Ripped threads off crank help!!
 

Hi i have a Kona frame and have has some trouble getting the cranks off.. i finally managed to get one side off but have ripped the threads off the chain set side.. if that makes sense.. is there anyway of getting this off.. i know i will need to replace the crank but what about the bottom bracket??

Also anyone know anywhere i could get my MTB frame shot blasted and resprayed??

i think its a carbon frame.. so would this cost more to respray?

ANY HELP would be grate. Thanks in Advance!!

As far as removing the Crank, if the threads are truly ruined and you cannot thread the removal tool past the bad threads, you can try using a gear puller with arms like this: http://cgi.ebay.com/ebaymotors/Combi...512&adtype=pla

The bb only needs to be replaced if it is worn or has been damaged.

I'm not aware of any way to bead blast a carbon frame. You might check with Calfee who does some great refinishing on Carbon Fiber Bikes.

I have seen it suggested elsewhere that
you can sometimes get a stripped crank
arm in such cases to loosen from the
BB spindle by simply riding the bike
around for a while with torquing nuts
or bolts removed. I've never been
unfortunate enough to have to try it
out, but it sounds like theoretically
it should work -- at least on a square
taper crank.

Probably worth a shot, since crank
is a goner anyway. Are you absolutely
certain there's not enough meat left
in the hole to retap it to one of the
older, larger crank puller sizes like
TA? A good shop could probably do
this for you and save (and remove)
the crank.

Mike Larmer

I can vouch that riding around without crank bolts will cause the crank arm to come off in fairly short order; if you simply need the arm off, that's probably the easiest solution. Build up the bike again, and just ride around the parking lot, it look me about ten minutes at best.

If you can get hold of a metal chisel or a similar wedge shaped tool, you may be able to remove the crank by hammering it between the bottom bracket and inside of the crank close to the axle.

A lot of shops don't even have a Stronglight or TA crank puller; forget about a 23mm or 23.15mm bottoming tap. An automotive bearing race puller is something most auto mechanics have. It works fine on cranks. It uses a pair of plates that bolt together behind the bearing race (or in this case, the crank), giving a two jaw puller something to grab that won't distort or slip. It distributes the force across the back of the crank. Looks like this: http://cgi.ebay.com/ebaymotors/SNAP-...item5642601b14

It depends on what the bottom bracket style is. If it is an older bottom bracket, it will have a metallic fixed cup on the chain side that will have a narrow (only about 3 mm wide) metallic surface that is flat on two sides and is 40mm around sticking out from the side of the bottom bracket; if this is a case, you can get a headset wrench from Park Tool (I use the HCW-9) that has a narrow 40mm fitting that will fit on the fixed cup off of the drive side and (just remember that the threads are reversed, so you will turn clockwise to loosen). Once you've gotten the crank and the ring off the other side, you can take the fixed ring off the drive side as described above and simply pull the bottom bracket through the drive side once it is off. The only downside of this is that the crank on this side will remain attached to the BB and you will have to buy a new crank (which you'll probably want to do anyway, since a crank with stripped threads is not something that you'll likely want to keep around).

If you have a more modern BB that doesn't have the metal surface for wrench flats on the drive side, all bets are off and you will have to try one of the other techniques mentioned above by other posters.

For a more detailed description of this process, see my post: http://www.bikeforums.net/showthread...kets?highlight=. In my case, none of the other techniques I tried for getting the crank off worked, so I had to figure out another way to get the thing off.

Hi thanks yeah ive heard of the riding around solution buyt was trying to avoid it as iv literally removed everything! including the gears and brakes from the handle bars.. im just gunna give smashing it with a hammer ago!

... Also with regards to shot blasting a carbon frame.. im not sure if its carbon fibre.. but it says Carbon Cycles on the back.. behind the seat bit... you know??

Thanks.. ill keep checking back to see if there are any other solutions!

DON'T SMASH AT IT WITH A HAMMER ! ! ! !

Doing so with any amount of serious impact force will certainly destroy the bearings in the BB and very likely will cause damage to a carbon frame. Take it around to a well equipped bike or car shop and have them use their bearing pullers on it that were mentioned above. Or suck up the loss of time and re-assemble it enough to ride it.

If it were the non-drive side you could set the arm knuckle up against a big block of something heavy to take the hammering forces delivered to the side of the arm. But since this is the drive side and the arm's spider legs are in the way you can't get enough effective force into the arm to split or deform the arm enough to let the crank loosen up. So all you'll do is end up ruining the BB bearings.

As for the frame material if the joints where the tubes join is a big smooth filleted shape then it's likely carbon But if they are an obvious weld joint then no, the frame is aluminium or steel. If in doubt post up some pictures taken of the BB cluster or seat post cluster showing the joints well. If it's metal then bead or other media blasting would be fine. If it's actually carbon then no, you don't want to blast it at all. It'll need to be wet sanded by hand to prep it for new paint. Special care needs to be used to only just barely sand down to the last sign of the original paint or primer and not to go further and sand into the actual carbon layup. In otherwords as soon as you see ANY signs of black then don't sand the black spots ANY MORE! And it's best if you just get through the existing top colour and see the primer and stop then. If the existing paint and primer is already black then that makes it all the harder. In such a case I'd live with just giving the existing paint some scuff sanding and fill any small chips then paint. It won't remove the two or three ounces of paint that you would have taken off with a full removal of the old finish but it's better than risking sanding into the carbon layup.

I just want to add: DON'T SMASH AT IT WITH A HAMMER ! ! ! !

Not Even A Really BIG Hammer?
 

:(

HAHA thanks for all the help but last night i managed to get it off by SMASHING IT WITH A HAMMER!! it just came off in the end.. the BB looks fine.. how would i know if the bearings have gone?

Also how much would a BB and new set of crank arms cost? and is there like different sizes to get??

Words Fail Me
 

:roflmao2: