Main and Rod Shim Sequence ???

[Bob C]

Isn't there something about not taking more shims out of the center
main than the front or rear??


Bob

[Patrick L.]

Originally Posted by Bob C

Isn't there something about not taking more shims out of the center
main than the front or rear??


Bob

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.

[Kohnke Rebabbitting]

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.

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.

[Patrick L.]

Originally Posted by Kohnke Rebabbitting

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.

I'm not quite sure what you're saying, but, thats OK. I guess we can maybe agree to disagree. I certainly don't do this as often as you, but I haven't ruined a bearing or crank yet. [ for whatever thats worth].

I like the bearings [ rods and mains] at .0015" [ no more than .002"] with each side of the shim pack equal thickness.

[Kohnke Rebabbitting]

I like the bearings [ rods and mains] at .0015" [ no more than .002"] with each side of the shim pack equal thickness.[/QUOTE]


Me too.

Herm.

[Patrick L.]

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Originally Posted by Kohnke Rebabbitting

I like the bearings [ rods and mains] at .0015" [ no more than .002"] with each side of the shim pack equal thickness.

Me too.

Herm.[/QUOTE]



I think I understand what you were trying to say, but, there was still some question. I understand about the 'bow', I'm not a big fan of that 60# wheel and only 3 bearings. But thats 1930s stuff and what we have to deal with. Every bearing I adjust I then make sure the crank turns freely. Maybe we're just taking different directions to get to the same place.

[50Trucking]

MY PROBLEM IS THAT WHEN I TOOK OFF THE ROD CAPS THERE WERE NO SHIMS IN THE CAPS. Is there a setup where no shims are used or is this crank just worn out?