|   Desparate call for help.. save my crank | L7
Oct 16, 2001 5:05 PM | | I was running a single 22t chainring (not a stock RF ring- sugino I think) on a pair of Turbine LP's with a bashring for about 5 days. I went to check the bolts today to make sure that my inner chainring was still tight, and the bolts were all pulled halfway out of the crank and mangled-looking. Turns out I used bolts that were too short for the inner ring. Now the crank's threads are stripped. Considering this crank just cost me quite a bit more money than I can afford to spend again, does anyone have any ideas about how to fix it? I have heard about helicoils but have no experience with them and I don't really understand how they're used or what for. I was thinking that I could possibly drill out the holes and re-attach the ring the same way that the outer rings are held on, but I'm concerned that the bigger holes would weaken the spider too much to support hard-core hits to my bashring. If anyone knows any good means of thread repair, please bail me out of this.
Thanks-
Nick |
| re: Desparate call for help.. save my crank | jummo
Oct 17, 2001 10:04 AM | | The first thing to try is to re-chase the threads. Anyone with a metric tap and die set can do this for you. If that doesn't work heli-coils are probably your only chance but the bike will probably creak and click and drive you nuts.Heli-coils don't come in every size and thread pitch, the only bike application I've seen is the rear derailluer hanger and the pedal hole in crank arms. |
| Since your bolts were the short ones that stripped the threads, | clary.
Oct 17, 2001 3:14 PM | | have you tried putting the longest ones you can find in to see if it will hold? After the longer bolts go in, maybe you can chase the threads to re-establish all of the threads.
Not much room on those turbines to drill them out for a heli-coil insertion or outer chainring bolt insertion.
As a last resort, you might use a narrow flat round punch around the outside of the holes to push some metal back towards the holes and chase from the opposite side (you might cross thread if you go in from the side the metal is pushed in from). |
| Thought about that... | L7
Oct 17, 2001 3:38 PM | | I was looking at the threads today and I've got about 1/8" of good thread left. I may try getting the longest bolts I can get, and see if I can thread them far enough through the crank arm to get a nut onto the other side. I'll try re-chasing them first, but the bolts were steel and pulled out a good bit of material when they came out. I'll re-post once I've tried a couple of options. Thanks guys-
Nick |
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