Stuck front rotor

I'm having trouble removing the front rotors on my '09 GT. I've removed the caliper, sprayed down the studs with rust penetrant, and tapped around the studs for over an hour. The rotor is loose, and moves freely on all five studs, but it won't come completely off. It feels like it moves out about a half inch and then comes to a dead stop.

Am I missing some screw or pin that needs to come out to release the rotor? I've been hammering at this for a long time and no progress seems to be made. Any ideas?

Lots of folks have been there. The rust between the hub and rotor gets really bad. You'll need an adequate size hammer with long handle (mini sledge works wonders). Golfer stance and hit hard on the outter edge, canatvailing force pops out the opposite side. 2-3 whacks and it'll come off. Old rotors will be toast. You will need a wire wheel or the 3M Roloc kit to clean the rust build-up around the studs and outter rim of the hub. Have to make sure the hubs are really clean, round, and true before mounting new rotors. Since you are doing rotors, have you considered the larger MS3 caliper upgrade?

kleinz said:

The rotor is loose, and moves freely on all five studs, but it won't come completely off. It feels like it moves out about a half inch and then comes to a dead stop.

Am I missing some screw or pin that needs to come out to release the rotor? I've been hammering at this for a long time and no progress seems to be made. Any ideas?

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Are anyone of your studs bent & binding? Are the studs rusty and getting stuck?

I wondered if the studs might be bent, however I can place a new rotor over the studs (on top of the old one) and the holes line up perfectly with no binding. I would assume that if they were bent in such a way as to prevent the old one from sliding off, they should be worst at their ends (and therefore the holes and studs shouldn't like up at all with the new rotor). But that's just my assumption - what's the likelihood/symptoms of a bent stud?

The issue is the rust build-up along the RIM of the hub, not the flat surface where the rotor mates the hub. Sounds like you broke the flat surface loose but you still have not cleared off enough rust build up along the rim. The hat on this rotor is a bit tall, which means all that depth has to clear the heavily rusted hub's rim. A reason why this area is so difficult is b/c the backing plate/dust shield prevents you from applying penetrating oil. Options are brute strength or bigger hammer. Once loose enough, you can then go under the car and knock it off from behind via the backing plate opening (where the caliper would be) with a smaller hammer, periodically turning the rotor to guide it along. You won’t damage anything (aside from the rotor) and anything damaged can be replaced.


FWIW: Had the exact experience, twice (on my 2nd Mz5). I would advise to be prepared to have proper rust cleaning ready, chemical or tool.

Unless you really swing a 4ft long maul, there is little risk to the studs but manly blows with a 5lbs object should do the trick.

If you get the idea to use grease on the prev. rusted surface, use as little as possible.
With heat

Thanks all!

Silentnoise713, that was exactly the issue. We ended up borrowing a 3-jaw puller from O'Reilly's and using that to pull off the rotor. Took a *lot* of cranking but it finally broke loose, and sure enough, loads of rust along the rim just poured out. The hub looked pretty good once we wire-brushed and cleaned it up, however one of the studs took a beating and ended up snapping off when we were replacing the wheel. Just got that replaced today. Brand new rotors on all four wheels, thanks to twintrbo!

Glad it is done with. There is where the “golfer stance” (poorly worded with the implicit translation to “golfer swing”) and big hammer = mo’powa. You get full leverage from shoulder down to tip of hammer vs swinging at the elbow or worst at the wrist, which only net very loud ear piercing metal to metal pings…