This incomplete vehicle, when completed, will conform to the above standards except CMVSS 1106 providing no alterations are made which affect the function, physical or mechanical properties, environment, locations or vital spatial clearances of the components identified below:
- Engine assembly*
- Exhaust emission control system
- P.C.V. system
- Intake system*
- Exhaust system*
- Fuel system
- Transmission assembly*
- Axle*
- Tires*
- Fan and drive*
- Diesel fuel injection controls
- Turbocharger and associated controls
- Catalytic converter and its location (6HE1-TC only) *
- Air cylinder for variable swirl system (6HE1- TCS only)
Transmission
The transmission is removed from the rear. Enough clearance must be provided to allow rearward movement of the transmission assembly. Clearance should be sufficient to allow 5 to 6 inches unrestricted movement of the transmission assembly. In addition, provide at least 2 inches clearance around the control lever on the side of the transmission to allow free movement without any binding.
At least 6 inches clearance should be maintained above the transmission to allow easy removal of the upper cover for manual transmissions. At least 2 inches clearance should be maintained above the automatic transmission to allow for transmission removal.
Exhaust System
If flammable materials such as wood are used in the body, provide at least 3.9 inches clearance between the body and any parts of the exhaust pipe, muffler and catalytic converter. If it is impossible to maintain this minimum clearance, use a heat shield. Also use a heat shield if an oil pump or line is located above the exhaust pipe, muffler or catalytic converter.
Body Installation
To maintain the performance of the truck chassis, either a side member or subframe should always be used for body mounting. Body mounting with low rigidity will often adversely affect riding comfort. When installing special equipment on the chassis, extra consideration must be given to the weight and construction of the equipment to assure proper distribution of the load. Localization of the load should be prevented. All special equipment should be properly secured into position. We recommend the use of subframe members when installing special equipment.
U-bolt Installation
When U-bolts are used to retain the subframe, reinforcement blocks must be installed in the frame members. This will prevent distortion of the frame flange as they are tightened. The drawing indicates the correct placement of reinforcement blocks. If you use wood blocks, be sure that there is sufficient clearance between them and any parts of the exhaust system. If any fluid lines or electric cables are located near the reinforcement blocks, you must provide at least 0.4 inch clearance between rigid or stationary portions, and at least 1.6 inch between moveable or flexible portions of the lines.
Working on Chassis Frame
The chassis frame is designed and built with consideration for proper load distribution. Sufficient physical strength is provided when the load is evenly distributed. Installation of special equipment on the chassis frame can cause variations in load distribution. If even distribution of load is not kept in mind when the equipment is installed, localization of stresses on specific areas of the frame could cause cracking of the chassis frame members or other problems, even if the total weight of the equipment is within the design limit.
Reinforcement of Chassis Frame
Reinforcements must be installed to prevent the considerable variation in the section modulus. They must be welded so as to avoid localized stresses. The frame of the NPR/W3500, NPR GAS/W4500 and NQR/W5500 is made of SAPH440 mild steel. The frame of the FRR is made of HT540A. See the FSR, FTR and FVR section for frame material specifications.
Electrical Wiring and Harnessing
To increase the reliability of the wiring, all frame harnesses are covered with corrugated vinyl tubing. The following instructions apply to extending or modifying these harnesses. See the Electrical Section for information on commonly used circuits in the NPR, NQR, FRR and W-Series. The FSR, FTR and FVR wiring information can be found in the service manuals.