Harmonic Balancer Question

**PERK** · 09-28-2020, 06:22 AM

I have a question in regards to a 2003 C5 Corvette LS1 that I installed in a build of a 57 Chevy that has the complete C5 drivetrain in car including the torque tube & C5 rear end & Tremec 6 spd out back. during the install of a GM Hot cam I made a major mistake not realizing harmonic balancer needed to be indexed marked which is only priority in the C5 Corvette. My question is what if any Problems might arise if any ? I drove the car for the first time last week & it ran Great the first few times out then on the last time out it started to misfire & run terrible. My main concern is that when I pulled into garage I notice a slight rattle sound from the front of torque tube where throw out bearing is located. Dropped inspection cover & all is new & everything checked out fine. I was told it probably was bearing in front of torque tube. I pulled complete drivetrain & all bearings are in excellent condition. I was just wondering if somehow the Balancer Problem has come back to bite me & what fix if any I might need to correct if there might be a resonance from the balancer transferring back to the torque tube. any & all help would be appreciated

Perk

**mrr23** · 10-30-2020, 03:54 PM

the balancer does not need to be indexed. its neutral balanced.

**PERK** · 10-30-2020, 09:39 PM

Why doe's the manual say make sure to index mark it before pulling balancer ?

**mrr23** · 10-31-2020, 03:11 AM

Why doesn't the manual explain why? Having built plenty of LS engines, there is no need. If it had to be indexed, they would have keyed the crank like they did SBC engines.

Most likely, their reasoning is to take an unknown variable out of the equation.

Here's one that'll bake your noodle. When you put a brand new balancer on, how would you index that one?

**PERK** · 10-31-2020, 05:05 AM

Supposedly it was only on the C5 Corvette manual LS motors, There is a article on it I read somewhere but like you said what the Hell do you do if Balancer needs to be replaced ?? But it states in GM Shop manual to make sure to mark balancer before removing due to static balancing from the factory whatever that means. I have the 04 Shop manual.
Perk

**mrr23** · 10-31-2020, 10:59 AM

Yep it's one of those just in case things. Not going to be your issue. Did you check codes to narrow down the misfires? Might have a plug wire touching the headers (assuming you have headers) or not fully connected to coil or plug.

**mrr23** · 10-31-2020, 11:02 AM

The static balancing they refer to is the once they completely assemble the motor, they make sure of no vibration. But what makes the manual so different than an automatic? Who knows, but I don't see it being the problem.