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Caliper bolts won't budge!

1996 Explorer - trying to do brake job and none of the 4 caliper bolts (2 each side) will lossen at all. I have quality tools - tried a 12 point 15mm metric socket and nothing. Sprayed with quality penetrating oil and even heated them and still nothing. Sockets won’t grip the head of the bolt at all. Any tools (sockets) that they make for bolts that are becoming “round” on the head ??

Try 1/2 drive 6-point socket and a breaker bar. You will NEVER break them loose with a 3/8 ratchet. Lock-tite was probably used on those bolts, but they WILL come loose…

Are you sure you are trying to loosen the correct bolts - the ones that hold the caliper onto the steering knuckle are the ones I think you mean to loosen. There may also be bolts that hold the two sides of the caliper together. I know I have come close to working on the wrong ones. ( I don’t know you car’s design, but I have faced this confusion on a few cars.)

I did use my 1/2" breaker and 6 point socket to start, and the socket just rounded them off even more. Didn’t even atempt to use my 3/8" drive. Switched to the 12 point thinking it would “bite into the head” even more, which it started doing, but then he same thing - rounding the head even more.

Definitely had the correct bolts. I did these brakes a few years back and didn’t run into any problem then.

Where are you located, Northern states in the ‘snow belt’, where they use a lot of salt on the roads? Do the bolts look like they have a lot of corrosion? I ask, because that would make sense to me. If the bolt heads are rounding off, the damage is done. Go to a dealer, and get replacement bolts first. These are already destroyed. That is the easy part.

Getting these bolts off will be a serious challenge. If the heads snap off, leaving the shank, you will still not be able to remove the calipers. You may need to cut the guides off with a metal cut-off wheel or a sawzall. Then, you’ll also need guides.

But, I’d use a 6-point 15mm socket and a breaker bar. This combination will either break it loose or break it off. Then, go from there. Good Luck.

Oooops. You already tried it. Try vise grips or pipe wrench next. As I stated, the bolts are shot, so anything goes.

Are you talking about the actual caliper bolts or are you referring to the bolts that hold the caliper yoke to the steering knuckle?
As far as I know, caliper bolts are not 15 MM but the yoke bolts might be; and they do not have to be removed if the rotors are not being serviced.

Since you’re looking at the bolts from the outside you are attempting to turn them in the right direction I hope?
A six-point impact socket on a breakover might do it assuming none of the rest of my post is relevant.

Yes - live in New England. However, when I did look at the bolt’s head(s), they didn’t look all that bad. I was wondering if they make a socket specifically for problems like this, where I could hammer it on the head of the bolt and it wouldn’t slip ???

The bolts I’m referring to are the two bolts (15mm head) which hold the caliper to the steering knuckle. And yes, I was positive that I was turning them in the right direction to lossen them.

They have those wrenches with the cam that push on the flat rather than the corners. The alternative is a impact gun which hits with more force all at once. Try whacking it with a hammer a couple times, perhaps breaking any galling loose

The only thing I can think of is an impact socket on a breakover. Impact socket walls are thick enough that flex is not an issue like in thinner, normal sockets.

Here’s what the bolts look like is why I asked. Yoke bolts, not necessary for non-rotor service.

Caliper bolts. They’re shown to be an 8 MM head.

OK - They are definiely not the smaller size bolts which hold the caliper glides. I never though of using an impact socket on the breaker bar. Thanks.

sears sells “bolt out” bolt removers. these are LAST resort.

are you totally sure you are turning these correctly? when looking at them from the outside they turn clockwise. when you are under the car they turn ccw.

it’s easy top get confused. it has happened more times you know.

Yes - positive that I turned them the correct way.

link to show what a sears bolt out is. zoom into the picture, you can see how they grab, and the more you turn, the harder they grab.

again, this is totally last resort…

but i do have a set and they have saved my bacon on several occasions.

Cappy ; just curious why you keep saying as a “last resort” ?? I’m already planning on replacing all 4 bolts with new ones even if I get them out the “standard” way. Thanks for the info and link. They do look like they would work.

cause if you round/ break these off, you have to buy used knuckles and replace all

i know you are certain, but you must ensure you are turning them the correct way. i know, i have gone over this myself numerous times, and think twice, break it once and you always remember.

Understand now Cappy - thanks. If I do decide to try these (bolt out), I’ll double (and triple) check that I’m turning them the correct way. Assuming that I am indeed loosening the bolts, has anyone ever heard of them snapping inside the knuckle assembly ??? I was under the impression that these bolts which screw into the knuckle assembly aren’t the ordinary metal type of bolts which would snap.

If you had used the CORRECT SIZE 6-point socket to begin with, the heads would NEVER have rounded off…Is your socket cracked (broken)? You are turning a simple job into a fiasco…

For the record, I’ve done at least a dozen brake jobs in the past 10 years (4 cars total in the family). I did indeed start off with a 6 point socket and that is what started the “rounding” of the bolt head. I’ll purchase another quality 6 point 15mm socket and give it a go. I’ve never had problems in the past (ever) removing the bolts going into the steering knuckle, that’s the only reason I placed the post here to begin with to see if thefre was something I might have done wrong. I agree it’s a simple job. I’m guessing that the bolt heads may have been rounded to start. My problem at this point is just removing them. I’m replacing them as soomn as I get them out (assuming I do).