4-tec 2.0 brushless driveline vibration

[Spug]

I just picked one up slightly used. I noticed the center shaft is flexing and developing a harmonic vibration so bad it hits the ESC and servo. Inspected everything multiple times. Been baffled for days! Bearings, carriers, shaft and everything are solid and straight. Only thing I can think of at this point is the chassis was molded wrong and it's throwing off the driveline slightly from front to rear. Even tried a new shaft and still the same.
Anyone have any ideas or experience with this?

 

[Bustedaw11]

Man in my experience when I have issues like that its the input shaft bearings to the diffs. Check for any play in them and if not maybe a slight bend in the shaft your not seeing? Take the shaft out and lay it on glass and roll it, see what you get.
Maybe if the shaft is true then swap out the carrier bearing and inputs with some better ones (traxxas bearings are junk) and see if it cures it.

I've been running for many years associated's and such. When I just got 2 4tec 3.0's recently I was absolutely let down in the out of the box quality of them. They're tuff but not very precise.
You gotta take care to make them precise on your own.

 

[Spug]

Yeah, it's really weird. I even tried replacing the shaft with a new one. All bearings are tight and super solid, end play is good too. I've never been stumped for literal days LOL!
Pulled the front and rear all the way apart multiple times inspecting things. Everything seems good. I'd be willing to bet it's a misaligned chassis. There has to be something throwing it off.

 

[Spug]

This is the second Traxxas I've owned and it will definitely be the last. My mini E-Revo was a piece of trash!