A/T - 440T4/F7 No Third Gear

SIL 19-89 (May)

1984-89 THM 440-T4/Hydra-matic 4T60
1987-89 THM F-7

SUBJECT:
No 3rd Gear - New Thrust Bearing For Distressed 3rd Roller Clutch and/or Input Thrust Washer







Bulletin Covers: (Figures 2 and 3)

A new Thrust Bearing Assembly (803) replaces the Input Shaft/Sun Gear Thrust Washer (628) and Lock Up Sleeve (690). The Thrust Bearing Assembly will minimize friction. Under some operation conditions, friction may result in excess heat damaging the Thrust Washer (628) and melting the plastic shoes of the 3rd Roller Clutch Assembly (644). If the plastic shoes melt, the rollers will not be held and the loose rollers will cause failure of the 3rd Roller Clutch (causing no 3rd Gear). For this change to be implemented the following parts were modified:

- Input Housing and Shaft Assembly (626) mating surface for the new Thrust Bearing (803) has been reduced 0.9mm (0.03") to make room for the new bearing. The Lock Up Sleeve is not needed anymore and is eliminated.

- The 3rd Roller Clutch Dam (696) I.D. has been opened up 6.5mm (0.26") wider and the lip eliminated to accommodate the new Thrust Bearing Assembly (803).

- The 3rd Roller Clutch Cam (643) has been made 0.96mm (0.04") thinner to accommodate the increased thickness of the new Thrust Bearing Assembly (803). The edge of the 3rd Roller Clutch Cam (643) that faces the new Thrust Bearing Assembly (803) now has a squared off edge. This is for more contact area with the rollers since the Cam is now thinner but the rollers stayed the same length.

SERVICE ACTION:

For 1986 and prior model years, use the new Input Housing and Shaft Assembly package for distressed 3rd Roller Clutch and/or Input Thrust Washer concerns, otherwise replace with previous parts that will still be available.

For a distressed 3rd Clutch Assembly, locate and correct the cause of the concern. This could be leaking Input Shaft Oil Seal Ring(s) or a dislodged Shaft/3rd Clutch Spring Return Snap Ring (639) causing a dragging 3rd clutch pack. Replace the Snap Ring with a new one if it was found to be dislodged.

Also inspect the Input Clutch Sprag Assembly (653) and Input Sprag Outer Race (654) for damage. This damage could be caused by the customer putting the transaxle in Drive 3 (D2) after a 3rd Roller Clutch Assembly (644) failure (no 3rd gear) so the car will travel at highway speeds causing excessive overrun speeds for the Sprag.

IMPORTANT
Perform the input Housing End Play Measurement when installing the new parts to assure proper end play.




Reference Figure 4 for proper assembly of critical lubrication passages for the Sprag and Roller Clutch.

DATE OF PRODUCTION CHANGE:

The new Thrust Bearing Assembly and associated components was used in production on all models starting November 28, 1988 2nd shift (Julian Date 333).




SERVICE PARTS INFORMATION:

IMPORTANT
DO NOT interchange parts from the two packages. The parts look similar but have different dimensions.

SERVICE MANUAL REFERENCE:

Refer to the appropriate Service Information Manual 7A1 Automatic Transaxle on Car Service and THM 440-T4/Hydra-matic 4T60 or THM F-7 Automatic Transaxle Unit Repair Section.