Developed by Gene Berg and Bob Dixon in 1972
Why a counterweight crankshaft? The VW air-cooled engine is designed for low RPM, low power output and high mileage use. When used that way it gives many years of trouble free service with little or no wear. However, the higher the RPM, power, or the quicker the acceleration, the more the centrifugal force bends the crank at the center main. This bending force occurs because the two center rod journals are on the same side, putting all the weighted forces on one side of the crankshaft. This pounds out the case at the center main saddle, plus makes the pulley and flywheel run out, often damaging the case at the pulley end. It also puts the rod into an acute angle, one of the things which drives wrist pin keepers out of the piston. If this bending gets too bad it can cause rod breakage or even the loss of a flywheel. Berg counterweights balance this effect so the crank not only stays straight, it also rotates on a film of oil, as it should. Crankshaft strength is also increased with the addition of the counterweight. This provides longer case, rod, piston, cylinder, and bearing life.
Through years of testing and development we developed exclusive techniques, material, and welding rod to install counterweights without any distortion, bending or inherent stress to the crankshaft. This exclusive Gene Berg counterweighting process provides us with the ability to add counterweights to a brand new crankshaft without any distortion or bending. We only use good used genuine VW cranks that have never had a burned journal, been bent, or have any damage. Our process includes properly adding the counterweights, machining the crankshaft with the proper angles for the latest case, and glass beading the entire crankshaft. We then check all four-rod journals for stroke and index, averaging the journals so that we regrind it to the same stroke and index on all four journals. This requires almost three times the grinding time as compared to simply regrinding the crank by following the out of stroke and index on each individual journal as our competitors do.
Next, we grind the mains on all four journals without removing the crank from the grinder. We do not follow the wear on the journal, we properly dial the crankshaft in at both ends so your timing gears, pulley, and flywheel run concentric, again taking almost twice as long to do. Most grinders do not have extra pre-set dial indicators (the cost is over $1000 each) for every size they grind as we do. They remove the crankshaft after the three big mains are done. After all, cranks are done on the three big mains, remember we use the 411 center diameter which means two gauges to do the big three, then they put the crank back in and redial it to as close as possible (they can never get it 100% correct again) and grind the #4 main. Some shops do not even redial the crank in when grinding #4. Further, other shops dial the main journals in and not the gear, pulley, and flywheel areas as it is far faster to simply grind the journal following the wear rather than having an interrupted grind to correct the crank back to a completely straight line.
We butt grind the flywheel end and the bearing thrust surface to assure flatness and bearing longevity. Any crankshafts that have wear in the flywheel shim area are welded up on our special submerged arc welder before grinding is started. These are then reground to the standard o'ring dimension when the mains are ground. We precision balance the crankshaft on our space age computer controlled ridged mount balancer. This, unlike our competitors, is included in the price of our crankshafts because it is critical to the life of the crank and engine case. Last is the finish micro polishing. Many people do not do this step properly, if at all. However, we have found that it can increase the life of the engine by as much as 25%.
Yes, we feel all of this extra work and quality (that no one else offers) is critical in providing smoother running and better life at any RPM. It's the smartest thing that can be done, even during a stock rebuild, and is an absolute must to achieve good longevity for any higher than stock performance engine.
We have run Berg properly counterweighted cranks in race cars at well over 9,500 RPM and in many street high performance engines producing three times the original HP, frequently being turned 7,000 RPM. Many of our customers report well into the 150,000-mile mark now and some over 200,000 miles with little or no case wear. If your Berg counterweighted crank has run longer than 300,000 miles without requiring a regrind let us know as that is the record at this time.
Our research and development cars naturally use our cranks, as do most quality engine builders. These people require the best for their use in the street engines they sell. Their reputation depends on it. They know we originated the unique processes to make crankshafts live as well as our famous wedgemated flywheel installation to keep the flywheel on in severe drag race use. These processes have been copied by many, but still never duplicated. Ours have the ultimate strength and the most counterweighting available today. We have what you need to do the job from a stock rebuild to all out street engines - the first time around. Compare ours to all others and see why it is far less to get a genuine Gene Berg counterweighted crankshaft that provides more resale value than anyone else's does.