Brake fade on long downhills: causes and prevention
Brake fade is what happens when your brakes get so hot they stop biting. On a long downhill with a loaded trailer, that is one of the most dangerous things that can happen to a truck. The good news is that fade is preventable, and the prevention starts long before the hill.
What brake fade actually is
Your brakes turn motion into heat. Hold them too long and the drums, linings, and hardware get hot enough that the friction material stops gripping. The pedal goes soft or long, and the truck keeps rolling. That is fade, and on a grade it builds fast.
Why grades cause it
A long downhill feeds the brakes heat without a break. Add the weight of a loaded trailer and the speed you are carrying, and there is a lot of energy turning into heat in those drums. Riding the brakes the whole way down is what tips them over the edge.
Use the engine, not just the brakes
The fix is to let the driveline do the slowing. Gear down before you start the grade, not partway down, and use your engine brake or exhaust brake. When you do use the foundation brakes, snub them: a firm application to slow down, then release to let them cool, instead of dragging them the whole way.
Start with brakes in spec
Fade comes sooner on brakes that are worn or out of adjustment, because fewer brakes are sharing the load. A truck where every brake is set right, within the pushrod stroke limits, spreads the heat across all of them. That is why brake adjustment and catching brake warning signs early matter before you ever see a mountain.
Check them after the hill
At the bottom, use your nose and eyes. A hot, sharp smell or any smoke means the brakes worked hard. Find a safe place and let them cool before the next grade, and have them looked at if anything felt off.
What we do
We inspect the brakes, set the adjustment, and make sure every brake is carrying its share before you head for the grades. You can find the work on our truck repair services page.
FAQ
What causes brake fade on a downhill?
Heat. Continuous braking on a long grade overheats the friction material until it stops gripping.
How do I prevent brake fade?
Gear down before the grade, use your engine or exhaust brake, and snub-brake instead of riding the pedal.
Do worn brakes fade faster?
Yes. Worn or out-of-adjustment brakes overheat sooner because fewer brakes are sharing the work.
What do I do if my brakes start to fade?
Get off the throttle, downshift, and head for a safe spot or a runaway ramp. Let the brakes cool fully before you continue.
Before you run the grades, have Royal Truck Repair near Allentown check your brakes. Call (610) 841-2521 and we will make sure every brake is doing its share.