Turning Brake Rotors

[cRiPpLe_rOoStEr]

If the brake feels sticky enough to cause some drag, take your foot out of the pedal.

[DragBean]

How much does your mpg increase with break spreaders?
How much does your mpg increase if you turn your rotor and replace your pads if they are to the point where they are almost bad?

I could get a torque wrench and the equation for power to figure out the power required to overcome this drag but that would be affected by the transmission.

[aerohead]

Originally Posted by DragBean

Does anyone know how much drag hydraulic disk brakes create?

The break pad doesn't come completely off the disk when you aren't pressing the brakes so you get a little drag.

Worse off on my car the brake rotor is radially pretty uneven (not unbalanced) but I hesitate to get them turned and put new brake pads on them because I don't have any braking issues and the pads still have enough meat in them to probably last for the remaining life in the car.

But I might be able to justify the work if it improves mpg.

The disk brake advantage over drum-type IS that the pads are always contacting the rotor, enough to wipe away water during inclement weather driving,and allowing 'stopping',where drum brakes might cause a rear end collision.
I bought a 1964 Karmann Ghia pretty cheap after a 16-year-old rear-ended a Cadillac during his first rainy day drive.
For safety reasons alone,I welcome the miniscule brake drag.

[DragBean]

True. That's why you should tap your brakes when you're in the rain every so often. Most cars have drums in the back anyways. Probably the bigger thing is that spreaders would require pushing on the brakes a little harder which would reduce the time your brakes engage by a very small time. If your brakes are calibrated right this probably wouldn't even be an issue.

[MobilOne]

A quick one eighth left/right turn on the steering wheel pushes the pads away enough so that there is little or no drag.

Most modern cars have disc brakes front AND back. Having said that, there are some that do have drum brakes on the back; these are usually low priced autos that are relatively light in weight (for a car).

If the caliper doesn't float freely, then one of the disc brake pads on that wheel will drag and partially brake constantly. I had a Crown Vic that did that.

How does one calibrate brakes?

[DragBean]

Bent out the brake pad spreader farther so the break pads were not touching.
The wheel now more freely rotates.
This is something so minuscule I did not notice any gains,
but why not do this while you're changing brake pads?