Quote:
Originally Posted by Patrick L.
I've heard/read that. Makes no sense to me.
When I've done them in the car, I put slight jack pressure on the crank to seat the crank in the upper bearing. I'm one that uses plasti-gauge and set all bearings to .0015". The one exception is the rear main which I usually set a bit tighter. I also keep the shim packs equal thickness for one bearing. I usually have trouble peeling shims so I usually just sand them on a piece of glass.
Usually you'll find more clearance in the center main than the front or rear.
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What the reference is to, the middle main, as most know, the hanging weight of the flywheel, causes the the crank to bowed, center bearing up, and rear bearing down.
In a center bearing, you can find .003, to .020, or burned out.
So, if the front is wore .004, and the rear is say wore .006, and the center wore .010, and you adjust all to .001-50, T
That would be No. 1 tightening of 002-50.
No. 2. would be .008-50.
No. 3. would be .004-50.
So when adjusted, to .001-50 thousandths, you have a bow in the crank, and when it runs, it will flex, which is a good way to break, a crank, and will have a vibration.
The other thing that happens, is the off center main will eat the bearing out until the pressure gets off the cranks center main bearing, from the bow, held in the bearings, after adjustment.
Herm.