Usage:
7231 And 7241 Marine Transmissions
- SUPPLEMENT: 01/00/86
ENGINE NEWS, JANUARY 16, 1985, PAGE 1. "Install Different Body Assembly In Clutch Group To Correct Harsh Shifting".
The 2N949 Dump Valve Body Assembly and the 1N8510 Plunger will still be used and not the new parts shown in the article.
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Description of Change: Reports indicate that a rough shifting noise or a "ratcheting noise" can sometimes result when shifting the clutches on the above marine transmissions. This noise usually occurs when the transmission oil is at normal operating temperature. This problem can be eliminated by replacing the two dump valve bodies and plungers with the body assemblies normally used for a trolling valve. This body assembly has a fixed orifice instead of a sliding plunger like the dump valve.
Adaptable As: The 3N5778 Body Assembly is a direct replacement for the 2N949 Dump Valve Body Assembly and 1N8510 Plunger on the above marine transmissions. See the chart for components of the 3N5778 Body Assembly. Two 3N5778 Body Assemblies are needed for one clutch group. See Illustration 1 for assembled dimensions.
Illustration 1. Components of 3N5778 Body Assembly.
Press the 3N5322 Pin into the 2N949 Body Assembly to the dimension shown in Illustration 1.
Modification Procedure
The 2N949 Dump Valve Body Assemblies that were removed from the clutch group may be used to make the fixed orifice body assemblies. Wear from the movement of the 1N8510 Plunger may prevent the correct interference fit of the 3N5322 Pin in the used dump valve body. There must be .025 mm (.0010") interference (press) fit between the pin and the body. A pin can be fabricated from mild steel to the dimensions shown on Illustration 2. The outside diameter of the fabricated pin must be .025 mm (.0010") larger than the inside diameter of the dump valve body. Install the fabricated pin to the dimension shown in Illustration 1.
Illustration 2. Dimensions for fabricated pin.