Self-extracting crank bolt failure

On extracting the drive side crank on a pair of FSA compact cranks, the self
extracting bolt stripped and pulled out of the crank arm.

The end result was damage to both the self-extracting cover of the bolt and
the crank arm.

My LBS was kind enough to realize that the extracting bolt either was
defective, or the system is defective. In either case, they replace the
crank arm and I am now using the standard crank extractor.

Has anyone else had problems with these self-extracting bolts

I got a pair of self-extractors assembled from dust cap and crank bolt
separately by Harris. On attempting extraction, the cap unscrewed a few degrees
so I stopped to investigate. I removed the bolt and attempted to run it in the
cap.

What I noted was that the bearing surface was on the outer rim of the bolt
flange, not the inner chamfer of its socket head. So I set up my grinder and
took off 0.1 mm in rec.crafts.metalworking under Truing Stone or something.
Then I put the bolt in the drill press and used a very fine file to polish the
flange.

Now the extractor bears in the center and my cranks are beautiful. I even put
the caps in so the holes line up, with blue nut lock.

You see, it's a question of moment and torque.....


Yours,

Doug Goncz ( ftp://users.aol.com/DGoncz/ )

My physics project at NVCC:
Google Groups, then "dgoncz" and some of:
ultracapacitor bicycle fluorescent flywheel inverter

4-1-9 Fraud
http://www.secretservice.gov/electronic_evidence.shtml

I got a pair of self-extractors assembled from dust cap and crank bolt
separately by Harris. On attempting extraction, the cap unscrewed a few degrees
so I stopped to investigate. I removed the bolt and attempted to run it in the
cap.

What I noted was that the bearing surface was on the outer rim of the bolt
flange, not the inner chamfer of its socket head. So I set up my grinder and
took off 0.1 mm in rec.crafts.metalworking under Truing Stone or something.
Then I put the bolt in the drill press and used a very fine file to polish the
flange.

Now the extractor bears in the center and my cranks are beautiful. I even put
the caps in so the holes line up, with blue nut lock.

You see, it's a question of moment and torque.....


Yours,

Doug Goncz ( ftp://users.aol.com/DGoncz/ )

My physics project at NVCC:
Google Groups, then "dgoncz" and some of:
ultracapacitor bicycle fluorescent flywheel inverter

4-1-9 Fraud
http://www.secretservice.gov/electronic_evidence.shtml

"MGS" (remove the remove) wrote in message
...
On extracting the drive side crank on a pair of FSA compact cranks, the
self
extracting bolt stripped and pulled out of the crank arm.

The end result was damage to both the self-extracting cover of the bolt
and
the crank arm.

My LBS was kind enough to realize that the extracting bolt either was
defective, or the system is defective. In either case, they replace the
crank arm and I am now using the standard crank extractor.

Has anyone else had problems with these self-extracting bolts

Yes, just the same, except that my crank was undamaged, once I'd picked the
stripped bolt cover threads out of the crank threads.
I put it down to the fancy anodizing having made the cover more brittle or
something, and got a different brand (Zero) in plain silver, which have been
OK since.

"MGS" (remove the remove) wrote in message
...
On extracting the drive side crank on a pair of FSA compact cranks, the
self
extracting bolt stripped and pulled out of the crank arm.

The end result was damage to both the self-extracting cover of the bolt
and
the crank arm.

My LBS was kind enough to realize that the extracting bolt either was
defective, or the system is defective. In either case, they replace the
crank arm and I am now using the standard crank extractor.

Has anyone else had problems with these self-extracting bolts

Yes, just the same, except that my crank was undamaged, once I'd picked the
stripped bolt cover threads out of the crank threads.
I put it down to the fancy anodizing having made the cover more brittle or
something, and got a different brand (Zero) in plain silver, which have been
OK since.