PDF Automatic Transmission - 48re - Центр Трансмиссий

21 - 130 AUTOMATIC TRANSMISSION - 48RE

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AUTOMATIC TRANSMISSION - 48RE

TABLE OF CONTENTS

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AUTOMATIC TRANSMISSION - 48RE DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . 132 OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . 134 DIAGNOSIS AND TESTING DIAGNOSIS AND TESTING - AUTOMATIC TRANSMISSION . . . . . . . . . . . . . . . . . . . . . 140 DIAGNOSIS AND TESTING - PRELIMINARY . 140 DIAGNOSIS AND TESTING - ROAD TESTING . . . . . . . . . . . . . . . . . . . . . . . . . . . 140 DIAGNOSIS AND TESTING - HYDRAULIC PRESSURE TEST . . . . . . . . . . . . . . . . . . . . 141 DIAGNOSIS AND TESTING - AIR TESTING TRANSMISSION CLUTCH AND BAND OPERATION . . . . . . . . . . . . . . . . . . . . . . . . 144 DIAGNOSIS AND TESTING - CONVERTER HOUSING FLUID LEAK . . . . . . . . . . . . . . . . 144 DIAGNOSIS AND TESTING - DIAGNOSIS CHARTS . . . . . . . . . . . . . . . . . . . . . . . . . . . 145 STANDARD PROCEDURE - ALUMINUM THREAD REPAIR . . . . . . . . . . . . . . . . . . . . . 158 REMOVAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158 DISASSEMBLY . . . . . . . . . . . . . . . . . . . . . . . . 160 CLEANING . . . . . . . . . . . . . . . . . . . . . . . . . . . 166 INSPECTION . . . . . . . . . . . . . . . . . . . . . . . . . 166 ASSEMBLY . . . . . . . . . . . . . . . . . . . . . . . . . . . 166 INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . 174 SCHEMATICS AND DIAGRAMS HYDRAULIC SCHEMATICS . . . . . . . . . . . . . 176 SPECIFICATIONS TRANSMISSION . . . . . . . . . . . . . . . . . . . . . 189 SPECIAL TOOLS RE TRANSMISSION . . . . . . . . . . . . . . . . . . 191

ACCUMULATOR DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . 193 OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . 193 INSPECTION . . . . . . . . . . . . . . . . . . . . . . . . . 194

BANDS DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . 194 OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . 194 ADJUSTMENTS ADJUSTMENT - BANDS . . . . . . . . . . . . . . . 195

BRAKE TRANSMISSION SHIFT INTERLOCK SYSTEM DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . 196 OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . 196 DIAGNOSIS AND TESTING - BRAKE TRANSMISSION SHIFT INTERLOCK . . . . . . 196 ADJUSTMENTS - BRAKE TRANSMISSION SHIFT INTERLOCK . . . . . . . . . . . . . . . . . . . 196

ELECTRONIC GOVERNOR DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . 197 OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . 198 REMOVAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199 INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . 200

EXTENSION HOUSING SEAL REMOVAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201 INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . 201

FLUID AND FILTER DIAGNOSIS AND TESTING DIAGNOSIS AND TESTING - EFFECTS OF INCORRECT FLUID LEVEL . . . . . . . . . . . . . 201 DIAGNOSIS AND TESTING - CAUSES OF BURNT FLUID . . . . . . . . . . . . . . . . . . . . . . . 201 DIAGNOSIS AND TESTING - FLUID CONTAMINATION . . . . . . . . . . . . . . . . . . . . 202 STANDARD PROCEDURE STANDARD PROCEDURE - FLUID LEVEL CHECK . . . . . . . . . . . . . . . . . . . . . . . . . . . . 202 STANDARD PROCEDURE - FLUID AND FILTER REPLACEMENT . . . . . . . . . . . . . . . 203 STANDARD PROCEDURE - TRANSMISSION FILL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204

FRONT CLUTCH DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . 205 OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . 205 DISASSEMBLY . . . . . . . . . . . . . . . . . . . . . . . . 205 INSPECTION . . . . . . . . . . . . . . . . . . . . . . . . . 206 ASSEMBLY . . . . . . . . . . . . . . . . . . . . . . . . . . . 207

FRONT SERVO DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . 208 OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . 208 DISASSEMBLY . . . . . . . . . . . . . . . . . . . . . . . . 209 CLEANING . . . . . . . . . . . . . . . . . . . . . . . . . . . 209 INSPECTION . . . . . . . . . . . . . . . . . . . . . . . . . 209 ASSEMBLY . . . . . . . . . . . . . . . . . . . . . . . . . . . 209

