Gaging Procedure

Tools Required:
J 8001 Dial Indicator Set
J 9397 Compressing Fixture
J 9402 Piston Assembly Tray
J 9661-01 Feeler Tension Gage Set

Two gaging procedures provide the running tolerances. The first procedure determines the size shoe discs to provide at each piston a 0.041-0.061 mm (0.0016-0.0024-inch) total preload between the seats and the axial plate at the tightest place through the 360 degree rotation of the axial plate. The bronze shoe discs are available in 0.013 mm (0.0005-inch) variations.

The second procedure, performed at the rear shaft thrust bearing and race pack, provides 0.064-0.077 mm (0.0025-0.0030-inch) preload between the hub surfaces of the axial plate, and the front and rear hubs of the cylinder. Fourteen steel thrust races, including a basic "zero" race, are available in 0.013 mm (0.0005-inch) increments. Use J 9661-01 for gaging the shoe disc size. Use J 8001 to determine the thrust race size.

1. Measure the clearance between the rear ball of the No.1 piston and axial plate in the following manner:
a. Select a combination of oiled feeler gage leaves to fit snugly between the ball and axial plate.
b. Attach J 9661-01 to the feeler gage. A distributor point checking scale may be used.

Gaging The Rear Piston Ball:

c. Pull on the spring scale to slide the feeler gage stock out from between the ball and axial plate. Note the reading on spring scale as the feeler gage is sliding out. The reading should be between 1.1 and 2.2 N (4 and 8 ounces).
d. If the reading in step C above is under 1.1 N (4 ounces) or over 2.2 N (8 ounces), reduce or increase the thickness of the feeler gage leaves and repeat steps a through c to obtain a reading of 1.1 N to 2.2 N (4 to 8 ounces). Record the clearance between the ball and axial plate that results in the 1.1 N to 2.2 N (4 to 8 ounces) pull on the spring scale.

2. Rotate the shaft 120 degrees and repeat for the No. 2 cylinder.
^ If the shaft is hard to rotate, install the shaft nut onto the shaft and turn the shaft with a wrench.

3. Rotate the shaft another 120 degrees and repeat for cylinder No.3.





4. Select a numbered shoe disc corresponding to the minimum feeler gage reading recorded in the three checks:
^ Place the shoe discs in J 9402 compartment with the discs corresponding to piston No. 1 and the rear ball pocket position.

Service Shoes And Thrust Washers:

^ Shoe discs are available in 0.013 mm (0.0005-inch) variations. Eleven sizes are available for field servicing. Shoe discs are marked with the shoe size which corresponds to the last three digits of the part number.
^ After selecting the shoe size, the matched combination of the shoe disc to the rear ball spherical cavity in the piston must be kept in the proper relationship during disassembly after performing the gaging operation and the final assembly of the internal mechanism.

5. Repeat the gaging procedure for pistons Nos. 2 and 3.
6. Mount a dial indicator on the edge of J 9397 with J 8001.

Gaging The Rear Thrust Plate:

7. Position the dial indicator on the rear of the shaft (39) and adjust to zero.

Checking The Piston And Shaft End Play:

^ From the bottom, apply full hand force at the end of the shaft a few times before reading the clearance. This will squeeze the oil out from between the mating parts. Now push upward and record the measurement. Dial indicator increments are 0.03 mm (0.001-inch); estimate the reading to the nearest 0.013 (0.0005-inch). An alternate method is to use J 9661-01 in selecting a suitable feeler gage leaf until the result is a 1.1 N to 2.2 N (4 to 8 ounces) pull on the scale between the rear thrust bearing and upper (or outer rear) thrust race.
If the pull is just less than 1.1 N (4 ounces), add 0.013 mm (0.0005-inch) to the thickness of the feeler stock used to measure the clearance. If the pull on the scale reads just over 2.2 N (8 ounces), then subtract 0.013 mm (0.0005-inch) from the thickness of the feeler stock.

7. For either method used, select a thrust race with a "number" corresponding to TWO (2) FULL SIZES LARGER than the dial indicator or feeler gage measurement of the amount of end play shown. (If measurement is 0.18 mm (0.007-inch), select a No.9 or 090 race).
Fifteen thrust races are provided in increments of 0.013 mm (0.0005-inch) thickness and one ZERO gage thickness providing a total of 16 sizes. The thrust race "number" corresponds to the last three digits of the part number Refer to Service Shoes & Thrust Washers chart.

8. Remove the nuts from the top plate of the J 9397.
9. Remove the top plate.
10. Separate the cylinder halves while the unit is in the fixture.
^ If necessary, use a wood block and a mallet.

11. Remove the rear cylinder half; remove one piston at a time from the axial plate and front cylinder half.
^ Do not lose the relationship of the front ball and shoe disc and rear ball.
^ Transfer each of the piston, ball and shoe disc sets to J 9402.

12. Remove the rear outer "zero" thrust race (it will be on top) from the shaft and install the thrust race just selected in Steps 6 and 7 that is in J 9402.
^ The "zero" thrust race may be put aside for reuse in additional gaging or rebuilding operations.