Burning smell.. brakes?

[jaydee]

I'm hoping Zekhausen and/or other knowledgeable brake guys can help. My 300C has about 18K miles on it. It has started developing a burning smell that is a combination of "waxy" and "rubbery". The Brake rotors are more than warm to the touch and the smell seems to be coming from the wheel wells particularly my right rear well. Is this "burn off" from the accumulated brake dust from the pads or something else? I don't see any obvious oil leaks etc...I will be taking the car tpo the dealers' on Monday in this regard but was hoping to nenefit from the wisdom of this board a- priori

Jaydee

[DZeckhausen]

Originally Posted by jaydee

I'm hoping Zekhausen and/or other knowledgeable brake guys can help. My 300C has about 18K miles on it. It has started developing a burning smell that is a combination of "waxy" and "rubbery". The Brake rotors are more than warm to the touch and the smell seems to be coming from the wheel wells particularly my right rear well. Is this "burn off" from the accumulated brake dust from the pads or something else? I don't see any obvious oil leaks etc...I will be taking the car tpo the dealers' on Monday in this regard but was hoping to nenefit from the wisdom of this board a- priori

After driving the car, do you notice that the right rear wheel is warmer than the left rear? I'm thinking this might be your parking brake. Sometimes the tabs holding a shoe can fail, causing the parking brake to remain partially engaged. When you activate the parking brake, does it feel any different than normal? Any roughness or unevenness in the pedal stroke?

An alternative possibility is that you ran over a plastic bag and it's stuck to the exhaust system.

[jaydee]

Originally Posted by DZeckhausen

After driving the car, do you notice that the right rear wheel is warmer than the left rear? I'm thinking this might be your parking brake. Sometimes the tabs holding a shoe can fail, causing the parking brake to remain partially engaged. When you activate the parking brake, does it feel any different than normal? Any roughness or unevenness in the pedal stroke?

An alternative possibility is that you ran over a plastic bag and it's stuck to the exhaust system.

Hmm didnt think of a plastic bag scenario- that *may* be a possibility. But I do believe the right rear is warmer than the left rear and the smell seems to be predominantly on the right side (passenger side)

[jaydee]

Originally Posted by jaydee

Hmm didnt think of a plastic bag scenario- that *may* be a possibility. But I do believe the right rear is warmer than the left rear and the smell seems to be predominantly on the right side (passenger side)

Yesterday, I had the opportunity to go out on the road and do the Zeckhausen bedding procedure- I managed about 5 or 6 hard braking manouevers before traffic caught up with me.. the smell seems to have gone- now I dont know if the bedding procedure burnt off the dust that was originally causing the burning smell or whether there indeed was a plastic bag stuck on my exhaust which ultimately burnt off... ah well

Jaydee

[teahead]

I had that smell for the 1st 50 miles. Seems to have gone away.

[goddardzilla]

Smells can transfer location easily and be difficult to pinpoint


Did you put any high wattage bulbs in any unit and cause extra current demand?


Double the original wattage = double the amperage = roughly double the heat = burning (smell) and possibly actual burning!










Zilla

[cmego]

Ditto on the plastic bag - I had that once, not on my C.

[jaydee]

Originally Posted by goddardzilla

Smells can transfer location easily and be difficult to pinpoint


Did you put any high wattage bulbs in any unit and cause extra current demand?


Double the original wattage = double the amperage = roughly double the heat = burning (smell) and possibly actual burning!
Zilla

Zilla,
double the wattage means half the resistance and SQUARE of the current - C sq RT/J is the formula for heat generated by an electrical circuit if I still remember my high school physics

No I didnt change anything electrical..
Jaydee

[goddardzilla]

Originally Posted by jaydee

Zilla,
double the wattage means half the resistance and SQUARE of the current - C sq RT/J is the formula for heat generated by an electrical circuit if I still remember my high school physics

No I didnt change anything electrical..
Jaydee

Does not apply R is not a variable.The resistance is constant in any given wire.


Zilla

[jaydee]

Originally Posted by goddardzilla

Does not apply R is not a variable.The resistance is constant in any given wire.


Zilla

Yeah but the wattage increase implies a lower resistance of the bulb filament, hence higher current through the circuit, hence the higher heat etc etc..

Jaydee