so i just got home from the store and i got out and smelled almost burning rubber and felt intense heat from the rear left tire. I went to get my IR heat reader..rear rotor was 640 deg...every other one was around 200

Now i did a stretch on the highway of about 110 mph. just to push my car a bit as i haven't in years. Didn't slam on brakes ect or wasn't riding brakes hard at all. Car felt fine when i was breaking..no issue.

The rear rotors have groves in them an i need to get them replaced..but what's with that intense heat? 600 deg? WOW Are my pads completely gone?

 

it the pad was completely gone, you'd hear it, a terrible metal on metal grinding. sounds like it could be a seized or semi-seized caliper.

on my 93 MR2, it felt like the car braked more than it should have when i let off the gas (and didn't touch the brake). turns out the front calipers weren't fully releasing due to rust build up in the cylinders. you can tell by letting the car cool and then driving without the brakes (if you have a manual). when you come back all rotors should be cool if one is hot the caliper is sticking. if you have an auto, you could jack up the body and try to spin each wheel by hand. if one spins harder than the others, could be sticking. burning smell would be the pad (just like you can smell pad if you use the brakes real hard before stopping).

 

yeah i looked and the pad looks to be almost gone and rotor has really deep grooves. I am thinking sticking caliper as well. Did this high temp warp my rotor..i needed new ones any ways

 

you'll probably find that the pad on the hot side is gone (due to faster wear by stuck caliper) and the pad on the other side is fine/normal. you'll know if the caliper is seized (sounds like your case is pretty bad) when you replace the pads if you go to press the piston back in and it won't go with channel locks or a regular c clamp. you can replace the calipers (take this opportunity to get a powder coated set) or you can get rebuild kits to replace the seals and what not yourself. you'd also need a hone to polish the inside of the caliper.

 

i wish there was a way like you said drive the car with no brakes for 15 min and come home and test it...i have an auto. I may be able to do this in M mode but not sure

 

yup..stuck caliper...just drive in M mode without using brake once on a 15 min drive. Rotor was 100 deg..every other rotor was about 45-50

Smell was back as well. Going to take off the wheel tomorrow have have a close look after work. Luckily work is only 2 miles down the road

 

Had to replace same one last year,, (driver side rear) wifey helped me bleed the brakes after,,,

 

I would recommend you clean and lube the caliper pins with brake grease once a year rather than just with every brake job.

Also, pay attention to brake dust. If one wheel is dusting more than the others, check out the pads/calipers sooner rather than later--chances are something is sticking.

 

It's possible this may even be related to your vibration issues. Besides just repairing your brakes, another thing to verify is the the runout in the hub on that wheel (which also could have contributed to the brake issue). Lastly, be aware that you may ultimately need to rebuild the seals on the affected caliper, depending on how much overheating it experienced.

 

i took the caliper off the other day and found it was fine..piston moving ect not freezing..so i figure the rotor is either warped and rubbing or something else. I may have to just replace the caliper.

It hasnt gotten that hot since that day

You know what..since i took the caliper off and put it back on...knock on wood..my vibration issues have gotten a little better on highway. May be on to something but not sure

 

Did you clean and relube the sliders? I would have suspected them of causing it more than a stuck piston. If the caliper is all ok, then look for runout on both the rotor and hub. Remember, it is possible to have an obstruction behind the rotor, between the rotor and the hub, which will cause runout even if the rotor and hub are true. Lastly, look for any kinks, dents, or pinch points in the brake line (both flex and hard) to that caliper. Oh yeah, It would be awesome if that were the cause of your vibes too.

 

line looked fine...nothing blocking rotor that i say and the sliders were fine. Lubed everything back up and put it back together..still kinda stumped

 

^^

that's very strange

 

The other day i drove 150 miles on highway..got home and rotor was 375 deg..the other was 160. An the vibrations were bad. But they always seem to get back when temps go out...another werid thing.

I guess i am just going to replace the caliper and maybe rotor on that side to see if anything changes..if it fixed it..i will do the other side.

 

Considering what you've said you've done already, if this were mine, I think I'd consider replacing the pads and rotor first, and then if still having issues, trying a caliper rebuild kit. As long as the inner cylinder isn't scored, there is very little to go wrong on a caliper that isn't addresses with a simple rebuild kit.

I guess I'm thinking that if you had an issue with the caliper sticking, that the rotor was overheated in spots and you're getting/got cementite formation which, in a never ending downward 'death-spiral' of degradation, accelerates the propensity for further pad transfer and rotor overheating.

Another more obscure idea would be that the hydraulic proportioning valve for you braking force distribution is faulty and sending undue pressure to that one caliper.