6 -- Flywheel Bearings.
FC1000/1, FC1000/2, & 20-Station Turret FC1250/30/1500 use #17562-000.
FC1000/3, 33-Station Turret FC1250/30/1500, FC750, and FC750/2's use #18221-000
Strippit has Experimented for Decades in this Area. Strippit has Tried Several Different Bearing Manufactures, has Specified Special Custom Bearings with Extra Internal Clearances Ground into the Races, has used Standard Bearings with Assorted Spacer Shims, and has even tried Specifying Special Custom Internal Bearing Contact-Angles.
You can do this My-Way, Your-Way, or Strippit's-Way.
You Pays Your Money, and You Makes Your Choice.
I Do It This Way;
-- New Bearings are Hand-Packed with New Grease. Keep Bearings and Grease Clean!
-- Strippit Used Originally Mobil EP-1 Grease. This grease seems to always Oxidize,
Burn, and turn Black after a few years. I am Using Mobil Mobilith SCH 100 or 220
Synthetic Grease to try to Improve Grease and Bearing Life.
-- Bearings are Shrunk, then Dropped into Flywheel Bore, where they Expand to form a
Tight Interference Fit. Liquid Nitrogen works best to Shrink, but Dry-Ice will work.
I put Greased Bearings in Plastic Bags (to keep Frost Out) then Cover them in Dry-Ice.
-- To Survive in this application, Flywheel Bearings Must be fitted "Loose"
(Un-Preloaded). Bearings Will Fail If Not "Un-Preloaded" Correctly!
-- I use a .008" Brass-Shim Fitted Between the 2
Bearings at the Small-Diameter "Inner" Races to accomplish this "Un-Preload".
The "Outer" Bearing Races are Clamped together by the Bearing Retainer Rings.
The "Inner" Bearing Races are Forced Apart by the .008" Shim,
which leaves .004" Clearance in each Bearing, which has worked well for me.
-- A Drawing of this Type Bearings and Shim Installation is shown Below.
-- The 2 Flywheel Bearings are Installed with
the Stamped-Faces "Back to Back" (Facing Each Other in the Middle).
Make Sure Both Bearings are Not Put In Backwards, or They Will Fail!
-- Apply Locktite 242 or 243 Thread-Lock to the 6 Bolts, and Bolt On the Inner Bearing
Retaining Plate (Side that Faces the Machine Frame) in a Chris-Cross Pattern.
Using a Good Torque Wrench and Hex-Bits, Carefully Torque these 6 Bolts to
23 Foot/Pounds. Then Lay the Flywheel Down Flat with this Plate on the Bottom Side.
-- Now take 1 of your Shrunken Bearings and put it in Flywheel Bore,
"Stamped-Face Up" so Un-Stamped Face will be Against the Inner Bearing Retainer.
It should almost Fall-In, but Tap it Lightly in Place with a Brass Rod and Hammer.
-- Carefully Set and Center the .008" Shim on to Bearing.
-- Take other Bearing and put it into Flywheel Bore with "Stamped-Face Down". The 2
Bearings should now have "Stamped-Faces Back-To-Back" with Shim in between.
Tap Top Bearing into place.
-- Cover Flywheel-Bore & Bearings with a piece of Bubble-Wrap or Towel to help keep
excessive Frost from forming. Let Flywheel & Bearings warm to room temperature.
-- Wipe Out any Frost Water.
Check that Shim is Perfectly Centered. Double-Check Bearings are Not Backwards.
-- Half-Fill Only, the remaining Space between Bearings and Retainers with Grease.
Do Not Pack It Full of Grease! Too much Grease causes a Condition called
"Churning" which can Overheat and Burn Grease causing Bearing Failure!
-- Put Locktite on the other 6 Bolts, and Bolt on the Outer Bearing Retainer.
Carefully Torque Bolts to 23 Foot/Pounds in a Chris-Cross Pattern. Excess Bolt
Torque will Distort Bearings and Bearing Retainers and could cause Failures.