Caprice Wagon V8-305 5.0L (1986)
Engine Mount: Customer Interest
A/T - Summary of Shudder Diagnosis
Number:
86-155
Section:
7A
Date:
Sept. 1986
Subject:
THM 440-T4 SUMMARY OF SHUDDER DIAGNOSIS
MODEL AND YEAR:
1984-1986 ALL MODELS WITH THM 440-T4 TRANSMISSIONS
TO:
ALL CHEVROLET DEALERS
This bulletin provides additional diagnosis information, and a new Part Number, cancelling and superceding Chevrolet Dealer Service Bulletin 86-41
(Section 7A) dated March 1986 which should be destroyed. This bulletin also supplements Chevrolet Dealer service Bulletin 85-34 (Section 7A) dated
February, 1985.
A vehicle equipped with a 1984 through 1986 THM 440-T4 transaxle may experience a shudder condition which could be described as similar to driving
over rough pavement. This condition may be the result of various engine and/or transaxle-related causes.
Before diagnosing for a transaxle-related shudder condition, make sure the condition is not engine-related.
Refer to the chart for trouble shooting procedures.
When performing any service procedure, refer to the appropriate service manual.
CONDITION
INSPECT COMPONENT
FOR CAUSE
ENGINE-RELATED SHUDDER,
Engine Fuel Delivery System
Restriction or imbalance. For example,
OR "CHUGGLE"
fouled fuel injectors due to deposits.
Engine Ignition System
Improper operation. Includes items such
as fouled or broken spark plugs.
TCC APPLY SHUDDER
Torque Converter Cover
Dimpling caused by too-long bolts (Max.
length 15 mm).
Torque Converter
See NOTE, following chart.
TCC APPLY SHUDDER OR
Turbine Shaft Seals
Missing or damaged.
CROWD SHUDDER (Crowd
shudder occurs after TCC apply,
TCC Accumulator Piston Seal
Cut or rolled. Refer to Bulletin HM 85-17
when accelerator is depressed)
TCC Solenoid O-Ring
Cut or broken.
Valve Body Gasket
Torn or mispositioned.
TCC CROWD SHUDDER
Downshift Delay Module
Improper operation.
(Canadian 2.8 LE2 Only)
1-2 SHIFT SHUDDER
2nd Clutch Plates
Replace steel and fiber plates (soak in
transaxle fluid for 30 mins. prior to
installation).
2-3 SHIFT SHUDDER
Servo Release Pipe Seals
Cut seals. Refer to Bulletin HM86-07.
SHUDDER UNDER LOAD OR
Right Rear Engine Mount
Engine grounding out.
ACCELERATION
(1986 3.8L H-Body Only)
NO TCC APPLY, DELAYED TCC
TCC Solenoid Apply Valve,
Sticking in valve body. (At start of pro-
RELEASE, OR TCC APPLY AND/
TCC Pressure Regulator Valve
duction 1986, the TCC regulator valve
OR RELEASE SHUDDER
Or Spring
spring was eliminated on the following
models:
AAH, ACH, ADH, AFH, AMH, ARH, BHH, CFH, CHH, CMH, CNH, HBH, and HJH.)
SHUDDER IN REVERSE
Right Rear Engine Mount
Engine grounding out.
(1986 E-Body)
