Automatic Transmission Overhaul & Testing - 4L60-E: Diagnosis Chevrolet Suburban C2500

TROUBLE SHOOTING

Note. For electrical trouble shooting, see procedures in AUTO TRANS DIAGNOSIS - 4L60-E article. For additional trouble shooting, see TECHNICAL SERVICE BULLETINS. For elements in use at specified selector lever positions, see CLUTCH & BAND APPLICATION CHART under CLUTCH & BAND APPLICATION.

STALL SPEED TEST

1. Torque converter whine is usually noticed when vehicle is stopped and transmission is in Reverse or Drive. Whine will increase when engine RPM is increased and will stop when vehicle is moving or when torque converter clutch is applied. Stall test is to ensure whine is coming from torque converter.
2. Start engine, and allow it to reach normal operating temperature. Apply parking and service brakes. Put transmission in Drive. Depress accelerator to approximately 1200 RPM for less than 6 seconds. DO NOT depress accelerator for more than 6 seconds or transmission damage may occur. Torque converter noise will increase under this load.

Note. Torque converter whine should not be confused with pump whine, which is usually noticeable in Park, Neutral and all other gear ranges. Pump whine will vary with pressure.

ELECTRONIC SELF-DIAGNOSTICS

Note. See AUTO TRANS DIAGNOSIS - 4L60-E article in the AUTOMATIC TRANSMISSIONS section.

ROAD TEST

Note. Shift speed charts reference throttle position angle instead of minimum or wide open throttle position. This measurement is more accurate. A scan tool should be used to monitor throttle position angle. For transmission model code, refer to metal identification tag attached to transmission. Shift speed information for 3.8L is not available.

HYDRAULIC PRESSURE TEST

1. Before performing hydraulic pressure test, check fluid level and condition. Check manual control linkages for correct adjustment, and ensure engine is properly tuned.
2. Connect scan tool to Data Link Connector (DLC). Apply parking brake and start engine. Check for stored trouble codes. If trouble codes are present, diagnose as necessary. See «AUTO TRANS DIAGNOSIS - 4L60-E»(ref-55998) article. Turn engine off. Connect oil pressure gauge to line pressure test port. (Scheme 3)
3. Start engine and warm to normal operating temperature. With vehicle in Reverse, line pressure should be 64-324 psi (441-2234 kPa). With vehicle in Park, Neutral or Drive, line pressure should be 55-189 psi (379-1303 kPa).
4. Shift transaxle into Park. Access Pressure Control Solenoid (PCS) test on scan tool. Increase DESIRED PCS in 0.1 amp increments and read corresponding line pressure on oil pressure gauge. Allow pressure to stabilize for 5 seconds after each current change. Compare readings to «LINE PRESSURE SPECIFICATIONS»(ref-25521-S22327415012001011700000). If pressure readings are not as specified, and no trouble codes are present, internal malfunction exists. See «TROUBLE SHOOTING»(ref-25521-S24431064452001011700000).

Note. Scan tool is only able to control pressure control solenoid in Park and Neutral with vehicle stopped. This protects clutches from extremely high or low pressures in Reverse and Drive.

LINE PRESSURE SPECIFICATIONS

Scheme 3

Cleaning & Inspection

Clean transmission case and dry with compressed air. Inspect case assembly for damage, cracks and damaged bolt hole threads. Inspect valve body surface for flatness and land damage. Check case oil passages for restrictions and blockage. Inspect case internal clutch plate lugs for damage and wear. Inspect servo and accumulator bores for damage. Inspect all snap ring grooves for damage.

Clean all parts and dry with compressed air. Inspect 1-2 and 3-4 accumulator parts for damage to pistons or housing. Inspect for flatness and condition of accumulator, oil passage plate and gasket. Inspect wiring harness leads and connectors for damage. Inspect speed sensor rotor teeth for damage and distortion.

