PISTON 7J1626 - Caterpillar

General Specifications
(1) The crankshaft must be dynamically balanced to within 3.6 gram-meters (5 oz-in) measured at each end.(2) D379 and D398 crankshafts must be supported at the outer-most main bearings.(3) To prevent whipping, D399 crankshafts must be supported at main journals No 2 and No. 8 (the second main journals in from the ends).(4) Always rotate the crankshaft at a speed, between 200 and 300 rpm, where the drive motor resonance is zero.(5) Always install counterweights with the part number toward the main journal.(6) Put 2P2506 Anti-Seize Compound on the seat and threads of the counterweight bolts. Do not dip the bolts in the compound. Tighten the bolts to a torque of 217 14 Nm (160 10 lb-ft).Balancing Information
(1) If an outer counterweight is being replaced, it should be possible to balance the crankshaft by machining only this counterweight.(2) If an inner counterweight is being replaced, it may also be necessary to replace both outer counterweights. Because the outer counterweights are usually machined at the factory, it may not be possible to remove additional material.(3) The preferred method for balancing the crankshaft is to force a heavy or positive (+) condition to the outer counterweights, then balance to zero.(4) If there is a heavy or positive (+) condition in the center of the crankshaft, remove material from the inner counterweights until the reading is zero or negative (-) [this indicates a light condition]. This will force the positive (+) unbalanced condition to the outer counterweights where it is much easier to balance the crankshaft to zero.(5) When an inner counterweight is machined, it will affect the readings at both outer counterweights. When an outer counterweight is machined, it affects only that counterweight. Therefore, it is always easier to balance the crankshaft by machining the outer counterweights.(6) When the force of unbalance is such that the angular location of the resultant force does not come out on a counterweight, it will be necessary to remove material from other counterweights in order to move the angular displacement so it comes out on the counterweight. [If the corrective angle is in space, it must be forced one way or the other so it comes out over a counterweight. The counterweight can then be machined to balance the crankshaft.](7) Always work the negative (-) unbalance condition from the crankshaft before the positive (+).Machining Specifications For 5L2662 Counterweights
(A) Measure to drill point to determine depth of hole.(B) Minimum wall thickness for balance holes is 3.0 mm (.12 in).(C) Drill sizes smaller than the 31.75 mm (1.25 in) diameter indicated can be used.(D) Holes can be drilled at locations other than those shown if they are a minimum of 3.0 mm (.12 in) from either of the bolt holes. (E) Spotface permitted only after both holes have been drilled to maximum depth.(F) Spotface permitted on outer holes, but inner holes are preferable.(G) Spotface permitted only after hole has been drilled to maximum depth.(H) Maximum depth of spotface not to exceed bolt surface