How to remove this broken bolt?

atikovi · Apr 12, 2020

I'm trying to drill out this broken M10 seat bolt and have worked my way up to a 7/32" cobalt bit about 0.4" deep. Can't seem to go any further. Bit is new. Bolt is probably HSS or work hardened, I've read about solid shank carbide bits. Would that be the next step? And with a hand drill?

This is the other one where the bolt came out fine.

LD · Apr 13, 2020

I usually try something like Liquid Wrench and an EZ-out first, if I can get a good hole drilled in it which you seem to be able to have done. Worst case is a nut spot welded onto the top of the bolt.

Absolute worst case would be to completely drill out the nut, and what looks like some corrosion around it, then weld in another captive nut.

atikovi · Apr 13, 2020

If I snapped off a 10mm thick bolt, a thinner ez out is just going to snap and make it 10 times worse. Still figuring it out.

crossthread · Apr 13, 2020

Atikovi you are probably correct when you say an easy out is not going to cut it. It looks like you can peel back the carpet and expose the area. I would not be surprised if those bolts were put in with lock-tite for safety reasons just as seat belt bolts are. Heat is going to be your best bet in my opinion. Heat the bolt up gently at first and apply penetrating fluid of your choice (PB blaster, Kroil even WD40. Let that sit and then do it again. You may have to heat the crap out if at that point and you may be able to get it out with an easy out. If it were me I would mig a nut to the top and let the heat help to get things going then put a socket on it.

SVE Performance · Apr 13, 2020

Those bolts are hardened at the end as they are thread forming bolts, so drilling thru the bolt is unlikely without carbide. Bill

atikovi · Apr 13, 2020

I've already enlarged the hole to 5/16 so nothing to weld on to.

guest · Apr 13, 2020

atikovi said:
If I snapped off a 10mm thick bolt, a thinner ez out is just going to snap and make it 10 times worse. Still figuring it out.

Absolutely. You stick an ez-out in there, then you have a broken bolt with a hard-as-hell busted ez-out stuck in it.

I'd just bite the bullet and weld another bolt to the broken one, and work it free gently. That's the best way.

I'd like to be the guy that invented ez-outs. Must have made a fortune on a product that never works, and usually just makes the problem 10x worse....

guest · Apr 13, 2020

atikovi said:
I've already enlarged the hole to 5/16 so nothing to weld on to.

Can you stick a 5/16-18 bolt in and weld that?

The heat helps free up the stuck threads, kroil helps too, let it soak for a day.

Booze Daily · Apr 13, 2020

Do you have access to the underside? Put some vise grips or double nut it and run it on thru.
I would expect drilling it open may have relaxed the threads a bit.

atikovi · Apr 13, 2020

Booze Daily said:
Do you have access to the underside? Put some vise grips or double nut it and run it on thru.
I would expect drilling it open may have relaxed the threads a bit.

No, it's a boxed section on the floor.

rustyironism · Apr 13, 2020

I agree that they are locktited.
Need 400 degrees to break the bond.
A heat gun can get that hot.

I have had more success using a Pipe Extractor easy out rather than the left hand twist ones.

If you can thread the hole you've drilled, screw in a bolt with jam nut.

Or keep drilling until you hit the threads, then gently chisel them out.

Welding a washer, then a nut is the standard procedure, if you have a welder.

Mike

atikovi · Apr 13, 2020

I enlarged the hole some more with a carbide burr, and was able to knock off the remains of the bottom of the bolt with an air hammer. Will check if the threads are salvageable tomorrow.

D Nelson · Apr 13, 2020

Drill that sumbitch out and tap it bigger
Don

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john.k · Apr 13, 2020

I would fill the drilled hole with MIG weld ,this will shrink the thread ,and burn up any loctite....When filled ,then weld a nut on top and apply a rattle gun ...done many ,never had one refuse to come out ......even where some one has screwd stainless into stainless.

morsetaper2 · Apr 13, 2020

Sometimes a left hand drill bit will help work things loose and unscrew the stuck bolt.

Superbowl · Apr 13, 2020

You of course are going to have to drill it out. There is no other way. To drill out a broken bolt, I always use a left hand drill bit and run the drill in reverse. Usually at some point in the drill out process, what is left of the screw shank will unscrew itself out. Harbor freight sells a set of left hand drill bits but like all their bits they are not the best. You may want to measure one of the screws you got out and look up its minor diameter so you can order a quality HSS left hand drill bit that is just smaller than the minor thread diameter. the process is: drill a little, apply some Kroil or PB Blaster, drill some more, apply more lube, and on and on until the broken shank twists out or you have completely drilled it out.

carlherrnstein · Apr 13, 2020

Don't use a easy out they don't work. Weld a nut on it and use a impact to remove. If the nut breaks off repeat it will come. You have to get it red hot, the red iron oxide will change to black iron oxide at that point the rust weld is broken.

BT Fabrication · Apr 17, 2020

Drill bits don’t work, they are hardened bolts. Impossible to drill, and can’t hand drill with carbide.
Weld to end of bolt with a nut a few times and hopefully it backs out.
Ive had to plasma cut some out before for body bolta

Scottl · Apr 17, 2020

Penetrant plus left-hand drill bit usually works best.

The product that has worked best for me over the years is Break Free CLP. Spray it on and then allow time to work. GENTLY tapping the broken bolt often creates vibration that helps the fluid penetrate. The other thing is to try and access the underside of the bolt so it can also be sprayed. Seat bolts are often in boxed in areas but usually there is enough of an opening to insert a spray tube. They wouldn't rust if the area were totally sealed.

gmach10 · Apr 17, 2020

FWIW Next time you have to deal with a stuck bolt don't try to unscrew it. GET IT TO MOVE FIRST!!! 1) Soak it whatever makes you happy. 2) Smack the side of the fastener with a hammer and drift, not hard enough to snap the head off just enough to shock it so the liquid whatever can get in the threads. 3) Use a 6 point socket or wrench and try tightening and loosening the bolt. Again, JUST GET IT TO MOVE!! Once you get it to move work it back and forth all the way out. Use heat if it is in a safe place to use it. Look under your car before you do anything, don't want to find out you're torching above a gas line or brake line the hard way.

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