sheared bolt

[steeevvvooo]

I have sheared off the head of an exhaust bolt! Argggh! :hissy: Given that I have agreed a deal on a new bike and am trading the monster against it this is a real pain in the ***. Looks like the nut has sheared off so there is still a remnant of a bolt in there.

I’ve read various ways of trying to get it out but am at a loss as to how I actually do it (heat, but how much? Reverse drill bit gadgets? Penetrating oil and mole grips?)

Any help greatly appreciated as I was due to have the bike collected in a couple of weeks by the dealership :grump:

[steeevvvooo]

posted before a search :flamed:... currently reading lots of old posts, apologies!

[J.P]

I didn't realize you were sooooo strong my dear.

[steeevvvooo]

I think the Mrs could snap one of these bolts :(

[gary tompkins]

Front or rear cylinder head?

[sapone cremoso]

They just screw into the cylinder and are tres easy to snap. Order another bolt it will have a thread on both sides & use any old bolt removing tool to get the snapped one out. Hope this helps if you haven't found out already :ukm:

[pegboy]

It's a bit of a tricky one and depends on how much is snapped off and how much is showing. If there is enough stud showing, can you get two nuts on and lock them together and then try to undo? Of not, then its mole grips, this may require heat applied directly to the cyclinder head alongside the stud, the idea is to heat the head with out heating the stud therefore the cyclinder head expands quicker than the stud. If this is no good then the last option is to drill it. then that depends on which stud and it's position in the bike. In an ideal world with unrestricted access you would file the stud to flatten the end of the stud with a file and try and center punch it as accurate to the center as possible, then its a time for the stud removing tool, drill it in and out comes the screw, you hope. Other wise drill a small pilot hole a then the oversize drill to take a Heli coil and then replace with new stud. The helicoil kit comes with a specific drill bit.

[utopia]

Its always tricky if you end up drilling to remove the stud, as its all too easy for the drill to run off centre, and once it finds the softer ally it'll head off in that direction even more.
If there's enough stud left to get a nut on it, even if its only by a single thread, you may be able to use that to guide your first drill, so as to get it as central in the stud as you can.

Another option, suggested by Mr Gremlin a while ago, is to get hold of some nitric acid, which will dissolve the steel stud but leave the ally untouched...apparently. A small hole drilled down the stud would enable you to inject the acid in the bottom of the stud hole.

You could drill oversize and tap for a helicoil insert or a stepped stud, but that's probably best avoided if you can, as you'll be left with an obvious repair which will function fine but is still a bridge burnt, if you see what I mean.

I'd start off by hitting the end of the stud along its axis with a hammer and punch, which will hopefully crack the corrosion on the threads, followed by a good long soak in a decent penetrating oil...."plus gas" is one such....

A good maxim is....don't try anything half-hearted. Give it your best shot first time, or you may well make things worse.

[steeevvvooo]

Thanks all. I have a mini blow torch pen and hopefully there is enough to try the two nut trick. I wasn’t sure what to heat so thanks for the explanation Paulo.

Wish me luck…

[utopia]

Good luck...!

And when you put the nuts on, lock them together as tight as you possibly can, then unscrew the stud using the INNER nut. This will help to avoid any slippage.
I would definitely give it the hammer and punch treatment as well....every little bit helps. You could maybe even do this after you've fitted the nuts, so as to peen (deform) the end of the stud so that the locknuts cannot unscrew. After all, the threads on the stud will be well corroded and may not grip all that well without a bit of help.

[Martin C]

Assuming you have decent access to the snapped stud, firstly try wire-brushing and soaking in WD40/etc overnight, and then heat the surrounding alloy with a hair dryer (if you lack a proper hot air gun), then try mole-grips (initially try tightening the stud slightly). If (when!) the stud then snaps off flush, use a set of good, sharp HSS drill-bits ('De Walt Extreme' from Machine Mart are excellent) to very carefully & squarely drill down the exact centre of the stud, starting at 2.0 mm and going up in 0.5 mm stages until you're using a bit 1.0 mm smaller than the stud's OD. Use light oil/WD40 to keep the cutting surface lubed/cooled, and don't let the hole wander off into the alloy!! Then use either a (second-cut) tap to re-cut the original thread (half-turn forwards & quarter-turn back, using more squirt), or a 'ReCoil' thread insert kit if necessary. This can be a slow & tedious task, but it WILL work if you are careful.

If you are unfortunate (= impatient/careless) enough to snap a stud-removing tool - or a drill-bit - in the broken stud you will probably then need to remove the cylinder head for attention by a good machine machine-shop..... which is exactly what happened to me on my previous ST4 (916 engine).

I learnt from that mistake to NOT use small-diameter stud-removers! For comparison, I recently drilled-out the 3 seized-solid 6 mm bolts holding my Monster's hugger to the swingarm: one was perfect; one was quite adequate; one needed a ReCoil insert from my kit. I lined up the drill using a set-square, and kept checking it, also ensuring the smaller drill-bits were not bent or allowed to jam. At the risk of stating the obvious, you must use a slow drilling speed for this job, and don't drill down too far, however the stud won't go to the bottom of the threaded hole, so try putting the 3.0 mm bit right through the stud.

Alternatively, you could consider telling the dealership about it instead. They might agree to only knock about £50-£100 off the agreed trade-in price, seeing as they should be fully-equipped to sort it out. themselves.

[Albie]

You are lucky its not a watercooled one, They have 3 x m6 studs per cylinder and snap even easier. Bit awkward getting it soaked from under but its not the end of the world but you have to use judgement before its gets worse. It may feel like its going and then snap. Take your time and you may have success.

[Darkness]

I've had success (On a Land Rover) welding a 1/4 inch drive socket to the remnant of a stud. The heat helps and the socket drive doesn't slip.

[Nickj]

I must admit to always having grave misgiving when removing exhaust nuts. The hot cold cycles tend to do nasty things to them and on a monster the horizontal pot gets all manner of rubbish thrown over it. Studs like this are poor forgotten things that are rarely touched so can get into a real mess!!
So rather than even attempting to undo them, unless I've had them off before I just split them off.
I did notice on my 750 that the nuts aren't solid, the standard items are more like folded pressings (is this common to all series??) so they break up really easily without damage to the threads.
When I have snapped off this kind of thing Darknesses suggection of welding on an old socket works if you have space for it, the welding gets the stud very hot which is usually enough to break some of the internal corrosion on alloy to steel.
Also getting everything hot works well, on steel to steel getting both both a dull dark cherry red will see most stuck threads almost dropping put. With alloy to steel if the stuck items big enough get it very cold (pipe freezer) and heat the surrounding alloy. You want to be careful with heating alloy, use a propane/butane torch not a oxy gas mix as too hot can do really nasty things to the alloy. If theres another half around who is into cooking those little chefs butane burners can do nice precise heating, do be careful and wipe off greasy paw prints after though!!
Even fitting a pair of plain nuts as Utopias suggestion then a few spots of weld from a mig/tig on the stud and lots of thin lube as it cools is often helpful.

[gary tompkins]

I had to replace two front cylinder studs on trike build. The nuts were rusted on and just crumbled when I tried to undo them. I cut the remains of the nuts off with a dremel and mig welded a replacment nut back on. The old exhaust studs then just wound out of the head and I replaced them.