Usage:
621E, 623E, 631E Tractors;
627E, 637E, 657E Tractor-Scrapers;
768C, 772B, 776B Tractors;
769C, 773B, 777B, 785, 789 Trucks
- SUPPLEMENT: 10/16/89
SERVICE MAGAZINE; JANUARY 25, 1988; PAGE 11; "Stronger Detent Cam Pin Arrangement Used in Selector and Pressure Control Valve Group of Transmission Hydraulic Controls" on 621E, 623E, 631E, 768C, 772B, 776B Tractors; 627E, 637E, 657E Tractor-Scrapers; 769C, 773B, 777B, 785, 789 Trucks. This article supersedes an earlier article in Service Magazine; July 7, 1986; Page 22; "Stronger Detent Cam Pin Arrangement Used in Selector and Pressure Control Valve Groups."
This article also applies to 621S, 651E, 776 Tractors and 777 Trucks.
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Description of Change: A stronger detent cam pin arrangement is used in the selector and pressure control valve groups on the above models. The cam pin arrangement is actually a retainer that holds the detent cam to the rotary selector valve. Formerly, the retainer consisted of two pins, a slotted roll pin (8C3347) and a spring pin (6V5341). In some instances it was possible for the slotted roll pin to break. The new retainer consists of three pins, an outer spring pin (6V8235) and two inner spring pins (6V5341). The new arrangement will provide increased strength to prevent pin breakage.
Adaptable To: The new 6V8235 Spring Pin is a direct replacement for the former 8C3347 Slotted Roll Pin. When a new 6V8235 Spring Pin is installed on earlier models, it is recommended that two new 6V5341 Spring Pins be installed.
Use the procedure which follows to install the new 6V8235 Spring Pin. The parts needed are one 6V8235 Spring Pin and two 6V5341 Spring Pins.
1. Use the appropriate Disassembly and Assembly module to gain access to the selector and pressure control valve group and rotary selector valve.
2. Install detent cam (1) in rotary selector spool (2). Holes (3) in the selector spool and cam must be in alignment with each other. This may be checked visually or it may be checked by extending a small diameter rod through the holes. See Illustration 1.
Illustration 1. Installing detent cam in selector spool.
3. Install the 6V8235 Spring Pin through holes (3) until it is approximately 2.5 mm (.10") below the outside surface of the rotary selector spool. See the detail in Illustration 1.
4. From each end of holes (3), install the 6V5341 Spring Pins inside and flush with the outer ends of the 6V8235 Spring Pin. After the 6V5341 Pins have been installed, be sure the 6V8235 Pin is 2.5 mm (.10") below the surface of the rotary selector spool. See the detail in Illustration 1.
5. Put clean SAE 30 oil on rotary selector spool (2). Install the spool in the valve body. Tighten bolt (5) with washer (4) that holds the spool in position. See Illustration 2.
Illustration 2. Installing detent springs on selector valve.
6. Install two springs (6), two retainers (7) and bolts (8) that hold the springs in position on the support. Each spring should be 4.5 ± 0.5 mm (.18 ± .02") from the side of the selector valve. See Illustration 2.
7. Loosen bolts (9) so the rollers in springs (6) are in the center of the notches in the detent cam. Retighten the bolts.
8. After reinstalling the rotary selector valve and the selector and pressure control valve group, check the operation of the transmission hydraulic controls.