Crank Seal Install - Kip?

[Big Mac]

Is there a consensus on which way the left side crank seal should best be installed--open side of the seal toward the crank webs, or open side toward the transmission oil?

Like fork seals, I've always put the open side toward the liquid being sealed in. But the pressure variation is in the crankcase so would think the high pressure should be against the open side, and the mag side crankseal has the open side facing in toward the crank, so...

Suggestions on what's worked best or what's not worked?

Jon McLean
Lake Grove, OR

[Mike Lenz]

Good question, however I have always put the lip in twards the crank because thats how they come from the factory, plus you wouldnt want to lose pressure there for sure.

[Kip Kern]

Mike is correct, lip/spring inside towards crank webs. Never seen them any other way.  Same as the shift shaft seal, not sure why people put them backwards???

[Big Mac]

I split the cases, pushed out the crank, found a bad seal, replaced it. Then installed the crank back through, making sure the beveled side of the spacer washer faced toward the inside, replaced the washer on the outside of the outer bearing, installed the pinion gear and torqued down the nut to draw the crank to the left case half.

The center gasket was fresh from recent install, so I reused it and put the right side case on and torqued the case screws to 5lbs all the way around. I can't think of anything that may have got out of whack.

The crank spins around now with noticeable resistance, like the main bearings are under tension on one side or the other. It seemed very free turning before installing the right case half, and when looking down on the crank from above, the free space gap between the crank web and the right-side case is smaller than the gap on the left side.

The drag on the crank's free spinnning isn't dramatic, but is noticeable. Any ideas on things to check? Concern enough to dis-assemble and start over? Kip--your suggestion?

As the main bearings and races didn't move, the outside left bearing may be holding things a hair off to the right. I expect a few heat cycles will likely re-align it, but it's a bit scary to run it with bearings tight, I fear.

[Kip Kern]

I always pull the pinion bearing when closing up a set of cases as this allows you to look only at the main bearing play to properly shim the crank end play.  The clearance should be about the same on both sides of the crank when the cases are closed and torqued but sometimes, there is a difference.  When shimming a crank in any engine you try to even out the thickness of shims as best as possible but sometimes it doesn't work out so the larger amount of shimming always goes on the clutch side of the crank.  Once the crank is properly shimmed (around .005 end play) between cases and web outers, then you install the bevelled washer and the pinion bearing.  You will then notice that the end play on the crank is "0" unless you have a old or worn pinion bearing.  I always change the pinion bearing when splitting the cases as it get's the most work from the clutch.  This should work for you!

[Big Mac]

Thanks Kip. Got it.

I'd replaced the new left outside bearing, seated it all the way in, and then pulled the crank through. It apparently needed to float just a bit out from full seated for the left side main bearing to be set right.

Put a little hot air around the left outer bearing to heat case up, wedged the crank webs so I could push from the right, and it one-tapped right over a hair and centered nicely. All went back together fine and crank spun freely. All this just for a bad seal replacement!

[Kip Kern]

Don't feel bad, I have had to take an engine apart as many as 6 times to get the crank shimming correct.  Comes with the job!:D