Flex plate question

[72supr]

Trying to figure out why this was done to the flex plate.Came out of a 72 half ton with a 350/th350.

[harpo231]

balance

[72supr]

Thanks harpo321.What I meant to say was how this was done to the flex plate.

[B. W.]

The flexplate is spun on a balancer. There is a drill press set up on the balancer, the operator drills the flywheel/flexplate where the machine shows it is heavy.

[72supr]

Thanks for the info B.W. Kind of an odd shaped hole that's why I asked .

[RodnRudy]

That kind of hole is caused by a dull or incorrectly sharpened drill

[A1971Blazer]

Originally Posted by 72supr

Thanks for the info B.W. Kind of an odd shaped hole that's why I asked .

it's odd shaped because the drill bit walked around as it was drilled into the metal....

[adricar1]

its easier to balance the outside of the flexplate than at the centre line of the crank, less material needs to be removed. they normally balance with a hand drill on the balance machine

[Steeveedee]

Originally Posted by A1971Blazer

it's odd shaped because the drill bit walked around as it was drilled into the metal....

Exactly! That is an artifact of a hand-held drill that has no pilot hole. Even if a pilot hole was drilled, the bit will wander if used in a hand held drill. The amount of metal removed here is in the single-digit grams.

[kwmech]

Most drill bits will leave a triangular hole in thin metal. If you want them round, then that's where a reamer comes in for the finish