Oppo, please touch your front brake rotors

"VincentMalamute-Kim" (VincentMalamute-Kim)
08/09/2020 at 21:54 • Filed to: None

after a normal city drive. For some reason, I felt the front wheels of my 2011 Sienna and they were pretty warm. So I touched the rotors - too hot to touch!

Is this normal? I certainly know brakes get much too hot after a track session with my Audi but didn’t think a normal car would get very hot after normal mild city driving.

I don’t think I’ve ever checked my rotor temps before to know if this is abnormal or not. Both sides were evenly hot.

UPDATE AFTER READING YOUR RESPONSES: ok, thanks, I’m satisfied it’s normal. Not sure what possessed me to check the front rotors in the first place.

Yeah, track driving is clearly rough and even a big brake kit on a fast, heavy car like my Audi S4 was insufficient, that needed brake cooling ducts to prevent boiling the fluid.

DISCUSSION (24)

jminer > VincentMalamute-Kim
08/09/2020 at 22:02

This is very normal, it’s why brake fluid can boil on the race tracks.

They operate on friction to slow your car so it generates a lot of heat.

ItalianJobR53 - now with added 'MERICA and unreliability > VincentMalamute-Kim
08/09/2020 at 22:05

Yup, its quite normal to have too hot to touch discs after driving in the city as well.

4kc > VincentMalamute-Kim
08/09/2020 at 22:06

Normal, deceleration is friction transferred into heat energy for the most part if I remember right.

Even my disc brake bicycle s would be uncomfortable to touch after a ride around the block

Dr. Zoidberg - RIP Oppo > VincentMalamute-Kim
08/09/2020 at 22:07

Stop and go traffic is bad for pretty much everything on your cars.

atfsgeoff > VincentMalamute-Kim
08/09/2020 at 22:07

Completely normal for brake rotors to be very hot after stop & go driving. Moving cars have a lot of kinetic energy which the brakes convert to heat, and all that heat goes into the rotors and pads. Takes awhile to dissipate into the surrounding air, especially when stationary.

If you’re concerned, compare the relative warmth of both front wheels. If they’re roughly equal, you’re OK. If one is significantly hotter than the other, you may have a stuck caliper.

RiceRocketeer Extraordinaire > VincentMalamute-Kim
08/09/2020 at 22:14

or just use an infrared thermometer ...

Kinja'd!!!

cheap, also useful for cooking, and you can annoy your family by rechecking their body temps

and the ones with the lasers are good for annoying the neighbor’s cat

Spanfeller is a twat > VincentMalamute-Kim
08/09/2020 at 22:14

Lol they be hot as balls. Frequent stops to zero and low speed means lots of heat gets trapped and little is dissipated.

Also, I think many modern cars also add a dab of rear braking now and again, so if you want to check for uneven heat it might be useful to check all four (though, after a city drive maybe rear disks don't get used at all)

facw > VincentMalamute-Kim
08/09/2020 at 22:16

Normal. And your rotors are probably cast iron, which can both absorb a lot of heat, and radiates it aggressively (which is why cast iron cookware is a thing).

VincentMalamute-Kim > Spanfeller is a twat
08/09/2020 at 22:17

yeah, Ford Transits are known to go through rear brakes faster than their fronts.

wafflesnfalafel > VincentMalamute-Kim
08/09/2020 at 23:30

if they are glowing don’t touch them

DipodomysDeserti > VincentMalamute-Kim
08/09/2020 at 23:40

Brakes are hot as shit after one or two stops. Have your girl give you lubeless handy, then imagine if her hand weighed 4k pounds, and both of you were made of steel. #friction

VincentMalamute-Kim > DipodomysDeserti
08/09/2020 at 23:56

Thank you for that unfortunate mental image!

DipodomysDeserti > VincentMalamute-Kim
08/10/2020 at 00:02

Unfortunate? Suit yourself.

Wacko > RiceRocketeer Extraordinaire
08/10/2020 at 00:05

Mine would make a beep when the laser turned on. And every time my cat heard a beep he would be looking around for the dot. It would drive him crazy.

Shift24 > VincentMalamute-Kim
08/10/2020 at 00:23

Did both feel similar hotness or one was definitely hotter?

Also under braking does the car or pedal shake. Does the car pull to one side under braking ? On flat ground and in drive does the car move when you let go of the brake ? Is the brake rotor Blue or discolored?

If yes to any of that you might have a hanging up caliper. (Thats also a good break down for the future, blue or discolored rotor though could be the result of heat treating (high water + hot rotor=heat warp/treating ))

Yes brakes will get hot and will be to the touch but anything over 120F to humans is hot. Brakes will see that in the first hard stop.

VincentMalamute-Kim > Shift24
08/10/2020 at 00:31

Both sides symmetrical. No other brake symptoms. Other than pedal feels mushy and I plan to flush and change the fluid.

I was just weird for checking in the first place. I once had a caliper “sticking” in an ancient Dodge Caravan. Finally tracked it down to an internally degrading flexible brake line that was causing a ball-valve effect preventing the caliper from releasing.

NKato > VincentMalamute-Kim
08/10/2020 at 03:31

I wonder how hard it would be to install brake cooling ducts for my Crown Vic once I start autocrossing.

nerd_racing > VincentMalamute-Kim
08/10/2020 at 08:16

I did a brake job on a Ford Fiesta for a co worker. I took it for a spin to bed the pads, came back and decided to check for heat on the brakes. Back of the hand felt no heat radiating. So I put my thumb on the rotor. Instant blister. Sucker was hot. I never felt dumber in my life. So no... I will not touch my rotors for you. lol

nerd_racing > VincentMalamute-Kim
08/10/2020 at 08:16

Same with most modern Mazda vehicles.

OPPOsaurus WRX > VincentMalamute-Kim
08/10/2020 at 08:40

i burned my finger touching the disc on my mountain bike. I dunno what would make you think it wouldn’ t hurt to touch a van

VincentMalamute-Kim > OPPOsaurus WRX
08/10/2020 at 10:53

Sometimes my brain is smaller than it usually is. I brake like a grandma, not a NYC taxi driver. I figured all the time spent moving, air cooling would have done something.

VincentMalamute-Kim > nerd_racing
08/10/2020 at 10:53

But you did already! Thanks.

VincentMalamute-Kim > NKato
08/10/2020 at 10:57

Not that hard. Just get high temp ducting. Crown Vic have plenty of space in the front for the duct vents. My Audi’s front is entirely taken up by radiator and twin intercoolers on each side. It’s hard to find space for the air scoops for the ducts.

Do you really need them? Although the Vic is heavy, it’s not hugely fast and the autocross lasts a minute .

nerd_racing > VincentMalamute-Kim
08/10/2020 at 11:22

T echnically they were my co worker’s rotors.