+1 on the bedding

I have read numerous times by people who really know brakes, that "warped rotors" are practically a myth.

From the link mentioned previously:

The all-important transfer layer

. . . the objective of the bed-in process is to deposit an even layer of brake pad material, or transfer layer, on the rubbing surface of the rotor disc. Note the emphasis on the word even, as uneven pad deposits on the rotor face are the number one, and almost exclusive cause of brake judder or vibration.

Let's say that again, just so there is no misunderstanding. Uneven pad deposits on the rotor face are the number one, and almost exclusive cause of brake judder or vibration.

 

Except for the imperical evidence. I've been driving for more years that you are likely old and I've only even tried to bed my brakes once, and it was a joke. Once the bad rotor was replaced, the problem went away. Most people will NEVER bed their rotors and NEVER have this problem. You just don't have to do it. Can you imagine what it would be like if evrery Midas shop told every grandmother who walked out the door that she now had to bed her rotors. Kind of makes you want to chuckle.

 

Emperical evidence - -> bedding fixed "warped rotors" on on two of my vehicles in the the past, and 3 different friend's vehicles. Not a huge sample, but 5 for 5. : )

LOL on the Midas shop example. That really did make me chuckle.

I do agree it is very rarely necessary to bed brakes for normal use, but I also think that if a vehicle's brakes are pulsing, then it is worth trying, before replacing parts (unless they already should be replaced because of wear etc. anyway)

 

This is COMPLETELY FALSE and inaccurate and I advise you to stop listening to whoever is giving you info on brakes. "Warped" is not the technical term for it, it's just what mechanics say. The technical terminal is "Parallel Runout" or "Rotor Thickness Variation" and there is a tool called a Runout Guage that is specifically designed to measure rotor warpage. If the runout is out of spec, more than 0.02-0.05" (depending on the vehicle), then it could cause a vibration. You can see the evidence that warpage is indeed not a myth the moment you put a rotor on a brake lathe and start to resurface it. The blade bit will not touch the low spots on the rotor surface and will only catch the high spots until you start shaving more off. If the rotor runout, or warpage, is too high, by the time you get a smooth, even cut, your rotor could be too thin to even use on the vehicle. So I don't know who you got you're info from, but that's not correct bro!

The info you gave about pad deposits on the rotor surface is more accurate for people that don't drive the vehicle every day and have the vehicle sitting for days or weeks at a time. But for people that actually use their vehicle every day, this almost never happens, unless it rains.

 

What is the bedding technique you used on these 5 vehicles?

 

By myth, I did not mean that rotors never get dimensionally out of spec, I just meant that according to some "experts" -> a large percentange of times a pulsing brake is probably not caused by a deformed rotor . . . It would be interesting to know in cases where rotors were replaced, how many were actually measured to determine if out, or just replaced and it fixed the problem.

I am far from an expert, just sharing the words of experts. The quote earlier was from professionals at Centric Parts (StopTech). They should know what they are talking about. . . I have read articles from equally qualified professionals. Granted, these articles tend to be aimed towards a high performance audience, but I think it applies to everyday also.

On forums like these there will always be differing opinions, everyone can listen, analyze, and decide what makes sense. Personally, I think "bedding" makes sense, and I have personal experience that it fixed my pulsing brakes.

 

Two different techniques:
1) the sequential "fast stops" from approx 60-5mph, approx. 8 times. I can't recall exactly how many cycles.
2) drove to top of curvy mountain pass on a day without much traffic, then drove back down at a brisk pace. This was much more fun.

There is some debate on here about whether a bedding process is necessary on everyday cars. I don't think we need to go thru the detailed fast-slow process, but if we get the brakes hot, and DON'T come to a STOP while hot, then this evens out the coating on the rotor.

edit:
Part of the trick is "how hot"? . . Racing pads require different temps than commuter car. . . In my case, once the brakes started fading, I quit.

 

Well, as an experienced technician, ASE certified in brakes, I can tell you that most times it is caused by warped rotors. Simply replacing the rotors is not the answer. You have to actually measure for the runout, and measure rotor thickness to see if they even have enough meat to cut. Most times you can cut them. A lot of places just service the rotors and throw the old pads back on. But the answer is to replace the pads as well because they start to wear to the old rotors. Only problem with cutting rotors is the thinner they are, the quicker they warp again. I actually prefer to replace them, but if spec says they can be cut, you have to let the customer decide.

Bedding too much can overheat and glaze your pads and make them worse, so you have to be careful with that, especially with new pads still within the break in period.

 

So you obviously have a lot of "real world" every day car experience! The "experts" I am quoting, may be looking at a totally different perspective of high performance aftermarket equipment when they say a large percentage of problems is even coating, not deformed rotors.

Now the question is, where does a brand new Durango fit? . . Which is most likely. . . If it was mine, I would take a trip to the nearest mountain pass and heat those brakes up.

BUT, not heat them up TOO much! : )

 

I can't believe all this for a simple problem.
1- Truck is Brand new and under warranty
2- Take it to dealer and let the warranty worry about the repair.

I'm no mechanic but I have been driving long enough that when I had this problem I took vehicle back to dealer and insisted on new rotors. Condition corrected.