GEARSHIFT CABLE DIAGNOSIS AND TESTING - GEARSHIFT CABLE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210 REMOVAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210 INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . 211 ADJUSTMENTS GEARSHIFT CABLE . . . . . . . . . . . . . . . . . . 212

OIL PUMP DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . 213 OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . 213 DISASSEMBLY . . . . . . . . . . . . . . . . . . . . . . . . 214 CLEANING . . . . . . . . . . . . . . . . . . . . . . . . . . . 214 INSPECTION . . . . . . . . . . . . . . . . . . . . . . . . . 214 ASSEMBLY . . . . . . . . . . . . . . . . . . . . . . . . . . . 214

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AUTOMATIC TRANSMISSION - 48RE 21 - 131

OUTPUT SHAFT FRONT BEARING REMOVAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . 216 INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . 216

OUTPUT SHAFT REAR BEARING REMOVAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . 216 INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . 217

OVERDRIVE CLUTCH DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . 217 OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . 217

OVERDRIVE UNIT REMOVAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218 DISASSEMBLY . . . . . . . . . . . . . . . . . . . . . . . . 218 CLEANING . . . . . . . . . . . . . . . . . . . . . . . . . . . 225 INSPECTION . . . . . . . . . . . . . . . . . . . . . . . . . 225 ASSEMBLY . . . . . . . . . . . . . . . . . . . . . . . . . . . 226 INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . 235

OVERRUNNING CLUTCH CAM/OVERDRIVE PISTON RETAINER DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . 236 OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . 236 DISASSEMBLY . . . . . . . . . . . . . . . . . . . . . . . . 236 CLEANING . . . . . . . . . . . . . . . . . . . . . . . . . . . 236 INSPECTION . . . . . . . . . . . . . . . . . . . . . . . . . 237 ASSEMBLY . . . . . . . . . . . . . . . . . . . . . . . . . . . 237

PISTONS DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . 239 OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . 239

PLANETARY GEARTRAIN/OUTPUT SHAFT DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . 241 OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . 241 DISASSEMBLY . . . . . . . . . . . . . . . . . . . . . . . . 242 INSPECTION . . . . . . . . . . . . . . . . . . . . . . . . . 243 ASSEMBLY . . . . . . . . . . . . . . . . . . . . . . . . . . . 244

REAR CLUTCH DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . 247 OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . 248 DISASSEMBLY . . . . . . . . . . . . . . . . . . . . . . . . 248 CLEANING . . . . . . . . . . . . . . . . . . . . . . . . . . . 248 INSPECTION . . . . . . . . . . . . . . . . . . . . . . . . . 248 ASSEMBLY . . . . . . . . . . . . . . . . . . . . . . . . . . . 249

REAR SERVO DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . 251 OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . 251 DISASSEMBLY . . . . . . . . . . . . . . . . . . . . . . . . 251 CLEANING . . . . . . . . . . . . . . . . . . . . . . . . . . . 251 ASSEMBLY . . . . . . . . . . . . . . . . . . . . . . . . . . . 251

SHIFT MECHANISM DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . 252

OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . 252 SOLENOID

DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . 252 OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . 252 SPEED SENSOR DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . 253 OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . 253 THROTTLE VALVE CABLE DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . 253 ADJUSTMENTS - THROTTLE VALVE CABLE . 254 TORQUE CONVERTER DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . 255 OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . 259 REMOVAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260 INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . 260 TORQUE CONVERTER DRAINBACK VALVE DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . 261 OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . 261 STANDARD PROCEDURE - TORQUE

CONVERTER DRAINBACK VALVE . . . . . . . . 261 TOW/HAUL OVERDRIVE SWITCH

DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . 261 OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . 262 DIAGNOSIS AND TESTING - OVERDRIVE

ELECTRICAL CONTROLS . . . . . . . . . . . . . . 262 REMOVAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262 INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . 262 TRANSMISSION RANGE SENSOR DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . 263 OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . 263 DIAGNOSIS AND TESTING - TRANSMISSION

