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Sheared bolt advice

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jjbunn

jjbunn

Jedi Knight
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I was removing the hood hinges yesterday, and sheared one of the bolts on the passenger side /bcforum/images/%%GRAEMLIN_URL%%/mad.gif

2142020498_5a0a93fb01.jpg



I'd welcome some advice on how to proceed: can I drill it out without damaging the threads on the captive nut? Should I try cutting a slot in the top with a Dremel tool and then unscrew it with a screwdriver?
 
Ummm... has it had a days' worth of PB Blaster?

Center punch the bolt, heat and cool it thru several "cycles" with liberal application of Blaster, get some anti-clockwise drill bits of increasing sizes and an "easy-out" or two... Take your time, and have a thread chasing tap of appropriate diameter/pitch handy.

Ooh... and if there's any thread showing on the inside, wire brush it clean and add Blaster from that side as well!
 
...I'm gonna go out on a limb here and tell you to do it my way......and only my way. First see if there is enough of the bolt sticking out of the nut on the other side to get vise grips on. If there is, good. If not, cut a slot in the sheared face deep enough to get a good slot screwdriver in it.
Now beg borrow or what ever a good actylene torch, heat the bolt and the surrounding area cherry red, ALL the way through,everything cherry red,but dont melt it. Once you have it red,douse it with water until it no longer sizzels and can be touched with your finger. Now use either the vise grips and turn it all the way through, or use the screwdriver and back it out,whichever gets the most grip. I will bet the farm that it comes out. By heating it cherry red you have turned the rust to carbon, by dousing it it shrinks it fast to break the bond and the water turns the carbon to a graphite type of lubricant. You can use the PB blaster for phsycological support if you want, but you don't need it.
 
Yeah, BOX, that's if there's anything stickin' out. You're right. Other thing is, Julian pro'lly hasn't the rig to get the rust to temp.


Though ya got me thinkin'... if the bolt did turn out at all, it MAY screw all the way through with clockwise drilling. If the bit catches, if there's sufficient 'creep' into the oxide by the Blaster, etc., etc., etc.
 
DrEntropy said:
Other thing is, Julian pro'lly hasn't the rig to get the rust to temp.
Click to expand...
Possibly, but $50 at Home Depot would fix that.

But it's going to do some damage to surrounding paint, etc.

Since the bolt presumably twisted off because it's stuck, and it's apparently flush with the surface, I don't think the screwdriver slot is going to work. The turning force will spread the end of the broken bolt, locking the threads even tighter.

If there is room in the cavity underneath, I'd probably try drilling (after taking pains to find & center punch the EXACT center of the bolt) clockwise, with hopes of driving the broken end through (rather than backing it out). Start with a pilot drill (like 1/8") then use a drill somewhat smaller than the minor diameter of the threads (like 3/16" if that's a 1/4-28 bolt). If you've hit the center well enough, it won't touch the threads and you'll be able to pick out the remains of the bolt with a dental pick.
 
I say go with the method that does not require cherry red heat. Be prepared to repaint everything in the area if you do. Plus, that is some pretty thin sheet metal there. The one you broke off goes through two pieces of metal, you may have a problem backing it out. Try a good set of Vice Grips on the inside of the fender (you should have about a quarter of an inch) and move the bolt into the hole and out through the wheel well. Would hurt to bang it a few times with a ball peen hammer.
 
"What you do is you heat the bolt till it's red hot. This will also help do de-harden the bolt." (You can purchase a MAPP gas tank and torch at Home Depot for <$50.) "Once you get it "(nearly) "glowing red and the material around it, place a piece of candle wax onto the broken bolt. The wax will then melt into the threads thus lubricating it when you go to remove it. Tap your ez-out in there and turn. Should screw right out with very little effort. If it does not the bolt iself will break apart before the ex-out does.

Mind you this won't work if the bolt is upside down or at a hard downward angle."

I saved the above from another forum but it is an old shop trick that sometimes works. Best to try to screw it in all the way through the nut if there's ample clearance.
 
how much room do you have on the other side. CAn you get a nut just a bit on there. If so you can then weld the inside of the nut to the stud that is sticking out there. THat will give you a purchase for a wrench to turn it out from that side. Now before you turn the welded nut to remove the stud I would heat the captive nut that is in your picture part only, trying not to get the stud too hot. WHat you are doing (among all the other lesser things) is expanding the metal of the captive nut. The metal expands as a function of length with increase in temperature. The "length" of the circumference is 3.14 times the diametre so you are actually moving the nut away from the stud. I have been able to do this on small 1/8" studs that had nuts seized onto them so bad I could hardly see the nut and they turned off with ease.

Good luck
 
Julian

It looks like the bolt that broke was the top one. If so you were trying to unscrew a bolt that was double nutted as the top bolt also secures a strap from the fender.

You may able to back that out from the fender side using a socket wrench. When you do this, do not clean the threads, as the rust, dirt, and undercoating will provide enough crud to bind the nut and turn the broken piece through.

You may need to remove the headlight housing if access from the wheel well is problematic.

Click to enlarge. Do I need to tell everyone to do this each time?
 
If you decide to drill, drill straight, try not to get the threads, start out with a small bit and progress to larger incraments. Again <span style='font-size: 12pt'>DO NOT get the threads with the drill</span>. Once you have a hole through the broken bolt, use heat like suggested and an easy out. It should come out easily.
 
...just kiddin....just kiddin...

ps, Ray is correct,and we are stupid, but that fender is dented,probably no strap is connected.
 
I heartily second PeterK's comment on the candle trick. I broke off a manifold stud as well as cylinder head stud on the 4a engine parts I acquired recently - but I still had enough of the old studs sticking out to grip. Small amount of heat, touch the candle to the area, and the wax will wick into the threads - in your case if you can grab the stud from behind to unscrew it might be worth hitting it with the wax first.

Randy
 
Uh... it's a nut cage, right?

Use a dremel to shear off the bolt parts so that they are as flush with the nut as possible. Open nut cage. Remove nut. Replace with new nut. Close nut cage.

No heat, and very little grinding work, at least on painted surfaces.

I did this for three badly damaged nut-serts.
 
Julian, you will be putting all new bolts in when reassembling, right??
 
Thanks for all the great advice. I am going to tackle this tomorrow (I've been soaking it in PB Blaster today). I don't have the kit to heat the area up, but I suppose I could buy a propane torch or something. The first thing I will try is to gain access at the rear - I didn't release I was undoing a double nut! DUH!. Then I will try cutting a slot, and then drilling.
 
MAPP gas not propane. Propane will not get hot enough for the purpose. MAPP looks just like a propane tank (but labeled as MAPP).
 
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