How hot should your brake discs be after driving??

alloutdoorsboy

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Dec 30, 2006
Location
Va
TDI
2000 jetta
Just curious as to how hot other folks rotors get whilst driving?? I checked mine mine after getting home today, very minor braking on the way home and all 4 rotors were too hot to hold your finger on. Is this normal?
 

OlyTDI

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Dec 18, 2007
Location
Olympia, WA
TDI
'04 Golf
Should be. The pads make contact albeit lightly all of the time. There's going to be heat and the fact that you cannot hold on to it means it's, what, 130 - 140 degrees? Too hot to handle but not at all "hot."
 

alloutdoorsboy

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Dec 30, 2006
Location
Va
TDI
2000 jetta
This low highway MPG is driving me nuts!! So I just went out and got on a highway and drove for 5 mins at 60mph without using brakes and came to a stop on an incline without using brakes. Rotors felt cool, guess just slowing down a bit to turn into my driveway does heat the rotors that hot. OK on to other things.....Guess the injector pump is next....
 

slamhouse

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Oct 3, 2011
Location
Stanwood, WA
TDI
2006 Jetta TDI SE
Ive personally had one bad caliper. after driving three corners were too hot to touch, the bad one, the heat could be felt 3 feet away, and the whole rim was hot to the touch.

That was on my 95 pathfinder, not my jetta :)

Brakes can get very very hot under normal use as all that is slowing you down is friction between a ceramic pad and a metal rotor, in which friction translates directly into heat.
 

lucho

Member
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May 29, 2011
Location
warwick ny
TDI
03 jetta wagon auto, 06 Beetle 5 speed
Sorry to hijack the tread but.
my front driver side rotor gets very hot, changed caliper , hose, rotor & pad.
help !!! going nuts.
 

otbBlaine

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Joined
Feb 2, 2006
Location
Orange County, Ca
TDI
2002 Golf
I received a nice second degree burn on my leg from my rear disc on my bicycle, and both rotors will boil water off of them after anything but mild downhill runs.

A 4000lb car requires a whole lot more energy to stop; if there's no smoke or burning smell there's nothing to worry about.
 

Jettascuba

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Joined
May 27, 2009
Location
South Africa
TDI
2002 VW Jetta
Remember... to stop a vehicle kinetic energy is converted into heat, mostly in the brake pads and discs... also a relative low (in machinery terms) temperature, I think, 60 Celcius, is too hot to touch..
 

JB05

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Oct 20, 2005
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Il.USA
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Golf,2005,anthracite blue
Jack up the rear of the car with PB off and see how easily the wheel will spin. IIRC, somebody here said the wheel should spin freely for one and a half revolutions.
 

04SlvrJetta

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Wheeling, WV
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15 Passat SE DSG
Occasionally, our cars can have a sticking e-brake cable that won't always stick. I had that on mine before changing cables. I have also read of other causes....I think vacuum booster issues maybe.
 

Henrick

Top Post Dawg
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Aug 24, 2010
Location
Ireland
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Golf VI TDI, 77 kW (CAYC)
Sorry to resurrect old thread but... I am on a 3rd set of front brake rotors and they are warped again!
Today I checked the brake rotors after some city driving. Rear rotors are completely cold.
Front left one is hot. Front right is even hotter, you can't hold the finger over half a second.

Question: has anyone ever measured the exact temperatures? What is considered normal and what's not?
Tomorrow I am going to do some actual measurements after mild driving.
 

Henrick

Top Post Dawg
Joined
Aug 24, 2010
Location
Ireland
TDI
Golf VI TDI, 77 kW (CAYC)
Ambient temps around 1 *C. After normal city driving and exactly 3 minutes rest time, front right rotor is at 54 *C, front left one is at 41 *C.
Rear left - 18 *C
Rear right - 24 *C

Any clues what temperatues are normal?
What are the maximum values which ae safe?
 

turbobrick240

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Nov 18, 2014
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maine
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2011 vw golf tdi(gone to greener pastures), 2001 ford f250 powerstroke
I wouldn't recommend touching the rotors to check temperature. The caliper is less likely to melt off a fingerprint.
 

Tdijarhead

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Joined
Nov 10, 2013
Location
Lawrenceville PA
TDI
2003 TDI Jetta Daughters Car, 2001 TDI Beetle, Wife’s car, 2005 Golf TDI Mine, all 5 spds
I was having problems with a sticking rear caliper a while back. So I pulled out my IR thermometer to check the rotor temps. The fronts were at about 130 (F). Neither of them were exactly the same. This caused me to check a couple of my other vehicles and temps seem to vary a bit. Fronts seem to be typically a little hotter than the rears. I came to the conclusion that the temps should be somewhat close say about 10 degrees or so on the same axle.

