Upgrading harmonic balancer, need application explanations
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Joined: Mar 2017
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Upgrading harmonic balancer, need application explanations
Hello everyone, I recently noticed that my stock harmonic balancer on 99 coupe has separated and begun to walk back to towards the block. Naturally I want to upgrade. I guess my big question is with Cam and heads coming, I want to future proof my build. What are the differences in applications for %10 vs %25 underdriven and then on the flipside going overdriven? Are there power thresholds that justify one over the other? I've been scouring these forums, but still am unclear on the whole issue. I figure since the stocker is broke I want to go ahead and setup for more power down the road. Any help would be greatly appreciated. Thanks
Acct Suspended APR 2026 by request
Joined: Dec 2010
Posts: 10,367
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2020 Corvette of the Year Finalist (performance mods)
C5 of Year Winner (performance mods) 2019
stick with the oem size balancer unless you plan to supercharge the car down the line, then you might consider an overdrive... personally I would stay away from underdrive balancers period... powerbond if you are just looking for an oem replacement and if you want to spend more then ati/innovators west are good choices... also pin the balancer to the crank and that will prevent it from spinning and the bolt coming loose
Safety Car
Joined: Jun 2004
Posts: 4,986
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From: Stoney Creek Ontario
25% UD pully here on ,my heads/cam setup for 8+yrs and several hundred drag strip passes and plenty of highway driving under all conditions, no issues, rebuilt/forged engine once, no issues of any kind with the UD pully....
