A/T - THM 200C Forward Clutch Design Change: Overview

SIL 88-15 (Apr)

SUBJECT: THM 200C

TRANSMISSION MODELS: All (Excluding 1984-85 CZ, JY)

1987 THM 200 C transmissions are being built with a new design "feed/bleed" system for the forward clutch. This system gives more cushioning during forward clutch apply and can be used on certain past models to reduce a harsh PARK/NEUTRAL to DRIVE engagement feel.




August 4, 1986 (Julian date 216, Figures 1 and 2), these changes were introduced for all THM 200 C models:

Forward clutch assembly, minus check ball in housing (619)

Forward clutch piston assembly (623)

Additional waved plate (627)

Front internal gear (636)

SERVICE ACTION

1984-87 Models built before August 4, 1986 (Julian Date 216):

If a vehicle equipped with a THM 200C transmission has a harsh PARK/NEUTRAL to DRIVE engagement, install the Neutral Drive Shift Package.

1987 Models built on or after August 4, 1986 (Julian Date 216):

Models built after implementation of the feed/bleed system can be serviced with individual parts.

IMPORTANT
When servicing the forward clutch, select the correct backing plate (627). Backing plate selection affects piston travel, shift feel and clutch durability.

Backing plate selection (clutch fully assembled):




Apply an evenly distributed load in the direction indicated in Figure 3, to remove slack from the clutch assembly. Use 20 lbs (9kg) of pressure against the backing plate -- excessive pressure will cause an inaccurate measurement. With the clutch assembly compressed, use a feeler gage to measure the distance between the backing plate and snap ring. Correct backing plate travel is 0.7 mm-1.5 mm (0.028"-0.059").