Note to self Inspect your rotors

I all of a sudden I was getting a shudder in the steering and a pulsing of the break peddle. The shudder was virtually all the time and the pulsing was really bad. I mean ABS kick your foot off the peddle bad pulse. This started last Tuesday morning The car was fine Monday.

So I ordered a new set or rotors Tuesday night (Less than $30 each delivered to my door from Amazon) They came in Thursday and I took a look at things today and found this. This crack was all the way through both sides. There were several others as well. Oh Ya this was only on the drivers side. the passenger side was ok.

This has me puzzled. My brakes literally went from being ok to totally messed up over night. The only thing i can think of is I did take the car on a spirited drive Monday night. Just as I got into the driveway there was a torrential down pore with some serious wind. The wind was blowing water against the drivers side of the car where it was parked I am wondering if the rotors were still very hot and were hit with some very cold rain water as well as the water coming off the car. When I say rain it was as if we were under a waterfall for 20 min or so.

Possible?

And the gratuitous photo of new rotor installed on the passenger side

Wow... what car is that on? Were the rotors OEM? I have had cheapo parts store brand rotors do that before...

I had a similar experience today. I finally got around to putting the SLP catback on my 95 Mustang GT (its deliciously raucous ). I decided to take the old girl out and burn some unleaded. I noticed the wheel was pulsating side to side while cruising at 45. Its never done that before. I probably put 25 miles on her. It got worse and worse so I went home. I could smell something was wrong. Hot brakes. Very hot brakes. I get home and the passenger side is so hot I cannot touch the wheel. Smoke is now billowing out of the fenderwell. It boiled the brake fluid and I think it cooked the wheel bearings. Its always something with that damn Mustang. I'm tired of replacing calipers! Now I'm worried I'll have to replace the hub, rotor, pads and brake fluid.

I'm no metallurgist, but I could see cold rain on hot brake rotor causing such a crack.

It almost seems like a casting flaw to me. I'm certainly no metallurgist either but I'd expect a expansion/contraction crack to start on the outer edge. That'd be the fasted to cool and the most exposed to the rain. Plus the center has more mass and would have the most gradual cooling.

The rotors were either OE or Zimmerman. Not cheap ones. The replacement ones are cheap ones but considering the cost and ease to replace them I really don't care. I also switched to a less aggressive pad. This should give me better brake balance as the fronts were locking up before the rears. The pads I had on the car were about 2/3 gone so I figured it was time anyway.

The car is a 87 924s

Regarding the exposure of the rotor to the weather. With the phone dial rims I have on the car at the moment the center of the rotor is most exposed. The inner and outer edges are hidden behind the rim.

Here is a photo of a car almost exactly the same as mine except my car is green and does not have the euro bumper.

The rims are exactly the same as mine. IT is not really clear but the center of the holes in the rims are about lined up with the center of the rotor. Thus the center of the rotor would see the most water in specific locations. I should look at the cracks on the rotor tomorrow and see if the line up with the holes in the rim.

EDIT

Here is a old photo with the same rims on it.

I'm not a metallurgist either, but I have a lot of trouble imagining rain doing that. According to the all-knowing Internet, the high temp that day where you live was about 85 and the low was about 65. (I'm converting in my head from Celsius.) OE rotors were presumably tested in both Arctic and desert temperatures, and I have to figure that precipitation was involved in the test protocol at some point.

That said, you do have a valid point: the rotors failed on the rain side only. Weird.

It's not out of the question, I'd say.

Had a similar problem (not as bad) on my BMW. Rotors were only 9 months old. Turned out to be cheap E36M3 from China. Some things shouldn't be purchased by price. You need to know where the parts are coming from. Same is true if work is done by a shop. Lots of bad quality parts out there now. Beware.

I know a bunch of guys who time trial and road race BMW M3s - mostly e36s - on cheap cast iron blanks with the most aggro of brake pads, at class-record intensity.

I've seen 'em crack radially like that fairly often - so I generally split the difference cost-wise and go with something a step up from the Chinese stuff, usually European rotors one step from the bottom cost-wise, Meyle or Balo come to mind. That said, I think Centric is one of the more respected Chinese brands.

Funny you mention Centric That is what the ones I got from Amazon are. Hay they were cheep OE are more than $200 each. Zimmerman's are close to $100 each. If I get a year out of these I am good.

The cost of replacing the Grade 8 metric nuts bolts and washers with that funky gold colored rust inhibitor coated ones was almost the cost of one rotor. I wish they made Stainless steel grade 8 hardware. This is one place where it would be worth it. You get a galvanic reaction between the aluminum Hub and the steel rotor.

I seem to recall that Zimmerman is not well thought of in the BMW community

Hmm. I'm right in the process of buying some brake rotors for my all trac. How good are "Parts Masters," and "Centric" brake rotors?