[Kirk]

Originally Posted by thom4782

I question DOF for one simple reason. Nobody that I've seen has provided one single hard fact that shows
lubrication is a problem for unsealed replacement bearings. Just because someone says something doesn't mean it's so.

Exactly, no one has proven exactly how much oil an unsealed replacement bearing gets, even LN Engineering has not shown us how much oil actually gets to their ceramic bearing if it is just left unsealed. What we do have though are pictures like this from Feelyx



This shows that the sump level is clearly below the IMS bearing (the green line). Then we also have pictures that show the small slit that the oil has to "splash" through to lubricate the bearing.



Then on top of that we have a dozen or more IMS Retrofit failures and a new video on the TuneRS website showing a badly worn Retrofit bearing after just 40K or so miles...

So you are right, there is no direct evidence to support the LN Engineering claim that there is sufficient splash lubrication for an unsealed bearing, but the indirect evidence would make me very uneasy about trusting such an important bearing to marginal, at best, oil splash. I think the indirect evidence is enough for me to want a more reliable and consistent supply of oil to this bearing = DOF. Now I have asked LNE in another post for any testing that they've done to show the oil level during dynamic running conditions, but they have not produced anything. On the other hand I just installed a DOF system on my 2003 Carrera 4S this last weekend and I have the peace of mind now that I know exactly what the state of lubrication will be for that bearing under all running conditions like hard cornering, hard braking, and acceleration - it will be exactly the same!!!

Kirk Bristol