working the crank - getting the shaft

[matt glascock]

AAAAAAAAARRRRRRRRG!!! Having just finished rebuilding the mag/shift case on a 94 and replacing the condenser and points, I was torquing the flywheel nut (14Ft/Lbs) and SHAZAM, before the torque wrench broke, the threads on the crank shaft stripped. Is there a simple fix for this situation? Also,this particular 94 was stripped for mx work by the DPO. The lighting coils are still present on the stator plate. Do these need to be exchanged for blanks? As always, thank you!

Best,

Matt

[Bullfrog]

I think Danny Cook posted his method for repairing exactly this problem sometime back - but it isn't any easy garage project.

The coils can be left in place or exchanged for blanks - your choice. It is quite possible that the original difference - wound coils or bare blanks - was primarily a cost control measure. There was no need to pay for the extra wire and mfg steps for lighting coils when the machine was going to have no lights.
Ed

[matt glascock]

Ah, makes sense. I'll look for Danny's post. Thanks, Ed.

Best,

Matt

[Bill2001]

Went digging for Danny's post-- it's in the "Crank Sizes" thread, and hopefully this link works:

viewtopic.php?f=1&t=2094&p=14873#p14873

[matt glascock]

Thanks Bill (and Ed). Yikes, I was hoping for a solution that is not quite as intensive. I was thinking about a few, probably ill-advised shade-tree mechanic solutions. Taking into account the fact that it is the taper of the crank shaft and the Woodruff key that does the heavy lifting in keeping the fly wheel locked in position, here's my off-the-cuff solution: Needless to say, blue strength Loc-tite will be involved. I have both copper and lead foil which I use to shield the electronics cavities on my electric basses from electromagnetic interference. The copper is practically see-through thin. The lead is as thin and more malleable. I would propose using one or the other similarly to how we use PTFE tape on the threaded components of air-compressor lines and fitments by simply wrapping the threaded end of the crank shaft with a strip of the foil after mounting the flywheel, add a skosh of Loc-tite and try to torque down the nut. Alternatively, some fine copper wire could be interposed perpendicularly between the nut and shaft in a similar fashion. I just need a little bite to torque the nut to spec and leave the Loc-tite in as ancillary support. Plus, the sound of the nut, star washer, and/or fly wheel freely spinning and rattling around inside the mag cover at 8,500,000 RPMs might be pretty cool. Danny's repair is really legit and very sexy but I'm concerned that I'm not nearly as crafty as needed to pull it off like a pro. Zero margin for error on that maneuver, you know. Thoughts?

[Bullfrog]

As mentioned in another post very recently . . . only ride uphill from home after doing the shade tree mechanic solution you have in mind.
Ed

[Bill2001]

Agreed. But one alternative fix might be to use a flywheel puller to fabricate a drill guide to be used with an in-place flywheel. Tap for M8 or M10, fine-thread or Grade 8. This might ensure a straight and centered hole for the replacement bolt.

[matt glascock]

Up hill, going out. I like it. Hey Bill, that addresses my major concern, that being how to make sure the hole is drilled on center AND axis. I'll see what kind of jig I can fabricate and report. One question though - do I need to mount a threaded stud in the crank shaft ala Danny Cooke or can I more simply tap the hole and install the fly wheel with a bolt. Thank you!

Best,

Matt

[dcooke007]

Hey Matt,
In the crank repair pictured I used a bolt that was one size smaller than original. You only have so much metal you can remove. Also, it is likely you may break through the bottom of the woodruff key cutout.

You might be able to thread the existing stud for a different non metric thread size/pitch in a pinch. Sometimes the over lap in sizes between metric and US standard will allow for simply threading on the appropriate die with good results. Die must be reasonably straight when threaded on. Fine threads would be suggested. Try to keep the die as straight as possible.

Danny Cooke

[matt glascock]

Hi Danny, I was hoping you would weigh in on this conundrum. The repair you demonstrated on the crank shaft sizes thread was elegant, effective, and I'm sure, durable. I think running a die over the existing stud is well-within my wheel house. I'm not sure about the safest means of stabilizing the crank shaft during the cutting process. The first inclination would be to place the transmission in gear to lock the shaft although I'm slightly concerned about the strain on the transmission components. Would you be able to suggest the gear most capable of dissipating the load of the cutting process most safely? Thanks Danny!

Best,

Matt

[dcooke007]

Matt,

The load applied to the transmission should not be that great using either tap or die. You only advance the tap or die about 1/4 to 3/4 turn, depending on material, reverse tap or die to break chip and repeat. Use cutting oil and low pressure air to remove chips.

First gear should offer the most resistance and maybe a wrench on the counter shaft nut would be better.

Danny Cooke

[viclioce]

I guess this means your not pulling the crank out of the cases?

By the way, here is a photo of a stator repaired by Danny with the gray RTV as described. He did it with the one he sent me for the 2nd Road Toad. I've done it on the other 1st Toad as well. Works very nicely! ; D Victor

[matt glascock]

Done and DONE!. First gear and wrench on the countershaft, cutting oil, low-pressure air gun, the whole schmear. Outcome...PERFECT!! Great idea, lucky execution. Salvaged crank shaft on a salvaged bike. Am I happy? Oh yeah!! Thanks Danny!!

Best,

Matt

PS Hey Victor, thanks for posting that picture. I'm going to keep that technique in my mental stash. Those coils are getting really expensive.

[viclioce]

Sure Matt! But credit goes to Danny! He did this one and told me how to do the other one by phone! ; D Victor

[matt glascock]

He's pretty darn sharp, that Danny Cooke!