Smoke during excessive downhill braking....Normal?

[PK470]

Not sure whether anyone has experienced this before, but I would like to share.

Over the weekend, I was going downhill on a lengthy, steep and curvy slope. 100% paved road but quite a long distance steep drop.

Inevitably, I had to apply my brakes every now and then every time I approached a blind corner then I started smelling something like burnt rubber. I pulled over to the side and I saw smoke coming from all the four tires. Yes smoke- Literally.

On a closer look, I could tell that the smoke originated from surface contact in between the rotors and brake pads. Very very hot indeed. I guarantee that I could have started a camp fire with a little spark application.

The last time I witnessed this happening was on an 18 wheeler semi-truck and not a SUV. Good thing no damage done whatsoever.

Do you consider this normal? Probable cause/ reason for this to happen?

 

[APKhaos]

Assuming your brakes are otherwise normal, it sounds like you were using the brakes often and hard enough to generate more heat than the rotors could dissipate. The smoke was from the pad material.

Most likely is that the pads are worn. The less pad material the less heat they can dissipate. Its also likely that the long descent was unusually tough on your brakes. Best bet for long descents is to switch out of overdrive to use some engine braking effort to limit speed. Much easier on the brakes that way.

 

[shogun2fire]

I would just take off one of the front tires, and check if your pads are running low. Check for uneven wear of the pads as if there is only a small pad area touching the rotor that can lead to excessive stress on that one pad section.

The only time I recall pad smoking was when I had my emergency brake on accidentally and I drove the car uphill. Not sure what condition you were driving in but if the pads and rotor look hokeydokey and the car drives fine under normal conditions I'd imagine it was just the special condition you were driving that day.

 

[mister bean]

Yep, it happened in one of my older cars. Since then I've learned manage speed going downhill as much as possible by downshifting. Unfortunately with the LC your gear options are somewhat limited since you can only disable overdrive or select first and second. Still, you can keep the brakes a bit cooler using what's available.

If they get hot like yours did it's better to not to fully stop and leave the pads in contact with the rotors because the hot brake pads can leave residue on the rotors. This is what causes warped rotors (they're not really warped, they just have pad material on them that causes vibration).

 

[LCHardriver_02]

Just out of curiosity, were you downshifting into your lower gears to maintain slower downhill speeds or just using the brakes? I am not trying to harp on you for your actions, but I am curious if your brakes got this hot even though you were using the motor as a brake. Thanks.

 

[PK470]

Assuming your brakes are otherwise normal, it sounds like you were using the brakes often and hard enough to generate more heat than the rotors could dissipate. The smoke was from the pad material.

Most likely is that the pads are worn. The less pad material the less heat they can dissipate. Its also likely that the long descent was unusually tough on your brakes. Best bet for long descents is to switch out of overdrive to use some engine braking effort to limit speed. Much easier on the brakes that way.

Actually, I replaced my front pads only about a week ago as the rear are still in good shape. At fast I thought maybe the friction is due to low quality pads but then smoke was on all four tires. No just the front.

I would just take off one of the front tires, and check if your pads are running low. Check for uneven wear of the pads as if there is only a small pad area touching the rotor that can lead to excessive stress on that one pad section.

The only time I recall pad smoking was when I had my emergency brake on accidentally and I drove the car uphill. Not sure what condition you were driving in but if the pads and rotor look hokeydokey and the car drives fine under normal conditions I'd imagine it was just the special condition you were driving that day.

ha ha. Nope. I was going downhill. Brand new pads.

Yep, it happened in one of my older cars. Since then I've learned manage speed going downhill as much as possible by downshifting. Unfortunately with the LC your gear options are somewhat limited since you can only disable overdrive or select first and second. Still, you can keep the brakes a bit cooler using what's available.

If they get hot like yours did it's better to not to fully stop and leave the pads in contact with the rotors because the hot brake pads can leave residue on the rotors. This is what causes warped rotors (they're not really warped, they just have pad material on them that causes vibration).

Nope. I wasnt using engine braking at all.

Just out of curiosity, were you downshifting into your lower gears to maintain slower downhill speeds or just using the brakes? I am not trying to harp on you for your actions, but I am curious if your brakes got this hot even though you were using the motor as a brake. Thanks.

Using brakes. 100%.

 

[elkaholic]

<snip>

Nope. I wasnt using engine braking at all.



Using brakes. 100%.

I believe you have just answered your own question. I do not recall the 2006LX shifter, but in my '06 LC, I can select each gear down from 5th and do so when I travel to my mother's place in the NC mountains near Asheville. 1st and 2nd can be very good friends to your brake pads and rotors ...