Best method for removing stripped allen bolts?
 

Rounded off an exhaust header bolt. :(
The 2 outside ones loosened fine, the 2 inside ones just courteously changed their shape when I turned the allenkey.

2 Questions...

1. What's my best option for loosening? I've thought of...

-Filing flats on the bolt heads, not easy.
-Sawing bolt head in half and using a screwdriver/bit with ratchet.
-Drilling into the bolt, .. :(

2. Do I need specific bolts? they have a very deep head on them. can I use regular allen bolts?

Is your Allen key still in good shape ? or has this occoured because the corners have worn from the Allen key?

Without seeing the state it's in its not easy to suggest a fix as the fix depends on the state and what you have available to sort it.

Suggestions I would throw in are;

1) Before starting, make sure the hex bolt is clean, properly clean with no debris inside. Then try a new allen key (with nice clean corners on it), you might just have enough contact to remove it. I'd be inclined to leave it (bolt) soak for a while with a good quality release oil, before starting. The stuff Scaffolders use to service the fittings is very good for releasing siezed bolts.

2) Mole grips, if you can get good purchase on the offending bolt, if not I wouldn't even try it as you could make things worse.

3) Heat. Getting lots of heat into the bolt will help, but you need to be able to grip it first!

4) Screw Extractors/Easy Outs. As long as you can get a good grip on the tool, in a straight line, otherwise they tend to snap.

5) using an oversized Allen key, hammer it into the bolt, or if you have a Torx bit, they work too. Using an impact driver will help.

Just a few, I'm sure I'll think of more as the day goes on!

Good luck

hi mrfijjitt, darren has covered every base, very good suggestions!

if i was dealing with it- after a soaking in release oil try the over sized allen key trick if it failed, next the grips, then resorting to welding a bolt to the damaged fitting using a mig welder let it cool for a minute or so and then loosen, drastic sounding i know but between the direct heat and a decent grip it's the most effective

the fitting is basically a nut shaped like a sleeve, driven by a allen key. the stud coming out of the head allows for a strong reliable fitting. so i would avoid changing to a bolt style which can be more easily pulled out from the head causing worse problems, get on to yamaha and get new allen nut jobbies and new studs if nessasary

bernard

Following on from this, it's not necessary to use an oversize bit...

If you hammer the head of the allen bolt (this works particularly well with button head rather than socket head, but socket heads still work if you hit them hard enough x) so that the rounded off faces look like a hexagon again, hopefully a bit smaller and tighter than before...

Then hammer in an allen key so it is a really snug fit (a socket type one is a good idea as you can get more leverage, but it works fine with regular allen keys too, although it's a good idea to use some sort of extension bar, such as a plug spanner over the long end of the allen key, again for more torque/leverage)... you'll find more often than not that the impact of the hammering, together with the snug (interference) fit of the allen key in the compressed socket, will have the bolt free...

I have done this on a number of occasions... and recently won a significant bet, when a friend said it wouldn't work... she has yet to eat my deep fried sandal!

Jx

ps. if you are happy to forfeit the bolt and allen key, you can even add a dab of superglue into the socket before you hammer in the allen key - I did this earlier this week with a bolt on my mountainbike suspension that has resolutely refused to budge for over 14 years... once the glue had set, a bit of leverage and it popped out a treat!

Or knock in a Torx bit into the damaged Allen Key head.

Thanks people!
Enough help to get it sorted i'm sure....

also a slight tighten first can help
just brakes the crud

Anyone manage it? My Allen header bolts are rusted. Tried plus gas soaking each bolt then tried a Allen key then torx then oversize torx. Now hole where Allen / hex shape. Any advice How to shift them. Two out side bolts may be persuaded easier than two middle ones.....??

Heat ?

Do you have access to a blowtorch ? It might work, but Oxy-acetylene would be better. Get it hot and it should budge without too much effort.

Thanks - Yes. Heat might help. But since the header bolts are round outer and Allen head inner has rusted away not sure what I can do? No oxy wasname gas set up. Two outer bolts might be easierto get at with heat. But ttwo inner onesside near oil filled frame post in front on engine. Wouldn't like to apply heat too close to that! :eusa_snooty: