'Working to make your car go faster can sometimes involve addressing what is slowing your car down. That's the situation we're facing with our hot street/strip car. The brakes are dragging mercilessly because of mismatched components causing excessive brake-pad wear, overheated rotors and slowing us down at the dragstrip. This situation has been eating through brake pads, ruining rotors, and slowing down the car at the dragstrip. This story is going to help you find out if your car has a brake-system problem and show how to correct this issue.
Brake-System Problem-Solving
Is your car incredibly difficult to push around? Are the brake pads completely worn to the backing plates in less than 1,500 miles? Do your rotors look black and scabby after a few thousand miles? Is your car slower at the dragstrip than it should be? While these symptoms are extreme, any even close indicate a disc-brake system that is holding the pads against the rotors even though the driver is not attempting to slow the vehicle.
To many, the thought of someone having these issues on their car and not knowing it seems surprising. But we know of cars out there that have these problems, and, until now, those owners didn't know why.
Dragging Brakes
In general, dragging brakes usually arise from mismatched components. Like most vehicles with this problem, the vehicle being improved in this story gained rear disc brakes in place of the production drums when an aftermarket rearend was added. This should have helped the vehicle performance, but it actually hurt it. That's because the production front-disc/rear-drum proportioning valve was left on the vehicle. This stock proportioning valve has a residual pressure valve in it that helps to slow the rate at which the brake shoes relax from the drums. Unfortunately, this feature makes the rear-disc brake pads drag on the rotor-causing excessive heat buildup and pad wear, slowing the vehicle.
Based on our research, there were lots of folks who said, "Oh, yeah, I made that mistake," which means you need to know about this situation.
The photos show the stock proportioning valve being replaced with a manual Wilwood proportioning valve, and the heat-damaged rear Wilwood solid discs and pads being replaced by Wheel to Wheel Powertrain (W2W) in Madison Heights, Michigan.
As a side note, this vehicle went from being almost completely unpushable to totally free, which told us everything we needed to know. It has gone faster than ever before at the dragstrip, and the manual proportioning valve has allowed the owner to tune the brake bias to provide maximum stopping performance.
