What You SHOULD Know About Harmonic Damper Pulleys | Harmonic Balancers 101 [TECH TALK]

Many people believe if their engine is balanced perfectly internally, an external damper is not necessary, leaving dampers/balancers often overlooked. These people are mistaken, as JC from ATI Performance Products explains.

The misconceptions around harmonic damper pulleys come from the common (but incorrect) belief that the harmonic damper is there to deal with the imbalance of the stock components in a factory engine. The reality is that no matter how well your engine components are balanced, a harmonic damper is still an important addition to your performance engine build.

The reason we need a damper is that each combustion event produces a small amount of torsional vibration in the crankshaft. As we move through the rev range we’ll find that at certain RPMs we will reach a resonant frequency where the effect of the vibration is magnified and this can become damaging, particularly if we happen to sit at the resonant rpm for an extended period of time. With a damper fitted this torsional twist can be counteracted, giving reliability and even keeping power levels where they should by ensuring the valve train is operating as intended.

A common failure we see in engines fitted with lightweight crank pulleys that eliminate the harmonic damper is the failure of factory oil pump gears that are driven directly by the crankshaft. While this is just one potential failure point, it illustrates how serious theses harmonics can be. A harmonic damper is designed to eliminate these damaging torsional vibrations and protect the engine components from damage with timing chain failures another common and dramatic failure.

At The SEMA Show, JC runs us through all this, along with how a damper is selected for the right application, how they work, what the construction is and when in the engine building process you should fit one. Also discussed is the ability to rebuild ATI dampers when you're rebuilding your high-performance race engine, or every 10 years or so on a street application.

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Comments
  • 's profile image
    Harmonic Damper Pulleys was a good read. I've been around cars and repairs since the 60's and I never gave them much thought, until now. I just had to replace the cam & lifters (the very last one on the driver side nearest the fire wall) because of scoring (chirping like a bird) an our 07 Corvette. Also, the timing chain, top gear and guide had some major wear in just one small area. It all seemed odd to me accept the fact that it IS a Corvette after all, but now I think it may have all been due to that Balancer slowly coming apart. I remember seeing it wobble as long as 5 years ago. I didn't noticed any vibration in the engine, so I thought it could wait especially since I have never had one go bad to date. Looks like my chickens have come home to roost. Vette mechanics tell me they have replaced a lot of them on the C5 & C6 Vettes at various mileage or ages. Warning Mates, don't make my mistake. "If is's a shakin', you need to be a takin,' it off!"
    - Bruhen USA
    5 years ago