******For some reason, I can't access my other thread on this subject, so I've reposted it here***********

I decided to drive the Vette to work today. As I was pulling into the parking lot, my power steering went out and I heard a thumping sound - I figured the serpentine belt had broken. I parked the car and popped the hood - the belt had come loose, but was OK. I started looking at the pulleys and all of them were in line except for the harmonic balancer - it was jutting out about 1/4". I figured the bolt had slipped or something and I'd just fix it after work.

Well, after work I had planned on tightening up the bolt or just banging the balancer back into place with a hammer. However, when I put my hand on the balancer it just fell off.

Here are pics of it and the bolt:
http://langhoff.dhs.org/balancer.jpg
http://langhoff.dhs.org/strippedbolt.jpg

As you can tell, the bolt was stripped pretty badly. The bigger concern, however, is the inside of the balancer - it's rounded out completely. It slips right on and off the crank without any resistance. The crank itself has some scrapes on it from where the notched edge of the balancer rubbed against it.

Any ideas on what could have caused this? Do you think I could get away with just using another balancer and helicoiling the crank bolt hole? Or does the crank probably need replacing?

Thanks for any input.



[Modified by Langadorf, 8:08 PM 9/5/2003]

 

The balancer is a press fit with a keyway and then the bolt. Jason, if the balancer spun to round out the inside, then the keyway must have given out, and rounded the crank off some. If the bolt hole in the crank is stripped out, maybe you can go to the next size up and have a machine shop tap the threads as that is really some hardened steel. The concern is did the keyway wipe out the crank slot? Have to take it apart to inspect closely. Sorry to hear of this.

 

LT1s don't have a key from the factory, so I didn't use one when I put mine together.

 

you MIGHT be in luck!

.
if the new one is loose, get a few beads of weld and file it to fit. will take a few hours but it sure beats changing the crank.
could not see the pics, so i assume u will figure out something for the bolt.




[Modified by Matt Gruber, 8:29 AM 9/6/2003]

 

I had one work loose during a 6000 rpm blast and it took the snout of the crank with it when it bounced off the radiator.If you into playing John Force,I'd definately replace the crank/balancer.If you drive like my Granddad,slap some JB Weld on it and helicoil the whole shabang back together.(kidding of course)

 

Well I definitely plan on revving my engine up to 6K+ on a regular basis. I didn't build a 500HP motor just to look at it. :D

What sort of damage to the crank snout surface is "acceptable"? There are some scrapes on it, but if a new balancer fits tight, is it OK to run with?

 

use Loctite with the new one.
.
A good repair can last.
A poor one won't.

 

Trust me on this one... Don't skimp on any of these components or the repair. I had one come off (or apart) about two months ago at 70 MPH on the highway (3K RPM) and it caused about $2500 in damage. Just about anything you can think of was damaged. I'll only use the best in the future.

 

I'd get a brand new balancer and a new crank bolt. The crankshaft is harder metal than your old balancer so there is a possibility the crank is still OK. As everyone has said I'd locktite the crankshaft bolt back in once you get the threads chased out and a new key for the keyway. Be very careful and look everything over real closely. You want to make sure the crankshaft is still useable otherwise there is no sense in trying to reseat the balancer. Hopefully, since you were going so slow it didn't do a lot of damage. Anyway here's hoping. :bb