A/T - THM 700R4 Slipping or Loss of Drive
Number: 87-107Section: 7A
Date: APRIL 1987
Subject: SLIPPING OR LOSS OF DRIVE
THM 700-R4 WITH AUXILIARY VALVE BODY
Model and Year: 1987 PASSENGER CARS WITH THM 700-R4 TRANSMISSION
1987 TRUCKS & VANS WITH THM 700-R4 TRANSMISSION
FIGURE 1 - AUXILIARY ACCUMULATOR VALVE BODY:
TO: ALL CHEVROLET DEALERS
A new auxiliary accumulator valve body (Figure 1 #377) and a
new cover (Figure 1 #371) went into production to prevent
the accumulator piston pin from working its way out of the
auxiliary valve body. If the accumulator piston pin comes
out of either end of the auxiliary valve body the following conditions could occur:
1. Loss of Drive
2. Slipping in Drive
3. Burned forward and overrun clutches
FIGURE 2 - TRANSMISSION I.D. NAMEPLATE INFORMATION:
Beginning January 27, 1987 (Julian Date 027, Figure 2) all
THM 700-R4 transmissions were produced with an auxiliary
accumulator valve body assembly that has a stepped bore at
one end of the piston pin and a new cover with an oval
instead of a round exhaust hole at the other end of the pin to retain the accumulator piston pin in place.
The new auxiliary accumulator valve body and cover can be used on any 1987 THM 700-R4 transmission that has an auxiliary valve body.
NOTICE:
If the accumulator piston pin has come out of the auxiliary valve body, check for burned forward and overrun clutches.
SERVICE PARTS INFORMATION
Part Number Description Models Affected
8663597 Auxiliary Accumulator MRM, MXM
Valve Body Assembly FAM, MAM, MFM, MMM
8667036 Auxiliary Accumulator MCM, MTM, PRM, TAM, TBM,
Valve Body Assembly YXM, PCM, TJM, TKM, TNM,
TRM, TUM, TXM
8667037 Auxiliary Accumulator MDM, MHM, MLM, MKM, MPM
Valve Body Assembly MUM, MWM, MZM
8667038 Auxiliary Accumulator TSM, YAM, YDM, YFM, YKM,
Valve Body Assembly YLM, YMM, YNM, YPM, YSM,
TYM, YZM