Automatic Transmission - 4L80-E - Overhaul & Testing: Overhaul GMC Sierra 2500

LOWER TRANSMISSION ASSEMBLY

1. Remove oil pan, gasket and oil filter. Remove wiring harness. (Scheme 10)and see scheme 69. Remove accumulator assemblies. (Scheme 11)and see scheme 54. Remove TFP position switch (also referred to as pressure switch assembly). (Scheme 11)
2. Remove valve body bolts. Remove valve body assembly. Remove spacer plates and gasket. (Scheme 11) Remove check balls and PWM solenoid screen from case. (Scheme 12) Remove parking pawl and manual linkage. (Scheme 13)

Scheme 10

Scheme 11

Scheme 12

Scheme 13

Low-Reverse Band Apply Pin Selection

1. Remove servo covers and assemblies. (Scheme 11), see scheme 52 and see scheme 53.
2. Install Band Apply Selector Pin (J-21370-10) into servo bore. (Scheme 14) Mount Band Apply Pin Selector Gauge (J-38737) and selector pin on transmission. (Scheme 15) Apply 25 ft. lbs. (34 N.m) of torque to hex nut on gauge.
3. Note which step on selector pin lines up with top edge of apply pin gauge. Use this information to determine pin length. (Scheme 14)and (Scheme 16). Record length for reassembly. Pins are available in various lengths. (Scheme 16)

Scheme 14

Scheme 15

Scheme 16

OIL PUMP ASSEMBLY

Using puller, remove torque converter oil seal. (Scheme 17) Remove oil pump assembly-to-transmission case bolts. Using Removal Tool (J-37789-A), remove oil pump assembly. Remove gasket and thrust washer. (Scheme 56)

Scheme 17

OVERDRIVE ASSEMBLY & 4TH CLUTCH

Remove turbine shaft and overdrive carrier assembly. (Scheme 38) Using appropriate Torx wrench, remove 4th clutch housing bolt and discard. (Scheme 18) Remove 4th clutch assembly.

Scheme 18

Disassembly

Remove snap rings. Separate center support, output carrier, reaction carrier and parts of rear gear unit. (Scheme 19)

Using clutch spring compressor and adapter, compress intermediate clutch springs and remove snap ring. Separate center support from intermediate clutch assembly. (Scheme 20)

Reassembly

Using Piston Installer (J-21363), install intermediate piston to center support. (Scheme 24) Reassemble center support and rear gear unit. (Scheme 25)- (Scheme 28). Install NEW oil seal rings to center support. Soak in manufacturer-recommended transmission fluid prior to installation. See LUBRICATION in appropriate SERVICING article.

Scheme 19

Scheme 20

Scheme 21

Scheme 22

Scheme 23

Scheme 24

Scheme 25

Scheme 26

Scheme 27

Scheme 28

Scheme 29

1. Remove intermediate clutch roller snap ring. Remove intermediate clutch sprag assembly and race, as an assembly. Remove intermediate clutch roller outer race. Inspect intermediate clutch sprag assembly for damaged rollers, damaged cage or distorted springs.
2. Remove direct clutch backing plate snap ring and backing plate. Remove direct clutch plates. Remove direct clutch (waved) plate. Inspect direct clutch backing plate and direct clutch plates for cracks, wear, burned, flaking, scoring and pitting. Install (J-23327 and J-25018-A) spring compressor and adapter, onto direct clutch housing assembly. (Scheme 29) Compress direct clutch spring assembly.
3. Remove direct clutch spring snap ring, and remove spring assembly. Inspect direct clutch spring assembly for collapsed coils and distortion. Remove direct clutch piston assembly. Direct clutch piston assembly is reusable unless it is damaged. Inspect direct clutch piston assembly for damage and cracks. (Scheme 30) Remove direct clutch piston intermediate seal from direct clutch housing assembly.

