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Buggered Crank Arm(8 posts)

Buggered Crank Armgrzy
Jun 28, 2002 1:32 PM
Looking for the voice of experience here - any one been down this road before?

Working on a parts swap on a buddy's bike and found the LH Ultegra crank arm threads for the removal tool are trashed. When I used the normal procedure for the self extracting bolts it simply popped the cap out with little bits of aluminum threads. The normal crank tool will not go in and even if it did there's very little to grip. Some evidence on the BB cup that someone made adjustments using the external tool required on a DA unit or only if you couldn't remove the crank arm. Hmmmm.....

So anyone get the crank arm off easily in a non-destructive sort of way? My thought is a wheel puller - hard to get the hooks in behind the crank arm. A pickle fork for removing ball joints on a car - mucho damage. Unthread the RHS BB cup and let it pull against the LH BB cup.
The curse of self-extracting cranks.Spoke Wrench
Jun 28, 2002 2:30 PM
I've tried to explain this problem before, but I don't think I did a very good job of it.

If you try to reinstall the crank with the self extracting rings still in place, you are effectively screwing in two different threads (crank bolt and extractor ring) at the same time. If they don't match exactly, something has to give and it's usually the threads in the crank arm.

I don't have any good ideas for removing the crankarm other than the three you already mentioned. I like the third one best because it's the least invasive.
re: Buggered Crank Armcurlybike
Jun 28, 2002 7:47 PM
There is a puller that is used to get in behind close fitting bearings. Smap-On calls it a bearing separator.Assembled it looks like a split square with a hole in the center the thickness thins down as it gets closer to the hole. There is a threaded rod that runs along each of 2 sides that will pull the 2 pieces together behind the crank arm. we always call this separator a clamshell style puller. You then use a 2 armed bearing puller on the clamshell puller and pull against it pushing on the bb axle to get the arm off. When the arm releases, parts will jump at you so prepare to catch. More hands will be handy. I have used this method with success several times. You should be able to get these tools at a rental place cheaply. Take the bike and a crescent wrench and do it there real cheap. This problem may have been caused if someone left the washer under the crank bolt in place after removing the bolt and then pressing against the washer to pull the crank, OOPs. Instant strip. Your results may vary. Good luck
re: Buggered Crank Armcurlybike
Jun 30, 2002 8:51 AM
This link, if it works, may help. I know I gave a lousy description of the separator. This page has a picture at the bottom, they call it a splitter. You would clamp it behind the arm and place your 2 arm puller on the side bolts.
http://www.otctools.com/catalog/files/page114.pdf
Thanks!grzy
Jul 1, 2002 8:00 AM
That looks like the ticket - your first description was good.

I was really amazed just how messed up the threads are - I've never had a problem with the self extracting setup before this. Someone really had to work at it - even the pin holes were messed up from trying to tighten it down. Definitely tips the balance towards the external puller and taking your time.
Oh, by the waycurlybike
Jul 1, 2002 8:08 AM
Just to be careful, make sure the pusher screw on the puller is smaller than the flats of the crank hole and bigger than the bolt hole. Otherwise the problems multiply. You might put an old crank bolt in the hole in the axle and push against that.
Suregrzy
Jul 1, 2002 9:29 AM
I was planning on using the crank bolt, but the crank is pretty much toasted any ways. The CR's look like table saw blades and once you add up the replacement cost of one crank arm and two CR's it's cheaper to buy a whole new crank. My goal is to spare the BB at this point and end up with a good RH crank arm.
Santana recalled their bikes with Ultegra cranks....Spoke Wrench
Jul 1, 2002 8:41 AM
a few years ago. Their fix at that time was to eliminate the self extractor rings and substitute a disc that completely covers the hex bolts. My tandem has those. Since that time, I think they have reverted back to using the self extractors, at least for the S&S coupler equipped bikes.

I'm still more comfortable using a conventional crank-puller.