earlier, material transfer does exist but differences in metal density can also cause high/low spots between the two sides of the rotor. The metal does move. Is gets squeezed where it is soft(er) resulting in a pulsation (just like material transfer resulting in high/low spots).

When I resurface a warped rotor on the brake lathe, the catch bin below the rotor is full of metal shavings, not pad material

When they make nice (more expensive) rotors they pay more attention to making sure the metal has the same density all the way around. The cheaper rotors are made out of molten metal that is whipped up like whipped cream (so they can make more rotors out of the same amount of material). Ever seen coolant weaping through a late 90s Saturn engine block? Same problem.. metal that isnt dense enough.

The weight can tell you a lot too, rotors made with denser metal will often be heavier than the cheapies

 

I really don't think that saying Warped rotors are bent rotors, theres 2 things that will cause vibes in the front end braking #1 would be Rotor runout caused by improperly torqued Lugnuts, #2 the Rotor itself worn down below its minimum thickness of 26mm or less. these people who are constantly saying their rotors are warped are more than likely overheating the brakes to the point of burning the pads to the rotors and causing an uneven surface to the rotors because of burnt residual pad material sticking to the rotors

 

Rotor warping yet again....

I think you just answered your own question.
Stop & Go Traffic.

 

that, or the pads he has on the truck aren't or weren't yet bedded properly even with 15k miles on them

 

went 100k miles on OEM rotors and pads.... never any pulsating at all. Only replaced the rotors when i replaced the pads (both oem) simply because why not. 150ish bucks for rotors that will last me 100k, aint even worth questioning and not worth dealing with having to replace mid cycle on the pads.

OPs problem is either driving style or a dragging pad.

 

If the clamping force isn’t even across the surface how can you expect it to run true? If the lateral run out is out of spec using a dial indicator it’s gonna cause uneven transfer as the miles pile on.

This explains it well. The lugnut torque is towards the end.

https://www.mechanic.com.au/news/solved-the-mystery-of-warped-brake-rotors

you can actually place something as thin as a piece of electrical tape on the hub under the rotor and throw your lateral run out out of spec. This is why most car dealerships require using an on car brake lathe that takes any corrosion build up between the rotor and hub into account. You can turn them off the car and be right back to square one in a few thousand miles if the hubs weren’t cleaned properly and everything torques down correctly.

 

You're answering a different question. You said "its uneven material transfer.. caused by --,---- , ----, improper torque".

I know that a uneven hub will deflect the rotor and make it runout.. but i dont see how a rotor with runout is going to make pad material suddenly jump from the pad to the rotor surface. I understand that holding the brake pedal down hard when the brakes are hot causes the material transfer..

What im saying is, both conditions exist. Runout caused by material transfer and runout caused by weak/soft spots from poor casting.

And technically, runout is the incorrect term. The correct term is "out of parallelism ". The two sides of the rotor not being perfectly parallel. Again, "not parallel" because of pad material building up on the rotor surface or soft spots in the metal allowing the two sides to "squeeze" together. You could see this with a dial indicator but that only looks at one side. A micrometer would reveal the "out- of- parallelism" between the two sides if you checked it all around.

Technically, runout is when a wheel bearing is loose or the hub surface is bent (or covered in corrosion like you mentioned) while the rotor is still straight/true. That lateral deflection can be seen with a dial indicator.

I'll say it again, anyone who has actually resurfaced a rotor on a brake lathe understands that the metal moves and changes thickness! The rotor can have thin spots and thick spots. You'll see it as soon as you run the cutting bits in and they make contact. The catch basin below the lathe is 95% metal shavings and some rust, not 100% pad material

 

I’m trying to figure out how to word this better.

If the rotor is completely true and not “warped” it should be running evenly between the two brake pads.. If it isn’t and it’s wobbling back and forth between the two pads this is where the uneven pad transfer happens. Which if all the lugnuts/wheel aren’t torqued evenly can occour since the rotor isnt evenly clamped across the hub.

 

I hear ya but disagree.. material transfer doesnt happen when the rotor is spinning (warped, straight or otherwise). When the rotor is spinning the pad material just flings off as dust and ends up on the wheel spokes (picture BMWs with dirty front wheels) and in the air.

The transfer of material happens when you're stopped at a stoplight, at the bottom of a long hill when the brakes are really hot (like hotter than normal braking) and you keep the pedal firmly pushed down. The rotor has to be stationary (not moving) for the transfer to happen.

 

I understand. But agree to disagree lol.

 

This bedding properly bullshit is ridiculous, very few are running cryo rotors. If you want to "warp" (disfigure, transfer material, whatever you want to call it) then go ahead and do 10 passes from 60 mph to 10 mph all in short span. Toyota does not have a team that takes every new vehicle that comes off the assembly line and breaks in your pads. I have also never seen a new vehicle with directions of how to "bed" your breaks. The TRD pads do state this method but they also state you can just drive the vehicle normally to do this (I also think the TRD pads are a waste).

As stated above by many others, check the calipers aren't sticking. The installation of the wheels is important also. An impact will not torque the lugs uniformly. I don't care what whiz bang gizmo torque sticks the shop has. I have had a many 3/4 ton trucks and until the last I've never had "warped" rotors until now. I also used to rotate my tires myself. Now I'm just to damn old to lift that shit (maybe lazy too).

Heat is the only thing that causes these problems. Caliper sticking, stop and go traffic, mountain decent, 60 mph to 10 mph ten times, etc.

 

This thread is very entertaining

 

A lot of the confusion can start with the over-use of incorrect terminology

Copied /pasted from google

-What is rotor runout for brakes?
ROTOR RUNOUT. When a brake rotor deviates from its axial plane viewed from the front edge of the rotor, this refers to a "wobble" of the rotor as it rotates.

-What is rotor parallelism and how is it checked?
Parallelism refers to variations in thickness of the rotor . ... To check a rotor's parallelism, measure the thickness of the rotor at eight different spots. Courtesy of American Honda Motor Co., Inc. Lateral runout. Excessive lateral runout is a wobbling of the rotor from side to side when it rotates.

-What is the difference between disc run out and parallelism?
Runout in the hub and a new rotor can stack up to cause lateral runout that's beyond the specifications.

The main culprit of chronic pulsation is disc thickness variation (DTV) or parallelism. ... The allowable tolerance is known as parallelism, also referred to as the rotor's DTV.


Say what you want about just googling shit but they're not wrong. If you sit through any basic high school/trade school brake class this is the stuff you're going to hear

 

The only rotors on any of my cars that have “warped” have been ones that I didn’t bed in. And Toyota states no hard braking for the first 500 miles as I’m guessing to do an easy bed in of brakes

 

I don't care to read through every post. Might have been covered already. If so, carry on. On the first page, there is some accurate information.

If you want to determine if your rotors are warped, use a precision edge setup yourself, or have a shop that can turn rotors show you.

It is metal. They can warp, no matter the manufacturer. Just depends on a lot of variables. Have seen it and dealt with it. No biggie.

As for pad material transfer, yup, that happens too. Annoying. Do a bed in procedure. Following the instructions of Stop Tech, Wilwood, Brembo, etc.... Works wonders.

Finally, critique your driving environment and self. You'll come to the what is the root source soon enough.

 

I thoroughly enjoyed all the comments about what "warping" "is", b_r_o, Greenedmc, eccracer104. Good to see not stupid informatino here. But we all know what OP means, customer walks in, you know what they mean.

Are you nose diving your truck then going right through a car wash? haha