Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

Over Heated Brakes?

I do a lot of driving in the mountains of Virginia. I have tried down shifting, etc. but still end up with hot brakes frequently. When they get hot I am seriously concerned about not being able to stop at the bottom of the mountain. I don’t remember this problem growing up in the mountains of NH. Have they changed the brake materials over the years? I use the higher priced ceramic brakes but they don’t seem to help. Any suggestions other than increasing my life insurance?

They’ve changed the mountains.
Seriously, you’re in different mountains now, ones with much longer downgrades than the mountains in most of NH.

Yes brake material has changed. They generally no longer contain asbestos, a fantastic brake material that causes cancer. The binders that hold both metal and ceramic materials together generally start to degrade at about 400 degrees Celsius. If you can smell the brakes after a mountain run, that is OK. If you start to notice the brakes don’t slow the car very well when you can smell them (fade), you are close to a very bad situation. If the front brakes fade, you will lose 70% of your braking. There are pads that can take higher temps. They can be had from TireRack and are labeled as street and track day capable.

You should also change your brake fluid every 2 years with this kind of driving especially if you have a front wheel drive car. If the fluid gets hot enough to boil, you will have NO brakes because the split system is split diagonally so both front brakes (the really hot ones) will boil the fluid on each circuit and you will lose ALL braking. THAT is a bad day!

The entire system that helps you slow down has changed. There maybe lesser air going under the car for aerodynamic reasons, which means less air available for brake cooling. Engines have lower friction. Variable valve timing maybe over lapping intake and exhaust to reduce pumping loss so that you can coast farther on flat ground. Nowadays, you have to use a lower gear than you would use to go up for proper engine braking.

What kind of car do you have? When I was a teenager, I had an '82 Honda Prelude. Although it was sporty, I found out that the brake system was not. The front rotors were unvented discs, and a single night of ‘spirited’ driving left them totally blued and fried. The reduction in braking ability was scary.

Mustangman, what you have said is all absolutely true and accurate, including the comment that brake pads “generally no longer contain asbestos”. Contrary to popular belief, asbestos use is not banned in the U.S., but the cost and liability for those using its is unacceptable.

But brake fade goes way back, well before the dangers of asbestos were even known. Modern brakes actually are much less prone to fade largely because discs dissipate heat so much better than drums. I clearly remember how common brake fade was in my younger days. It was just considered part of driving, and knowing how to mitigate it and to deal with it were just considered part of driving skills.

The mountains are, however, different. We don’t generally have the long, steep downgrades here in NH that are more common in VA.

The stretch of Interstate across Montana to Seattle Washington seemed to be the toughest mountain driving that I have ever dealt with. The grades were severe and the traffic was relatively congested. Anticipating a long steep descent and finding the gear that best suited the hill helped a great deal but I smelled a lot of hot brakes and never knew if mine were part of the aroma. It would be worthwhile to have brakes checked often when dealing with long steep grades.

Perhaps the OP could install some drilled and slotted rotors to help keep things cool.

Any chance this is aged brake fluid which has become contaminated and suffering from a drastically lowered boiling point?

What year car and how many miles on it? My gut feeling is that like the majority of cars on the road it has never had a brake fluid change.

My car was one of those that never had a brake fluid change and never had faded brakes. Generally, I keep it in a gear low enough to safely get to the bottom of the hill without using the brake pedal, even if the engine is spinning within 1k from the redline

You could flush and fill with racing brake fluid. It has a much higher boiling temp, 600deg.

Racing Brake Fluid is not recommended for street use.

Have you tried using your cruse control? I use mine on my F150 in the mountains and don’t touch the brakes unless a fool in front of me slams on their brakes

I’ve done lots of mountain driving in NC, VA and never had any problems with overheating the brakes or brake fade. I never stay on the brakes more than a few seconds at a time which allows them to cool between uses. When driving mountain roads I try to keep my speed reasonably low by staying off the accelerator as much as possibly, coasting as much as possible, using lower gears, and short light bursts of braking. I’ve seen many people accelerate heavily on short straight stretches then ride their brakes continuously once they come to long downhill grades and curves. My strategy is to watch the road ahead and adjust my speed accordingly rather than constantly going from 60 mph to 20. It may take a little longer, but helps fuel mileage, prevents overheating and excessive wear on the brake pads/shoes.

And your driving technique is much less stressful on the nerves also, @FordMan1959. If only more drivers would realize that sooner rather than later/never.

@keith Why would racing brake fluid be any different than normal brake fluid as long as it was compatible with DOT 3 or DOT 4?

You could try aftermarket premium pads and rotors like Wildwood mBaer, or SSBC.

Also you probably not downshifting enough. You should thy to get the engine rpm to 4 to 5000 rmp.

@knfenimore Racing brake fluid is not always qualified for road use as brake fluid. I believe that it neither meets all the requirements for Dot 3, 4 or 5.1 for wet boiling point or viscosity or some other requirement. Dry boiling point, however is VERY high, making it great racing fluid because it gets changed very, very frequently.

Besides, high temp fluid doesn’t prevent fade (reduced brake torque), it prevents the fluid from boiling and giving you no brake torque.

Just curious. What are the symptoms when brake fluid boils?

I would think boiling fluid both expands and becomes gaseous, which would cause the brakes to apply/drag a bit, as well as producing a mushy pedal.

True, false, other ideas?

Boiling brake fluid causes the brakes to fade and pedal to go to the floor like there is air in the system.