Fix for bad threads in Crank ?

[ch4x477]

I sure hope this isn't as bad as it seems. All the threads are gone in the end of my crankshaft, and now the vibration damper/harmonic balancer will be loose. Anyone know of a fix for this, other than tearing this great running lil 350 apart ? I sure hope so ! Thanks.

[Russell]

You arn't at a total loss yet

What many guys do when they strip the threads in their crank out, or break some super hard tool in there that they have to chisel out, damaging the threads beyond repair, such as I did, lol is put a 454's balancer bolt in.

Its larger than the SBC balancer bolts, so you can drill out the snout of the crank (make sure you get it centered!) then tap it for the 454's threads. After that, you can use it like normal, and be careful not to strip them out again

[cgrossl]

Just drill and tap it for 1/2-20 threads then buy a grade 8 1/2-20 bolt of the correct length and tighten it up. You'll have to drill out your washer, but that isn't a big deal.

[chevyjr73]

you can also buy a helicoil thread repair kit at many fastener shops or some hardware stores. it will repair the threads to the original size and is just as strong as the original threads. kit normally comes with the drill bit, tap and coil and tool to install it.

[swervin ervin]

This has probably happened to a great many of us. First thing I would try is a bolt a tad longer. It's very possible you might have some threads a little deeper.

[corn]

Its not how you do it, but you have to do something. About 20 years ago I left the bolt out of a stripped hole & got to replace the crank for being lazy. The balancer came loose & wore the key way so bad that the crank was junk. Please fix it right away...

[ch4x477]

Thank You all for your responses ! Last night when this happened, when I felt those threads give, all I could think was no way, that did not just happen !! But it did. Cornfed63 T.Y. Truck isn't moving until this thing is fixed ! I like your idea Swervin Ervin, I'll check the depth and length etc... Perhaps a thinner washer... Russell & cgross, You guys said what I was thinking I would have to do. For some reason I get the feeling that tapping this thing is going to be a real headache ! Heli-Coil , T.Y. chevyjr73. Perhaps I can get a Heli-Coil that fits into the threads that are (or were) already there. It would make the bolt a lil smaller in diameter, but I doubt that would hurt anything. I'd definately Loctite the coil in... Well parts stores are open, gotta go and fix this thing. I let you know how this goes.

[MylilBowTie]

Its a really good idea to use a harmonic balancer installer tool whenever you install/reinstall one. Kind of late now but it really does help save the crankshaft from getting ruined.

Im also a member of the messed up crank thread club.

[ch4x477]

Well said Mylilbowtie ! Whenever I remove the balancer, I do use the Press on tool made for these things whenever I'm putting one back on. Mine just came loose. I found that I have anouther full inch of threads available so I'm off to the local hardware store to get a longer bolt. Only 1/2 an inch or so was actually grabbing. Swervin Ervin Thank You ! And thanks all for your suggestions. I really dig this site ! Gotta go, I have 1/2 hr. till closing !

[swervin ervin]

Good deal. I had the same problem. Sometimes, the hardware store is our best friend.

Mike