LS1 Vibration - Flywheel? Converter? Harmonic balancer?

b.lee

b.lee

Forum Member
2000 SS A4

1. Vibration sitting in Park and Neutral @ 1,450 RPM

2. Vibration when taking off slowly, at the top of 1st, 2nd, D and OD (Every time the car hits 1,450 RPM)

3. Vibration on deceleration around 45-50 mph (1,450 RPM)

4. It runs pretty smooth otherwise, the vibration will go away depending on speed / RPM.


- Engine doesn't flop around when brake torquing a little in Drive or Reverse.
- Trans mount seems fine, Trans not hitting tunnel when shifting in/out of gear
- Bangs thru all the gears fine, runs out good, no codes for misfire.
- Stock engine mounts, Stock Trans mount


Mechanic is trying to tell me I should try injectors and plugs
I'm thinking not because it vibrates on deceleration with foot off of gas pedal
Maybe the flywheel or converter? OR bad harmonic balancer?

Would a bad harmonic balancer cause these types of vibrations?
Or would the stock engine mounts soak up the vibration and make it un-noticeable?

I'm searching around but any help would be much appreciated
The only codes it is throwing are driver side rear 02 and AIR pump.
 
generally a bad harmonic damper on a v8 wont show 1st order vibrations until 3000rpms, so its unlikely, but you can remove the belt and grab the outer iron ring and see if it has any movement
 
mods done to it? reach under and grab the ballancer and see if you can move it. (one time i had one rip off in my hand when i pulled on it lol) not on a chevy, im a ford guy so im kinda stabing in the dark.
 
I'll take the belt off and give it a tug... maybe disconnect ignition and turn it over a few times with the belt off and look for wobbling.
 
I removed the belts and started it, same vibration around 1450 RPM.
The Harmonic balancer/dampener is firmly attached, I couldn't move it at all. The rubber inside the dampener isn't walking out either.

Double checked the trans mount, its in good condition, no movement.

I'm thinking converter or flex plate ... ? Anyone seen this before in LS1 cars?
 
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