Please tell me I'm crazy! (brake job)

Yeah, it could be. A 1.2% reduction is not very much, so it's a pretty tight call. There could be a tiny bit of brake drag until the pads bed in. Keep driving it and see what happens, it's certainly very minor if indeed there's anything in it at all.

 

Try putting the car in Neutral and braking to a stop from 40 mph several times over the course of a drive.

If it still seems to be a problem, then jack up the car and see if the front wheels turn freely. It is possible that you have a stuck caliper, if they did not take the time to lubricate the slide pins. Check the back wheels too, even though presumably they did not work on them.

 

This.

It's possible they didn't clean, or properly clean, the caliper pistons and then pushed them back into the bores to make room for the new, thicker brake pads. That accumulated grime can cause the pistons to stick thus not allowing the pads to fully retract away from the rotors and causing drag.

Telling signs would be more brake dust residue on the wheel, noticeable drops in mpg, and as mention above, spinning the wheel off the ground.

 

If the calliper is not free to slide every time you use the hydraulic brakes the calliper will apply both pads to either side of the disc but will only release one side causing it to drag, and wear one pad more quickly.

Jacking the car up and rotating the wheels will soon show if there is a problem.

You will not hear a noise with new shiny discs.

One thing that could cause you to loose MPG, did you change the front wheels from side to side and are the tyres directional. (If the tyres have an arrow on them are the arrows pointing in the direction that the tyres normally rotate)

John.

 

Anyway, remember that a 1.2% drop in FE is very little, so there's still a very good chance that this is just random variations. Definitely track it for a bit longer before worrying too much about it.

BTW. Have you checked you tire pressures?

 

Most disc brakes have some light drag, but can be designed to minimize this (using seals that pull the piston back a little).
It's possible that the new pads have a slightly higher coefficient of friction (to improve pedal feel) than the OEM pads. It's also possible that the drag is slightly higher with the newly machined rotors.
Feel free to go ahead and check things, but be aware that you may hear a rubbing sound of pad on rotor and that it's probably a normal thing to hear.
I'd give it a week or two to see how it goes as the pads get burnished in.

- Chris

 

The only time you should notice a difference is when you brake in an emergency since the hydraulic brakes are only used then, or below 7MPH above this regen braking is used.

 

My experience with brake jobs is that the brakes are a little less responsive before they're bedded in. They'll probably get a little more aggressive with time.