Let me explain here, also, the idea behind this mod. I explained it in another thread, but it's better to have all the informations in one spot:
It's really simple what is happening with three bearing mod. Everybody says that new lip on the pinion is too thick, so the pinion is too far into the crown. I have to believe this as I never tried to install a HD pinion with two bearings. Let's suppose it is true, therefore we need to pull back the pinion as far is needed. Now, two bearings plus one original spacer mean 12.82mm, according to my measurements. And now consider that lip is not needed, that mean we will need 12.62mm for everything to be right. Ok, but three bearings mean only 12.00mm, which mean we are 0.62mm too short, or too far away from the crown. So we will need to add the necessary amount of shims to compensate. Of course, considering all the tolerances, maybe you will need more or less than 0.6mm, I needed 0.7mm. And maybe you'll need to add some shims behind the first bearing, near the C-clip. Also this is why you don't need to remove the lip, because you'll just need to add more shims to compensate.
I'm not saying removing the lip won't work, again, I never tried HD pinion on two bearings. And I'll never try because of the other good thing brought by this mod, you'll have the third bearing to take over all the forces, which mean you'll have less forces per bearing, hence all the bearings will last longer. And if one of them will fail, it won't be so catastrophic to the pinion.
Happily was only the bearing and the case, no other damages