Scheme 30

1. Remove direct clutch hub snap ring. (Scheme 31) Remove direct clutch hub. Remove direct clutch housing thrust washer (plastic). Remove forward clutch hub and thrust washer (bronze). Washer may stick to forward clutch housing assembly. Inspect direct clutch hub for spline wear, open lubrication holes or damaged clutch surface.
2. Remove forward clutch snap ring. Remove forward clutch spring assembly. Inspect forward clutch spring assembly for collapsed spring coils and distortion. Remove forward clutch piston assembly (forward clutch piston assembly is reusable if it is not damaged). Inspect forward clutch piston assembly for cracks. Inspect seal on forward clutch piston assembly for cuts, tears and nicks.
3. Remove forward clutch steel and composite plates. Remove forward clutch (waved) plate. Inspect forward clutch plates for burning, scoring, flaking, pitting or wear. Using Spring Compressor and Adapter (J-23327 and J-25018-A), compress forward clutch spring assembly. (Scheme 33) Forward clutch piston intermediate seal assembly is reusable. Replace forward clutch housing assembly if seal is worn or damaged. Inspect forward clutch piston intermediate seal assembly for cuts, tears and nicks. Inspect forward clutch housing assembly for wear, restricted or clogged oil passages, damaged thrust faces and free movement of checkball.

1. Install direct clutch piston intermediate seal onto direct clutch housing assembly with seal lip facing upward. Lubricate direct clutch piston assembly with manufacturer-recommended transmission fluid. See LUBRICATION in appropriate SERVICING article. Install Seal Installers (J-21362-1 and J-38732-1) onto direct clutch housing assembly. see scheme 27 Lubricate tools with manufacturer-recommended transmission fluid. Install direct clutch piston assembly into direct clutch housing assembly using a rotating motion until direct clutch piston assembly is seated. Install direct clutch spring assembly. Install Spring Compressor and Adapter (J-23327 and J-25018-A) onto direct clutch housing assembly. Compress direct clutch spring assembly. Install direct clutch spring snap ring.
2. Dip all direct clutch plates in manufacturer-recommended transmission fluid. Install direct clutch (waved) plate. Alternate clutch plates, starting with steel clutch plate (5 steel, 5 composite). (Scheme 31) Install direct clutch plates. Install direct clutch backing plate. Install direct clutch backing plate snap ring. Turn direct clutch housing assembly over. When installing intermediate clutch sprag assembly, lip of cage must face direct clutch housing assembly. Assemble intermediate clutch sprag assembly into intermediate clutch roller outer race. Install intermediate clutch roller outer race with grooved side facing up. Use a clockwise rotating motion to ease assembly.
3. Clutch roller outer race should not rotate counterclockwise. Install intermediate clutch roller retainer. If intermediate sprag clutch retainer ring has been removed, a NEW ring must be used. Install intermediate clutch roller retainer snap ring onto hub of direct clutch housing assembly. Use Snap Ring Installer (J-38695) in order to complete installation of intermediate clutch roller retainer retaining ring. see scheme 28 Rotate installer counterclockwise while pressing down.
4. To check forward clutch piston travel, place turbine shaft in a soft-jawed vice. Install forward clutch housing assembly onto turbine shaft. Install dial indicator. (Scheme 32) With index finger, close one side of fluid passage. Apply compressed air to other side, piston should travel.050-.172" (1.3-4.4 mm).

Scheme 31

Scheme 32

Scheme 33

1. Remove 4th clutch backing plate snap ring. Remove 4th clutch backing plate. Remove clutch plates. Install clutch housing onto Spring Compressor Adapter (J-38731-3). (Scheme 34) Using Spring Compressor (J-38882) and Adapter (J-23327), compress 4th clutch spring assembly. Remove 4th clutch spring snap ring.
2. Remove Spring compressor and adapter. Remove 4th clutch spring assembly. Remove 4th clutch piston. Remove 4th clutch piston inner seal. Remove 4th clutch piston outer seal from 4th clutch housing. Inspect 4th clutch orifice.

