FAW Transmission Housing Assembly: A Critical Focus on 37 Core Components

Welcome to this critical, in-depth guide on the FAW Transmission Housing Assembly, the complete structural “skeleton” for the gearbox in the FAW Jiefang CA4251P66K24T1A3E5 6×4 diesel semi-trailer tractor. This is the foundation upon which the entire transmission is built.

The FAW Transmission Housing Assembly is not a single part, but a set of precision-machined casings, including the ‘Front housing’ (1701015-A9P) and ‘Mid-housing’ (1701035-A9P). Its function is to contain the gear oil, protect all internal gears and shafts, and provide rigid mounting points to the engine and chassis.

This guide is an essential resource for professional transmission rebuilders, fleet technicians, and parts managers. We will deconstruct the entire FAW Transmission Housing Assembly into its 37 serviceable components, including every cover, plug, gasket, and fastener required for a complete overhaul.

Core Casings: Front (1701015-A9P) & Mid (1701035-A9P)

The FAW Transmission Housing Assembly is a “two-piece” or “split-case” design, consisting of two main structural components.

**1. Front Housing (1701015-A9P):** This is the ‘Front housing with steel wire sleeve assy’. This is the “bell housing” section of the FAW Transmission Housing Assembly. Its primary function is to connect the entire gearbox to the back of the engine’s flywheel housing. It also contains the clutch release mechanism (fork and bearing). The “steel wire sleeve” (e.g., Helicoil) designation is a high-quality feature, indicating that the aluminum casting has been reinforced with steel thread inserts for the high-torque mounting bolts, preventing stripping and ensuring durability.

**2. Mid-Housing (1701035-A9P):** This is the ‘Mid-housing with steel wire sleeve assy’. This is the main “gearbox,” the largest part of the FAW Transmission Housing Assembly. This heavily-ribbed casting (likely aluminum for light weight and heat dissipation) is the “skeleton” that holds all the critical, torque-bearing shafts: the main shaft, the counter-shaft, and the reverse idler shaft. Its internal, precision-bored “saddles” are where the main shaft bearings are seated.

These two halves of the FAW Transmission Housing Assembly are located with ‘Dowel pins’ (1701052-A9P, 1701037-A2K) and bolted together with numerous high-tensile ‘Hex flange bolts’ (Q1840820S, Q1841030S, etc.) to form a single, rigid, leak-proof unit.

Access & Inspection Covers

The FAW Transmission Housing Assembly is designed for serviceability. This is evident from its multiple access covers. The ‘Cover – upper left’ (1701037-A9P) and ‘Cover – lower right’ (1701043-A9P) are “idler gear” covers. They seal the large holes in the casing that are necessary for the factory to assemble the counter-shaft and idler gear clusters. These covers are sealed with gaskets and secured with ‘Hex flange bolts’ (Q1841060S, Q1841065S).

Additionally, the ‘Front housing’ (bell housing) features a ‘Cover – outer observation hole’ (1601042-A2K), which is sealed by a ‘Gasket’ (1601041-A2K). This small, removable plate is the “clutch inspection cover.” It allows a technician to use a light and a mirror to inspect the condition of the clutch friction disc, the pressure plate, and the release bearing, without having to remove the entire transmission. This is a critical diagnostic feature of the FAW Transmission Housing Assembly.

Lubrication System: Plugs and Sump

The FAW Transmission Housing Assembly is also a “sump” that holds several gallons of heavy-duty gear oil. This parts list details all the service points for this fluid.

**1. Filler Plugs:** The ‘Oil filler plug’ (1701042-A2K) is the main “fill” port, located high on the side of the FAW Transmission Housing Assembly. The transmission is filled until oil begins to weep from this hole, which is how the correct level is set.

**2. Drain Plug:** The ‘Drain plug assy’ (1701765-A2K) is the service point for removing the old oil. This plug is located at the absolute lowest point of the FAW Transmission Housing Assembly. It is magnetic, designed to trap microscopic metal particles and provide a visual “health check” of the internal gears during an oil change. It is sealed with a ‘Gasket-plug, drain’ (1701042-A2K… *Correction*: 1701042-A2K is listed as filler plug and gasket, likely a typo in list, should be drain plug gasket 1701765-A2K’s sub-part).

**3. Oil Sump:** The ‘Oil sump assembly’ (1701025-A9P) is a bolted-on component at the bottom of the FAW Transmission Housing Assembly. This acts as the main oil reservoir, ensuring the oil pump pickup is always submerged.

Shaft Support: Bearing Caps and Bushings

The most critical function of the FAW Transmission Housing Assembly is to hold the input, main, and counter shafts in perfect, parallel alignment under thousands of pound-feet of torque. This is achieved by several key components.

The ‘End cap – intermediate shaft front bearing’ (1701028-A9P) is a heavy-duty cap that bolts to the front of the main housing, securing the “pocket bearing” of the counter-shaft. Similarly, the ‘Cover – first shaft rear bearing’ (1701141-A7G) and its ‘Gasket’ (1701142-A7G) seal and secure the main bearing on the transmission’s output shaft.

This FAW Transmission Housing Assembly also provides the mounting points for the shift-fork shafts. The ‘Bushing-shift fork shaft’ (1701013-A9P) and ‘Bushing-reverse idler shaft’ (1701014-A9P) are the “wear” surfaces. These bronze bushings are pressed into the case, providing a low-friction, replaceable surface for the hardened steel shift shafts to slide in.

FAW Transmission Housing Assembly Parts List (1/2)

The following table provides the complete, detailed breakdown of all 37 components for the FAW Transmission Housing Assembly.

Technical Specifications and Assembly Context

The specifications for the FAW Transmission Housing Assembly are defined by its function as the structural, precision-machined skeleton for a heavy-duty manual transmission. The entire FAW Transmission Housing Assembly is built for durability.