1. Clean all parts and dry with compressed air. Inspect reaction and input carriers for pinion gear damage, excessive wear and improper staking of pinion pins. Inspect carrier bearings for heat damage, flatness and roller condition. Place output shaft sleeve inside reaction carrier and input carrier.
2. Rotate sleeve and note smoothness of bearing operation. Replace carrier assembly if roughness is felt. Check pinion gear end play on reaction and input carriers.
3. Pinion gear end play should be .008-.024" (.20-.61 mm). Inspect internal reaction gear and support for cracks and damaged splines. Inspect low-reverse clutch plates for wear and signs of excessive heat.
4. Inspect low-reverse clutch piston for roughness or damage in seal ring area. Inspect retainer ring and spring assembly for damage. Inspect sun and internal gears and supports for spline and bushing wear and damage. Replace damaged parts as necessary.

Inspection

Inspect all plates for damage, distortion, flatness and burred edges. Inspect spring retainer for distortion. Check piston for deformation or damage. Inspect clutch housing bushings for wear. Inspect clutch housing for dishing. Replace worn or damaged parts as necessary.

Note. Soak clutch plates in ATF before installation.

Disassembly & Inspection

Remove inner race and snap ring. Remove roller clutch assembly. Check inner race for damage and surface finish. see scheme 20 Inspect roller and springs for damage and distortion. Inspect support for loose cam, cracks and damaged surface finish. Replace damaged parts as necessary.

1. Inspect sprag assembly for weak or damaged springs and retainers and worn rollers. Inspect overrun clutch hub for spline damage, excessive wear and open oil passages. Inspect retainer and race for spline damage, surface wear and damaged ring grooves.
2. Replace sprag assembly if damaged. Inspect forward clutch race for spline damage, excessive wear and open oil passages. Inspect input shaft and housing for spline damage, wear and open feed passages.
3. Inspect 3 sealing balls located in rear of turbine shaft for tightness. Turbine shaft contains one open lubrication hole. Ensure orifice plug is installed. Inspect turbine shaft seal areas for roughness and burrs.
4. Inspect check ball located in input housing for free operation. Inspect pistons for wear, damage and porosity. Inspect spring assemblies for damage and distortion.
5. Inspect steel and composition plates for damage. Inspect snap rings for distortion and damage. Check backing plates for flatness and distortion. Inspect clutch apply rings for distortion and damaged tangs.
6. Inspect forward clutch housing check ball for proper operation (if equipped). Inspect housing for cracks and damage in seal areas. Inspect bearings for excessive wear, flatness, damage and flat rollers.

