Caliper Bolts

2004 Mustang GT…Cannot remove rear caliper bolts.I do not have a impact wrench.Tried wD-40 but won’t budge.

You need a piece of pipe 2 ft long or better to slip over your ratchet nor breaker bar.

If you are trying to take it off with a ratchet wrench, get an 18" breaker bar. Sears sells them. That worked for me. When you reinstall the bolt, put high temperature grease on the threads to keep the bolt from seizing next time.

Thanks for the suggestions…

Boss, I’m Afraid You’ll Break Those Bolts Clean Off.

I don’t believe WD-40 is made to loosen rusted, stuck parts. Get something like PB Blaster and hose it on and give it a few minutes. Then give them another shot and try. You can buy the stuff everywhere.

Blaster Link:

You can even turn the bolts slightly clockwise (tightening) and then counterclockwise (loosening) and see if that helps. You may have to work them in and out a couple of turns each direction once they break loose.

I’d work them with a regular size ratchet or a medium length wrench with the PB Blaster rather than a breaker bar. How big do you think those caliper bolts are ? Do you know the bolt or wrench size ?


I believe Ford put a permanent type of threadlocker compound on those caliper bolts to prevent them from backing out. Try going to a hardware store and get a propane torch and a little blue bottle of propane. Both can usually be had for less than $20. Apply the heat around where the bolt threads into the caliper or anchor, being careful to keep away from rubber components and wiring. Heat it for a couple minutes, then try loosening them. Also remember to avoid touching the parts with your bare hands for 15-20 minutes after heating them. Needless to say, they will be HOT!!!

Sorry Boss And WD-40. I Stand Corrected. I Finally Went And Looked At My WD-40 Can.

It definitely says, “Loosens rusted parts”. I use mine as a protectant spray, not a penetrating oil. I just seem to get better results with PB Blaster on rusted stuff.


Its true that WD40 bills itself as a loosening rusty parts type of thing, but it really isn’t a good penetrating oil. I have WD40 for various things, but always use PB blaster when I need to loosen rusted parts.

Heat will indeed work, but it’s too risky to use near a caliper unless the mounting point is well isolated from the caliper itself. The fuel tank/filler hose is nearby also…And yes, the factory uses thread-locker on these bolts…As others have mentioned, use the correct tool for the job. NEVER put a handle extension on a ratchet if you value the ratchet at all…

I suggested propane for this purpose for a few reasons. Aside from being cheap and easy to acquire, it is also fairly safe to use for this purpose because it doesn’t burn super hot. As long as you stay an inch or so away from anything rubber, including the piston seals, and don’t train the flame on the seals, hoses, or wiring, you won’t damage anything. You only have to get the hardware up to about 300-400 degrees to get it to come loose, and that’s about all you can do with just propane. The brake system already sees higher temperatures than that under normal operating conditions.

To the OP: There are always caveats to repairing a vehicle yourself. If you are at all uncomfortable about your abilities, or the possibility of damaging your vehicle, your best bet may be leaving it to the pros. Most shops charge a flat rate per axle to install brakes of around $60.

a one two punch is to heat the bolt, then spray the blaster on it. You can improvise a heat shield from a pie tin to protect sensitive or dangerous parts lines and components.

Tried all the above suggestions with no luck…

An '04 Mustang should not have bolts frozen this solid unless it’s a northern Rust Belt car or one that has been sitting at a beachfront house.

I don’t mean the following comment in a snide manner at all so please don’t take it that way, but you are attempting to loosen them in the right direction aren’t you?

What kind of hand tool (wrench, ratchet, etc.) are you using in the attempt to loosen them?

Do These Mustangs Have A Caliper Carrier That Unbolts ? Those Bolts Are Larger, Torqued Higher And More Likely To Rust. The Bolts Holding The Caliper To The Carrier Are Generally Smaller, Not So Tight, And Better Protected.

We are just talking about the caliper bolts, right ? What size wrench fits them ?


Finally got them loose.Tried some more pb blaster.From the Chicago area and the car is driven in the winter so I guess they were really rusted.


Well congratulations and thanks for posting back…

This was the first time I have done brakes.Took awhile and after a few problems got everything back together and everything works.Replaced pad and the rotars.

Thanks Again!!