warped rotors - why? - PeachParts Mercedes-Benz Forum

Will_w202 · #1 06-14-2007, 10:37 AM

I went through 150k on original rotors and 90k on pads with NO issues after purchasing this car under warranty at 61k. I bought Mercedes parts-counter rotors and Pagid pads from Phil's store. They are warped with 5k on them.

WTF?

mbdoc · #2 06-14-2007, 11:04 AM

That is an excellent question. Excessive heat is the Most common answer.

I have never had warpage problems on any of MY cars OR trucks except my Toyota truck & they installed modified rotors, pads & calipers on it & they still warped!

Will_w202 · #3 06-14-2007, 11:16 AM

So, heat? Nothing has changed that would cause heat buildup. The car sits on AMG 2002-2004 style split-spoke wheels, which get PLENTY of air. There is no obstruction in either brake vent at the front of the wheel wells.

What can be done? I'm tempted to call the parts counter and find out if they're selling knock-offs.

?????????

mespe · #4 06-14-2007, 12:48 PM

I believe if you don't tighten the lug nuts properly,,, i.e. every other one, the rotor can warp, or if the lugs are over tightened,,, Of course a bad rotor from the git-go is self-explanatory,,,

gmercoleza · #5 06-14-2007, 11:29 AM

It's not so much heat as it is rapid and marked change in temperature. Ever hear an ice cube crack when you put it in a glass of water? That's because the instantaneous temperature differential causes the ice to warp and crack.

Imagine slamming really hard on the brakes, or using them on the highway slowing down from 70mph to 30mph (exit ramp), and then running through a puddle of cool water. The result is going to be warpage. There are a hundred normal everyday-type driving scenarios under which the same result can occur. Which is why I go with the cheapest rotors I can find.

Will_w202 · #6 06-14-2007, 11:33 AM

well, that's fine, but I bought these because I was told they were the BEST rotors, and as I'd seen 150k on the last set of OEM rotors, which FYI were the ONLY set of rotors on ANY car I'd ever owned that DID NOT warp or require turning, I figured they were the way to go.

My driving style has not changed in the past 5k, and I"ve put 95k on this car. 90k no problem, the next 5k, problems.

No valid explanation yet,.

truckinik · #7 06-14-2007, 11:32 AM

One time, of accidentially riding your brakes down a hill, or getting them wet while they're hot, is all it takes to warp them. ( I.E. Car wash, after some driving, puddle, etc.)

Are you a two footed driver..?

General rule of thumb though, is to cut them once before installing them. I've seen plenty of brand new ones come right out of the box warped, simply from the heat created while machining them at the factory.

gmercoleza · #8 06-14-2007, 11:36 AM

Like said before, it is just a random occurrence and probably has nothing to do with your driving style. It just happens. The price and build quality of the rotors doesn't have as much to do with warping as we would like to think. Heat up a nice high-performance cross-drilled rotor, run it through a puddle, and it's going to warp just as easily as the $30 KIA rotor.

Will_w202 · #9 06-14-2007, 11:42 AM

truckinik · #10 06-14-2007, 12:04 PM

Well, fact be told, that no matter who's name is on the box, all rotors, and things like that are made in China these days, by the lowest bidder. They start out as a huge chunk of the cheapest steel they can buy, or get away with, and it's inserted into a an even bigger machine, which over a course of the next few hours, spits out rotors one after the other. All they do next, is swap out the tooling, and make them for the next, Year, Make, and Model scheduled for the day's production...

I've visited, and toured many companies of which do this, in many parts of the world, and seen it in person..

It does not matter who's label is on the box, Just like electronic items, like car stereos, and T.V.'s etc.

Did you know that there are only TWO companies in the world producing televisions..? Yet, How many name brands are on the market..? Same thing, just different products.

Surf-n-Turf · #11 06-14-2007, 12:09 PM

Do the MB rotors warp if torqued too tight or wrong sequence? I have heard of it happening on other makes/models before. I have never used an impact wrench on lugnuts just for that reason.

gmercoleza · #12 06-14-2007, 12:15 PM

As a rule of thumb, any mechanical part which has a specified torque measurement and pattern can warp if these are not observed. I would think it more likely that the wheel would warp rather than the rotor, though I suppose it is possible.

Will_w202 · #13 06-14-2007, 12:20 PM

if I remember correctly, the only thing holding the rotors on is a hex screw of some kind. Maybe 2. Really no way to overtighten that, and it's really small anyway. Lugnut torque would be the culprit, but as always, I hand-tightened them.

Parrot of Doom · #14 06-14-2007, 07:25 PM

Quote:

Originally Posted by Will_w202

if I remember correctly, the only thing holding the rotors on is a hex screw of some kind. Maybe 2. Really no way to overtighten that, and it's really small anyway. Lugnut torque would be the culprit, but as always, I hand-tightened them.

That screw holds the disc in place to stop it falling on your foot when you remove the wheel

It is the wheel bolts that hold the disc to the hub.

OP: are you certain they're warped? It seems more likely that a buildup of pad material has occured.

Will_w202 · #15 06-14-2007, 08:09 PM

I know my car well enough to know when a rotor is warped. 95k in 3 years on this one, abuot 400k in other cars of various makes and models.

When I begin to slow down, anything under 25mph or so, I get the usual uneven-feel stop, and then as it comes to a stop it will grab and just - well, stop. You know what I'm talking about, and you also know it IS a warped rotor (or 2)

"you drive you get warped rotors" is not a valid answer BMW. Out of about a dozen cars I have owned, this is the ONLY car that has never warped rotors (until this set), in 90k of driving. I've put more miles on this car than any before it, and ALL of them warped their rotors at regular intervals. I believe what I've heard when MBDOC says MB rotors are superior - so, either my MB shop went to cheap replacements, or I have bad luck.

No sense in any more replies. I'm just going to pay to have them turned. makes sense to me.