Getting a stuck self extracting crank off.

[Racing roadkill]

I've been working on the old Boardman Pro Carbon over the past week. I have come to an impasse. The crank bolt is well and truly welded on, the crank isn't coming off without a fight. Today I had a genius idea. I'm not using that crankset again, so why don't I hacksaw the crank off, between the crank and frame?

Stay tuned folks

 

[HLaB]

When I first tried to take one off the left non drive crank came off easy but the drive side crank refused to budge so I gave up and put it to a lbs. I don't know what they done but its been easy since and just a few light taps of the rubber mallet are required.

 

[Racing roadkill]

When I first tried to take one off the left non drive crank came off easy but the drive side crank refused to budge so I gave up and put it to a lbs. I don't know what they done but its been easy since and just a few light taps of the rubber mallet are required.

It's the left crank ( non drive side) that's got the problem, it's not going anywhere. It's the bolt that's had it. I haven't had any need to remove it in 4 years of riding in all sorts of crappy conditions, I guess it's not surprising that it's siezed on. In any case, the Allen bolt head has rounded off, so even if I could un-seize it, it would still be a ball ache to get it out. Hacksaw time.

 

[ianrauk]

Had exactly the same problem. FSA crank. Bolt sheared and just wouldn't budge. Mechanic in the bike shop had to cut it off.

 

[keithmac]

Sometimes you just have to resort to cutting!.

I've had to cut motorcycle wheel spindles out before now due to being completely seized in (not a nice job..).

I use this quite a lot.

 

[subaqua]

You could ask the engineering genius who made this bike ........ View attachment 345803

 

[Racing roadkill]

Sometimes you just have to resort to cutting!.

I've had to cut motorcycle wheel spindles out before now due to being completely seized in (not a nice job..).

I use this quite a lot.

View attachment 345820

What is that? How much? Where do I get one?

 

[keithmac]

What is that? How much? Where do I get one?

It's called a reciprocating air saw (you need a decent compressor).

I think they run around ten thousand strokes a minute.

I've had my Snap-on one for years and it comes in very handy!

Sometimes I get motorcycles in for exhaust swaps with rusted on manifold nuts, I can accuratey cut 2 sides of the nuts off with the air saw and then peel the remains of the nuts off (breaking a stud causes hours of work).

The stroke is around 10mm.

 

[mjr]

Cut the crank - it'll probably be alloy and an easier cut than the steel BB axle.

 

[Globalti]

The solution is to support the RH end of the BB axle very firmly and give the bolt a sharp, positive tap with a heavy hammer, which will break the chemical bond that has stuck the threads together.

 

[Racing roadkill]

The solution is to support the RH end of the BB axle very firmly and give the bolt a sharp, positive tap with a heavy hammer, which will break the chemical bond that has stuck the threads together.

Tried it, ( I'm a big fan of the 'whacking stuff with a hammer' school of maintenance) it's a Carbon frame, I really didn't fancy hitting it any harder than I did, so I cut through the spindle behind the crank. That got it

 

[Globalti]

If you had supported the RH end of the BB axle firmly, say on top of a heavy bench vice, the hammer blow would have gone straight through the bolt and axle without affecting the frame. Simply whacking the bolt without supporting it would transmit the force straight into the frame, which would absorb the force and might cause some damage.