The crankshaft is the heart of the engine. Few people realize its importance. An extremely large amount of failure can stem from a crank that does not have the proper rigidity. As you read this you should become extremely clear that no one has addressed these problems as I have.
First let's look at the case. Many people say to shuffle pin it to stop it from walking around and pounding out. I, personally, approached this completely different thanks to Claude Bushard the automotive machinist that I started with when I was 16. He continually preached to me to step back and take a good hard look at what was happening before I made any judgments or decisions, and never, never put a bandage on your elbow for a sore on your knee. Never listen to anyone else's cure until you have figured out on your own what you think is the problem and then listen to at least two people's opinions of what they independently think caused the failure or damage.
With the VW case it was obvious to me that something was causing the damage, the case did not just give way. My first clue was having to run a lot of deck height as compared to my Ford or Chevy engines. When I also found bent crankshafts in high RPM engines it was obvious that it was the crank causing the problem and not the case. Needless to say, I also was looking at a Porsche engine that was not suffering from these problems at higher RPM's so I was impressed with the counterweighted crankshaft. Naturally, this was the first cure.
As HP and RPM increased, we saw the problems return. We even had some new problems. Again, to the crankshaft. Not only did we find the deck height was a problem, but the lack of crankshaft rigidity caused the wrist pin keepers to burr up or be knocked out. The rest of the industry simply put in Teflon buttons. I determined that this problem was completely from the crankshaft actually bending up at the top of the stroke (and down at the bottom) putting the rod out of alignment, pushing sideways on the pin rather than having "0" load when the crank stays straight. We also found that ring life was much worse and in some cases when the
rings were new, blow-by was a problem, even when the leak down test was good. This also was from the bending of the crankshaft pushing sideways on the pin and piston unloading the rings and naturally this bending was pounding out the case.
At the time (1975) we were trying to solve these problems for race cars. A couple of our street customers that we had testing our Rabbit rod, drop in 78mm stroker crank kits started to report wrist pin keeper problems and/or bad blow-by in only about 10,000 miles. It seems these cranks were bending and the harder they ran them the worse they got. It was obvious right off that these were headed for premature failure so they were not produced for sale from that time on. This did not surprise me as anyone that has seen one knows this journal is super small and there is no way to add material to the cheek between the journals to provide rigidity. Furthermore, the Rabbit is an in line engine and has none of the problems the opposed VW has with flexing.
Our first cure in 1973 was to weld up the center main to the 411 bigger journal size to add strength to the center of the crank. Yes, this worked fine for some of the cranks, however was expensive and did not cure all these problems with the longer stroke cranks. It was obvious that it would be cheaper and far stronger to cure everything with an all-new forging. With this new forging I had the ability to make all 3 big mains to the larger 411 size and better yet was able to make the web in between each journal much thicker, greatly increasing the strength. Naturally, our forging is a true forging that is forged to journal shape. This is the only way that you have grain orientation and full strength, regardless of material or heat treatment.
Naturally, the 411 center main became standard so next was to determine at what stroke to go to the thinner Porsche or Capri rod to get this thicker web. Thousands of tests revealed that any stroke beyond a 78mm should have the thicker web to provide full case life. This eliminated 99.9% of all the case pounding, even with 86mm stroke and all the wrist pins (never a need for Teflon buttons) and ring unloading problems. If you have a low HP low RPM engine, these problems may not be as prevalent, however they are still going on in some form, reducing the life of engine parts to some degree, costing more per mile to run.
Processing of a crankshaft is as valuable as the quality of the forging's strength. Few people know what it takes to do the job right and no other company in the VW business offers all of the processes that we do to assure the consumer of the best dollar value available any place.
First, is the machining which is fairly straightforward. Well, not really, because some people machine almost exactly to size on the journals and to finished size on the gear and pulley area. This is because they are not going to do the next two processes. If they do the stress relieving it reduces the part of the crankshaft that is already to size. The 36-hour stress relief process stops all the surface stress cracks that machining always causes and costs about $85. Next, a process called "green grinding" is performed to grind out the surface stress cracks and this costs about $120. Then the oil holes are added. One extra step is done to the main bearing oil holes, which adds leads into the hole at a cost of $65 per crank. What this does is centrifugally forces the oil into the rod journal at greater oil pressure than what the pump can provide by itself.
The higher the RPM, the higher this hydrodynamic pressure becomes. People that cut a groove around the main journal reduce the pressure at the rod as the oil is allowed to escape and "rope" around the main journal, reducing the pressure at the rod. Now, this groove around the journal is far cheaper to put in by a single cut with a radius tool. Next, the rod journals are finished. All four are ground to the same stroke and index. This requires much more time than pulling journals out of stroke or index to get it to clean up faster which is common to cranks that are machined too close to the finished size. The main line is critical, as it must all be on one centerline. We have five different dial indicators (over $1000 each) so we can grind every surface on the main line at one time. All of the competitor's cranks I have checked have only the mains ground and the rest is machined when the crank is first started.
Many of these have run out from the mains to the gears, pulley, and flywheel area. Most other people's cranks I checked did not even have the small main ground at the same time as the 3 big mains. The crank was removed from the grinder and put back in to grind the small main. Now, we all know it is impossible to get the crank dialed back in the same again once it has been removed. It seems they only have one dial indicator for their grinder.
This is also a wide spread problem with all re-ground crankshafts and 99% of the counterweighted/ground and welded stroker cranks others sell as they are not ground properly or on the center line of the crankshaft, suffering from run out or out of square to the rod journal.
Doweling the crankshaft to its mating flywheel as one unit is the only way to have a proper fit from one to the other. People offering crankshafts that are already drilled (with or without dowels installed) are selling a product that will never have a correctly fitting flywheel, (see index for page number for doweling). To offer the crankshaft with the flywheel custom fit to that crankshaft also provides us with the opportunity to dial the run out on the flywheel to assure that it is less than factory specs. Having less run out than stock is critical in high RPM engines and if allowed to be too far out could cause the flywheel to shake itself off the end of the crankshaft. To dowel, check and correct run out costs $70 or more than simply drilling some holes in the end of the crankshaft and sticking some dowels in as all others do.
Lastly, is the proper balance of the crankshaft and flywheel. Our cranks all include dynamic balance of the crankshaft in the price of the crankshaft. I do not know of anyone else that includes this in their price. That's another $50.
Most companies do not offer Nitriding (surface hardness) to their crankshafts or charge extra for it. This accounts for $95 more expense that others do not do as a standard procedure.
In summary, if you think our cranks are expensive you need to consider that our (true) forging costs $195 more than anyone else's and we do $485 more work to the crank than anyone else. All this work adds up to as much as $680 more to produce our crankshaft than if we were to cut out all the processes our competitors do.
We know our crankshafts offer at least 75% more value per mile than anyone's. Why settle for less?
Furthermore, if you have case pounding, pin keepers coming out or burring up, crank gear, flywheel, and/or pulley run out, poor ring seal (even with quality P/C) you likely have a crankshaft problem (provided it is not in a line bored case). That is common to all other aftermarket cranks we have tested. Some companies are even cutting more out of the web to make a super lightweight crankshaft, which also makes it far weaker and flexes even more.