277 rephase loctite 620?

[Marvelicious]

So I've torn down the top end, I'm reasonably happy that the pistons and sleeves are good for another go-round, since the budget is tight, but I'd really like to rephase the crank and drop in the OD 5th, since I'm already in this deep. In a perfect world I'd just drop it in the mail and send it to Hugh, but a friend once told me that in a perfect world they'd make milkshakes that taste like teenage girls. Pray he never has children...

Anywho... I was thinking on doing the dirty deed myself, but was reading on Hugh's blog about the crankshaft walking apart problem and the tig welding solution. Now I can run a tig torch, but I don't have a rig at the house. It popped into my head that I remembered a high temp bearing retaining compound that loctite makes - 620 seems to be the one with the most realistic specs. It takes over an hour to start curing, longer in cold temps and actually heat cures stronger at the temps our engines run, and its 100% resistant to oil. Cured at 120C it has a shear strength of nearly 5000psi, which isn't nearly on par with welding's 70,000, but the weld only runs around the edge of the joint while this is applied to the entire joint, so I'm fairly confident in the strength factor as well.

My only question is whether it is reasonable to shoot for being able to true the crank up inside that hour work time? Could I just work one joint at a time, truing each pin first, then curing them before reassembling the splined center and truing it? Not 100% how I'd go about that, but thats why I'm asking for input! I know I'd have to be extra careful on tolerances, making sure they didn't stack, so to speak.

Any thoughts? Does this seem reasonable? Should I just suck it up and find a tig machine I can get access to for a couple hours?

 

[irristeve]

It;s not mandatory to weld crank,my rephase was done over 2 years ago(10000-12000kms)no probs so far used loctite spline lock,if you weld the crank its scrap once it wears out,if you are planning on reving it past red line weld it up,good luck

 

[irristeve]

almost forgot,you true crank after splines back togeather,if you shim crank up properly it wont,move to much,but check it anyway & get as true as posible .000mm if posible

 

[tonyc]

I would have it welded. It is true it may be toast if you have to go into the crank again, but most of these have not been apart since new. I am sure my crank, after I have Hugh re-phaze and rebuild, will outlast me and the rest of the bike. Good luck. Tony C.

 

[Marvelicious]

Yeah, now that I think of it, pressing the center together pretty much makes any truing I did on the outsides null and void doesn't it. That brings the entire operation down under an hour (as much as 6 if I do it in the cold) which is pretty ambitious. Makes sense that no one has tried this - it just isn't reasonable.

To weld or not? Having it done simply won't happen, I just can't get around paying people for things I'm capable of doing - except fiberglass work, but thats itchy. I suppose I should check out the condition of my main bearings and make the decision based on that. If I have to replace them all, or they're like new; why not weld? Then again, if I have to replace over $300 worth of bearings, there goes my budget! I do plan to have it (top end) apart again in a year or two due to the condition of the top end, there is just too much money going into the rest of the machine right now to warrant a full and proper rebuild. The plan is to build, refine the design, then make it nice, with riding seasons in between.

As for revving it past the red line, I really can't imagine me NOT doing that. I explained to a friend once as we were spinning cookies in the sand that if Toyota didn't want me to run the engine that high they should have had the rev limiter kick in lower. I'm hard on shit.

Further discussion is more than welcome!

 

[osteoderm]

As much as I like your Loctite 620 idea, I think you just answered your own question...

As for revving it past the red line, I really can't imagine me NOT doing that... ...I'm hard on shit

Like I heard an old Maine boatbuilder once say, "Nuthin' too strong ever broke". I say weld it.