M12 Crank Bearings - Preload Normal?

[svt721 27]

Hey guys,

 

Putting my M12 back together after a rebuild and have a question.  Following the Kohler manual, I pressed the new crank bearing into the PTO side of the block, then pressed the crank into the bearing.  I then pressed the other new crank bearing into the bearing plate.  Installed the gasket and the original spacers, installed the dowel pins I made and began pulling the bearing plate onto the crank using a long set of bolts (per the manual).  Before I got the bearing plate pressed fully onto the crank, the crank spun with little resistance.  As soon as I bottomed the plate down on the crank and torqued it to 35lbs, I noticed the crank was more difficult to turn.  Not substantially and it still turns very smooth, but there is definitely tension on the bearings.

 

I measured the end clearance on the crank per the manual and came up with .008-.009 with the original spacers and new gasket which is within spec.  Is it normal for these bearings to tighten up once everything is installed or is something not right?  I know taper roller bearings run with preload, but didn't expect it with ball bearings.

 

I hate to put it all together and wipe the bearings out of it, so any insight is greatly appreciated.

[Achto 29,223]

19 hours ago, svt721 said:

Is it normal for these bearings to tighten up once everything is installed or is something not right?

 

Slide a pipe that just fits over the crank shaft and give the center race of the bearing a couple good taps. Using the bearing plate to push the bearing on applies pressure to the outer race of the bearing. The inner race is facing interference on the crank during this process. A couple of good taps will allow the inner race to catch up with the outer race. Check your clearance again after this.

Edited June 7 by Achto

[953 nut 59,142]

Also the bearing could have gotten slightly cocked over but @Achto Dan's method will straighten it out for you.