Our complete engine balancing is done with all reciprocating parts assembled together. This is accomplished by first installing the timing gear key and gears (our gears) onto the crankshaft. The crankshaft is dynamically balanced to one half gram or less. The flywheel is installed and balanced to one half gram or less. The front of the crankshaft will then need to be balance corrected for "plane" balance to one half gram or less. This comes from slight runout always being present on the flywheel. The pressure plate is added and balanced to one half gram or less. Again, the crankshaft nose is corrected for "plane" balance to one half gram or less. The pulley is added and balanced to one half gram or less. The crankshaft flywheel end is corrected for "plane" balance to one half gram or less. Because the pulley is smaller in diameter, this affects the "plane" balance far less than with the flywheel.
As you can see by using this method all of the parts are balanced on the same center line they will run in and the entire system is corrected to under 1/2 gram. The flywheel, pressure plate, and pulley always have some runout. By balancing them on the crank they will run on assures you of the correction of balance in the radial direction and also in the "plane" to the other end of the crankshaft. Performing balancing in this fashion is far more time consuming, however it produces superior results.
Companies that balance each part individually to 1 gram or less could have from 4 to 6 total grams of out of balance radically and 1 to 2 grams in the "plane", which is little or no better than what the VW factory did when the parts were new. In fact, most genuine VW parts are actually closer. Because the VW is an opposed 4 cylinder engine, the pistons, pins, and rods are done separately, matched to one another, with the rods balanced end to end and for total weight.
The pressure plate when first installed to the flywheel is punched (if needed) in 12 places to fit the flywheel tightly. So, that when you remove it and reinstall it, the balance will be as close as possible to the same as when we balanced it. It is marked (stamped in) with an "O" on both the flywheel and pressure plate. We have also found that when installing the pressure plate, you must also follow the same installing sequence (schematic is furnished with our balanced parts) as we did when we balanced it to maintain accuracy of our balancing. It is important to snug the bolts up by hand first and then torque to the stock torque specifications using the sequence on our schematic each time. Sometimes it is necessary to draw the pressure plate in (a little at a time) with a wrench to avoid chafing off of the punched area material. Remember to remove the 3 clips from the pressure plate after torquing and before installing the engine.
The crankshafts that have been doweled by us receive the industry standard one offset dowel pin so the crankshaft and flywheel can only be assembled one way. Crankshafts that are not match doweled or were doweled with the even pattern by someone else are marked inside the bottom of the gland nut hole with an "O" that lines up with a corresponding "O" on the flywheel close to the center.