Scheme 34

1. Install 4th clutch piston inner seal onto 4th clutch piston. Install 4th clutch piston outer seal into 4th clutch housing. Seal lip should face bottom of piston when piston is installed. (Scheme 35) Place Seal Installer (J-38731-1) into 4th clutch housing through smaller opening. Place Seal Installer (J-38731-2) onto larger opening of 4th clutch piston. Place Seal Installer (J-38731-2) and 4th clutch piston onto Seal Installer (J-38731-3). (Scheme 35) Install 4th clutch piston into 4th clutch housing by gently pushing down on 4th clutch housing, until 4th clutch piston is through 4th clutch housing, exposing retainer ring groove.
2. Place 4th clutch spring assembly and 4th clutch spring retainer ring onto 4th clutch piston. Using Spring Compressor and Adapters (J-38882), (J-23327) and (J-38731-3), compress 4th clutch spring. (Scheme 34) Install 4th clutch spring retainer ring. Alternate clutch plates, starting with steel clutch plate (4 steel and 4 composite). (Scheme 36) Locate steel plate index notch opposite 4th clutch bolt hole. Install 4th clutch plates into 4th clutch housing. Install 4th clutch backing plate. Align notched tab in same direction as steel plate index notches. Install 4th clutch backing plate retainer ring.
3. Using a feeler gage, measure piston travel between 4th clutch backing plate and 4th clutch backing plate retainer ring. Piston travel should be.040-.100" (1.02-2.54 mm). (Scheme 37)

Scheme 35

Scheme 36

Scheme 37

Remove overrun clutch housing from overdrive carrier assembly. (Scheme 38) Disassemble overrun clutch. (Scheme 39)and (Scheme 46). Using clutch spring compressor and adapter, compress spring retainer and remove clutch piston. (Scheme 40) Disassemble overdrive assembly. (Scheme 46) If necessary, disassemble overdrive carrier assembly. (Scheme 45)

Scheme 38

Scheme 39

Scheme 40

1. Using Piston Seal Protector/Installer (J-38729), install piston into overrun clutch housing. (Scheme 41) Lubricate seal with manufacturer-recommended transmission fluid. See LUBRICATION in appropriate SERVICING article. Rotate overrun clutch to aid in assembly. (Scheme 39)
2. Install spring and compress, using compressor. (Scheme 40) Install snap ring. Install steel plate, and then alternate between composition plate and steel plate. Overrun clutch uses 3 steel and 3 composition plates. Install backing plate and snap ring. Using feeler gauge, ensure clearance between backing plate and snap ring is.033-.094" (.84-2.38 mm). (Scheme 43)
3. If necessary, reassemble overdrive carrier. (Scheme 44)- (Scheme 46). Install thrust washer into overdrive carrier. (Scheme 45) To complete reassembly, install turbine shaft and overdrive carrier to overrun clutch. (Scheme 38)and (Scheme 46). When turbine shaft and overdrive carrier are installed into transmission case, install thrust washer onto overrun clutch housing. Place a straightedge from oil pump mating surface to overrun clutch housing thrust washer. (Scheme 47) Both surfaces should be flush.

Scheme 41

Scheme 42

Scheme 43

Scheme 44

Scheme 45

Scheme 46

Scheme 47

Clean and air dry oil pump. Disassemble oil pump. (Scheme 48) Note location and direction of all components.

1. Reassemble oil pump. Prior to assembly, lubricate all gears with manufacturer-recommended transmission fluid. See LUBRICATION in appropriate SERVICING article. (Scheme 48) Install oil pump gears into pump body with identification dots facing upward. Using straightedge, measure gear clearance between oil pump gears and pump body. Clearance should be.0008-.0028" (.020-.071 mm).
2. Ensure pump body mating surface is flat. Install pump cover onto body. Install cover bolts and hand tighten bolts. Install Alignment Pin (J-25025-1) or pump bolt into pump. Install and tighten oil pump Alignment Band (J-21368). (Scheme 50) Tighten oil pump attaching bolts.
3. To install TCC enable valve, compress spring into oil pump body and insert a small rod into hole "A". (Scheme 49) Install spring retainer and then remove small rod.

