Here is a copy of a post from the big list on BB turbos:
>Ball bearings have been used off and on since the 30's. It's certainly
> >possible that ball bearing turbos handle axial loads better than plain
> >bearings, but in terms of friction, ball bearings have inherently more
> >drag than plain bearings especially when they are flooded with oil. The
> >real question is how much axial loading is there, and why. There are
> >lots of methods of controling axial loads with ball, needle, tapered
> >needle and roller bearings.
> >
> >As far as the stories, if you go to Garrett's site, they claim ball
> >bearings spin up faster. They make no claims at all about longer life,
> >better axial load control, or any of the other things I have heard about
> >ball bearing turbos. If I really wanted to know about plain vs. ball
> >bearings, I'd ask a truck mechanic (one with a few smarts, not like some
> >of your typical diesel techs). Truckers put more stress on their turbos
> >than we can imagine. Just think about what it takes to haul 40,000 lbs
> >up a hill like the Grapevine on I-5 in CA. That turbo is screaming its
> >little heart out all the way up the hill...we're lucky (and flat hauling
> >ass) if we get a continuous run at full load for a whole minute, they do
> >it for 5, 10, 15 minutes straight. That's a real workout. If ball
> >bearings are so superior, the trucking industry wouldn't even bother
> >with plain bearing turbos. Last I heard, the jury is still out there
> >too.
> >
> >Lance
> >'93 TT 6 speed Coupe
Has anyone tried putting oil pressure into a BB turbo and comparing it to regualr bearing turbo?? The regular bearing turbo spins easier! It is only when the two turbos are dry does the BB spin easier. Think about it, less surface area bearing wise. I have personally never seen a BB turbo spool any faster and with the new 360 degree thrust bearings available I see no reason to use a BB turbo ever from a reliability standpoint.
Lar
SP