Curious crank damper/pulley movement

[GT@50]

Installing belts
Adjusted oil pump belt tension and tightened.
Squeeze belt by hand and notice the crank balancer moving, about .008.
I've never noticed this before. It's not leaking. I don't see any witness marks on the crank bolt that would indicate movement. I'm not THAT strong!
I put an 18mm socket on the bolt and gave it a light tug. Doesn't appear to be loose.
Has anybody observed this before?

New video by Rob Henderson

photos.app.goo.gl

vid of movement

 

[2112]

Dang, that looks like real movement to my eye.

 

[HighHP]

Interesting. If you hang the ratchet on the crank bolt, does the ratchet move as well? If so, that would indicate that the crank is moving that much as well, which, I highly doubt. Did you use a dial indicator to measure the play?

 

[PeteK]

I'm not sure about the GT, but most crank balancers (Harmonic dampers) consist of a steel inner hub and an outer pulley with rubber between them. Is the rubber flexing?

 

[GT@50]

When my dial indicator was on the pulley it was pretty hokey so hard to get a real measurement, I just wanted to prove to my eyes what I was seeing.
With a socket on the bolt, I think I see movement too. I'll have to get my other dial indicator to prove it though.
The oil pump drive pulley bolts inside the crank pulley. I can't see under it, and I don't see rubber for a damper outside of it. But, with the crank bolt moving......call me Superman?

 

[nota4re]

OEM rubber isolated harmonic balancer... normal.

 

[GT@50]

OEM rubber isolated harmonic balancer... normal.

Kinda figured, just never noticed before. Thanks