Thanks kids. I've been putting it off because the last two times I went to remove a wheel, I've rounded the acorn nut ( I have a 4-way wrench and even though the size should be exact for the nut, it seems that my gorilla hands can round it ).... Perhaps if the weather is nice this weekend I'll go pickup new nuts, a 21mm, breaker bar and plan to curse the gods trying to get them off.. Or I'll take it to a shop and see what they will charge to do the work
? You rounded it yourself while tightening it? OR, you've rounded the nut trying to loosen them? Often shops overtorque the lug nuts because they use air impact wrenches to tighten the lug nuts, but idea, and it ruins the lug nuts and studs, if NOT causes them to break and pop off while driving.
If you're rounding the lug nuts, something is wrong, either they were overtorqued by a previous owner/shop, OR your wrench/socket does NOT fit properly, OR you're overtorquing the lug nuts yourself.
The socket size for the OEM lug nuts is 19mm or 3/4", both are the same size, and will fit properly and NOT round off the lug nuts.
With aluminum wheels it is critical to have the correct clamping surface (tapered, rounded, flat) make sure the replacement lugs have the correct surface, take an old one with you to the auto store to compare with the new set you're looking at buying.
After you get the caliper off there is a rubber o ring that holds that rotor on.
It is on the hub or unit bearing.
That is if it is still the stock rotor.
Most people leave it off after they put new rotors on.
I think it is there more for assy. at the factory.
That is exactly what it is there for, to hold the rotor flush against the hub while it is moving down the assembly line to the next station where the caliper gets installed.
No need to keep it, but some people do because if you remove the caliper to change pads, the rotor will tilt and NOT hold flush on the hub. You can accomplish the same effect by just threading one of the lug nuts down to the rotor to hold it in place.
Make sure you torque the caliper bracket back on to factory specs! It may see excessive but I have seen them come loose before.
Use a little blue loctite on it, not only to prevent it from coming loose, but to seal out road salt and moisture that might cause corrosion and seize those bolts for the next time you need to pull them.