Scheme 4

1. For input housing check ball replacement, drive retainer and ball assembly from housing using 1/4" diameter drift. Install NEW check ball assembly using 1/4" drift. Check ball assembly should seat on housing shoulder. Assemble forward clutch sprag assembly.
2. Install sprag assembly in forward clutch race. Notches located in sprag must face upward. (Scheme 4) Install snap ring on sprag retainer and race. Snap ring flange must face away from retainer and race.
3. Hold forward clutch race in left hand. Support sprag assembly. Install sprag retainer and race assembly in sprag assembly. see scheme 16 Rotate sprag retainer and race assembly counterclockwise. Install remaining retainer ring. Install overrun clutch hub. Install snap ring.
4. Check sprag operation. Holding forward clutch race, rotate overrun clutch hub. Overrun clutch hub should turn freely clockwise and lock counterclockwise. (Scheme 4) NOTE: If replacing forward sprag or overrun clutch hub, see OE parts department for updated and redesigned parts availability.
5. Place input clutch housing with turbine shaft downward. Install 3-4 piston seals with lips facing away from hub. Install 3-4 piston in input housing.
6. Install 3-4 clutch apply ring. Install "O" ring seal in input clutch housing. Install forward clutch housing. Install seals on forward clutch piston with lips facing away from tangs.
7. Install forward clutch piston in forward clutch housing. Install 3-4 spring on 3-4 clutch apply ring. Install forward clutch assembly on 3-4 spring assembly. Align forward clutch piston legs with tangs of 3-4 apply ring. Install Seal Protector (J-29883 ) on input housing.
8. Install 3-4 apply ring and forward clutch assembly in input clutch housing. Hold apply ring tangs while installing. DO NOT allow forward clutch piston to separate from assembly. Ensure assembly is firmly seated.
9. Install Seal Protector (J-29883 ) on input housing. Install overrun clutch piston with hub facing upward. If fully seated, overrun piston should be 3/16" below top of snap ring groove in input housing hub. Install spring assembly on overrun piston. Compress springs, and install snap ring. Install input housing seal. NOTE: Soak clutch plates in ATF before installation. Coat all seals and "O" rings with ATF. Coat thrust washers and bearings with petroleum jelly.
10. Install 4 overrun clutch plates, starting with steel plate. Align wide notches with case lugs. Install remaining clutch plates, alternating steel and composition plates.
11. Install bearing assembly on input clutch hub. Bearing inner race must face input housing hub. Ensure bearing is centered. Align clutch plate tabs. Install forward clutch sprag assembly in input housing. Align overrun clutch hub with clutch plates.
12. Install forward clutch apply plate in input housing. Install waved forward clutch plate. Ensure all plates are aligned with input housing tangs. Starting with steel plate, install clutch plates, alternating steel and composition plates. Install backing plate and snap ring. See «FORWARD CLUTCH PLATE SPECIFICATIONS»(ref-25521-S05751860312001011700000).
13. Using 2 feeler gauges, measure clearance between backing plate and snap ring. Clearance should be.030-.063" (.75-1.60 mm). Install proper size backing plate with chamfered side upward. See «FORWARD CLUTCH BACKING PLATE SPECIFICATIONS»(ref-25521-S14593972782001011700000). Install snap ring. FORWARD CLUTCH PLATE SPECIFICATIONS Plate Type Quantity Thickness In. (mm) Apply 1.169 (4.29) Backing 1 Selective Composition 5.070 (1.78) Flat Steel 5.090 (2.29) Waved Steel 1.070 (1.78) FORWARD CLUTCH BACKING PLATE SPECIFICATIONS ID Letter Thickness In. (mm) A.274-.278 (6.96-7.06) B.251-.255 (6.38-6.48) C.228-.232 (5.79-5.89) D.205-.208 (5.20-5.28) E.180-.185 (4.57-4.70)
14. Install 3-4 clutch plates and backing plate. Install clutch plates and backing plate with chamfered side upward. Install retainer ring. Using feeler gauge, measure clearance between backing plate and first composition plate. Clearance should be.035-.083" (.90-2.10 mm).
15. Select proper backing plate to obtain correct clearance. See «3-4 BACKING PLATE SPECIFICATIONS»(ref-25521-S04824867412001011700000). Air check all clutches at feed holes in turbine shaft.
16. During overrun clutch test, air pressure will blow past forward clutch piston seals and exit out forward clutch feed hole in turbine shaft. Turbine shaft seals require sizing and should be installed just before oil pump installation.

3-4 CLUTCH PLATE SPECIFICATIONS

3-4 BACKING PLATE SPECIFICATIONS

1. Inspect all valves, springs, sleeves and bushings for chips, burrs, distortion and free movement in bores. Check pressure relief ball and spring for damage and distortion. Low line pressure will exist if ball and spring are damaged.
2. Inspect pump cover screen and "O" ring for wear and damage. Clean pump body and cover. Check all bores for obstructions. Inspect mating sides of cover and body for scoring, flatness and damage between channels. Check channels for dirt and damaged passages. Inspect stator shaft and pump body bushings for damage.
3. Inspect rotor and slide for scoring, cracks and damage. Check rotor guide and pump vane rings for excessive wear and damage. Inspect all seals for damage. Measure pump rotor and slide thickness in undamaged area if replacement is required. Replacement parts must be same size as those removed to provide proper end clearance.

Inspect all pistons for porosity and damage. Check for ring groove damage and servo bore in case for any wear which may cut servo seals. Check all springs and oil seal rings for distortion and damage.

Inspect valves and sleeves for scoring and cracks. Ensure valves move freely in bores. Inspect valve body for cracks and scored bores. Inspect machined surfaces for damage. Inspect springs for damaged coils. Replace damaged parts as necessary.