Possible stripped crank threads/bolt
Thread Starter
Instructor
Joined: Apr 2005
Posts: 187
Likes: 0
From: Renton,Kennydale area WA
Possible stripped crank threads/bolt
This past weekend I attempted HB replacement as well as a cam install with a buddy. As I was away from the car taking a phone call, my buddy attempted to install the UD Harmonic balancer on his own. Once I got off the phone, he tells me the bolt won't back out 
My question is, is the crank repairable or am I screwed? I put the car back together as best as I could. I did the job due to a wobbling balancer and now is doing exactly the same thing just not as bad.
Thanks in advance
My question is, is the crank repairable or am I screwed? I put the car back together as best as I could. I did the job due to a wobbling balancer and now is doing exactly the same thing just not as bad. Thanks in advance
Pro
Joined: Jul 2000
Posts: 590
Likes: 1
From: Suffolk New York
I can see stripping the first few threads if he tried to pull the new underdrive balancer on but not all the threads.
You can get a screw extractor kit to drill and reverse out the bolt ( hope it's not torqued down a great amount).
If the threads are stripped you might re-tap them and then use a
try a longer bolt
You can get a screw extractor kit to drill and reverse out the bolt ( hope it's not torqued down a great amount).
If the threads are stripped you might re-tap them and then use a
try a longer bolt
Melting Slicks
Joined: Mar 2005
Posts: 2,252
Likes: 181
From: NE OH
Hope you are sitting down buddy....chances are pretty good that the crank threads are jacked. Now looking on the bright side, you haven't broken the crank bolt off in there yet, so that's a plus.
This is a pretty common problem when trying to install the crank pulley (harmonic balancer) using the crank bolt.
Here's a link to the latest person on tech that this has happened to:
http://www.ls1tech.com/forums/showth...ighlight=crank
Best of luck to ya.
This is a pretty common problem when trying to install the crank pulley (harmonic balancer) using the crank bolt.
Here's a link to the latest person on tech that this has happened to:
http://www.ls1tech.com/forums/showth...ighlight=crank
Best of luck to ya.
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
You are sort of screwed. You need a threaded rod to put on the balancer. When you use the bolt, you only engage a couple of threads and as soon as you load it up trying to push on the balancer the threads rip out, the more you turn, the more threads get damaged. There are several threads over on LS1Tech on this, and the way they were fixed. You can try backing it out, but the bolt will likely break and then it is drill and tap time, possibly heli-coil. Read up on this on all the threads you can find before attempting to do anything. The other option is to take it to a machine shop and hope they can take care of it.
If you can move it at all, you can try and come out a bit, then in, then out a bit, then in to see if you can slowly back it out. If it won't move at all, the threads are damaged and likely gauled.
This is the tool I made to re-install the balancer.
Good luck.
If you can move it at all, you can try and come out a bit, then in, then out a bit, then in to see if you can slowly back it out. If it won't move at all, the threads are damaged and likely gauled.
This is the tool I made to re-install the balancer.
Good luck.
Melting Slicks
Joined: Mar 2005
Posts: 2,364
Likes: 1
From: Rugby North Dakota
Vettenuts & Connecticut - are you guys using a grade 5 or grade 8 ready rod, or are you using standard "soft" ready rod to make the pulley installer?
Connecticut - you say M16 thread, what diameter bolt though??
Thanks for the info - I'll be doing this this winter.
Connecticut - you say M16 thread, what diameter bolt though??
Thanks for the info - I'll be doing this this winter.
Thread Starter
Instructor
Joined: Apr 2005
Posts: 187
Likes: 0
From: Renton,Kennydale area WA
Thanks to all your responses. I tried backing out the bolt since I was able to brake it loose. I could reverse the bolt but I would not physically come out. I figured it was stripped to the point that the bolt had nothing to catch on to for it to reverse. I'm hoping one of our fellow corvette member that lives near by could help out. He offered to help out on the install but was unavailable this past weekend. I'll take all of your advice and read up on the issue. I'm hoping I don't need to replace the crank, that was the screwed part 
Keep the comments going so that I could hopefully find a fix and document it for others benefits.
Keep the comments going so that I could hopefully find a fix and document it for others benefits.