RANGE SENSOR (TRS) . . . . . . . . . . . . . . . . 264 REMOVAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265 INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . 266 TRANSMISSION TEMPERATURE SENSOR DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . 267 OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . 267 VALVE BODY DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . 267 OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . 272 REMOVAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . 286 DISASSEMBLY . . . . . . . . . . . . . . . . . . . . . . . . 287 CLEANING . . . . . . . . . . . . . . . . . . . . . . . . . . . 298 INSPECTION . . . . . . . . . . . . . . . . . . . . . . . . . 298 ASSEMBLY . . . . . . . . . . . . . . . . . . . . . . . . . . . 299 INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . 309 ADJUSTMENTS - VALVE BODY . . . . . . . . . . . 310

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AUTOMATIC TRANSMISSION 48RE

DESCRIPTION

The 48RE (Fig. 1) is a four speed fully automatic transmissions with an electronic governor. The 48RE is equipped with a lock-up clutch in the torque converter. First through third gear ranges are provided by the clutches, bands, overrunning clutch, and planetary gear sets in the transmission. Fourth gear range is provided by the overdrive unit that contains an overdrive clutch, direct clutch, planetary gear set, and overrunning clutch.

The transmission contains a front, rear, and direct clutch which function as the input driving components. It also contains the kickdown (front) and the

low/reverse (rear) bands which, along with the overrunning clutch and overdrive clutch, serve as the holding components. The driving and holding components combine to select the necessary planetary gear components, in the front, rear, or overdrive planetary gear set, transfer the engine power from the input shaft through to the output shaft.

The valve body is mounted to the lower side of the transmission and contains the valves to control pressure regulation, fluid flow control, and clutch/band application. The oil pump is mounted at the front of the transmission and is driven by the torque converter hub. The pump supplies the oil pressure necessary for clutch/band actuation and transmission lubrication.

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AUTOMATIC TRANSMISSION - 48RE (Continued)

Fig. 1 48RE Transmission

21 - 134 AUTOMATIC TRANSMISSION - 48RE AUTOMATIC TRANSMISSION - 48RE (Continued)

1 - TORQUE CONVERTER 2 - INPUT SHAFT 3 - OIL PUMP 4 - FRONT BAND 5 - FRONT CLUTCH 6 - REAR CLUTCH 7 - PLANETARIES 8 - REAR BAND 9 - OVERRUNNING CLUTCH

10 - OVERDRIVE CLUTCH 11 - DIRECT CLUTCH 12 - PLANETARY GEAR 13 - INTERMEDIATE SHAFT 14 - OVERDRIVE OVERRUNNING CLUTCH 15 - DIRECT CLUTCH SPRING 16 - OVERDRIVE PISTON RETAINER 17 - OIL PAN 18 - VALVE BODY

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IDENTIFICATION

Transmission identification numbers are stamped on the left side of the case just above the oil pan gasket surface (Fig. 2). Refer to this information when ordering replacement parts.

Fig. 2 Transmission Part Number And Serial Number Location

1 - PART NUMBER 2 - BUILD DATE 3 - SERIAL NUMBER

GEAR RATIOS

The 48RE gear ratios are: 1st . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.45:1 2nd . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.45:1 3rd . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.00:1 4th . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.69:1 Rev. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.20:1

OPERATION

The application of each driving or holding component is controlled by the valve body based upon the manual lever position, throttle pressure, and governor pressure. The governor pressure is a variable pressure input to the valve body and is one of the signals that a shift is necessary. First through fourth gear are obtained by selectively applying and releasing the different clutches and bands. Engine power is thereby routed to the various planetary gear assemblies which combine with the overrunning clutch assemblies to generate the different gear ratios. The torque converter clutch is hydraulically applied and is released when fluid is vented from the hydraulic circuit by the torque converter control (TCC) solenoid on the valve body. The torque converter clutch is controlled by the Powertrain Control Module (PCM). The torque converter clutch engages in fourth gear, and in third gear under various conditions, such as when the O/D switch is OFF, when the vehicle is cruising on a level surface after the vehicle has warmed up. The torque converter clutch can also be engaged in the MANUAL SECOND gear position if high transmission temperatures are sensed by the PCM. The torque converter clutch will disengage momentarily when an increase in engine load is sensed by the PCM, such as when the vehicle begins to go uphill or the throttle pressure is increased. The torque converter clutch feature increases fuel economy and reduces the transmission fluid temperature.

Since the overdrive clutch is applied in fourth gear only and the direct clutch is applied in all ranges except fourth gear, the transmission operation for park, neutral, and first through third gear will be described first. Once these powerflows are described, the third to fourth shift sequence will be described.

