Shear or Free seized bolt?

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Doubt it would make a lot of difference, but I would try the impact wrench. Also try to tighten it first and then loosen.

would you be able to heat it with a propane torch? this is what I did. It expands things and breaks up any corrosion. Worked great for me.
 
I've been very successful at shearing bolts off with both... However I'd think the cheater bar would be less likley. If you can heat the seized bolt or get some liquid wrench on it before you mess with it.
 
I think the impact because you're not applying forces out of the bolts axis of rotation.
Add some heat and giving it a few raps in as well as out has worked for me.
 
be sure and use a 6 point socket and lots of your favorite penetrating oil.

I would say the impact if used in a controlled manner. try working the neut back and forth each direction a little at a time. The vibrations help break it loose.

Once loose I would switch to a breaker bar/ratchet and keep working it back and forth adding more penetrating oil to help free the threads up.

my $.02
 
The impact is much less likely to break the bolt mostly due to what Indylan alluded to: very few users of a breaker bar actually only apply rotational force. You'll frequently hear about someone 'jumping up and down' on a breaker bar! This or careless hand use puts significant direct shear load on the bolt itself, in combination with the internal shear loading at the thread interface due to the twisting motion.

Heat, tapping with a hammer & penetrating oil are all your friends here. An impact is 4th and a close 5th would be the breaker bar.
 
Try heating the bolt with MAPP gas vs propane. Provides more heat than propane and somewhat safer to use than acetylene.

Cylinders are available at most hardware stores, home improvement stores (HD, Lowes, Menards). TSC (Tractor Supply Corp) also carries.

Make sure you have nothing that is combustible near the flame and wear safety glasses.

I have never had a bolt that I could not loosen when I heated it with MAPP gas
 
Originally Posted By: cjcride
What would be less likely to shear off a seized bolt/nut, an Impact Wrench or a long Johnson/Cheater Bar?



Impact wrench. It delivers many small pulses of torque. A cheater builds the torque up to a high value and holds it, which is much more likely to shear a bolt.

That said, you CAN shear a bolt either way.
 
if you use a cheater bar make sure to put force on it even, like not have the bar at an angle when you put your weight into it. You can try: heating, soaking in oils, pounding on it with a ball peen hammer, list goes on.
 
Impact wrench will have a higher tendency to shear. If you remember your strength of materials class, material strength and behavior is dependent on strain rate. Higher strain rates cause a material to behave in a brittle manner, which requires less strength to break.

On a practical note, the shock imparted by an impact wrench may do a better job of breaking the corrosion that holds the bolt.

Other wise, I agree with Texan and his idea of working the bolt back and forth and working penetrant into the crevices.
 
Could a nut breaker/splitter be used here, or maybe a Dremel tool to cut a groove or two into the nut (almost to the threads?
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i would heat it up, soak it in liquid wrench as it cools, give it a few whacks with an impact wrench, heat it up again and soak it as it cools then use a breaker bar.
 
The impact is less likely to shear because it does not get tired when underused for a long time. A breaker bar operator will grow tired after a few minutes and push too hard.

Many stuck fasteners can be removed with impacts by pulling the trigger part way for a long time. The rapping stresses the frozen parts without overstressing the fastener.

If you think the trigger on an impact is an on off switch then it's best to leave the job to someone else.
 
Many people have given the right advice. Here's mine.

Oxy-acetylene heat directly to nut only. Then an impact wrench because it only applies a rotary force. Working the impact from tighten to loosen repeatedly tends to help on really stubborn ones (even after you initially break it loose as the threads can become jammed with rust and shavings.) Using a penetrating oil and heat alternating can help. And an old-timers trick is to use wax as a penetrant with the heat! A birthday candle will even work. This is actually one of the better tricks!
 
If you're going to use a breaker bar slip a pipe on it so it's six feet long! The rotational torque remains the same but the sideways shear force gets halved for every doubling of the lever length.
 
Originally Posted By: j_mac
Many people have given the right advice. Here's mine.

Oxy-acetylene heat directly to nut only. Then an impact wrench because it only applies a rotary force. Working the impact from tighten to loosen repeatedly tends to help on really stubborn ones (even after you initially break it loose as the threads can become jammed with rust and shavings.) Using a penetrating oil and heat alternating can help. And an old-timers trick is to use wax as a penetrant with the heat! A birthday candle will even work. This is actually one of the better tricks!


+1 exactly what i was going to say.
 
Thanks for all the info guys.

Impact Gun added to next tool list, as I have nut splitters and cheater bars.
 
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