Some considerations regarding bearing installation. Somewhat complicated by our not completely stock combination of 912 crankshaft with a B Super 90 case. Let’s see if I can articulate this clearly…
We have a 912 crankshaft with main bearings measuring:
- 50 mm
- 55 mm
- 55 mm
The Super 90 case has slotted bearing seats in all three positions. This is fine for the split main bearings #2 and #3 from our NLA main bearing set, as the bearings are tabbed. The #1 main bearing in the set is a single piece, which is not tabbed. This would appear to leave us the dowel pin. As some are aware, there are two different dowel pins.
Going by the case, the larger 616-101-172-00 C / 912 pin will not fit into the case hole. I wouldn’t say the smaller 539-01-110 A / B pin is sloppy, but it goes in / comes out of the case easily.
Neither pin fits well into the bearing. The bearing hole is concave at the bottom and the pin would probably catch the side wall of the bearing and presumably keep it from spinning, but neither pin seems to fit well.
Luckily the Pellow video suggests the pins are to provide correct alignment of the oil holes. Not to hold the bearing in place. So as long as things are lining up, maybe it doesn’t matter how snug the pins are. As long as the don’t exceed the length when the bearing is crushed. So small pin wins.
