How do I pin the harmonic balancer on a Chevrolet Corvette C6?

Pinning the harmonic balancer on an LS2 or LS3 C6 Corvette is a highly recommended upgrade, especially if you are installing an aftermarket balancer or planning for a supercharger. The factory setup relies purely on a friction fit, which is notorious for slipping or wobbling over time.

Difficulty: Moderate (The pinning itself is easy, but gaining access by moving the steering rack makes the overall job moderate). Safety: Disconnect the negative battery terminal before starting, and ensure the car is securely supported on jack stands.

Before you start, the community consensus is unanimous: do not reinstall an OEM AC Delco balancer. They are prone to failure. Use a quality aftermarket unit like a Summit Racing (C2501), Powerbond, or ATI damper, and secure it with a new ARP crank bolt ¹⁰.

Pinning Methods

There are two primary ways to pin the crank on this platform ⁵:

1. Parallel Pinning (Standard): This is the most common method for DIYers. You drill straight back into the face of the crank snout, cutting a half-circle into the crank and a half-circle into the balancer hub. The downside is that if you ever remove the balancer, it is nearly impossible to realign the exact same hole, meaning you’ll have to drill a second hole upon reinstallation. Basic parallel pinning tool kits can be found online for around $20 ².
2. Perpendicular Pinning (ATI Style): This method drills a hole at 90 degrees to the crank snout. It allows the steel pin to sit directly in the pre-machined keyway that comes on many aftermarket balancers. The major advantage here is that you can remove and reinstall the balancer repeatedly without having to drill new holes ⁵.

General Procedure (Parallel Pinning)

Assuming you are using the standard parallel pinning kit, here is the typical procedure:

1. Gain Access: You will need to move the steering rack out of the way. You don't have to remove it completely from the car, but you do need to disconnect the lines near the steering box and shift the rack to the passenger side to clear the balancer ⁸.
2. Install the Balancer: Seat your new aftermarket balancer fully onto the crank. Never use the new crank bolt to pull the balancer onto the snout—use a proper Chrysler-style puller for removal and an LS-specific installation tool to press the new one on ⁹.
3. Mount the Drill Fixture: The pinning kit will come with a metal guide fixture. Bolt this fixture securely to the front of the crankshaft using the provided bolt.
4. Mark Your Drill Bit: You do not want to drill too deep. Measure the length of the steel dowel pin provided in your kit, and wrap a piece of tape around your drill bit at that exact depth so you know when to stop.
5. Drill the Hole: Use a little cutting fluid and drill into the crank/balancer joint through the guide hole in the fixture. Take your time and keep the drill straight.
6. Clean the Area: Remove the fixture. Use a magnet and brake cleaner to thoroughly remove all metal shavings from inside the crank snout. You do not want metal debris binding up the threads of your new crank bolt.
7. Insert the Pin: Tap the supplied steel dowel pin into the hole. It should sit flush with or just slightly below the face of the crank snout.
8. Install the Crank Bolt: Install your new ARP crank bolt.

Note on Torque Specs: I don't have the exact verified torque figures for the factory GM bolt or the ARP bolt for your specific engine, so don't take a hard number from me here—check the instructions that come in the ARP box or consult a factory service manual. The general procedure is to apply the manufacturer-specified lubricant to the bolt threads and the underside of the bolt head, thread it in by hand, and torque it in multiple stages. If using an OEM torque-to-yield bolt, it will require a specific initial torque followed by a set number of degrees of rotation. If using an ARP bolt, it will typically require a much higher straight torque value done in three equal passes.