A/T - KM170 Series Transaxle Case Gasket - Improvement

89mitsubishi05

SUBJECT:

KM170 SERIES TRANSAXLE CASE GASKET IMPROVEMENT
No: TSB-89-21-008

DATE: April, 1989

MODEL: Sigma, Galant, Cordia, Tredia, Mirage

NOTE: READ ENTIRE BULLETIN BEFORE ORDERING PARTS OR ATTEMPTING REPAIR PROCEDURES.

PURPOSE

From March 12, 1988 a new type of automatic transaxle case gasket has been used to provide better case sealing. This improved gasket can be used during assembly or when repairing a case gasket leak on the described older vehicles, This bulletin describes the gasket upgrade kits and their vehicle application, and procedures to be used when installing the new gasket on vehicles built prior to March 12, 1988.

AFFECTED VEHICLES

1988 Sigma produced before 3/12/88 All 1985-1987 Galant All Cordia All Tredia All Mirages built before 3/12/88

DETAILS OF CHANGE

To improve transaxle sealing, on the above mentioned date the main case gasket was changed in material from rubber impregnated fiber to rubber coated metal. A typical gasket location is shown. Because the rubber coated metal gasket is thicker than the rubber impregnated fiber one, a gasket upgrade kit is available. The kit includes a new gasket, an oil pump o-ring, a set of differential spacers, and a set of transfer shaft spacers. The spacers are provided because a new formula must be used for the differential end play and transfer shaft preload measurements.

Case Gasket Kit Component Parts:

SELECTING AN UPGRADE KIT

Three upgrade kits are available:

MD726244 - For KM171 built before 12/3/86.
- Rubber coated metal gasket with 13 case bolt holes, oil pump o-ring, selected differential and transfer shaft spacers.

MD726246 - For KM172 and KM175 built before 5/85.
- Rubber coated metal gasket with 13 case bolt holes, oil pump o-ring, selected differential and transfer shaft spacers.

MD730803 - For KM171 built between 12/3/86 and 3/12/88;
- For KM172 and KM175 built after 4/85 and before 3/12/88;
- For KM177 built before 3/12/88.
- Rubber coated metal gasket with 14 case bolt holes, oil pump o-ring, selected differential and, transfer shaft spacers.

NOTE: All KM170 seroes tranaxles belt since 3/12/88 have the rubber coated metal gasket factory installed; the gasket is available as a separate part. No upgrade kit ot special procedures are necessary as it is covered in the appropriate Service Manuals.

Use the following chart to choose the correct gasket upgrade kit, KM177 (88 Galant Sigma, 89 Sigma V6) Sigma produced before 3/12/88
Use: Kit MD730803

KM175 (85 through 87 Galant) Golont produced before 5/85
Use: Kit MD726246

Galant produced after 4/85 to end of production (old body style Galant).
Use: Kit MD730803

KM172 (84 through 87 Cordia/Tredia, 88 Cordia) Cordia/Tredia produced from 6/83 to 5/85
Use: Kit MD726246

Cordia/Tredia produced after 4/85 to end of production.
Use: Kit MD730803

KM171 (83 Cordia Tredia, 85 through 89 Mirage) Cordia/Tredia produced up to 6/83
Use: Kit MD726244

Mirage produced from 6/84 to 12/3/86
Use: Kit MD726244

Mirage produced from 12/3/86 to 3/12/88
Use: Kit MD730803

The chart on the following pages show the contents of each upgrade kit.
UPGRADE KIT SPACER MEASUREMENT FORMULA

Due to the change in gasket thickness when the rubber coated metal gasket is installed, the following procedures should be followed to arrive at the correct differential end play and transfer shaft preload (where applicable). All other transaxle assembly procedures remain the same.

NOTE: On various automatic transaxles the transfer shaft was supported either by a bearing on the end of the shaft ("end supported"), or by both bearings between the gears ("center supported"). End supported transfer shafts will need new spacers, center supported transfer shafts will not.

> When changing from rubber impregnated fiber gasket to rubber coated metal gasket is the only operation (as in repairing a case gasket leak) follow these steps:

1. Remove the converter housing and remove the spacers for both the differential and the transfer shaft (if end supported type transfer shaft).

2. Measure the thickness of the removed spacer(s). Select a spacer which is 0.1mm thicker than the measured thickness and install the new thicker spacer in the transaxle housing.

3. Clean the gasket mounting surface of the transmission case and coat it with silicone grease (not sealant). Install the new rubber coated metal gasket. Install the new o-ring to the oil pump. Reinstall the converter housing and tighten the bolts to specified torque

> When replacement of housing, shafts, differentials, gears or bearings will change the end play and preload specifications while changing to the new gasket, follow these steps:

1. Remove the converter housing and remove the spacers for both the differential and the transfer shaft (if end supported type transfer shaft).

2. Place solder approx. 10mm long and 3mm in diameter on each of the differential spacer and transfer shaft spacer mounting areas. Reinstall the converter housing without installing the transmission case gasket and tighten the bolts to specified torque.

3. Loosen the bolts, remove the converter housing and take out the solder

4. Figure the differential end play.
a. Using a micrometer, measure the thickness of the flattened differential solder.
b. Add together the solder thickness (T) as measured above, and the gasket thickness [0.38mm (0.015 in.)].
c. Then, for the differential end play add the end play range values to that sum to obtain the acceptable differential spacer thickness range

Standard differential case end play: 0 - 0.15mm (O - 0.006in.)

The formula for finding the correct spacer would be as follows:
Solder thickness + gasket thickness + 0mm (0in.) = smallest possible spacer Solder thickness + gasket thickness + 0.15mm (0.006in) = largest possible spacer.
d. Select a differential spacer that falls within this range.

5. Figure the transfer shaft preload (for vehicles with end supported transfer shafts only).
a. Using a micrometer, measure the thickness of the flattened transfer shaft solder.
b. Add together the solder thickness (T) as measured above, and the gasket thickness [0.38mm (0.015 in.)].
c. Then, for the transfer shaft preload subtract the preload range values from that sum to obtain the acceptable transfer shaft spacer thickness range

Standard transfer shaft preload: 0.1 - 0.15mm (0.004 - 0.006in.)

The formula for finding the correct spacer would be as follows:
Solder thickness + gasket thickness - 0.1mm (0.004in.) = smallest possible spacer. Solder thickness + gasket thickness - 0.15mm (0.006in.) = largest possible spacer.

d. Select transfer shaft spacer that falls within this range.

6. Install the selected spacers to the housing.

7. Clean the gasket mounting the transmission case and coat it with silicone grease (not sealant) install the new rubber coated metal gasket. Install the new o-ring to the oil pump. Reinstall the converter housing and tighten the bolts to specified torque.