The permissible angle on our AquaDrive is MUCH less than 12 degrees. We replaced engine mounts last year and tweeked and tweeked to achieve an equally-distributed compound angle of 3.5 degrees.
I have several different manuals
on older models, not for a "new" B-12, so for what it's worth here's an overview:
"Max recommended joint angle is dependent on shaft speed ... The CV joints do not need to run at equal angles, but the effective lifetime is determined by the amount of the angle ... try to have as equal angle-distribution as possible."
There are tables and diagrams that illustrate how you measure 3-dimensionally and do the math to come up with "effective compound angle." At least for older models, the maximum compound angles permitted are:
= 8 degrees
= 6 degrees
3000 rpm = 5 degrees
4000 rpm = 4 degrees
5000 rpm = 3 degrees
Less is better, although you don't want zero. My BMW was replaced with a 50hp Yanmar
in 1997, and the top-dollar yard in Connecticut screwed this up. Didn't catch up with us until 5 years later, on the other side of the planet. Now we carry a spare unit, swap out and rebuild
every 5 years or so. The rebuild
is NOT EASY, very messy and time-consuming, so best to hire a professional (against my general rule).
PM if you would like me to forward the documentation