A/T - Torque Converter Clutch Shudder Diagnosis

Bulletin No. T 85-1
File In Group 7
Number 110
Date Sept. '84

SUBJECT: [1][2]TORQUE CONVERTER CLUTCH SHUDDER DIAGNOSIS

MODELS AFFECTED: 1982-1984 CIMARRONS WITH THM 125C AUTOMATIC TRANSAXLES

This bulletin contains new as well as supplemental information pertaining to Torque Converter Clutch (TCC) diagnosis and correction for 1982-1984 Cimarrons equipped with the THM 125C transaxle. New information is contained in items #6, 10, 11 and 12 of this bulletin. References to previously issued bulletins are made (in parentheses) at the end of each supplemental item of this bulletin.

Some THM 125C transmissions may exhibit Torque Converter Clutch (TCC) shudder as the TCC applies and/or after it applies when the accelerator pedal is depressed slowly (Crowd Shudder). These types of shudders are best described as a jerking sensation. In some cases the shudder may cause the instrument panel to vibrate.

CONDITION CAUSE AND CORRECTION
TCC APPLY TCC CROWD
SHUDDER SHUDDER

X X 1. An intermittent incorrect signal from the Vehicle Speed
Sensor (VSS). Dirt or grease on the reflective bar in the VSS may be sending an incorrect or erratic signal so that the converter clutch engages early. Remove the speedometer cluster and VSS and clean it of any excessive grease (refer to Serviceman Bulletin 83-102, Group 7, Number 74, Item D).

X X 2. The auxiliary valve body cover attaching bolts may be
loose or the bolt threads/holes may be shallow. If the holes are shallow, the bolts will bottom out without torquing the cover down (refer to Serviceman Bulletin 83-62, Group 7, Number 64).

X 3. Some 1982 models were built with either an exhaust
hole or an orifice cup plug in the auxiliary valve body cover. The auxiliary valve body cover was changed to a solid cover (no exhaust hole or orifice cup plug) in 1982. The service auxiliary valve body cover, part number 8643645, should be used on all models to prevent shudder. The service part does not have an orifice cup plug (refer to Serviceman Bulletin 83-102, Group 7, Number 74, Item E).

FIGURE 1 - AUXILIARY VALVE BODY (COVER SIDE):

X 4. There are two types of auxiliary valve bodies in
service. One has an orifice cup plug and the other does not (Figure 1). If the transmission being serviced has the auxiliary valve body with the orificed cup plug, particles of the auxiliary valve body cover gasket may have torn loose. This material may be sticking the

CONDITION CAUSE AND CORRECTION
TCC APPLY TCC CROWD
SHUDDER SHUDDER

[1][2]Torque Converter Clutch apply valve and/or plugging the converter release orifice in the control valve body spacer plate. If this is found, disassemble the auxiliary valve body and thoroughly clean. Also, be sure to remove any gasket particles in the valve body spacer plate converter release orifice hole and replace the auxiliary valve body cover gasket, P/N 8653947 (refer to Serviceman Bulletin 84-70, Group 7, Number 101).

X 5. Check the valves in the auxiliary valve body for
freeness. (They must move in and out of their bore without sticking.) (Refer to Serviceman Bulletin 83-102, Group 7, Number 74, Item F.)

FIGURE 2 - THM 125/125-C TRANSMISSION I.D. NAMEPLATE YPSILANTI, MICHIGAN:

FIGURE 3 - THM 125/125-C TRANSMISSION I.D. NAMEPLATE WINDSOR, CANADA:

X 6. The auxiliary valve body converter clutch control
regulator spring may be weak and require replacement with the new stronger load spring. Beginning with 1984 model year transaxle serial numbers CA 2226 and CB 156657, the new spring (P/N 8637888) went into production. To correct apply shudder on any 1982 or 1983 as well as before number 1984 model year transaxles, install the stronger load auxiliary valve body converter clutch control regulator spring (P/N 8637888). For explanations of transaxle nameplates, refer to Figure 2 (U.S. built) and Figure 3 (Canada built).

X X 7. Inspect the pump shaft to valve body seal for cuts,
damage, or distortion (refer to Serviceman Bulle-
tins 83-102, Group 7, Number 74, Item C, and 82-93,
Group 7, Number 45).

FIGURE 4 - TURBINE SHAFT:

FIGURE 5 - TURBINE SHAFT SEAL REPLACEMENT:

X 8. Inspect the turbine shaft Teflon seals and "O" ring seal
for damage, cuts, or distortion (see Figure 4 for these parts). If the Teflon seals require replacement, make sure they are installed and sized as shown in Figure 5 (refer to Serviceman Bulletin 83-102, Group 7, Number 74, Item A).

FIGURE 6 - TURBINE SHAFT SEAL GROOVES:

X 9. Inspect the turbine shaft seal grooves. A step in the
bottom corners of the seal groove will keep the seal from contacting the side wall of the groove and will prevent proper sealing (Figure 6). If this condition is found, replace the turbine shaft and seals (refer to Serviceman Bulletin 83-102, Group 7, Number 74, Item B).

FIGURE 7 - CASE COVER-VALVE BODY SIDE:

CONDITION CAUSE AND CORRECTION
TCC APPLY TCC CROWD
SHUDDER SHUDDER

X 10. Check the case cover sleeve converter feed oil hole for
being out of alignment with the oil channel in the case cover (Figure 7).

X 11. Check the converter end play, using tool J-29830A. The
end play specification is .5 mm (.020"). Converters with end play more than .5mm (.020") must be replaced.

X 12. The turbine shaft sleeve may have excessive internal
leakage. If all of the above items are OK, replace this shaft.