SEAL-O-RING 9X7550 - Caterpillar

3406 ( 90U, 92U ),
3408 ( 67U, 28V ),
3412 ( 38S)Introduction
The 6N9829 Adapter Group gives the necessary parts to connect CT700, HT700, 5000 and 6000 Series Allison Transmissions to 3406 and 3408 truck engines and industrial engines with SAE #1 housings.This adapter group cannot be used on 3406 truck engines which are installed in the truck with the engine tilted, unless it has a 700 Series transmission, or on engines equiped with a Brakesaver.On all engines except 3406 Truck Engines 92U19776 and up, and 3408 Truck Engines 28V2048 and up, modifications must be made to the flywheel housing before the transmission can be installed on the engine.Reference: Service ManualInstallation
6N9829 Flywheel Adapter Group
1. Remove flywheel (1). Refer to Service Manual for removal instructions. 2. Remove starter (2). Refer to Service Manual for removal instructions. 3. Drill hole (A)1 in the flywheel housing to 23.8 mm (.94 in) diameter and make threads with a 1 in-14 tap in the hole.Use a steel chisel to damage the threads on the end of hole (A) toward the flywheel. This will not let the plug go inside the flywheel housing.If a 5000, 6000, or HT700 Series transmission is to be used, drill hole (B) to 11.13 mm (.44 in) diameter and 51.0 mm (2.0 in) deep.Hole (A) gives access to the transmission coupling bolts. Hole (B) is an oil drain hole from the flywheel housing to the transmission. Throughly clean the flywheel housing and holes (A) and (B).1This modification is not needed on truck engines that begin with the serial numbers that follow: 3406 - 92U19776 and 3408 - 28V2048.
Hole (B) must be made when a power takeoff is used with HT700 transmissions. Make sure plug (3) does not cause restrictions of hole (B).
4. Install 6N9667 Flywheel (4) on the crankshaft with 8L7951 Bolts. Use engine oil as a lubricant on the threads of bolts (5) before installation. Tighten bolts (5) to 270 N m (200 lb ft) torque. Install discs (6) and bolts (7), which are part of the transmission, on the flywheel.5. Heat 7N6114 Bushing (8) to 320°C (608°F) and install it on torque converter hub (9). Be sure the bushing bore is pressed tight against the end of the torque converter hub.6. Install 6N9918 Adapter (10) and gasket (11). Use Allison part number 5181902 Gasket (11) on each side of adapter (10). Turn the crankshaft so one of the holes (C) in flywheel (4) is