Question... I put Carbotech Bobcat pads and Brembo OEM replacement rotors all around last weekend. The install went well and I bed them in according to the instructions. After driving around a bit, I jacked the car up and spun the wheels. All corners are dragging slightly, rears worse than fronts. If I spin the wheels moderately, I'll get a couple rotations out of the fronts and one out of the rears before stopping. I'm pretty sure it's not runout as the sound is constant. My rears are definitely warmer to the touch after a drive. I'd say around 150F since I'm able to hold my finger on them for a couple seconds. The fronts seem to be in the threshold of being alright but I don't like how my rears are grabbing. Parking brake issue? Comments, suggestions?

 

When you installed the rear pads, did you get the inboard clip on the back of the pad installed correctly on the caliper piston? The piston has a grove the clip will reside in.

 

Yeah, they're clipped in. I just checked again and it's actually the right rear and left front that are the tightest.

 

The rears are probally draging a little due to the parking brake.
Set and release brake several times.
Drive a little bit.
Repeat process.
Other issue maybe rotor runout due to surface rust or dirt on hub before mounting rotor.
That maybe the same on the front.

 

Ok, tried to set and release and it didn't feel like it changed that much. Took my infrared thermometer out when I got home from work and both fronts are sitting around 120-125F, left rear is at 105 and right rear is 150.

 

Same temps after coming home from work today. I checked the parking brake and it's adjusted fine. I was able to actuate it by pulling the lever at the rear calipers and there's definitely movement before it engages.

So I decide to pull everything on the right rear corner. The inner pad didn't look like it was sitting right and the clip was pinching part of the dust boot. Fixed that and reinstalled (making sure it clipped into the piston on all sides). Checked the rotor and it spins freely when the caliper was removed. The outer inch on the inside face of the rotor was a blueish color indicating the inner pad is the one that's rubbing. Reinstalled everything and went for a drive and additional bedding in. Came home, jacked it up, and it's still rubbing about the same. It's almost as if the pad is cocked slightly which doesn't seem that far fetched considering the amount of components and tolerances involved Maybe the pad just needs more bedding in and it'll end up wearing flat with the face of the rotor. I guess I'll let it go for a couple weeks and see if it gets any better. I'm just worried about glazing the pad and rotor. Also, I doubt it's runout on the rotor as it's a constant sound throughout the rotation of the wheel. If it was runout, it would come and go. At least that's my take on it. Any comments?

 

I would expect the rotors to drag just a bit. They don't freewheel like a bike wheel or something, or like old drum brakes for that matter. On most cars I have owned, it is rare to get more than a fraction of a revolution out a wheel when I jack the car up and try to spin it, assuming the parking brake off/tranny in neutral. An older car might spin more, but that is likely more because of sloppy bearings. Front may also spin a bit more due to greater rotor mass, offset though y typically much larger swept area. More generally though, if I had a car w/ pretty freewheeling spin, my conclusion would tend to that suggesting a problem like an out of true rotor forcing the pistons to back off or some such.

Meanwhile agreed of course if your pads are not sitting square to the rotor, that is goofed up and needs further attention. Similarly it does sound like some issue in that one of the rears maybe hanging up. Variously look at the lever actuator hardware that drives the parking brake function, but maybe also your caliper. Could be that the piston is scored or worn enough it is cocking in the cylinder area of the caliper, or otherwise hanging up. Rare, but I've seen it once or twice. Have also seen issues w/ backing plate h/w not sitting right, or a clearance problem w/ side guide type tabs on pads where they don't interface right to the caliper machining. Would have to visually inspect and compare it to any unusual pad wear to get a clearer sense of that.

 

Brakes always drag on the rotors a little bit. The only number I might be concerned with was that 150. And not because it was hot, but because it's different from the others. It's probably fine.