Extracting the LH crank bolt on FSA (Gossamer/MegaExo) crank
On these cranksets there's a bolt for pre-loading the BB.
It's one of these:
As far as I know, the correct installation procedure is:
1. Put cranks in place, push them on the splines firmly from both sides.
2. Screw in crank bolt, using torque wrench at 0.7 Nm (that's about finger-tight -- really pretty loose)
3. Do up the crankarm pinch bolts to the required torque (i.e. fairly tight).
Have I got these steps in the right order?
Now, ride around for a good old while.
When I come to extract it, I try the following:
1. Undo pinch bolts completely
2. Undo crank bolt
However, every time the bolt has seized, and despite some tapping of both cranks with a mallet to try shifting any stuck bits, the thing still doesn't want to move. Eventually the allen key just tears through the soft alloy head of the bolt (it's definitely the correct size), and I resort to some big screwdriver-hammer bashing into the bolt to get some purchase, and I'm left with a useless bolt.
The threads of the crank were clean, and there was a little threadlock on the bolt (it comes with it), but I've never known it be quite that strong.
Any suggestions? How about greasing the threads? Would that interfere with threadlock?
It's one of these:
As far as I know, the correct installation procedure is:
1. Put cranks in place, push them on the splines firmly from both sides.
2. Screw in crank bolt, using torque wrench at 0.7 Nm (that's about finger-tight -- really pretty loose)
3. Do up the crankarm pinch bolts to the required torque (i.e. fairly tight).
Have I got these steps in the right order?
Now, ride around for a good old while.
When I come to extract it, I try the following:
1. Undo pinch bolts completely
2. Undo crank bolt
However, every time the bolt has seized, and despite some tapping of both cranks with a mallet to try shifting any stuck bits, the thing still doesn't want to move. Eventually the allen key just tears through the soft alloy head of the bolt (it's definitely the correct size), and I resort to some big screwdriver-hammer bashing into the bolt to get some purchase, and I'm left with a useless bolt.
The threads of the crank were clean, and there was a little threadlock on the bolt (it comes with it), but I've never known it be quite that strong.
Any suggestions? How about greasing the threads? Would that interfere with threadlock?
Sometimes parts break. Sometimes you crash. Sometimes it’s your fault.
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Comments
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I've always daubed copaslip on mine and never had a problem with it coming loose. Perhaps the crank is not releasing when you've undone the pinch screws, perhaps they are binding on the axle? Try putting a screwdriver in the gap in the crank and gently lever the two sides apart (I hope that makes sense) after you loosen the pinch bolts.- - - - - - - - - -
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DesWeller wrote:I've always daubed copaslip on mine and never had a problem with it coming loose. Perhaps the crank is not releasing when you've undone the pinch screws, perhaps they are binding on the axle? Try putting a screwdriver in the gap in the crank and gently lever the two sides apart (I hope that makes sense) after you loosen the pinch bolts.
Oops, sorry. Forgot to say that I thought that too, and I tried levering the split at the thick end of the cranks apart with a screwdriver, exactly as you've suggested.
ta, though. I think I'll probably stick copperslip on it next time -- do yours have threadlock on?Sometimes parts break. Sometimes you crash. Sometimes it’s your fault.0
