Hi,
What's the best bet for getting a headless bolt out? The one I need to deal with is situated under the n/s rear jacking point of my car at the end of the sill that side. There's about 15mm of its shank left behind sticking out but it's not much to get a grip on (M8 thread by the looks of it). I've tried welding a nut to the end of it but welding upside down is clearly not a skill I've mastered as all the molten filler rod ends up on the deck due to gravity. Any tips or suggestions?
cheers.
Not for the welding but if you really mean that there is 15mm sticking out then that should be enough to get some decent self locking pliers on ('Mole grips') after giving the thread a good soaking of Plus Gas.
If you can't get the toothed / gripping part of the grips to hold, then grinding a pair of flats on it often helps (along with more Plus Gas / time etc).
If you have welded on the end then you may have already 'warmed it up' (another trick).
Giving the end of the bolt some short sharp shocks with a small hammer may also help (depending on what it's screwing into).
Assuming you have the time, it's rare for me not to get such a stud out, even if it means drilling it out and using a stud extractor (along with more Plus Gas / impact / heat etc).
Cheers, T i m
Two M8 lock nuts spannered tight together on the shank having been liberally dosed with red threadlock beforehand. And then unscrew the bottom one ?
If you already had an appropriately sized, but substantial spanner, you could try filing flats on either side of the shank.
michael adams
...
+1
I have several different mole wrenches and try to find the one most appropriate. If you have room to grip with the rounded cutaway part of the grips, this probably gives you the best chance of success. You need to do the grips up as tightly as you possibly can, this will deform the stud giving it "splines" which match the grooves in the jaws. If you have to work right at the tip of the mole wrench jaws (where they are flat) that is where you need the flats on the stud. Sometimes you can get enough of a grip with a mini-mole which has grooves right up to the tip of the jaws.
As Tim says, penetrating oil and heat may help.
Same here.
And why you need 'a small selection' of such things.
Good explanation of the process. You get to know what feels likely to be a 'very good' chance of either undoing the stud or shearing it off, that's how tight they should be.
And will have better chance with good quality grips (that can stay parallel when maybe only 50% of the width of the jaw is being used).
I have a pair of those as the earth clamp on my MIG welder. ;-)
I work on the basis that it can't hurt ... but does sometimes need to be left on a while (and possibly re-applied a few times) and as you say, used with heat.
Another thought is that sometimes people forget to do things back up again a bit, especially when say the rusty end of a bolt has fouled as it's been unscrewed from an enclosed section (like chassis member or sill ) and , sheared the head off before coming free. Before it gets too tight I might first work the bolt back and forth to get some Plus Gas down the thread and even follow that up with some WD40, light oil or even some spray grease.
It has sometimes taken a few days persistence (depending on the timescale's / importance / alternative solutions etc) but I usually get there in the end. ;-)
Cheers, T i m
If the thread was exposed and undamaged I would recommend this as being the easiest and most effective way applying a torque to what is now a stud.
I am rarely successful with mole-grips, or with just two flats to take an open spanner. I have been successful grinding or filing 6 flats that can take a hammered on socket or a ring.
Sometimes it is worth tightening before loosening.
Except I have found that the splines don't have much depth, and are 'rolled' off when applying any pressure with the mole-grips.
For loose threads, or ones not to tight, moles can be very effective.
However in this case the OP has suggested he has an M8 thread. The best thing is to make use of this with a nut and a second lock nut. Another poster recommended threadlock too. Then unwind the inner nut.
If money was no object then an M8 left handed die might do it whatever the state of the thread.
michael adams
...
Then you might not be using the right grips, not good quality grips or doing them up tightly enough. ;-)
From my POV, if you get that right, you will shear the stud of before the grips slip. ;-)
And I've found then good for shifting (initially) tight / seized studs. YMMV etc.
Whilst you might get enough of two M8 nuts on the remaining thread for that to work, you are relying on the frictional force you can generate between the nuts and the shaft and if the force was sufficient to shear the head off the bolt in the first place ... ?
Unless a permanent thread lock (or liquid metal epoxy etc) I'm still not sure you would sufficient holding force top move the stud before the tension in the shaft created by the nuts forcing against each other sheared the stud off again? Don't get me wrong, I have used that method (many times) to remove a straight stud that had been sheared off by an over tightened nut (cylinder head / exhaust manifold stud) or a machine screw with a mullered head but in theory, 'just turning it' (by grip) would be better than introducing extra forces in the stud unnecessarily?
'Just' bonding or welding a nut on the end is ok because it isn't setting up any additional forces in the thread.
Cheers, T i m
I don't think I'd even try to use a spanner like that on the remains of a bolt where the head had been sheared off by un tightening?
