COMPLAINT: Converter clutch shudder
CAUSE: One cause can be low converter regulator charge pressure, Figure 1, Another cause can be slow drain of converter oil in front of clutch piston,
CORRECTION Install stronger regulator valve spring 8637887 or use a spring from a THM 400 forward or direct clutch retainer Figure 2. Drill converter exhaust hole in separator plate to .080”.
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THM 4L60 (700-R4) HARSH DOWNSHIFT CLUNK IN D3 ONLY
COMPLAINT: Harsh downshift clunk with selector in D3 only.
CAUSE: The cause could be the 2nd apply piston.
CORRECTION: Modify the 2nd apply piston by machining the inner hub and remove .125″ (See Figure 3).
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Vehicles equipped with 1987 THM 125C built between the dates of April 13, 1987 through April 21, 1987 (Julian Dates 103- 112), may have a rolled or miss assembled l-2 accumulator piston seal, resulting in a possible harsh l-2 shift. These 1987 THM 125C transaxles (Julian Dates 103-112) have a new design accumulator piston (flat inner surface) and a soft synthetic rubber l-2 accumulator piston seal that may be inadvertently miss Assembled.
DATE OF PRODUCTION CHANGE (Figure 1) New design accumulator piston (flat inner surface) and synthetic rubber accumulator piston seal on all 1987 THM 125C transaxles built April 13,1987 (Julian Date through April 21,1987 (Julian Date 112).
SERVICE ACTION (Figure 2) If a vehicle equipped with a 1987 THM 125C transaxle built between Julian Dates 103-112 experiences a harsh l-2 shift examine the l-2 accumulator piston and seal for damage or miss assembly. If necessary, replace the piston and the seal with the original design accumulator piston (raised rib) and P.T.F.E. seal. These parts are not interchangeable.
SERVICE PARTS INFORMATION
8631657 l-2 Accumulator Piston
8631985 l-2 Accumulator Oil Seal Ring