Reverse Input Housing and Drum Assembly

TRANSMISSION APPLICATIONS: SUBJECT:

1987 THM 700-R4 (MD8) New Reverse Input Housing And
Drum Assembly


TRANSMISSION MODELS:

All Models

FIGURE 2 - REVERSE INPUT CLUTCH ASSEMBLY:

FIGURE 3 - REVERSE INPUT HOUSING AND DRUM ASSEMBLY:

CHANGE TO ASSEMBLY COMPONENTS: (Figures 2 and 3)

New reverse input housing and drum assembly (605) is revised as follows:

^ Smaller (round versus rectangular) feed hole in hub is 2.413 mm (.095"); was 3.85 x 5.0 mm (.151 x .197")

^ Longer inner housing splines

^ Check valve retainer and ball assembly removed

^ New cast aluminum reverse input clutch piston (607) with 2.057 mm (.081") orifice

^ Reverse input clutch waved plate (611) replaced by a "belleville" plate

^ Thinner reverse input clutch fiber plates (612) thickness now is 1.73-1.88 mm (.068-.074"); was 1.93-2.13 mm (.076-.084")

^ Selective reverse input clutch backing plate (613)

FIG. 4 - OIL PUMP COVER:

New oil pump cover assembly (217) changed as follows: (Figure 4)

^ Larger diameter reverse input feed hole in stator hub

SERVICE ACTION:

Component parts of the new reverse and input housing and drum assembly are available through the G.M. Service Parts Organization (GMSPO) catalog. These parts cannot be used with parts from transmissions built prior to February 9, 1987 (Julian Date 040).


SERVICE PARTS INFORMATION:

Part Number Description

8663068 Reverse Input Clutch Housing And Drum Assembly Complete

8663071 Reverse Input Clutch Piston

8657922 Reverse Input Clutch Seal Package

8663079 Reverse Input Clutch Plate Assembly

* * * * * * Pump Cover Assembly (Refer to GMSPO Catalog for Part Numbers and Model Usage)

Backing Plate - Reverse Input Clutch

FIG. 6 - BACKING PLATE SELECTION CHART:

8663075 Identification 5 - Figure 6

8663076 Identification 6 - Figure 6

8663077 Identification 7 - Figure 6

8663078 Identification 8 - Figure 6

SERVICE MANUAL REFERENCE:

1987 Service Manuals do not contain the information found in this bulletin. Use this information when disassembly or assembly of the reverse input housing and drum assembly is required on transmissions built after February 9, 1987 (Julian Date 040).

FIG. 5 - CUT-AWAY OF REVERSE INPUT HOUSING:

Reverse Input Clutch Backing Plate Selection Procedure

1. With the reverse input clutch fully assembled, apply an evenly distributed load to the clutch pack in the direction and diameter as shown in Figure 5. Medium pressure (approx. 20 lbs.) on the backing plate applied by fingers on five evenly distributed points will obtain the backing plate travel for measurement. (CAUTION: Excessive pressure will distort the "belleville" plate resulting in an inaccurate measurement.)

2. Using a feeler gage, measure between the snap ring and the backing plate. Backing plate travel should be 1.02 mm - 1.90 mm (.040" -. 075").

FIG. 6 - BACKING PLATE SELECTION CHART:

3. Select the proper backing plate to obtain the specified travel. (Figure 6)