Re: Crank hub problem--what about Loctite??? (archive)

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I would suspect that using any of these sorts of compounds would just make the motor that much more difficult to dismantle next time somethign breaks :)

If I understand what you're saying though..loctite the keyway in place, loctite the harmonic balancer assembly onto the crank directly, and then use threadlocker additionally on the crank nut .. i.e. glue everything together to try and make a fixed unit ?

There is Loctite Sleeve/Bearing retainer formula that is used on light press fittings. It is supposed to give superb shear strength. I'm thinking that if you clean the crankshaft nose and hub toroughly, apply the sleeve retainer, and install, the retainer compound should act like glue, effectively locking the crank hub onto the crankshaft with a lot of surface area contact. Wurth also makes a green liquid that's equivalent.

I used it on my 535 engine that has seen better days. When I rebuilt it back in 1995, I did not torque the crank hub properly. I took it to two track events, and I redlined it a lot. The next year, the chain tensioner rail (new) broke(!). When I went to remove the crank hub nut, I found that the crank hub could spin 20 degrees in relation to the crank. GREAT! I got the nut off with an impact gun, and inspected everything. The hub was fine. The nose of the crank showed a little galling, the Woodruff key was bent, and the keyway was torn a little. Being poor and having little time and resources, I JB-Welded a used key (had 2 M30 blocks sitting around) back into the torn keyway. I let that sit overnight, then cleaned the nose of the crankshaft and inside the hub thorougly. I used Loctite when I slipped the hub back on--it was less than a tight fit. I torqued the nut down really, really long at 125 psi with the impact gun. I don't think it's possible to strip the nut or crank. Oh yeah, I did fix the broken chain tensioner parts and replaced the chain.

The car actually idles a lot smoother, and I don't get a loud grumbling when revving really hard. I hope it's held. The car will get an E34 engine soon, so I'll dismantle it and see if the repairs are still good.

Why am I telling you this? Uhh... I guess my point is: The hub only has the ends that hold it to the crank. When people don't install the crank hub nut correctly (too tight=hub "barrels", too loose, hub vibrates, comes off), you have problems. Maybe if you torque the hub correctly with the bearing retainer compound, it will glue the parts together so the hub can't vibrate in relation to the crank (which is the real problem at high RPMs). Or maybe get the Fahey hub and loctite it, too. Kinda like suspenders AND a belt! I never hit the rev limiter and I RARELY take my M5 above 6000RPM, for fear of either losing either the cam chain or crank hub. It's about to turn 130k miles. I was planning to do the chain and Fahey hub this summer.

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