A few Pics of my crank assembly which is off for balancing as soon as the NCR internals arrive.. Many many hours of work to get get the crank to this finish, but it will save money when it's balanced..
Is this now a kitchen thread, not sure what constitutes going off thread in this instance, cranks & garages are related, kitchens?
It is my workshop....... .......'s kitchen.. Yes it is being balanced and knife edged.. It's just the guys doing the work said if you want to save money polish it and then they will do their work after.. Leaving them only a little polishing work to do..
At this stage I remove any casting edges first of all and then rub down the webs till as-smooth as poss using ever finer grades of wet and dry.. There after dremel with soft wire brushes to get the fiddly bits.. Then lots of polishing with mops.. These con rods are not being used in the build.. I just polished them to keep for another project later.. However, each rod and it's cap and bolts were weighed and matched gramme for gramme... Pic below of web as it was before..
It comes down to rotational inertia, the majority of the mass on the con rod is at the big end which is also the end that rotates. If the big end mass is matched it makes it easier to balance. Its not as important on a v twin as the big ends are next to each other and the counterweight can be tweaked to achieve a good balance, on an IL4 or a Cross Plane Crank it makes more of a difference.
With respect.. I quote from your reference.. pistons should all weigh the same, with rings installed (after being gapped) and with pins and their retaining system. The connecting rods should all weigh the same, end-for-end, with bearings and bolts (with nuts) installed, I know exactly what your saying it's all down to reciprocation of the mass.... The pistons etc are going in opposite directions most of the time and often at speed.. But, although it's a bit nit picky it's also important for the overall mass of the outward moving components to be as similar as possible.. As an extreme example, if on a v twin you had one piston weighing twice that of the other, it's going to make balancing it at the crank nigh impossible. Extreme yes but every little piece of weight matched before it's attached to the crank and then balanced makes a difference, all be it in this instance small.. But of use when your looking for balance ultimately ...
We We all have the right to our own opinions after all that's what makes for good discussion.. When I completed my technicians certification working on Ferraris and Porsches of all kinds of spec for a main dealership.. Everything would be weighed and matched x 12 in many cases. We woul d then crate it up and send it off to be balanced by those that know.. There was no such thing as simply fitting stock pistons etc.. Everything was matched up
