What caused this?

[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??