Balancing a harmonic balancer

[02 Graphite GTS]

I wanted to share some pictures and details of some work that we did for a fellow VCA member last week. He removed the OEM harmonic balancer and pulley and shipped them out to my shop.
Once received in, we did a quick inspection and proceeded to make tooling to properly mount the harmonic balancer on our machine.




Once the tooling was finished, we set it up on our balancing machine.



The harmonic balancer comes balanced from the factory.....
The original as found unbalance was 5 grams at the radius. Using some basic formulas for calculating the maximum allowable unbalance, we found the part to be 6 - 7 times out of tolerance. We drilled holes to remove material and achieved a final balance of less than .1 gram at the radius.

The drive pulley was then bolted on and checked for unbalance.



Since we had already balanced the harmonic balancer, it now acts as part of the tooling. Any new unbalance found in the assembly was attributed to the pulley. The pulley did not appear to have any OEM visible balancing marks on it. The initial readings showed almost 4 grams of unbalance at the radius.
We were able to reduce the unbalance to less than 1 gram on the pulley.



The harmonic balancer and pulley is now balanced well below the OEM originals.
I feel that this will help reduce any additional vibration to the front end of the crank. In terms of performance, only before and after testing on a dyno would qualify the findings.

Items such as turbos and superchargers will greatly benefit from precision balancing. If anyone needs help or has any questions, please feel free to ask and I will be more than happy to help.

Mahalo, Guy for allowing me to share this with the VCA and I hope your viper is back on the road again soon.

(Electronic Balancing Co. is capable of balancing rotating parts that weigh as little as 1/8 oz and as large as 100 ton in weight. Our most sensitive machines are able to accurately find .00001 grams of unbalance in a rotating mass.)