Servo Bore Repair

The 4F27 Servo Bore Master Repair Kit NRL4F27 should be used to repair a transmission case with 2-4 band servo pin bore wear. The use of this kit will repair the 2-4 band servo pin bore back to OEM specifications.

1. Install the drill jig and the 6mm bolts.

2. Secure the 7/16” guide into the jig using the 3/8” allen screw.

3. NOTICE: Cutting oil must be used for lubrication. The use of substitutes, particularly ATF, may result in an over-sized bore. NOTICE: When reaming the servo bore do not push too hard on the reamer or exceed 500 RPM or an over-sized bore can occur. Ream out the bore using ample cutting oil and the 7/16” reamer.

4. Secure the 1/2” guide into the jig using the 3/8” allen screw.

5. NOTICE: Cutting oil must be used for lubrication. The use of substitutes, particularly ATF, may result in an over-sized bore. NOTICE: When reaming the servo bore do not push too hard on the reamer or exceed 500 RPM or an over-sized bore can occur. Ream out the bore using ample cutting oil and the 1/2” reamer.

6. Thoroughly clean the transaxle case to remove any metal debris.

7. Apply Loctite® 680 or equivalent to the outside bushing.

8. NOTE: Make sure the 1/2” reamer fits smoothly through the hole before installing the bushing.

   Align the hole drilled in the side of the bushing with the v shaped notch cast into the case.

9. Using the driver, drive the bushing in until the bushing chamfer is flush with the transaxle case.

10. NOTE: Check the pin finish for burs and coarseness.

    Insert the sizing pin into the bore, chamfer side first. Using a punch, drive the pin all the way through the bushing. Repeat as necessary.