I tried and tried, even with the car running in N and able to turn the hub, I could not bang the rotor off the back end. any special trick I am missing ? parking brakes were totally off but it would not budge.

I ended up replacing the pads, so the car could be used and did not update the sensor.

Can I reuse the pads when the new rotor are replaced and I guess I will be able to reset the brake warning once the new sensor is installed...

first thing first, removal of rear rotors...

any idea is appreciated.

 

PB Blaster + Sledge Hammer tried?

 

+1 on the hammer. Just make sure the emergency brake is off and the one screw is out of the rotor before you hit it. Just wack it twice with a lager hammer or once with a sledge hammer and it will come right off. You should not need any PB Blaster if you are hitting it off just an over kill and unnecessary money in my opinion unless you need it to take the rusted screw out. If you strip the screw when taking it out don't worry about it because it is not needed. It is only there to keep it in place while you finish putting the caliper back on.

 

As previously written, make sure that the rotor screw is removed and that the e-brake is off. It takes more than one or two hits to break the rotor loose. You've got to whack that rotor with a big ball-pein hammer- or a dead blow ball-pein hammer is even better. When you re-assemble the new parts make sure that you coat the hub with anti- seize to prevent this occurring again.



Dead blow hammer

Trusty Cook dead blow ball pein hammer

 

Several months ago I was in exactly the same place as you. But even before I got to the step of removing the rotor I stripped one of the rotor screws and had to first drill it out. PITA!

Then I tried removing the rotor but nothing! First I tried the PB Blaster and other penetrating oil. Then a rubber mallet and finally a small sledge. Nothing. They wouldn't budge. Swinging a sledge around your car while it is on jack stands and you are on your knees is not my idea of a safe situation anyway. And I have heard that if you strike too hard you can actually dimple the wheel bearing raceway and possibly even bend aluminum suspension parts.

Some also recommend heat, but I am not a welder and I have also heard that you can cook the grease in your wheel bearing if you apply too much heat to the wrong place.

I was close to putting my tail between my legs and taking it to my mechanic when I wandered over to my tool chest to see if I could come up with any other ideas. And what did I spot?

A wheel puller I hadn't used since I did the timing belt on my wife's Lexus. A Harbor Freight 8" puller (some call it a gear puller, bearing puller or wheel puller) designed to remove parts from shafts.

I hooked it to the rotor (the hooks on the jaws slide right into the cooling slots in the edge of the rotor) and started cranking with a 20" breaker bar (another HFT purchase). As the cranking got harder the rotor began to flex on the outer diameter, opening a space between the rotor and hub and allowing more penetrating oil to reach the rust spot.

After cranking another few turns BANG! That baby popped right off. No future pounding for me. I'll never start another brake job without a puller by my side.

8 in. Three-Jaw Gear Puller

One other technique I read about but haven't tried is to remove the rotor screw and then put the wheel back on but leave your lug nuts loose on the wheel. Back out into your driveway and then apply the brakes hard. Pull forward and backward a few times applying the brakes hard. The theory is that without the lug nuts tight the rotor can spin between the wheel and hub as the pads grab it which will break the rust connection to the hub loose. The rotor can only spin until the edges of the rotor holes meet the loose studs. You don't want to go driving down the street with the wheel loose, but back and forth in the driveway is safe.

But I still like the gear puller because you only have to remove the wheel once, and no pounding is necessary. It comes off like butter.

 

wow! some people have had some bad luck with the rear discs!

In my years of mechanics the main problem with the type of disc/rotor fitting to BMW's is the inner hand brake pads that expand on the inside of the disc/rotor

If the discs/rotor are old the disc will wear a lip on the inside outer lip of the rotors.
So even when you have released the handbrake and removed the disc retaining screw, the brake discs will still be too large and will not allow the rotor to be removed over the brake pads.

The easiest way is to release your hand brake pads with the adjuster before attempting to remove the disc/rotor
This will make the pads smaller than the warn lip on the rotors and allow the rotor to easily and without any stress to be removed

Then when you fit the new rotor you can simply readjust the hand brake pads.

 

x2 on this. had the exact same problem on my toyota with the lip on the edge of the rear rotor. even with the e-brake off, it was still catching on the e-brake shoes. adjusted the shoes inward and the rear rotor slid right off.

 

My trick is to heat the alum hat of the rotor with a torch for a couple of minutes. Prod with a wooden stick or 2X4. Pops right off. Easy says Peasy.

 

HI,it may be late but I'll chime in on this,any time a rotor os off,always clean every mating surface, when ever you break away metal from metal,there is a rust ring, clean the hubs,clean all surfaces,till they are smooth, apply a little never seize on the hub before install of rotor,that's were it sticks,I've cleaned the rotor inserts and never seize those as well,but I just snug them,that's all you need,the lug nuts do the rest,and properly torque the nuts,even pressure, this works flawlessly for all my brake jobs.

 

I got my E60 off without a hitch.. but recently ran into this same problem with my wife's 2013 CX-9. The problem was indeed the parking brake shoes were hanging up. what a horrible PITA, and I was told Mazda has almost no clearance with the pads.. bad design.

I also went with the harbor freight puller, but I didn't know if the 8" puller would go around a 12.8" rotor so I bought the 5 ton hydraulic puller. This cost me $80 with a discount coupon I think it's 67.99. This tool was like the jaws of life and it got it off.. I still had trouble picking out the parking brake shoes still.. but there was no way I could have muscled or banged these rotors off.