MPG terrible?

[Kymerik]

you want to make damn sure the rear caliper slider pins are lubricated properly, because from what i've seen none were properly lubricated from the factory.

The remanufactured ones you get from parts stores have corrected this issue according to the "re-manufacturers"

 

[njaremka]

The remanufactured ones you get from parts stores have corrected this issue according to the "re-manufacturers"

yeah, but if i'm putting them on the car, it a two minute check and re-lube if needed. no sense in putting them on the car, then finding out 5000 miles later that they need to be re-lubed and your pads are shot. another reason i do all my own brake work.

 

[GolerDude]

Rear brakes

I had the same problem with my calipers not releasing. They kept rubbing against the rotor making this awful sqweeking sound. I brought it in and turns out there was a rip in the rubber so dirt got in, got a new caliper and everything is fine.

 

[Rusty]

How "freely" should they turn? I jacked mine up the other day and it seemed to me the rear pads were dragging a bit.

I took it to a brake shop for inspection and they said everything was fine. They only drove it and did a visual inspection with the wheels on.

Their prognosis was probably correct.
When you let off the brakes, there is nothing that actually draws the pads away from the rotor, so they do still touch slightly, but as you drive, that quickly burns off and becomes an immeasurably small gap. You applied brakes when you parked it, so they remained lightly in contact. Because of that, you will feel a slight drag, but you shouldn't really need to muscle it to turn the wheel, and both wheels should feel the same. You may be able to feel slight defects in the rotor when you spin them by hand, but they don't necessarily affect it when driving.

 

[mazdaddy]

Hmmm...I have always averaged 27.5-28mpg: but that may be my lead rt foot! But in Ca, if you're not going at least 75 on the freeway---you are too slow!!!(drive2)(five-0)

 

[winston3x]

thanks rusty,

they both turned with little effort but i could hear the pads against the rotor. Just wasn't sure if that was normal.

 

[pasadena_commut]

When you let off the brakes, there is nothing that actually draws the pads away from the rotor

Bicycle brakes have a spring that pulls the pads off the rim when the brakes are released, anybody know why cars don't also have a mechanism to positively move the pads away when the brakes are released? The only reason I could think of was to have the pads as close as possible to the disk so that they would keep the rotor clean. Also, by leaving no gap it would prevent something macroscopic like a twig or a rock becoming jammed between the pad and the disk.

In any case, it makes it a bit difficult to tell if the pins are sticking just a little. If one wheel drags a bit more than the other (when the car is jacked up and they are free to rotate), but isn't stuck tight, is it sticking pins or just normal operation, and that side would have "released" in a few seconds of driving?

 

[Magus]

Update: I got 32.97 mpg from the Protege the other day. I can only imagine what the mpg would be if I got a header, mid pipe, and highflow cat!

 

[Rusty]

...The only reason I could think of was to have the pads as close as possible to the disk so that they would keep the rotor clean. Also, by leaving no gap it would prevent something macroscopic like a twig or a rock becoming jammed between the pad and the disk.

And water too, but you're right, you want it on the job instantly with no confusion in between.

In any case, it makes it a bit difficult to tell if the pins are sticking just a little. If one wheel drags a bit more than the other (when the car is jacked up and they are free to rotate), but isn't stuck tight, is it sticking pins or just normal operation, and that side would have "released" in a few seconds of driving?

Rear wheels should be about the same, but if one is really dragging, there will be a bigger difference. You just have to take your best guess though. When in doubt, grease'em up.

 

[pasadena_commut]

And water too, but you're right, you want it on the job instantly with no confusion in between.

Understood, even so, one would imagine that brakes could still be designed to back off 0.1 mm or so, rather than to "release" by wearing off whatever tiny bits of pad are still in contact with the disk when no pressure is applied. It would save a little gas while also reducing pad wear.

 

[Rusty]

.1mm would be a huge gap, I'll have to look it up, but I think we're talking less than 50 microns or so when the brakes are disengaged.

It wears off in a flash, so I don't think there would be any gain. Also consider the inertia of our 2700 lb car; it wouldn't feel anything that small for the half second that bit of drag exists, and then it's gone until you hit it again.

I'm going to go read about this before I swear to any of it.