I'm trying to get the 19mm bolts that hold the calipers on...and they won't budge.
Are they reverse threads?

I've been soaking them in Penetrating oil for a week...I've tried heat...

Any suggestions?

Not sure but look on PMB Performance web site. They have suggestions on how to rebuild calipers. This is one of the problems.

I had bolts stuck and changed from one penetrating oil to PB Blaster. Taped it with a hammer a little more PB and let it sit overnight and it worked just as I was going to give up on it


Bob B



Bob B

Normal threads. The bigger bolt just means more surface area for corrosion to happen. All the normal methods - Cheater bar, hit wrench with hammer, hit bolt to "shock" it. More heat and apply paraffin on threads while till hot - paraffin will wick along the treads and lubricate them where penetrating oil will evaporate when metal is hot.

Front or rear or both? You should be able to get to the fronts with an impact. For The rear upper bolt I have a favorite BMW ring wrench. It get it positioned and hit it with a hammer to break it loose. Lots of fun. No room to work in there. I good Six point box end or socket works best.

Sometimes people get confused because they are not facing the head of the bolt and are actually tightening it. Double check to make sure you're turning the right direction.

More heat and again and again,then spray hot bolts with cold water or penetrant,good luck.

None of them have broken loose (but primarily working on the rears. There's not enough room to get a socket in there (at least any sockets I own).

Gave it another soaking last night, I'll giver another wackin' tonight.

Thanks for the insights.

The caliper mounting bolts are NOT reverse (left hand) threads. I suggest getting a long box end wrench and a heavy hammer. Put the box end of the wrench on the bolt, and whack the other end of it in the correct direction with the hammer. Normally, a few blows like that will free up the bolts. Make sure you hold the box end over the bolt head as you hit the wrench. That will keep the wrench from slipping off and tearing up the bolt head.


Good Luck!

Us east coasters are used to dealing with stuck fasteners. I have a pair of $10 welding gloves that I use when I’m working corroded parts. They go a long way to protecting my hands.

I'm kinda wishing for a fuel fire right now on this damn thing.

That might free it up.

...us midwesterners are also familiar with rust belt issues. Too bad I don't have any AeroKroil left over!

Get some.

Impact wrench.

if you are using a wrench and hammer, try placing a car jack stand under the wheel hub.

I custom built a 18mm spanner for my Brembo calipers,cut one end off ,bent it and welded a piece of heavy wall pipe for leverage as I like caliper bolts to be tight.
This spanner can be used @ the top or bottom bolts without getting in the way.

Need a good 6 point box end wrench, i.e. snap on,mac, Not so sure others have good 6 point box wrenches

Seafoam "Deep Creep". It's the best penetrating fluid. I'll 2nd the 6 point box end wrench and a hammer, counterclockwise fo sho

1/2 impact, just let it hammer the bolt for a few seconds at a time. It'll either break them loose or it'll break them off.

I can get an impact on the fronts...rears are another story.
Car is on QuickJacks right now.

Mine are 19mm. Not 18.

And yea, I've got a 19mm flare nut wrench...and some crows foot rachet heads.

Counter would be towards the front of the car (confirming my (real) dyslexia isn't screwing me).

Thanks again!

Don't use the flare nut wrench. It's not made for that. Use a long box end wrench.

Click to view attachment

This is how I have done that same exact thing.

right rear wrench 12 oclock

Use a3/4 " six point that way you won't damage your good 19mm

I still say Acetone and ATF mixed 50/50 is the best penetrating oil. It has never done me wrong.

Box end wrench and a cheater bar. Make the lever long enough and you will break it free.

Heat the boss, not the bolt.

Also try tightening the bolt just a smidge and then loosening it. The key is to just get it moving one way or another.

When you reinstall, put a dab of copper high temp antisieze on it. It helps a LOT.

Zach

BINGO! I have one loose...on my way!

Thanks everyone.

There is a plate that goes behind the bolts, and has tabs on it to keep the bolts from backing out. Did you bend out the lock tabs on the bolt heads before you tried to unbolt them???