Warm Rims - question about heat from braking

[iametarq]

How warm should the rims get in the front from braking? I think my front rotors which are two years old (maybe 3) are beginning to warp. I thought I'd feel the rims when we got home this weekend to see if they were warm, and they were. But it didn't feel at all bad.

How warm should they get? Are the rotors maybe getting too warm and the constant heating/cooling they are going through making the rotors warp?

[Ranger]

I think rim temperature will depend on how long since th brakes were applied and how hard the braking was as well as outside temperatures.

Rotors have to get really really hot to warp. More likely that you have uneven brake pad deposits on them than warping. I think more "warped" rotors are replaced than need be, when all they really need is to be resurfaced.

[submariner409]

TarQ.......Go to a sports car road race, one that runs into the night. The front rotors on most of the cars will glow at least dull red hot on twisty infield turns.

Disc brakes run at staggeringly hot temperatures.......if you were to do 2 moderate stops from 60, one touch of a rotor would instantly blister your fingers.

Even in town stop-and-go traffic, you would be unable to touch a rotor without burning yourself.

The rims, particularly aluminum, transfer rotor and tire heat very well. Non-problem.

[iametarq]

Thanks, perhaps it is the pads then. It's not annoying by any means, but I notice it, but I am very picky too. Nothing is glowing, that is for sure. Pads have 50% life left and I'm not changing them until the car says to.

[Ranger]

What makes you think that they are warping?

[iametarq]

Originally Posted by Ranger

What makes you think that they are warping?

When I apply the brake I am feeling a pulsing, especially in hard braking, down our big hills we have. The wife to be has not said anything, so I doubt she notices it, but when I was driving it this weekend I can feel it.

[submariner409]

Tarquinius........Depending on the barometric pressure and the phase of the moon I feel judder or pulsing in either the F150 or the STS. No kidding......one day, one stop, they'll judder. Tomorrow, silk.

Just for grins and kicks, take the car out to the boondocks and do a half-dozen stops (quick, not panic) from progressively higher speeds and see if that doesn't smooth things out.

[Ranger]

http://www.stoptech.com/tech_info/wp...rakedisk.shtml

[MN-STS-LOVER]

Originally Posted by submariner409

Tarquinius........Depending on the barometric pressure and the phase of the moon I feel judder or pulsing in either the F150 or the STS. No kidding......one day, one stop, they'll judder. Tomorrow, silk.

Just for grins and kicks, take the car out to the boondocks and do a half-dozen stops (quick, not panic) from progressively higher speeds and see if that doesn't smooth things out.

Try what Sub says. I do have warped rotors but if I do several hard brakes in a row, the "pulsation" will ease until the next time I drive when the rotors are cooled.

[iametarq]

Originally Posted by Ranger

http://www.stoptech.com/tech_info/wp...rakedisk.shtml

I had to read half of that site twice. It makes sense now. I will have to try several of these high speed near stops to get the junk off. Interesting site in general. I've never changed break fluid on any of my current cars, had to on an old buick...the site says to do it annually.

[Ranger]

I think annually is a bit anal myself. I flush the brake lines at 100K. I think I recall the Guru saying 10 yrs/100K should be good.

If the high speed braking doesn't do the trick, I'd try resurfacing them.

[iametarq]

Thanks for the tips! Don't know when I'll get to resurface in the same day, since the wife can't be 4-door-sedan-carless for her job until after she is done with the contract time.