Boiling HOT Rotors!! Why?

[Kdubslugga]

I took my car for a cruise, and cam home and washed it today, and when i sprayed the wheels, it sizzled, theres no way way its supposed to be that hot. Whats causing it? I just replaced the front rotors and brake pads, less than 100 miles on both, does it sound like the calipers are sticking?

 

[ECU5.0]

definetly sounds like the calipers are sticking...unless they just happened to get that hot from driving around. did you replace the bearings and grease them and make sure you didnt tighten down the bearing retainer nut too much? that could cause extra friction that would heat things up a lot

 

[90mustangGT]

Water boils at 212*F, brakes get much hotter than that normally. Brakes use friction to stop the car, friction turns to heat, end of story.

 

[ECU5.0]

Water boils at 212*F, brakes get much hotter than that normally. Brakes use friction to stop the car, friction turns to heat, end of story.

thats very true....but usually by the time you get to the wheels they are cooled down enough so that they dont do that..unless they were super hot. but i agree that it was just because the brakes were hot. also, for kdub....be careful doing that, its a great way to warp your rotors

 

[MustangPunk302]

Stock rotors can get up to 500 degrees easily on a hot summer day... You ever take a pan outta a 350 degree oven and put it in hot dish water (100+ degrees) it still makes a sizzling noise... You spraying cold water from a hose on just slightly warm rotors can make a sizzling noise.. Nothing I'd worry about..

 

[Michael Yount]

I would worry - you just worked on the brakes, and now something that's never happened before is happening -- it ain't coincidence. Under normal driving, the brakes/wheels shouldn't do that. If they did, every car you see driving in the rain would have steam pouring off the front wheels -- but they don't. You'd better reconsider what you did and see if you can find the problem.

 

[89MustangGX]

It's normal.

I wouldn't spray them if they're that hot -- something tells me they might crack.

 

[ECU5.0]

im with michael yount on this one....tightening down the bearing retainer nut can cause problems...also sticking calipers can cause problems

 

[Kdubslugga]

Yeah, i didnt spray them directly but, water got on them, and i heard sizzling. Maybe its nothing to worry about, everything looks good.. I never payed much attention to how hot brakes got. Should they be to hot to touch after ohh say a half hour of city driving?

 

[MustangPunk302]

I would worry - you just worked on the brakes, and now something that's never happened before is happening -- it ain't coincidence. Under normal driving, the brakes/wheels shouldn't do that. If they did, every car you see driving in the rain would have steam pouring off the front wheels -- but they don't. You'd better reconsider what you did and see if you can find the problem.

Michael I have seen normal everday cars brakes steam in the rain... Under harder then normal braking conditions. Though he took a drive and then sprayed cold water on them.. Nothing I'd worry about.. Brakes get freaking hot no matter how hard your driving it. I've been burnt bad enough to blister by some rotors, and they've been sitting for a hour before we got to them..

 

[MustangPunk302]

Yeah, i didnt spray them directly but, water got on them, and i heard sizzling. Maybe its nothing to worry about, everything looks good.. I never payed much attention to how hot brakes got. Should they be to hot to touch after ohh say a half hour of city driving?

They'll burn you... lmao

 

[89MustangGX]

Yeah, i didnt spray them directly but, water got on them, and i heard sizzling. Maybe its nothing to worry about, everything looks good.. I never payed much attention to how hot brakes got. Should they be to hot to touch after ohh say a half hour of city driving?

Yes. They will probably be too hot to touch after one good brake stop.

On a side note, I had my truck overloaded -- pulling too much weight and ended up taking a highway that went through a canyon that was not marked on the map I was using -- this was in Arizona. I ended up not realizing what I had gotten myself into until it was too late -- by the time I realized how bad I was losing my brakes, I had to literally stand on the brakes and pull my brake controller over to max for the trailer and just barely slowed down enough to get over to a runaway truck ramp. When I stopped I immediately noticed smoke BILLOWING out of my front brakes, it looked like they were on fire there was so much smoke -- and that was all with no water.

Lesson learned there about brakes and heat.

 

[MustangPunk302]

Yes. They will probably be too hot to touch after one good brake stop.

On a side note, I had my truck overloaded -- pulling too much weight and ended up taking a highway that went through a canyon that was not marked on the map I was using -- this was in Arizona. I ended up not realizing what I had gotten myself into until it was too late -- by the time I realized how bad I was losing my brakes, I had to literally stand on the brakes and pull my brake controller over to max for the trailer and just barely slowed down enough to get over to a runaway truck ramp. When I stopped I immediately noticed smoke BILLOWING out of my front brakes, it looked like they were on fire there was so much smoke -- and that was all with no water.

Lesson learned there about brakes and heat.

Your luckly, I've heard stories where people overload RV's and such. The brake fluid can overheat and start to breakdown, making it so you have little or no pedal at all..

 

[89MustangGX]

Your luckly, I've heard stories where people overload RV's and such. The brake fluid can overheat and start to breakdown, making it so you have little or no pedal at all..

I know I had some serious luck that night!

Fortunately the brake fluid seemed ok (didn't look like it was boiling), but I still had almost no pedal -- that's why I was standing on them so hard and using the trailer brakes so much -- I can't even tell you how scary it is to do that and it feels like you're not even touching the brakes. Make no mistake, if it weren't for one of those well-placed runaway truck ramps I wouldn't be here. Anyway, I let the brakes cool for a couple hours (they were still warm!) and crept my way down to the bottom of the canyon and up out the other side.

I did change everything right afterwards. The pads (new) were all cracked and falling apart and the rotors looked like they changed color because of the heat. Fluid still looked ok, but I flushed it anyway. I was worried about bearings and grease, etc. but they looked good after I cleaned them up.

Like I said, lesson learned the hard way.

 

[blk92stangg]

Try starting your car in the morning, drive for a mile or so without hitting the brakes, and then jump out, (watch for traffic of course), and sprinkle some water on em to see if they sizzle. If they don't, then try driving, brake once, then drive a mile or so again, and do the same test. While the test would be far from perfect, I think you would at least get an idea if your brakes are sticking badly or not. Water may boil at 212, but for it to sizzle, especially after sitting awhile, it would need to be considerably higher than that. I would err on the careful side and assume that there MAY be a problem.

 

[MustangPunk302]

I really don't think there's a problem... Rotors get really friggin hot, hotter then alot of you probably think... Here's some info:

One brake manufacturer breaks vehicles down into generations to illustrate how much brake systems have changed:

Traditional RWD (say, an '80 Caprice): 22 lb. rotor, large friction area, average surface temperature of 350 deg. F. Also, a non-overdrive trans and a boxy body (in other words, the car slows down when you take your foot off the gas).
First Generation FWD (the GM X-Body, for instance): 12 lb. rotor, average surface temperature of 500 deg. F. Low performance, no overdrive, and still boxy.
Second Generation FWD (Lumina, Taurus, etc.): 10 lb. composite rotor, average surface temperature of 800 deg. F. Now, you've got overdrive, V6 and multi-valve performance, and an aerodynamic design that not only lets the car coast farther, but also cuts air flow to the brakes.
Third Generation FWD (we're talking Chrysler's LH): The rotor's back up to 12 lbs., and the cab-forward, longitudinal engine design means this is another whole animal. Data is still being compiled from testing and real-world experience, but you can bet these cars will need their own special semi-met recipe.

BTW the car I burnt myself on was a Honda Civic and the car had been sitting for about an hour before we got to it, I doubt the 40 year old lady that drove it rode the brakes any harder than normal. No the cailpers weren't sticking either.. I've heard stock foxbody rotors can get upwards of 500 degrees...

 

[blk92stangg]

Aye, I am not refuting your info and experiences. The rotors on my CBR will heat up enough to vaporize spit off my finger after one hard braking. I was just thinking that it is better to be safe than sorry, and if it was me, I would want to know for myself for sure. Different strokes for different folks I guess. I wonder if there are any engineers or physics people who would be able to figure out the heat retention of our rotors.

 

[custom89stang]

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