What caused this?

[YENKO DEUCE REGISTRY]

Still can't get an answer as to what caused the harmonic balancer to split open like this. I think it was because the bolt loosened up, allowing it 'wobble'. When I dropped the clutch to spin the tires, the shock may have broken it open Anyone ever see this b4?

[BUIZILLA]

if it broke like that on the complete keyway slot, you used a key that was incorrect or too tall, meaning the same thing... LOL

[Salvatore]

Marlin, I believe metal fatigue. Happened to my 61 vette driving down 309 a few years back. Balancer came right off. Split/cracked at the key way. Called Pete, he said not to worry and I got another 283 balancer and put it on. The balancer was probably dampening the vibration in your motor as your monster tach was pushing on 9,000rpm's and cracked from fatigue. Maybe to many missed shifts on a 36 year old balancer.!

[YENKO DEUCE REGISTRY]

[ QUOTE ]
if it broke like that on the complete keyway slot, you used a key that was incorrect or too tall, meaning the same thing... LOL

[/ QUOTE ]

Hmmmm.... would the balancer slide onto the crank if the key was too 'tall'? I never really thought about it, but....

You might be right Sam, these are old parts so it could just be fatigue. I have your old balancer ready to install - I bought it from Pete after delivering it to him for ya! I must say, I have yet to miss a shift and completely bury the rpm's. I've never even tried to power-shift it, so I still pull my foot off the gas between gears. Ya have draw the line somewhere when it's the original drivetrain, no sense over-revv'ing it It's seen 7500 rpms, but never 9000

[BUIZILLA]

[ QUOTE ]
Hmmmm.... would the balancer slide onto the crank if the key was too 'tall'? I never really thought about it, but....

[/ QUOTE ]actually, the balancer is a snug, virtually press fit so it should NEVER slide right on. I am on my third stock GM LT1 balancer on Mighty Mouse, but mine spins on the outer shell, I have now staked the last one, and it is holding up pretty good, granted I have been as high as 8,400 rpm, 8,000 plenty of times, and shift it at 7,200-7,400 so a stock balancer is NOT happy with my methods LOL I have broken 2 ATI balancers on my Buick like yours, and that was because they were too loose on the crank snout.

JH

[Mr70]

This may be the work of the dreaded two footed,frustrated,Pennsylvania garage gremlin.
.................................

[Xplantdad]

I might as well get some use (mileage) out of my screen capture...don't you think?

[Kim_Howie]

Staking the balancer. The outer ring and inter ring together, haven't you lost the reason for the balancer??

[Kim_Howie]

Was the bolt & washer loose when you found this??

[YENKO DEUCE REGISTRY]

I love that pic, we spent this past Sunday afternoon hand-sanding the rear diff. Can't beat the father-son time!

Kim,
Yes, the bolt was very loose when I limped it into the trailer at SCR9. Pete Gerling and I started looking at it, and noticed the slop in the belt. I unscrewed the bolt with my fingers, and the balancer nearly fell off. The key fell out onto the floor of the trailer. The key initially fit nice and tight when I installed it, but it was mangled pretty bad after the break. This was the original balancer for this engine, and fit very tight when installed. The replacement balancer also fits very tight - but I can only get it installed for about an inch. I need to finish cleaning up the keyway area with a small file, then I can install it completely.

I'm open to any advice!