Balancing and dampers

[ajkulish]

Hey guys. Had an issue with my rear main so pulled the motor and am taking care of a few things while it is out. Addressing an additional VTA catch can, new oil drain line, etc and also took it upon myself to order a fluidampr.

Some back story; built the motor 6 or 7 years ago now, has run mostly well for me outside of some oil pressure issues I fought for a while (now sorted out, with engine temp under control). When I built the motor, I removed the balance shaft, and I believe I took a few minutes to look at the masses on the rods and pistons and did my best mix and match combo to get overall masses as close as I could to each other, but I do not remember specifically how much time I spent on this and how accurate this ended up being. Being my first built motor, I was anxious to get the thing done and in the car, and a full rotating assembly balance was not on my radar. So, fast forward to today, I have the motor out and am wondering if it is worth removing the rotating assembly, rebuilding, and balancing. The car had some excessive vibrations before the engine removal, but it has run for 10k miles mostly issue free. The vibrations are felt in the interior mid RPM range, making the mirrors vibrate, some interior trim, nothing violent but certainly noticeable. I ordered the fluidampr but do not have a reference point for how much vibration reduction I should expect with it. I am leaning towards not getting back inside the motor, throwing the damper on and being happy with what I get, but wanted to bounce it off of this community to get some thoughts on the subject.

 

[Easter Bunny]

Balancing the rotating assembly is not going to eliminate the vibrations you are talking about. They are a harmonic resonance that happens in some rpm ranges for inline four cylinders. The balance shaft is supposed to cancel some of these out. I would not remove the rods and Pistons but if you want to try something I would reinstall the balance shaft. Just be aware there is a procedure for it that it needs to line up a certain way yo the crank and then you have to shim it for lash on the drive gear

 

[ajkulish]

Balancing the rotating assembly is not going to eliminate the vibrations you are talking about. They are a harmonic resonance that happens in some rpm ranges for inline four cylinders. The balance shaft is supposed to cancel some of these out. I would not remove the rods and Pistons but if you want to try something I would reinstall the balance shaft. Just be aware there is a procedure for it that it needs to line up a certain way yo the crank and then you have to shim it for lash on the drive gear

Thanks for the feedback EB. I considered that in the past, but remember reading that someone else with a built motor did it with not much effect, as the BSD is weighted for stock internals, and aftermarket internals were a different mass, negating the effectiveness of the BSD. I suppose I could still give it a shot after I run just the fluidampr, as I can access all of this while the engine is in the vehicle.