But isn't that reducing the CSA of the (seized?) stud even further? When you distort the stud by crushing the 'rounded jaw / teeth' bit of some decent Mole grips onto the stud, you aren't actually reducing the CSA at all (just ovalising the stud a bit)?
Agreed. ;-)
It's funny, much of this is 'feel' derived by experience (inc making mistakes of course) and practice. Like, I rarely turn a nut or bolt the wrong way, no matter which hand I'm using (I'm right handed) or my orientation (unlike the Mrs who often asks me which way to turn a new_to_her tap on? ).
I guess having to get a washer and nut on the end of a bolt up inside somewhere where you can't see or can hardly reach, even by fingertip means you have to get it right pretty quickly or you will be there all day (or until you run out of nuts and washers). ;-)
Because of my patience, experience and reasonable range of tools, I seem to be the one others bring such things to when they give up. ;-)
The only time I have had to ask for help from others is when they have some specialist tools (threaded flywheel pullers etc) or more powerful tools than I. Once such example was when I was trying to remove a locknut from the end of a motor armature and the only way of doing so was with an rattle gun (as you couldn't hold the armature or output without damaging either). My cheapo gun and small compressor was no match for mates 3 phase compressor and Snap-On gun (that had the nut off on the first try ... maybe mine had already loosened it). ;-)
Cheers, T i m
I was waiting for mention of the 'left hand drill bit' but a left handed die comprehensively trumps that in every way. A piece of cheddar cheese and a cream cracker would be more effective.
Proper penetrating fluid i.e not shit like WD40 Heat Dwell time Repeat
Learn to weld upside down or move the object so it's less 'overhead'
Whilst I agree very much with the 'proper penetrating fluid', you can apply it 'intelligently so that it actually / only goes where it's needed and sparingly.
I've seen people over-applying such with (as you say), 'most' of it going elsewhere so again, it needs a little bit of common sense / logic / understanding to apply it where it's required and the best way possible.
So, if the screw is vertical and you can only gain access from underneath you would probably be better off using a spray but even then you could spray it in a very controlled way where you nearly / only 'wet' the boundary between the screw and it's hole and let capillary action take it where it's required.
If the screw is more accessible then I will generally apply (again, using Plus Gas) from the long nozzle liquid can, again, only applying that that will stay around the screw, not all run onto the ground / bench.
For the worse cases I've even made up a small dam using Blue Tack or Plasticine and again, just put enough in to ensure the entire thread / hole interface stays wetted (topping up over time if required).
I think the mentality for this sort of job is assuming that you *will* get the thing out, as long as you repeat all the available steps and never push it too far (and make matters worse) over as long as it takes.
Yup ... and with the proper frame you won't dent the roof. ;-)
Cheers, T i m
Now that's a good tip which I have never seen before.
Also, if it is a long bolt going through (say) a nut welded on the back of a chassis member, then it could be rust on the concealed protruding bit that caused the head to shear. Another good reason to try winding inwards.
Feel is everything!
My neighbour used to call me Mr Fixit :-)
One thing that hasn't been suggested yet and might be worth a try - if all the remaining shank is threaded - is to cut a slot in the end with a hacksaw and wind the thing back *in all the way* with a flat blade screwdriver until it topples back into the void within the chassis member. This might be the best way, cos you can easily clean the exposed thread up with a wire brush and lube it first, so it's highly unlikely to get stuck whilst going back in.
Good point. Or slitting disk on a dremel if no access for hacksaw.
The funny thing is, I bet you also consider what you can do to be 'perfectly normal' and can't understand why everyone else isn't the same?
I was talking to the Mrs on the walk back from the Doctors earlier about the instance I read / heard somewhere where someone stopped to help a female driver who looked like she was having trouble with one of the wheels. It turned out one of the tyres had exploded and the guy noticed that the other three were highly inflated. He asked her if she had recently inflated them and she said yes. To what pressure he asked, ... 'till they were full' she replied ... ;-(
My point is I am sure there are many many people out there moving amongst us who really have no idea about things as simple as that and I'm not sure they should be allowed to be (driving, not existing particularly). ;-)
Cheers, T i m
I have managed to move things like this before with a small Stillson wrench due to its self-tightening action. Access can be a problem though.
SteveW
Rally style - roll it onto its side on a load of spare tyres. :)
SteveW
Pretty small if it worked on M8!
No I agree really, but you do need something more or less as long as the jaws are wide. Chain wrenches also work by the same mechanism.
For nuts which are completely rounded off, you can sometimes move them with a suitable chisel. You need something a bit like a centre punch, but with a tapering shank of square section, and then instead of being ground to a conical point like a centre punch, ground with a flat, but angled along a diagonal. So that the tip "digs in" when the chisel is hammered at about 50 degrees to the surface. And you need to hammer tangentially in the direction which undoes the nut.
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.