C5 Corvette ATI Balancer Installation Parts Required: ATI Serpentine Damper (917278 10% under drive with A/C pulley) Katech Manual Belt Tensioner (KAT A4424 RED) ARP Balancer Bolt (234 2503) Accessory and A/C drive belts 2 Each Button Head Allen Bolts (M10 x 1.5 x 40) 2 Each flat washers (M10) Front Cover Oil Seal (GM 12585673) Tools Required: Hand Tools Torque Wrenches T40 Plus Bit Loctite 242 Medium Strength Thread Locker (Blue) Loctite 262 High Strength Thread Locker (Red) J41665 or equivalent balancer installation tool J41816 or equivalent balancer removal tool J41478 or equivalent front oil seal installation tool Optional Tools: ATI Crank Pin Drill Fixture Kit (918993) Extra 3/16 Pin (958025) Pin Specifications: Diameter:.188 Length:.505 Torque Specifications: Damper to hub: 16 ft/lb Hub to Crankshaft: 240 ft/lb Tensioner to water pump: 37 ft/lb Tensioner locking bolt: 40 ft/lb I. Crank Pin Procedure: If pinning the crank complete the following operation, otherwise skip to section II: Using ATI's crank pin drill fixture kit, 1 or 2 dowel pins can be installed in the LS1 crank to eliminate the damper twist on the shaft a must for engines used for circle track racing or supercharging! Note: All drilling and reaming dry - no lubricants or cutting oils are necessary! All ATI LS1
dampers have one 3/16 keyway in the hub or ATI can key an existing damper or hub. A. Remove the existing balancer using J41816 or equivalent. See figure 1 Figure 1 B. Install the fixture to the crank and position 1 bushing hole for best drill access C. Using the old crank bolt, lock the fixture to the crank so it cannot move D. Install the 11/64 bushing in the adapter and snug the holding screw E. Using the 11/64 drill bit, drill through the crank to the center bore F. Change the bushing to the 3/16 bushing and ream the 11/64 hole to 3/16 with one pass in and out at low RPM G. For a second pin at 180 degrees, rotate the crank. Do not loosen bolt! H. Repeat steps 4, 5, and 6 on the opposite side if installing 2 pins I. Blow the outside and center bore clean of all chips before removing adapter. Then remove adapter J. Applying Loctite 242 Medium Strength thread locker, install the 3/16 pin. Allow it to protrude above the crank surface.093" to fit the keyway in the hub. II. Front Oil Seal Installation: A. Gently pry old seal from front cover. See figure 2
Figure 2 B. Important: Do not lubricate the oil seal sealing surface. Do not reuse the old seal. Lubricate the outer edge of the oil seal with clean engine oil C. Lubricate the front cover oil seal bore with clean engine oil D. Install the crankshaft front oil seal onto the J41478 guide E. Install the J41478 threaded rod (nut, washer, guide, and oil seal) into the end of the crankshaft. See figure 3 Figure 3 F. Use the J41478 in order to install the oil seal into the cover bore 1. Use a wrench and hold the hex on the installer tool 2. Use a second wrench and rotate the installer nut clockwise until the seal bottoms in the cover bore 3. Remove the tool 4. Inspect the oil seal for proper installation. The oil seal should be installed evenly and completely into the front cover bore G. Install the crankshaft balancer
III. Balancer Installation: A. Inspect the crankshaft for burrs, nicks, etc and file to clean up. Using a stone or file, create a slight radius on crankshaft end to break the sharp edge B. Anti seize lubricant is highly recommended for the crankshaft hub prior to installation. C. Press fit of the hub to the crankshaft is vital to transfer harmonics to the damper assembly. The recommended press fit for the LSx engine is.0007.0009. For non OEM cranks, the crank must be checked with micrometers and the hub with a dial bore gauge to verify fit. Most OEM cranks are held to +/.0002 while most aftermarket cranks are held to +/.0005. Hub bores are tight to accommodate aftermarket cranks and most hubs will require honing. DO NOT HONE ALUMINUM HUBS. See special instructions for dampers with aluminum hubs D. The hub may be installed onto the crankshaft first, with the damper installed afterwards. If the balancer is disassembled for installation and has an A/C pulley, the A/C pulley MUST be installed during hub installation because it affixes to the rear of the hub 1. Using the T 40 Plus bit, disassemble balancer by removing the damper from hub 2. The damper is indexed to the crank hub. The indent dimple on the hub and damper are aligned for proper assembly. Note both dimple s for assembly step 3. LSx balancers with an A/C pulley have long and short attachment bolts. The long bolts retain the A/C pulley and the short bolts retain the damper to the hub E. Using a proper balancer installation tool, J41665 or equivalent, install the hub on the crankshaft. The following steps are for J41665, use equivalent for other tools: 1. Assemble the threaded rod, nut, washer, and installer. Insert the smaller end of the installer into the front of the balancer. See figure 4 Figure 4 2. Use a wrench and hold the hex end of the threaded rod. 3. Use a second wrench and rotate the installation tool nut clockwise until the balancer is started onto the crankshaft 4. Remove the tool and reverse the installation tool. Position the larger end of the installer against the front of the balancer 5. Use a wrench and hold the hex end of the threaded rod 6. Use a second wrench and rotate the installation tool nut clockwise until the
balancer is installed onto the crankshaft 7. Remove the balancer installation tool 8. Install the used crankshaft balancer bolt and tighten to 200 ft/lb 9. Remove the used crankshaft balancer bolt 10. Measure balancer for correct installation. Important: The nose of the crankshaft MUST be recessed 2.40-4.48 mm (0.094-0.176 ) into the balancer bore. If the balancer is not installed to the proper dimensions, install the tool and repeat the installation procedure. See figure 5 Figure 5 F. The hub to damper fit is held to an extremely close tolerance. To install the damper to the hub: 1. Align the indent dimples on hub and damper, noted in previous step 2. Using Loctite 242 Medium Strength thread locker, start the three long A/C pulley bolts in a circular order. Do NOT tighten 3. Start the six remaining bolts, using Loctite 242 Blue, to draw the damper assembly onto the hub evenly. Using the T40 Plus bit, torque all bolts to 16 ft/lb in a criss cross order G. Install a new balancer bolt (ARP 234 2503) with Loctite 262 High Strength thread locker and torque to 240 ft/lb IV. Katech Manual Belt Tensioner Installation: A. Remove production tensioner by removing the two bolts holding it to the water pump B. Install Katech tensioner, without provided stanchions 1, using the new bolts (M10 x 1.5 x 40) and flat washers (M10). Apply Loctite 242 Medium Strength thread locker to bolts. C. Torque the lower bolt first to 37 ft/lb, then the upper to 37 ft/lb D. Install the belts. If installing an under drive balancer, shorter belts are required. See belt length table for proper belt dimensions. See figure 6 for belt routing
Figure 6 E. Using the square hole provided, insert a 3/8 torque wrench and apply 25 ft/lb of tension F. Tighten the tensioner locking bolt to 40 ft/lb G. Periodically check belt tension NOTES: 1 Corvette does not use stanchions
V. Belt Length Table LS6 with 10% under drive balancer and LS2 P/S pulley: A/C: 4 rib, 40.5 Accessory: 6 rib, 79 LS6 with 10% under drive balancer and LS6 P/S pulley: A/C: 4 rib, 40.5 Accessory: 6 rib, 78.5