Rounded Crank Bolt

[N Roach]

Hey,

Im rebuilding a dh bike which has a rounded crank bolt, I need to get this bolt out. Any ideas?

I've tried:

*drilling a hole through the middle and using a reverse thread tap

*hammer and screw driver

*using bigger allen and star keys

Nathan

[Fishy]

Do you want to keep the BB?

[duncan_echo26]

You could try and drill two holes and use a pin spanner.

A bike shop could probably get it out.

Edited October 27, 2009 by duncan_echo26

[2sixstreet]

Does the bolt head have the plastic 'washer' on the outside?

Edit: I'd probably go for drilling the head off with progressively bigger drill bits (use lots of cutting fluid) and then ezy-out the remaining bolt when the crank is off.

Otherwise cut the BB shaft/cut the arm off the BB/have someone spark erode it.

Edited October 27, 2009 by 2sixstreet

[King C]

If you've managed to tap a reverse thread into the bolt and there's enough decent thread in there, whack a reverse threaded bolt in there, do it up until the head reaches the surface, then keep screwing. Should come out that way.

[jim-p]

i had this problem before :/

if you have a spare 8mm allen key then what i did was used the adhesive stuff they use in bathrooms to stick the allen key inside the bolt and then it unscrews like normal

Messy but it works

and some time you can get your allen key back if your lucky

[Stanners]

Drill the hell out of the head of the bolt then give the crank arm some hell with a rubber mallet.......pop......(maybe)

[HarriLye]

i have had this problem aswell

What i did was got a flat screw driver and on the rim of the bolt like the outside i hammered it into the bolt so it made an indent (quite deep)

And then got the flat screw driver and pushed down and it came loose...If you dont understand me add my msn : motorcross94@hotmail.com

[Matthew_Gibson]

Might be the pricey option but it should work:

1) Buy your self one of these (http://www.pr-motorsport.co.uk/acatalog/Tools.html) [ the DRAPER EXPERT 35 PIECE BIT SET]

2) Get a spline drive one thats a tight fit, and hit with a hammer.

3) Undo as normal.

In theory it will work. When I rounded a alternator belt drive pulley bolt I use them with an air gun and it worked.

[N Roach]

Thanks for the idea's! I managed to weld an allen key into the the rounded off slot and undo it that way. Shame the crank extracting threads got damaged during the welding, new chainset time!

[Stanners]

Thanks for the idea's! I managed to weld an allen key into the the rounded off slot and undo it that way. Shame the crank extracting threads got damaged during the welding, new chainset time!

If you don't want the crank just grind it off??

[DannyBazz (:]

If you don't want the crank just grind it off??

Haha, we did that to shearers old crank