Quote:
Originally Posted by Wayne at Pelican Parts
There is a space between the bearing and the cover, so that area would be washed with oil and wash away the grease within a few miles, I think. Interesting thought though - I do believe there must be a good solution to this problem somewhere.
-Wayne
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Quote:
Originally Posted by WhipE350
Great idea! Would the pressure from the grease packing at each oil change weaken the inner seal and cause it to fall off? If it did then wouldn't the splashing just wash away the grease? I suppose if this did happen then there would be no back pressure when greasing and it would be obvious a replacement was needed.
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Absolutely, the grease washing out is the entire problem with these bearings! lol
For design purposes, rotary lip seals are limited to about 7 psi positive pressure, since the seals in a brg like this are seated very tight, the grease should just push out the lip and not unseat the whole seal…theoretically!
The trade off is always this; a sealed brg will last IF you can keep it from getting contaminated, if you can’t, then you provide a way of lubricating it with grease or a flow of oil. I have seen gearboxes with sealed units, but there is usually another lip seal inboard that is there specifically to keep the gear oil away from the brg seal.
It seems like the basic problem is that just enough engine oil gets in there to dilute the brg grease, but not enough to keep the brg lubed. Since the grease washes out slowly (thousands of miles), if it could be replenished on a regular basis, we might be able to keep the IMS brg in the “safe” zone.
Obviously, Wayne and others have all the technical prowess needed to analyze this issue, I just wanted to point out that there is a wealth of engineering and application data on these problems out there. You just won’t find it in the automotive world because only Porsche has ever tried a sealed ball brg INSIDE an engine…and with limited success!