Scheme 48

Scheme 49

Scheme 50

Thoroughly clean valve body and dry with compressed air. Cover bores when removing roll pins, as some valves are under pressure. Remove valves, springs and bushings and place them on a clean surface in order removed. (Scheme 51) Note location and direction of all components. Remove solenoids. Remove blind hole roll pins with drill bit. Remove servo pipe lip seals.

To reassemble valve body assembly, reverse disassembly procedure. (Scheme 51)

Scheme 51

TRANSMISSION REASSEMBLY

Note. All selective thrust washer measurements taken during disassembly must be rechecked at appropriate reassembly stage. To aid in transmission reassembly, refer to appropriate illustrations. see scheme 71- see scheme 73.

1. Install 4th clutch support (without clutch plates) into transmission case. Using No. 40 Torx wrench, install NEW 4th clutch support bolt. (Scheme 52) Tighten bolt to 17-19 ft. lbs. (23-26 N.m).
2. Remove turbine seal sizer from turbine shaft. Install turbine shaft and overdrive assembly. (Scheme 38) Ensure assembly is fully seated. Place a straight edge from oil pump mating surface to overrun clutch housing thrust washer. (Scheme 47) Both surfaces should be flush. Install 4th clutch plates, starting with steel plate, and then alternating with composition plate (4 steel and 4 composition). Install steel plates with narrow tang "V" notch at 1 o'clock position in housing. (Scheme 53) Install backing plate with flat side down. Install snap ring. (Scheme 54)

Scheme 52

Scheme 53

Scheme 54

1. Install Locating Pins (J-25025-1) at 12 o'clock and 5 o'clock positions. Install oil pump cover gasket. (Scheme 55) Install selective thrust washer. Using Handle (J-37789), install oil pump assembly. (Scheme 56) Ensure turbine shaft spins freely. Tighten oil pump bolts to 18 ft. lbs. (24 N.m).
2. Using dial indicator, check front unit end play. see scheme 10 Front unit end play should be.004-.022" (.10-.56 mm). If front unit end play is not correct, select proper size thrust washer. See «OVERRUN CLUTCH HOUSING THRUST WASHER IDENTIFICATION»(ref-130161-S35567189852001112800000) table. If necessary, remove oil pump assembly to change selective thrust washer.

OVERRUN CLUTCH HOUSING THRUST WASHER IDENTIFICATION

Scheme 55

Scheme 56

SERVO ASSEMBLIES

Note. Low-reverse and manual 2-1 bands and servos may be referred to as front and rear bands and servos.

Install selected low-reverse band apply pin. If necessary, check low-reverse band apply pin using Band Apply Selector Pin (J-21370-10) and Band Apply Pin Gauge (J-38737). See SERVO ASSEMBLIES under TRANSMISSION DISASSEMBLY. Install manual 2-1 and low-reverse servo assemblies. see scheme 52and see scheme 53.

1. Install parking pawl and manual linkage. (Scheme 13) Install check balls in case. Check ball No. 2 is only used on some models. (Scheme 12) Assemble and install accumulator assembly. see scheme 54 Tighten accumulator assembly bolts in sequence. see scheme 68
2. Install valve body assembly and TFP position switch. Tighten TFP position switch bolts to 97 INCH lbs. (11 N.m) in alphabetical sequence. see scheme 69 Tighten valve body bolts in a spiral pattern in numerical order. see scheme 70 Install lube pipe and wiring harness. see scheme 69 Install oil pan and oil filter. (Scheme 10)