Penetrating oil on brake rotor hold-down bolt: opinions?

[aurelius]

There seems to be some doubt as to whether penetrating oil will actually penetrate the threads of the hex bolt on BMW brake rotors. Ultimate goal being not to strip the bolt head upon removal attempt.

Discuss...

[danewilson77]

Oil and heat.

HTC DNA, Williamsburg, VA

[derbo]

Have you seen the penetrating oil article?


Recently “Machinist Workshop Magazine” did a test on penetrating oils. Using nuts and bolts that they ‘scientifically rusted’ to a uniform degree by soaking in salt water, they then tested the break-out torque required to loosen the nuts. They treated the nuts with a variety of penetrants and measured the torque required to loosen them.

This is what they came up with:

Nothing: 516 lbs

WD-40: 238 lbs;

PB Blaster: 214 lbs;

Liquid Wrench: 127 lbs,

Kano Kroil: 106 lbs

(ATF)/Acetone mix (50/50): 50 lbs.


Course ATF/Acetone mix is flammable and probably not a good idea to heat up.

Also perhaps you can look into an Impact screwdriver too as well.


I like liquid wrench.

[ryankokesh]

I had to drill the sob out. Not cool.


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[BCS_ZHP]

Impact screw driver FTW. Go by a motorcycle store or a Harbor Freight if you have one nearby, should only be $10-20.

[ryankokesh]

Impact screw driver FTW. Go by a motorcycle store or a Harbor Freight if you have one nearby, should only be $10-20.

Didn't work for me, but I'd imagine it would for most! (I may have kinda stripped mine....)


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[UdubBadger]

I just did the same thing this weekend.

dane suggested heat and oil, no go. had a good DIY on drilling it out manually. You start with a smaller drill bit (about 2/3 width of screw head), grind it down about a half inch so it creates a centering mark then use a drill bit about .1" smaller than the actual bolt size and give it hell. eventually you'll snap the head right off and then pull the rotor. Then you can go to town on the tail of the screw. Mine was easy to get out with some oil and pliers after that.

hit me up if you need any help.

[danewilson77]

I just did the same thing this weekend.

dane suggested heat and oil, no go. had a good DIY on drilling it out manually. You start with a smaller drill bit (about 2/3 width of screw head), grind it down about a half inch so it creates a centering mark then use a drill bit about .1" smaller than the actual head and you'll snap the head right off. Then pull the rotor and you can go to town on the tail of the screw. Mine was easy to get out with some oil and pliers after that.

hit me up if you need any help.

Yep. That's what we had to do with Chad44's I believe. We used vice grips after the rotor hat was removed.

[ZHPRegistry.net]

Heat is your 1st line of defense. Take a torch, warm the bolt up nice. Then lean onto a wrench very gently... it's a bit of black art, you have to be able to gauge when the metal of the bolt begins to deform and you begin to strip the bolt. If this takes place, throw some PB blaster on it and give it an hour or so.