Now we need to move back in time. Here is a guess as to how the bearing ended up submerged. The engine was designed wet sump, the first Porsche boxer engine with that approach since the 912/356. When they started testing it in the prototype 996, they found the oil pick-up was sucking air instead of oil (with the new suspension and great tires under high lateral "G’s"). When sump baffling changes did not fix it, they added a couple liters of oil to the sump. Cheap fix, new dipstick. But, the bearing (which was designed dry) was now wet when not running. Well,….. someone had to sign off the engineering change forms, including the impact of the change assessment. Now we have a paper trail to the guilty. When the bearing problems started, the cover up began.

So, the guy who messed up ….either found a way to get it blamed on the least liked guy in the group (and is now the area manager), or…..he has long since left Stuggart, and made a career making weinerschnitzel in the Black Forest. You might laugh, but this happens all the time in big organizations. The case everybody remembers ……..is the space shuttle o-ring disaster.

When we do the math on the grease lubed (but not immersed) dual row bearing, it looks really good . Lots of load margin, and the combination of small OD and small ***** keeps the ball speed and centrifugal loads down. No problem at all grease lubed. The problems start when the grease is gone.

The second generation single row bearing is simply the dual row cut in half. It is really that basic. Same ID and OD, half the ball count. So the contact stresses are doubled. We now have a bearing that is far more likely to overheat and die. Based on the failures seen , this is exactly what is happening. These engines should have the hybrid ceramic upgrade done now, don't wait for the clutch to go.

You can’t admit you made a mistake and go backward , so……..you make a third design! You fix the contact stress by putting this big single row bearing in place. The load capacity math on this bearing looks fine, but the limiting speed is very questionable. The increased diameter makes a big jump in ball speed (speed varies as the square of the radius) because the OD of this bearing spins. The ***** are large and heavy, making high centrifugal force that wipes lube off the race. If you are driving around town, and rarely redline the engine, it is OK. Endurance running this design at sustained high rpm is asking for trouble. We have not completed the analysis on the impact of just changing the ***** to ceramic on this bearing. With the ceramic ball’s weight reduction, it will help the centrifugal issue quite a bit. (We do have a ceramic ball version of this big bearing on the road, but it is far to early to tell if the solution is adequate. All indications are it is an improvement, and we can custom make one of these for you if you really want it.) Question is, will it be enough. Since you have to tear the engine down to service this bearing, we are considering making the shaft go back to the (field service capable) dual row. It will require a very precise, cylindrically ground spacer sleeve to make it happen. We would have to do the upgrade in-house to control the fit. More work is needed on this one. Since every engine has to be torn down to fix this bearing, we don’t expect very many sales for a period of years.

So, all this probably happened because ……….no one wanted to tell the boss a $300 bearing was needed to fix it, or the business people could not make a case for spending the money.

Clearly this is a point of the engine that is prone to failure, it's just anyone's guess at this point what percentage of cars it affects - and the best estimate given so far was the 10% in 90,000 mile figure by the retired bearing engineer. Whether that is classified as a guess or estimate requires more data.

The ***** are large and heavy, making high centrifugal force that wipes lube off the race. If you are driving around town, and rarely redline the engine, it is OK. Endurance running this design at sustained high rpm is asking for trouble.