Stripped Crank threads installing harmonic balancer. HELP!

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Stripped Crank threads installing harmonic balancer. HELP!

Post by Stroker Ace »

So putting on my balancer and it was really going on hard. I put the torque wrench on it to make sure I wasn't over torquing it while snugging it down. I put it to 70 ft-lbs (80 is spec) and it pulled the threads in the crank. The worst part is the balancer isn't even in far enough to use my Hesco spacer. So should I tap the crank for the next bigger bolt size and install a stud with a nut? If so, what size & thread count?

Also, my setup is correct right? I have 12 weight crank, stock 4.0L (98) balancer and a Hesco spacer. Just want to make sure.

Anyone have this problem before? Am I doing it wrong by sucking up the balancer using the bolt & washer? What to do! HELP!!! :brickwall: Thanks. Stroker Ace (aka The Red HEEP)
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Re: Stripped Crank threads installing harmonic balancer. HE

Post by DaemonForce »

I'm just trying to wrap my head around how this can happen. Did you dry fit the bolts at all? It doesn't make sense how you can strip the threads on the crank. O_o
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Stroker Ace
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Re: Stripped Crank threads installing harmonic balancer. HE

Post by Stroker Ace »

DaemonForce wrote:I'm just trying to wrap my head around how this can happen. Did you dry fit the bolts at all? It doesn't make sense how you can strip the threads on the crank. O_o
Well, actually I first installed the balancer with the Hesco spacer behind the balancer. When the belt did not line up I asked the question here and found out it goes on in front of the balancer. So I swapped it and that is when it happened. Same parts just moved the position of the spacer to the front. :huh:
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Re: Stripped Crank threads installing harmonic balancer. HE

Post by IH 392 »

Were you using an installer tool?, or the bolt to pull it on?
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Re: Stripped Crank threads installing harmonic balancer. HE

Post by Stroker Ace »

IH 392 wrote:Were you using an installer tool?, or the bolt to pull it on?
Um… Oops… I used the bolt. Now the crank is stripped. So I googled it and I guess if I tap it bigger and install a stud I can use a similar size bearing and a nut to accomplish the same thing.
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Re: Stripped Crank threads installing harmonic balancer. HE

Post by Retlaw01XJ »

How many threads are stripped? It's just some at the end, it may still be usable. There are formulas to tell you how many threads you need to obtain full clamping.
Drilling/tapping it oversize would be a chore to do properly. Should be done on a lathe.
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Re: Stripped Crank threads installing harmonic balancer. HE

Post by Stroker Ace »

Retlaw01XJ wrote:How many threads are stripped? It's just some at the end, it may still be usable. There are formulas to tell you how many threads you need to obtain full clamping.
Drilling/tapping it oversize would be a chore to do properly. Should be done on a lathe.
Looks like the balancer needs to go on about the thickness of the spacer so about 1/2" more. I don't think I have the patience to pull the engine out of the Jeep, tear it down and have a machinist tap it for me. Think I'll push it over a cliff before I go through that again.
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Re: Stripped Crank threads installing harmonic balancer. HE

Post by SilverXJ »

Stroker Ace wrote:
IH 392 wrote:Were you using an installer tool?, or the bolt to pull it on?
Um… Oops… I used the bolt. Now the crank is stripped. So I googled it and I guess if I tap it bigger and install a stud I can use a similar size bearing and a nut to accomplish the same thing.
Yah, I would never install a balancer with the crank bolt. You can rent a harmonic balancer installer tool from advance or autozone. Tapping it larger or maybe even the mertic size up from that is your best bet.
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Re: Stripped Crank threads installing harmonic balancer. HE

Post by cruiser54 »

I've used a bolt before. I keep it in my toolbox. It's about 1/2" longer than the stock one. I use the long bolt to pull the balancer in as far as it will go, then remove that bolt and use the OEM. I think if the OP got a longer bolt and carefully threaded it in with some anti-seize on it cleaning the threads, the crank could be salvaged.
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Re: Stripped Crank threads installing harmonic balancer. HE

Post by 6TIME »

Ditto. A bolt works fine as long as you confirm enough thread engagement... A 1/2-20 grade 8 bolt can create clamp loads over 14,000lbs. Plenty to pull a damper on. Find a longer bolt that goes deep into the snout... The issue is when there isn't lube on the threads along with minimal thread engagement that can pull the threads out of the crank. When I get a tight one, I use a longer bolt and tighten it down then wack the inner portion of the damper with a rubber mallet and it'll relax the tension on the bolt as it works its way on. Repeat the process. Also, look for any burrs on the crank snout or in the id of the damper and smooth them out. Good luck.
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