Harmonic Balancer

[Benjamin '97 WS6]

Hey Guys,
My harmonic balancer started to wobble, and at 145,000 miles I figured it was time for a replacement. I've never had to replace one before so I have a couple of questions. What does to the plug in my factory balancer do? (picture attached) I bought a new harmonic balancer but I'm not sure if I need to put that plug in the new one (at the corresponding location)? Thank you for the help.


FYI: I have a 1997 Trans Am WS6 that is mostly stock.

[Injuneer]

Its not a harmonic balancer, its a harmonic damper. It should be neutral balanced, and I suspect they use the little weights to achieve that balance. There has been speculation that the plugs were also used at the factory to "trim" the rotating assembly balance, but I can't see that being reasonable. There's an article on rebuilding the LT1 that states that, but if the damper was used for balancing the rotating assembly, it would have been logical to have included a key to maintain the damper's position on the crankshaft.

http://www.automotiverebuilder.com/ar/ar99928.htm

Consider the fact that many of us have replaced the stock damper with the ASP integrated damper/underdrive pulley assembly, with no one noticing any sudden increase in engine vibrations.

HUB AND BALANCER

The balancer is a two-piece assembly with a pulley that bolts onto the hub. Separating the two made it easier to install the Optispark distributor on the assembly line and out in the field. The holes in the hub are offset, so the balancer only fits on it one way, but there’s no keyway in the hub to index the hub on the crank. This shouldn’t be a problem unless the damper was drilled at the factory to "trim" the final engine assembly.

If it was drilled a lot to compensate for an engine that was out of balance, you could end up with a shaker, depending on how everything stacked up with the remanufactured engine compared to the original engine. If you encounter a balance problem on a remanufactured LT1, try rotating the balancer assembly on the crank 90° at a time to see if it eliminates the problem.

[Benjamin '97 WS6]

I just put the new dampner on the car, and it wobbles too, I think more then the original. Is this just normal to have a bit of wobble to the outside ring of the dampner?

And I already have an underdrive pulley or I would go with the ASP, I've heard they make a quality product.

[Injuneer]

The damper should not wobble at all. It is composed of inner and outer steel rings, with a flexible rubber ring in between holding the steel rings together. If the rubber cracks, it will wobble, but it would be unlikely that you got a new damper with a broken rubber ring.

Are you sure you have the three bolt holes properly aligned? The three arms on the hub are not equally spaced. Are you sure your "sandwich" style underdrive pulley is not causing it to wobble, due to improper installation?

[Benjamin '97 WS6]

I figured out the new dampener was defective. It appears that the outter steel ring and the rubber were not properly compressed onto the inside ring during construction. I could literaly see a misalignment between the parts. I took it back to O'Reilly's and they agreed that it wasn't built properly. So, now my for them to order me another one. The company that built the dampener is Dorman. Do you know if that is a good quality company? Thank you for your help.

[97LT1Z28]

Yes - that's a good company. My old LT1 ate a few of them due to a bad crankshaft and the company sent me replacements every time it happened with no questions asked.