A/T - Accumulator Pistons & Seals Enhance Shift Points

Number: 86-148


Section: 7A
Date: Sept. 1986
Subject: NEW ACCUMULATOR PISTONS AND SEALS FOR ENHANCED SHIFT POINTS AND SHIFT SMOOTHNESS


Model and Year: 1982-1986 ALL MODELS WITH THM 700-R4 TRANSMISSIONS


TO: ALL CHEVROLET DEALERS

FIGURE 1 - THM 700-R4 TRANSMISSION IDENTIFICATION INFORMATION:

Beginning June 18, 1986, or Julian Date 169, (Refer to Figure 1) all 1986 THM 700-R4 transmissions are built using new 1-2 and 3-4 accumulator pistons and seals to assist in maintaining consistent shift points and smoothness.

FIGURE 2 - NEW PART VS PREVIOUS PART:

When servicing a 1982 through 1986 THM 700-R4 transmission, use the new pistons and seals (refer to Figure 2) which are available as service package part number 8635909 (one piston and one seal per package). The oil seal is available separately as service part number 8635568.
Important: The same design accumulator piston and seal are used in both the 1-2 and 3-4 circuits.

Refer to the appropriate Service Manual for removal and installation procedures.