Originally Posted by TobiasSing
Sounds like it would have been better to stick with OEM. Even if you manage to get it on there, I imagine getting it back off again might be even harder
A quality aftermarket balancer that is an interference-fit onto the crank will outperform the slip-on OEM balancer. The engine vibrations will be more effectively cancelled, and the engine will run more smoothly.
I've not used a Fluidamper before, as I'm kinda an ATI guy... Not saying anything wrong with Fluidamper, but in racing land I've just had and seen so much success with ATI that I default to them.
Anyway, ATI supplies their balancers with a nominally-sized hub bore. For a balancer to work properly, it is imperative that it "become one" with the crankshaft. To achieve this, the balancer must be a somewhat heavy interference-fit with the crank snout.
Unfortunately, the OEM doesn't grind the crank snout to such a precision, that a precision interference-fit can be achieved if the balancer hub bore is honed to one particular size. What fits one crank perfectly might be too loose or too tight on a different crank. Therefore, ATI hones their hub bore to the smallest "in spec" dimension. It will be correctly sized for some cranks, but too small for others.
You must use a micrometer to measure the crank snout diameter. Then you need to use either telescoping gages + micrometer, or a hole micrometer, or perhaps gage pins to determine the inside diameter of the hub bore. Then calculate the difference between the two. ATI publishes a specification on what the interference oughtta be. Generally between .0008" and .0015".
If your interference is too much, it'll be hell to get it on/off the crank and you risk galling or otherwise damaging something. If too little interference, the balancer will not be fit to the crank as intimately as it needs to be for proper function.
When the interference is set correctly, a balancer installation tool has zero problems pulling the balancer onto the crank, and a balancer removal tool has no problem pulling it off.
All this to say - It's likely Fluidamper has similar install instructions to ATI. Read and follow them.