Square taper crank removal

Hmmzis

Hopefully someone can shed some light on the matter below.

So, I got a crank extractor from a friend of mine to service the bb on my mtb. Yesterday evening was attempting to remove the left hand side crank with the extractor tool but the only thing that it removed were the threads in the crank itself

I'm assuming I'll need a new crank now. But the main question is how to get the old damaged one off?

I searched around a bit and the general consensus is that you need to use the tool but how to use it with the threads in the crank gone?

Mycroft H

Hmmzis wrote: »

Hopefully someone can shed some light on the matter below.

So, I got a crank extractor from a friend of mine to service the bb on my mtb. Yesterday evening was attempting to remove the left hand side crank with the extractor tool but the only thing that it removed were the threads in the crank itself

I'm assuming I'll need a new crank now. But the main question is how to get the old damaged one off?

I searched around a bit and the general consensus is that you need to use the tool but how to use it with the threads in the crank gone?

Ia it an old style cup+cone bb? If you can get the other crank off (the drive side), you might be able to dismantle the adjustable side (the side with the lock ring) the bb and pull the spindle off the bike with the left crank attached.

You may be able to remove it with a hammer and a chisel by brute force when it's off the bike.


Lesson learnt here, always use penetrating fluid before even attempting to remove cranks. And the bb for that matter

Holyboy

There are a lot of ways to go about removing it but the one that requires the least effort would be to spray a bit of oil on the axle re-fit the crank bolt but don't tighten it and go for a short ride, it will work its way loose eventually, you will obviously need to stop and check progress from time to time so you don't kill your self! It will destroy the crank but you needed to replace it any way. Other than that, all the other ways require a very expensive tool or a lot of blood, sweat and tears. Good luck!

cdaly_

I have managed to remove one by use of a big spanner and a hammer:

1. Loosen retaining bolt and back it off about two turns or enough to protrude slightly.
2. Place open end of spanner behind crank and lever outwards.
3. While levering, hit the head of the bolt a couple of smart whacks with the hammer.

The vibration from the hammer blows along with the levering pressure may be enough to free it up...

Hmmzis

Thanks folks for all the advice. Looks like there are some options I can try before packing out the angle grinder.

Squidgy Black

Holyboy wrote: »

There are a lot of ways to go about removing it but the one that requires the least effort would be to spray a bit of oil on the axle re-fit the crank bolt but don't tighten it and go for a short ride, it will work its way loose eventually, you will obviously need to stop and check progress from time to time so you don't kill your self! It will destroy the crank but you needed to replace it any way. Other than that, all the other ways require a very expensive tool or a lot of blood, sweat and tears. Good luck!

You could use this method, but it'd be safer to get your hands on a bike stand and rotate the cranks by hand.

cdaly_

Rotating the crank won't be enough. You need the repetitive pressure of actual pedalling to flex the crank enough to work loose.

Tonyandthewhale

cdaly_ wrote: »

Rotating the crank won't be enough. You need the repetitive pressure of actual pedalling to flex the crank enough to work loose.

Turbo trainer would probably be the safest way of going about it so. Wouldn't it?

Holyboy

Tonyandthewhale wrote: »

Turbo trainer would probably be the safest way of going about it so. Wouldn't it?

If you happen to have one handy, then yes. With crank bolt still in the chances of the pedal arm coming off are tiny, it's the easiest solution to the problem, even Park tool recommend it!

wendell borton

A gear puller might work.

Keep_Her_Lit

Some good suggestions above. Also, previously discussed here.

kumate_champ07

Blow torch, quick and easy.
Aim the flame at the axle end, it wont heat the bike frame so is safe. Once the alluminium is heated enough it will expand, hit it from the otherside with a mallet.
Usually takes 30seconds at most

Hermy

If the crank axle is also being replaced might it be possible to remove the crank arm and BB cup from the opposite side to aid removal of the damaged crank arm.