Disc brake rotor temps - JeepForum.com

 
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post #1 of 7 Old 09-09-2013, 06:59 PM Thread Starter
jstaples
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Disc brake rotor temps

My front disc brakes on my 1996 Jeep Cherokee overheated (non-ABS, front disc, rear drum) to the point where smoke was coming from the right front wheel well. I changed the calipers, master cylinder, and proportioning valve. Also planned to change the brake hoses but couldn't get the flare nuts loose, even with a flare nut wrench and PB Blaster. After a test drive, I measured the temp of the front rotors with an IR thermometer. Both were about 190F. Seems a little high to me. Anyone know what would be considered a normal temp? I plan to put on new rotors and pads but I'm afraid I'll damage $250 Hawk rotors and pads.

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post #2 of 7 Old 09-09-2013, 09:07 PM
wgirvine
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Only two reasons for disc brakes to overheat like that...
(1) You were driving with your foot on the brake pedal, or
(2) The brakes hoses have swelled up on the inside. They will look normal on the outside, but the inside will be swelled shut. They act like a one-way check valve. You can force the fluid to the brakes with your foot, but when you release, the pressure keeps the pads clamped to the rotor.

Change the hoses.

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post #3 of 7 Old 09-10-2013, 04:57 AM
cruiser54
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I think we need to verify that 190* is too high. I doubt it is as I've done brake testing with an IR gun and saw temps after application of brakes up in the 500+* temps.

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post #4 of 7 Old 09-10-2013, 05:30 AM
Newtons3
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Those temperatures sound reasonable to me depending, of course, on the pad material you are running.
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post #5 of 7 Old 09-10-2013, 08:22 AM
wgirvine
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He said it was smoking. That is too hot.

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post #6 of 7 Old 09-10-2013, 10:04 AM Thread Starter
jstaples
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The brakes were smoking before I did the repairs. I did not measure the temps at that time but I could barely could hold my hand near them. I'm assuming the caliper was stuck. But I changed the master cylinder and proportioning valve as well. I planned on changing the brake hoses but couldn't get the flare nuts to budge. In fact, the flare nut wrench was starting to round off the nuts. I'm afraid if I do enough damage, I'll need to change the hard lines as well. I'm willing to do that repair at some point but not a good time right now.
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post #7 of 7 Old 09-10-2013, 11:17 AM
CJ7-Tim
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Use a propane torch to heat up the nut. Spray on penetrating oil while still hot. You may need 2 vice-grip wrenches to break it loose.

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