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AUTOMATIC TRANSMISSION - 48RE (Continued)

PARK POWERFLOW

As the engine is running and the crankshaft is rotating, the flexplate and torque converter, which are also bolted to it, are all rotating in a clockwise direction as viewed from the front of the engine. The notched hub of the torque converter is connected to the oil pump's internal gear, supplying the transmission with oil pressure. As the converter turns, it turns the input shaft in a clockwise direction. As the input shaft is rotating, the front clutch hub-rear clutch retainer and all their associated parts are also rotating, all being directly connected to the input shaft. The power flow from the engine through the front clutch hub and rear clutch retainer stops at the rear clutch retainer. Therefore, no power flow to the output shaft occurs because no clutches are applied. The only mechanism in use at this time is the parking sprag (Fig. 3), which locks the parking gear on the output shaft to the transmission case.

NEUTRAL POWERFLOW

With the gear selector in the NEUTRAL position (Fig. 4), the power flow of the transmission is essentially the same as in the park position. The only operational difference is that the parking sprag has been disengaged, unlocking the output shaft from the transmission case and allowing it to move freely.

Fig. 3 Park Powerflow

1 - PAWL ENGAGED FOR PARK 2 - PARK SPRAG 3 - OUTPUT SHAFT

Fig. 4 Neutral Powerflow

1 - PAWL DISENGAGED FOR NEUTRAL 2 - PARK SPRAG 3 - OUTPUT SHAFT 4 - CAM 5 - PAWL

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AUTOMATIC TRANSMISSION - 48RE (Continued)

REVERSE POWERFLOW

When the gear selector is moved into the REVERSE position (Fig. 5), the front clutch and the rear band are applied. With the application of the front clutch, engine torque is applied to the sun gear, turning it in a clockwise direction. The clockwise rotation of the sun gear causes the rear planet pinions to rotate against engine rotation in a counterclockwise direction. The rear band is holding the low reverse drum, which is splined to the rear carrier. Since the rear carrier is being held, the torque from

the planet pinions is transferred to the rear annulus gear, which is splined to the output shaft. The output shaft in turn rotates with the annulus gear in a counterclockwise direction giving a reverse gear output. The entire transmission of torque is applied to the rear planetary gearset only. Although there is torque input to the front gearset through the sun gear, no other member of the gearset is being held. During the entire reverse stage of operation, the front planetary gears are in an idling condition.

1 - FRONT CLUTCH ENGAGED 2 - OUTPUT SHAFT 3 - LOW/REVERSE BAND APPLIED 4 - INPUT SHAFT

Fig. 5 Reverse Powerflow

5 - OUTPUT SHAFT 6 - INPUT SHAFT 7 - FRONT CLUTCH ENGAGED 8 - LOW/REVERSE BAND APPLIED

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AUTOMATIC TRANSMISSION - 48RE (Continued)

FIRST GEAR POWERFLOW

When the gearshift lever is moved into the DRIVE position the transmission goes into first gear (Fig. 6). As soon as the transmission is shifted from PARK or NEUTRAL to DRIVE, the rear clutch applies, applying the rear clutch pack to the front annulus gear. Engine torque is now applied to the front annulus gear turning it in a clockwise direction. With the front annulus gear turning in a clockwise direction, it causes the front planets to turn in a clockwise direction. The rotation of the front planets cause the sun to revolve in a counterclockwise direction. The sun gear now transfers its counterclockwise rotation to the rear planets which rotate back in a clockwise

direction. With the rear annulus gear stationary, the rear planet rotation on the annulus gear causes the rear planet carrier to revolve in a counterclockwise direction. The rear planet carrier is splined into the low-reverse drum, and the low reverse drum is splined to the inner race of the over-running clutch. With the over-running clutch locked, the planet carrier is held, and the resulting torque provided by the planet pinions is transferred to the rear annulus gear. The rear annulus gear is splined to the output shaft and rotated along with it (clockwise) in an underdrive gear reduction mode.

1 - OUTPUT SHAFT 2 - OVER-RUNNING CLUTCH HOLDING 3 - REAR CLUTCH APPLIED 4 - OUTPUT SHAFT

Fig. 6 First Gear Powerflow

5 - OVER-RUNNING CLUTCH HOLDING 6 - INPUT SHAFT 7 - REAR CLUTCH APPLIED 8 - INPUT SHAFT

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