Usage:
When an 1100 Series or 3208 Truck Engine uses one of the above Allison Transmissions, either the Caterpillar 9L6918 or 9N2485 Transmission Mounting Group is used. The parts in these groups connect the tranmissions to the flywheel and flywheel housings. Two of the parts, the flywheel adapter and flywheel housing spacer, need to be checked for bore and face runout to prevent a failure of the flexible drive plate for the transmission and transmission bearing. See Illustration.
Too much runout will cause stress in the flexible drive plate and can cause a failure of the new plate or transmission bearing. Use the procedure that follows to measure runout.
If any of the four parts are not within specification, install a new part.
Bore and Face Runout of Flywheel and Flywheel Housing
The flywheel and flywheel housing have a direct effect on the bore runout and face runout of the adapter and spacer that connect to the transmission. So, first the bore runout and face runout of the flywheel and flywheel housing must both be measured to be sure they are correct. Use the procedures for these four items as shown in the Service Manual for 3208 Truck Engines, Form Number SEBR0506. Refer to the section "Specifications".
View of parts used to connect the Allison MT640 or MT650 Transmission. Too much bore runout or face runout of the adapter or spacer can cause a failure of the drive plate.
NOTE: On Page 23 of this section, add a note to read this article if there has been a failure of the drive plate or transmission torque converter bearing.
Bore and Face Runout of Transmission Adapter
First, install the transmission mounting parts. Tighten the adapter bolts to 55 ± 5 lb ft (74 ± 7 N·m.). Do not put washers on the bolts for the spacer around the flywheel housing.
Bore Runout of Adapter:
Measure the bore runout of the adapter in the same way as the flywheel bore for the pilot bearing. See above Service Manual. Maximum permissible runout of the adapter bore is .005" or 0.13 mm (worn out).
Face Runout of Adapter:
1. Fasten a dial indicator to the spacer with the point in contact with the face of the drive plate. (It is not necessary to make contact with the face of the adapter.)
2. Push or pull the crankshaft all the way to the rear to remove all end clearance. Do this each time before you take the reading from the dial indicator.
3. Adjust the dial indicator to show zero.
4. Turn the flywheel one complete revolution. Write the dial indicator reading (figure on the face) at five of the bolt locations, or every other bolt since there are 10 bolts.
5. The difference between the maximum and minimum readings must not be more than .003" (0.08 mm).
Bore and Face Runout of Spacer
Bore Runout of Spacer:
Measure the bore runout in the same way as bore runout for the flywheel housing. Use the same specifications; that is, the chart readings as shown in the Service Manual on Page 26 for the flywheel housing.
Face Runout of Spacer:
1. Fasten a dial indicator to the flywheel with the dial indicator in contact with the outer face of the spacer. See illustration.
2. Push or pull the crankshaft all the way to the rear to remove end clearance. Do this each time before you take the reading from the dial indicator.
3. Adjust dial indicator to show zero.
4. Turn flywheel one complete revolution. Write the dial indicator reading for every 1/4 turn (90°).
5. The difference between the maximum and minimum readings must not be more than .008" (0.21 mm).