Kinda stupid question concerning rear rotor

[Medic]

 Had to have the rear tire replaced when on a cross country trip last year. Took the tire off this week for replacement of the 3 o-rings and maintenance on the splines, etc. Want to make sure the rotor is installed correctly.  I dont have a "install this side out" but I'm pretty sure I never did. Side facing out right now has the thickness minimum and another number stamped on it. surface is flat. The inside has ridges around the bolt openings so the rotor is lifted off the wheel ever so slightly...is this correct.
 One of the reason's I'm concerned is that when checking the rear pads..they are wearing drastically uneven. (the two put together sit evenly, but it's like putting two triangle blocks together..they match because they're wearing unevenly but exactly opposite each other).

Thanks,

[Jack]

Check your bearings.  The only time my pads wore like that, the bearings were shot.

[gordonv]

I just checked my photos of the rotors I sold. There is a directional arrow I saw on the rear rotor, so that would make that side out.

[Bobbo]

It sounds like your caliper is not mounted "square" to the rotor.  Can you check how it's mounted?

[GOOSE]

MEDIC.....WHEN YOU GET THE DIRECTION THING STRAIGHT ABOUT THE ROTOR...MAKE SURE YOU LUBE THE THREE PINS THAT ALLOW THE CALIPER TO "FLOAT".  IF THE CALIPER IS NOT FLOATING LIKE IT SHOULD, THEN THE PADS WILL WEAR UNEVENLY.  THE BOOK CALLS FOR YOU TO USE SILICONE GREASE TO LUBE THE PINS, BUT YOU CAN USE DIELECTRIC GREASE INSTEAD.  I USE THIS GREASE BECAUSE I ALWAYS HAVE TROUBLE FINDING SILICONE GREASE. 

[Bobbo]

MEDIC.....WHEN YOU GET THE DIRECTION THING STRAIGHT ABOUT THE ROTOR...MAKE SURE YOU LUBE THE THREE PINS THAT ALLOW THE CALIPER TO "FLOAT".  IF THE CALIPER IS NOT FLOATING LIKE IT SHOULD, THEN THE PADS WILL WEAR UNEVENLY.

That is good advise for when one pad wears more than the other, but Medic said they are wearing at an angle, like the top is worn more than the bottom and vise-versa for the other pad.

[Medic]

MEDIC.....WHEN YOU GET THE DIRECTION THING STRAIGHT ABOUT THE ROTOR...MAKE SURE YOU LUBE THE THREE PINS THAT ALLOW THE CALIPER TO "FLOAT".  IF THE CALIPER IS NOT FLOATING LIKE IT SHOULD, THEN THE PADS WILL WEAR UNEVENLY.

That is good advise for when one pad wears more than the other, but Medic said they are wearing at an angle, like the top is worn more than the bottom and vise-versa for the other pad.

Actually on one pad its the front wearing a lot more than the back, and visa versa on the other (back a lot more then the front), the two pads fit together exactly though when off the caliper.

[gordonv]

MEDIC.....WHEN YOU GET THE DIRECTION THING STRAIGHT ABOUT THE ROTOR...MAKE SURE YOU LUBE THE THREE PINS THAT ALLOW THE CALIPER TO "FLOAT".  IF THE CALIPER IS NOT FLOATING LIKE IT SHOULD, THEN THE PADS WILL WEAR UNEVENLY.

That is good advise for when one pad wears more than the other, but Medic said they are wearing at an angle, like the top is worn more than the bottom and vise-versa for the other pad.

Sounds like the caliper is cockeyed. Either mounted off line, or like mentioned, the pins are not moving freely.
Actually on one pad its the front wearing a lot more than the back, and visa versa on the other (back a lot more then the front), the two pads fit together exactly though when off the caliper.

[John U.]

Check the front pin that the pads ride on. Being steel into aluminum, it can be easily cross threaded which will put the pads out of alignment.

[Ricky-D]

I don't think the uneven wear on the brake pads is related to anything other than a problem with the pistons within the caliper.

One piston is stuck some and the result is uneven pressure on the brake pads causing uneven wear on the pads.

I don't believe the caliper can get so out of alignment; but I do believe a badly stuck floating pin can exacerbate the situation.  An inspection would be indicated.

***

[hubcapsc]

I don't think the uneven wear on the brake pads is related to anything other than a problem with the pistons within the caliper.

One piston is stuck some and the result is uneven pressure on the brake pads causing uneven wear on the pads.

I don't believe the caliper can get so out of alignment; but I do believe a badly stuck floating pin can exacerbate the situation.  An inspection would be indicated.

***

I had a piston in one of my front calipers that became cocked in the cylinder while I was rebuilding
the caliper - putting the piston back in. I couldn't move it for nothing. I went down to the NAPA place
where the guy in the machine shop let me use his giant air compressor, and that wouldn't move it... a
clean piston in a clean caliper with new seals lubed with brake fluid - it went a little rooster-eyed while
I was pushing it back in with my fingers, and even this giant air compressor wouldn't unwedge it.
The machine shop guy took interest in what I was doing, and he bonked on it with little brass hammer,
and it freed up, and I figured I was good to go.

Not long after, my front wheel bearing went bad at The Fall Color Ride. There's a great shop in
Robbinsville (Wheelers, http://www.wheelersperformance.com/) and he had the bearing and
installed it right away, I was going again in 35 or 45 minutes. Anywho, he noticed that the front
caliper (the one that I had previously noticed had the ability to go cockeyed) was kind of sticking.

I had some extra calipers ($35 from pinwall) and I rebuilt them and replaced them both when I
got home. I threw away the one that had the ability to go cockeyed, so now I just have one extra
caliper...

Long story short, RickyD is right, your problem could be a dirty sticking piston, or worse, a malfunctioning
piston, like mine. I shouldn't have used that caliper after I noticed there was something wrong with it, duh.

Next time you go for a ride, put some spit on your finger and touch your rotor when get off and see
if it sizzles...

-Mike "don't leave your finger on there long  "