Why and When Do Brake Rotors Warp? - PeachParts Mercedes-Benz Forum

shertex · #1 05-06-2011, 08:17 AM

Just lookin' for some basic education....did a few searches and didn't find anything.

Why and when do brake rotors warp?

If rotors going to warp, does it usually happen early in their life?

Does warping indicate a manufacturing defect? Or not necessarily?

If not, then what are the external factors that cause rotors to warp?

Thanks!

woodboat3 · #2 05-06-2011, 08:28 AM

They warp from heat. When new they are thicker making it better at dissipating the heat. Now from where the heat comes is a whole other thing. For example a stuck caliper can drag and overheat a rotor.

charmalu · #3 05-06-2011, 09:31 AM

I did a Google search "warped brake rotors" hours of reading enjoyment.

Here is one:
Root cause of warped rotors?

Charlie

connerm · #4 05-06-2011, 10:00 AM

Brake rotors warped on my Taurus because king kong at the emission/safety check station overtightened the lug nuts. After they ruined one set of rotors, I always insist on torquing lug nuts myself with my torque wrench following the inspection. They laugh at me, but I don't care. Filthy animals.

Diesel911 · #5 05-06-2011, 11:52 AM

I am guessing that Made in China or India Brake Rotors are more likely to warp due to the lack luster quality control that seems to come from those areas or the Mcparts sellers that buy them do not care to insure quality control.

When speaking of heat driving habits make a difference. If you are a person that accelerates fast between Traffic Lights and stops hard when the Traffic Light turns Red you are a candidate for warped Brake Rotors.

I also suppose if your Wheel Bearings play is not adjusted properly that also puts more stress on the Rotor.

warmblood58 · #6 05-06-2011, 12:02 PM

I put new (I think Ate or Brembo, cannot remember) last year on two cars. The 123 car also received new calipers and is fine -my 126 car has a warped rotor which no doubt came from a sticky caliper overheating the rotor. I did a flush and thought that I could get caliper to respond positively -nope! Now I will need to pull and machine if possible after replacing two new rebuilt caliper units . . .

charmalu · #7 05-06-2011, 12:11 PM

They laughed at you because they are incompetant idiots. If they were good mechanics or educated that every fastener on a vehicle has a torque setting.

Maybe that is why they work at a State inspection station. right up there with Jiffy lube

Charlie

shertex · #8 05-06-2011, 12:14 PM

I wonder if rotors are likely to have problems at lower mileage if the car is not driven much (rust building up, uneven wear). My rear pads and rotors have only 25,000 miles on them, BUT for the first 8,000 of those miles it was owned by the proverbial little old lady who RARELY drove the car.

amosfella · #9 05-06-2011, 12:27 PM

Heating up the rotor, and then shock cooling part of the rotor can warp it quite nicely as well...
I was driving in the city, and some idiot cut me off and slammed the brakes for some reason... I had to really pile onto the brakes to stop in time. within about 40 seconds, I got stopped in a big puddle at a stop light. The next time I used the brakes, I could feel the chunk, chunk, chunk that warped rotors have...
Kinda funny, I have driven the car for over a year like that (I have the parts, but the problem isn't really severe... It's not causing nosedives or anything), and at certain temps, they don't do the chunking... Between about -8C and +6C, they are perfectly smooth...

Chris W. · #10 05-06-2011, 12:43 PM

Don't mean to start or contribute to a brake holy war, but there is a school of thought which says that most "warps" are not in fact warping, but uneven deposits of pad material.

See this link: http://www.stoptech.com/tech_info/wp_warped_brakedisk.shtml

I am only one anecdotal example, but I followed the basic break-in method described on this link for my last front disks and pads, and I have had excellent life without any shudder - I'm currently at double the miles of my previous set of disks with no sign of shudder/judder.

Rgds,
Chris W.
'95 E300D

whunter · #11 05-06-2011, 01:42 PM

The answer is EXTREME HEAT.

The most common cause on a Mercedes is:
* Bad brake hoses.
* A seized brake caliper piston= overloading the rest of the system.
* Riding the brake.
* Constant Extreme last second braking.
* Corroded rotors.

The "Warped" Brake Disc and Other Myths of the Braking System
-Warped- Brake Disc and Other Myths

============================================

Some Facts About Brake Hoses:
#1. The the industry standard average safety life of a brake hose is six years. FYI data SAE: J1401, J1703, J1705, J1873, J1406, J1288, J1403, J1833, J1402.
#2. Brake hoses deteriorate from the inside as well as the outside.
#3. Moisture is absorbed into brake fluid systems through brake hoses.
#4. Contaminants in brake fluid act abrasively on the inner wall of brake hoses.
#5. The brake hose reinforcing fabric deteriorates through expansion and moisture.
#6. High operating temperatures contribute to the deterioration of hoses.
#7. Brake hoses swell with age and restrict flow.
#8. Generally all brake hoses on a vehicle deteriorate at the same rate, So all hoses should be replaced if one is found to be faulty!

Brake hose failure mode:

#A. Rupture (burst hose) = age, exercise (too many miles) or impact are the typical cause.

*B. Partial internal collapse = the inner ply becomes damaged/detached acting as a partial restriction and/or one way valve.

#C. Full internal Blockage = the inner ply becomes damaged/detached acting as a plug = brake pedal still feels good but there is no brake application.

--------------------------------------------------------------------------------

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TYPICAL 'RUBBER' BRAKE HOSE FAILURES
Maltech
Automobile Brakes - A Short Course on How They Work | CarParts.com

Incredible data, a must read.
Brakes FAQ Home Volvo Maintenance FAQ for 7xx/9xx/90 Cars
Brakes:

The Brake Bible
Car Bibles : The Brake Bible

Bendix Instructional Videos
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ATE Caliper half O ring source
ATE Caliper half, O ring source - PeachParts Mercedes ShopForum

Brakes caught fire 1999 C280 (with pictures of damage)
Brakes caught fire 1999 C280 - PeachParts Mercedes ShopForum

Tell my dad my tire is on fire!

Tell my dad my tire is on fire!

Stretch · #12 05-06-2011, 02:04 PM

I once heard a good car talk program where some guy was always complaining about warped discs (sorry you call 'em rotors)

It turned out he loved to wash his car after his weekly long road trip and he was using a power washer to clean his wheels whilst the brakes were hot. This caused the warping.

So heat yes that's part of it - but the rate of cooling is also a problem...

The Gears · #13 05-06-2011, 05:29 PM

After a long braking or a very hard braking the the pads get very hot. Very hot.
You screech to a halt at a light and hold your foot on the brakes. The heat from the pads concentrate the heat in the disks at one spot, the disk expands at that point. Never to return to the exact original thickness. (you can feel 2 thou)
When driving hard try to stop a little back from the line and let the car creep a head slowly. That will help to distribute pad heat around the disk.

Stevo · #14 05-06-2011, 06:13 PM

Hose story..While swapping off my studded snows I felt a blister on the back side of the R/F brake hose, (where you cant see it) there was no sign it had been leaking until I TOUCHED it.

I just barley touched it and it started leaking like crazy. I wonder how far I was from having a bad day

pawoSD · #15 05-07-2011, 08:07 AM

Gotta wonder what percent of people actually repair their brakes to the level required. A perfect example of this is the brake hoses. Most people would glance at it and say "looks good"....and carry on with their 14 year old hoses.