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
If it will turn, can you get any pressure behind the head to help it start backing out.
As for my little tool, I bought the rod from McMaster-Carr along with the nuts. Total cost was about $17 if I remember right.
As for my little tool, I bought the rod from McMaster-Carr along with the nuts. Total cost was about $17 if I remember right.
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Race Director
Joined: Sep 2005
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From: Pasco WA
Originally Posted by 94legaleagle
Vettenuts & Connecticut - are you guys using a grade 5 or grade 8 ready rod, or are you using standard "soft" ready rod to make the pulley installer?
Connecticut - you say M16 thread, what diameter bolt though??
Thanks for the info - I'll be doing this this winter.
Connecticut - you say M16 thread, what diameter bolt though??
Thanks for the info - I'll be doing this this winter.
Melting Slicks
Joined: Mar 2005
Posts: 2,364
Likes: 1
From: Rugby North Dakota
Originally Posted by zeevette
Actually, the diameter is the M16, and the thread pitch is 2.0. Factory bolt is 100mm long, and I got a 140mm one to install my Powerbond pulley. Went right on , no problem.
At the risk of asking a stupid question, where did you purchase the 140 mm bolt?
Thread Starter
Instructor
Joined: Apr 2005
Posts: 187
Likes: 0
From: Renton,Kennydale area WA
If I was to retap, would it be difficult to find a bolt to that will fit the crank? Are there any kits out there for the DIY type? connecticut mentioned a NAPA kit that doesn't work.
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
Use a heli-coil or Keensert. You tap to a larger size and then install the heli-coil. If you go SAE, you will have bastardized your setup and won't be able to use the stock bolt or the ARP bolt. The proper preload is critical to keeping that thing on there.
Drifting
Joined: Oct 2004
Posts: 1,384
Likes: 8
From: Southwest Virginia
The threads in these cranks don't start for like 2" down in the front of the crank so fixing those threads that far down in the hole is next to impossible. What someone on here who broke off the bolt in the crank has done in the past is thread (not re-thread) the larger part of the front of the crank. Then used a much larger shorter bolt. I forget what size bolt they used but I'm pretty sure it was a perfect size to tap without drilling. They machined out a jig that slid over the snout of the crank and the tap threaded through it and it held the tap straight as they threaded the end of the crank. If you have to go this route simply pin the balancer when you install it and it will never go anywhere.
Le Mans Master
Joined: Dec 2003
Posts: 5,561
Likes: 448
From: Atlanta metro Ga.
Originally Posted by SpeedyZ
The threads in these cranks don't start for like 2" down in the front of the crank so fixing those threads that far down in the hole is next to impossible. What someone on here who broke off the bolt in the crank has done in the past is thread (not re-thread) the larger part of the front of the crank. Then used a much larger shorter bolt. I forget what size bolt they used but I'm pretty sure it was a perfect size to tap without drilling. They machined out a jig that slid over the snout of the crank and the tap threaded through it and it held the tap straight as they threaded the end of the crank. If you have to go this route simply pin the balancer when you install it and it will never go anywhere.
Solid advice..
Thread Starter
Instructor
Joined: Apr 2005
Posts: 187
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From: Renton,Kennydale area WA
I didn't try putting any pressure to back it out. I wasn't thinking straight. The combination of being pissed off and a few beers did not do well on my senses. I have to strip the car down again and try that. I'm positive I can get the bolt out is just the fixing the threads part I've never done before. I hate to monkey it up more than it already is.
St. Jude Partner since 89
Joined: Oct 2005
Posts: 774
Likes: 4
From: Lebanon, TN
St. Jude Donor '09
We always just used a longer bolt to pull the pulley on and then switched to the old stock one to tighten it down and then finally to the new bolt just like in the ls1howto instructions recommended (without any problems on about 7 I've seen done this way). Is this not recommended?
Thread Starter
Instructor
Joined: Apr 2005
Posts: 187
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From: Renton,Kennydale area WA
Just discovered something new!!! As I was cleaning out my garage last night I found the NEW BOLT that came with the kit. I think my buddy put in the factory bolt back in
Could that explain the stripped bolt or is it still possible the crank is screwed up?
Could that explain the stripped bolt or is it still possible the crank is screwed up?