The rears seem to be somewhat less as a rule. My one side was at about 90 (F) and the other, the sticking side was a little over 600 (F). That was of course the problem side, the heat could be felt from 3 feet away, there was a very distinct brake smell even the rim was hot. After replacing the caliper I did a complete brake job, rotors, pads, etc.

I haven’t had to replace the wheel bearing yet, this was about six months ago, but I wouldn’t be surprised if I have to sometime in the near future.

So after checking temps across several vehicles, I’m not sure you can say the temperatures should not exceed X. I came to the conclusion that each side on the same axle should be approximately the same. If for instance one rear wheel is at 98 and the other is at 140 you probably have a slightly dragging e brake or frozen slider. 98 on one side and 108 on the other, and I wouldn’t worry about it.

Maybe someone else has done a little checking and can chime in with their experience and conclusions.
 

ToxicDoc

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Joined
Mar 1, 2018
Location
Virginia, US
TDI
2001 Jetta, S7, .216
Ambient temps around 1 *C. After normal city driving and exactly 3 minutes rest time, front right rotor is at 54 *C, front left one is at 41 *C.
Rear left - 18 *C
Rear right - 24 *C
Any clues what temperatues are normal?
What are the maximum values which ae safe?
Rotors can reach a few hundred centigrade Fahrenheit (300-400) and be well within operating range. Yours don't seem to have an imbalance when looked at it from that scale, and rear brakes carry much less load than the front when braking, so they will run cooler.
http://www.crashforensics.com/brakefailure.cfm
 
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UhOh

Top Post Dawg
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Dec 24, 2014
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PNW
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2000 & 2003 Golf GLS (2005 Mercedes E320 CDI)
Sorry to resurrect old thread but... I am on a 3rd set of front brake rotors and they are warped again!
Today I checked the brake rotors after some city driving. Rear rotors are completely cold.
Front left one is hot. Front right is even hotter, you can't hold the finger over half a second.

Question: has anyone ever measured the exact temperatures? What is considered normal and what's not?
Tomorrow I am going to do some actual measurements after mild driving.
BOTH rotors are warping on you?

Biggest impact on rotors is a hard and complete stop and then sitting still. All the built up heat by the pads will stay concentrated on one spot. I look to creep forward a bit after a hard stop. But...

Rotors really shouldn't be warping unless they're utter junk. I'd suspect calipers (sounds like you got one sticking) are your real problems. This past year I replace the front calipers (rotors and pads) with VW OEMs for the wife's car after I found one caliper sticking; it was crap work and crap parts the PO had commissioned that I didn't want anything more to do with (couple years back I'd found a stripped slider pin- required a heli-coil).
 

Henrick

Top Post Dawg
Joined
Aug 24, 2010
Location
Ireland
TDI
Golf VI TDI, 77 kW (CAYC)
Yeah, it feels like they both are affected.
Anyway, I wil lbe doing a brake job next week. OEM rotors and pads this (last) time.
While I'm there, I'll also check the calipers.

If after this they still continue warping, then hell, I'll drive with that.
 

Tdijarhead

Top Post Dawg
Joined
Nov 10, 2013
Location
Lawrenceville PA
TDI
2003 TDI Jetta Daughters Car, 2001 TDI Beetle, Wife’s car, 2005 Golf TDI Mine, all 5 spds
Your temps are about what mine are when operating normally. I read Docs link, and found this.

The typical generic "normal driving" temperature range for well balanced vehicle brakes is 100 to 200 degrees. A controlled mountain grade descent can produce brake temperatures between 200 and 400 degrees. Carlisle reports that a brake resin odor is produced at about 550 degrees and visible smoke is produced at 850 degrees.

These irregularities commonly cause brakes on big trucks to catch fire soon after being replaced. These irregularities are also more likely the cause of the previously discussed green fade. Green linings reportedly do not distribute application pressure evenly across the friction surface until they are burnished. I have seen vehicles that experienced green fade within a few miles of having both their rotors and linings replaced. These cheap imported brakes sometimes show evidence of localized overheating (1000 + degrees) from only a few stops!

Would that be China’s finest I wonder.

Just food for thought and certainly worth checking the calipers, but as previously stated my sticking caliper caused an overheat on the rotor of 600F and that was just driving with very little usage. My other rotors were all below 130F and I could touch each of the other three with my fingers.
 

ToxicDoc

Veteran Member
Joined
Mar 1, 2018
Location
Virginia, US
TDI
2001 Jetta, S7, .216
I think that link is to a US organization so I'm going to say that those temps are in Fahrenheit.
Some of the other links I read were in centigrade, but it looks like the link I posted was actually in Fahrenheit. Idiotic US can't join the metric system ugh.
 
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