Jon- If your getting 5 full days of running on 2 clutch bell bearings I'd be more than happy with that. If I run clutch bell bearings for practice then 3 heats and a main, their goin in the trash!!
Considering that clutch bell bearings only cost a buck($1) each, it's not worth getting takin out of a main because of bearing failure. Personally I run the metal shielded bearings, I had terrible luck with the rubber sealed bearings failing, seemed like 2 tanks and the rubber seals would fly out and the bearings would get full of dust and go out during a race!
I get the metal shielded bearings in the 10 packs and put them straight from the pack into the clutch bell and then into the trash. I actually try to put the fresh bearings in a little before the main, for example I raced over the weekend and I put new bearings in before the 3rd round of qualifying, and I ran them in the main. So this coming weekend I will run the same bearings in practice and the first two rounds of qualifying and then put fresh bearings in before the 3rd round. I keep this cycle going from weekend to weekend.
