[eschaider]

Something to keep in mind when using externally balanced rotating assemblies is that changes in the damper or clutch flywheel assembly should have the entire assembly rebalanced — which requires removing the crank from the engine.

The always asked 'why' question has to do with the precision associated with balancing the assembly. The advocates who say, " Don't worry, a few grams here or there will not matter, " are not pointing you in the right direction if it is a performance engine.

When you send your rotating assembly to a shop to have it balanced, they will balance to within a gram on a normal balancing job. On an engine that is expected to run over 6000 rpm, they will balance even more precisely.

Why do you balance? Well, several reasons; one is rotating assembly life, and another is that OEM parts can easily be off by 5 or 10 grams. When you are talking about a damper with an external weight measured in ounces that weighs a reported 28 oz, if it is off a little bit, it is off by a lot of grams.

One ounce is 28 grams. If your external damper counterweight is accurate to within ½ ounce, then you could be off by +/- 28 grams. That is a 56 gram window! We haven't even talked about the attaching bolt holes being off by a little and shifting the counterbalancing weight from where it is supposed to be to a different location — creating a new and different imbalance.

For a Sunday, go to meeting or proletariat daily driver (DD) that rarely gets over 3000 rpm not a big deal, but still not right. For a performance engine, we have moved into the big deal country.

When will the problem present itself? The first time you upgrade or replace the damper. The first time you upgrade or replace clutch and flywheel components. To avoid these unhappy experiences, use an internally balanced assembly where the clutch and damper are independently balanced.

When you need or want to change out a damper or a clutch, you simply balance the new pieces individually, and your rotating assembly balance will still be as it originally was — correct.