Stuck front rotors: to heat or not to heat?
 

I'm replacing all four rotors on my dad's S320 as his are a bit warped after sitting for 10 years. Unfortunately even on this nearly rust-free specimen, the rotors are rusted stuck. Have done quite a bit of slamming with the sledge, and use of AeroKroil. I've noticed this issue has come up in searches a lot, but I see differing advice on use of a torch. When my w124's rear rotors where stuck on, a torch got them off immediately ... however, I knew I would be replacing the rotors and the bearings. On this W140 the rotors are getting replaced but not the bearings ... will I damage the bearings or overheat the grease if I lightly torch around the top of the rotor "hat"? Some people say they use a torch; others say don't. Thoughts?

Dry Ice ?
 

Go To Publix and get some.
USE THICK leather gloves and oven mitts.
Get those suckers COLD, and then rap with your hammer.
(I know the COLD will Shrink the Rotors! But at this point you're just trying to
get some Movement to break the "Italian" Bonding.)
['e-mails to Glinda Good Witch of the North]

To answer your Direct question:
Just How HOT do the Rotors get under HEAVY breaking?
(I'll bet those suckers are a couple of hundred degrees,If you pull that Chassis
down from 80MPH a couple of times with no rest in between.)

If y'all wanted to be empirical you could slap the wheels back on and road test for HEAT then "Shoot" the rotors with a Infrared Thermometer.

This is what I was wondering, but assumed they didn't get as hot as a torch flame. However, heating the rotor with the torch does not make it as hot as the torch itself ... I'd just be making a light pass over the surface. I'd just be worried about making a slip, though I'm pretty careful when it comes to fire.:eek:
Dry ice sounds like an option. Do you just hold it on there? Stupid question, but how does one dispose of dry ice?

Shouldn't it just melt and turn back into CO2 in gas form? :confused:

Well, I told you it was a stupid question, didn't I? ;-) I wasn't sure how long it took to melt or if it needed to be kept in a special container.

Daft question - stuck as in caliper and pads stuck and rotor won't spin or stuck as in caliper and pads removed and it still won't come off?

I assume you took the little retaining screw out...

Don't grab the dry ice with your bare hands

I think a rotor in use gets a lot hotter than 200 degF

Frozen CO2
 

Yes it'll Transmifograte from the Frozen State back into it's Gaseous State right
Quickly if not kept COLD (As in cheap Styrofoam Cooler).

No,You don't wanna handle it with Naked Skin.
[That's what the Dual protection of Gloves and Pot Holders are for]

Other Poster was correct in assumption that the Dry Ice is applied Directly
to the Rotor Hub.(Again Gloves and Pot Holders.)

brake rotor/ won't come off
 

hit it hard with a big hammer.

I torched mine off.

give it a good whack with a heavy hammer instead of a torch

As a 15 year mechaninc, I've never encounted a "stuck" rotor. You just have not hit it hard enough yet. A 1lb hammer swung at arms legnth should have it loose in 3 whacks or less. That wheel bearing holds up one heavy car, you aren't gonna hurt it with a 1lb hammer, so swing that sucker like you mean it. Hit it square on the hub, trying at least to miss the dust cap and they'll be on the floor in no time.

Thanks guys. I found out what store to buy dry ice at but decided to give it a few more whacks first. I tried lightly heating the outer edge of the hub area, but I'm not sure it really helped so much as just swinging harder did, like you guys said. I think they key was finding the right angle to actually get a good swing. A few big, loud hits and off they came. My neighbors are probably glad that's done ... won't tell them I've still got the rears to do ...:D

I have (on another make). It took me an hour of hammering on each side. The rotors broke in pieces before they came off. Like already mentioned, the moral of the story with a stuck rotor is to keep on hammering as hard as you can until something gives.