Tried a new penetrating oil on a seized caliper bolt, it snapped clean off.

Used the whole can, heated it, still sheared. What's your go-to method when a bolt just won't budge?

3 comments

3 Comments

That acetone and ATF mix is interesting, I've heard about it but never tried it myself. When you say a sharp crack with a hammer, are you hitting the bolt head directly or just the wrench handle? I've snapped a few bolts hitting them straight on.

maryt621mo ago

My old shop teacher swore by a 50/50 mix of acetone and ATF. You let it soak for a day, then give it a sharp crack with a hammer on the wrench handle. If that doesn't work, you're usually looking at drilling it out, which is a whole other headache. I've had the best luck with that mix over any store-bought penetrating oil, honestly. Sometimes you just need that shock from the hammer tap to break the rust's grip.

cooper.linda1mo ago

Wait, have you ever tried heating the bolt first? @maryt62, I get the acetone mix works for some, but I've seen too many rounded-off heads from hammering. A little heat from a propane torch makes a HUGE difference, then you can usually just turn it out normal. That hammer shock can mess up the threads or the tool in my experience.