IMS - Going with SKF hybrid

[Silber]

I'm thinking it may be beneficial to post some of my thoughts about this, so if you don't like rambling skip this post.

Porsche had some of the best engineers in the world designing this engine. They looked at the numbers for the bearings, and their load data, and came up with their bearing being a lifetime solution. These were smart guys, they didn't just go to a bearing catalog and pick something at random.

But, obviously, they made some sort of mistake or we wouldn't see the failure rates we do. What was their mistake? I think it was the open tube inside the IMS shaft. Thing is, that tube acts like a small lung. Every time your car heats up, the air inside it expands and it "exhales" through the seals of the IMS bearing. Then when you stop your car and it cools it "inhales" oil from the sump through the IMS bearing seals and into the IMS tube as it cools and the air contracts.

So, I think the enemy of the IMS bearing is heat cycles. Every time the car heats up and cools down, a little bit of grease gets washed out of the bearing. Does evidence support my theory? The bearings have the grease washed out, the IMS tube is usually full of oil. At least some evidence exists. Sealed bearings running in an oily environment don't normally wash out as bad as these IMS bearings do, by a long shot. Reading some Machining forums sealed bearings in oil is fairly common and not problematic.

So, I think the Porsche engineers got it right, in that the bearings they specified, if kept intact, will work as long as they thought. They did not predict the lung effect.

I think the lung effect can be countered by plugging the IMS shaft tube with a freeze plug. Your lung will go from the size of a small dog's lung, to the size of a gerbil's. Not near as much, if any, oil will get pulled through the bearing. This allows the 2rs seals to do their job of keeping the grease intact and allowing the bearing to live to its rated service life.

Is this theory a good one? I think so. The bearing washout and oil getting into the IMS tube in the quantities it does has to be explained somehow. Will my solution (2rs + Freeze plug) actually work? I think so, but you are all right, it has to be proven, as unproven it is nothing more than ramblings of an internet nobody.

Silber