Lippert IsoFlex™ Pin Box OEM Installation Manual

Introduction

The 21K rubber-isolated IsoFlex™ Pin Box is designed to fit the Rhino Pin Box bolt pattern, offering improved ride performance at a lower cost compared to other upgraded Rhino Pin Box options. The IsoFlex Pin Box is specifically designed for the Space Saver Upper Deck and is not compatible with other bolt hole patterns. This chassis design enhances fifth-wheel floor space and reduces the common large step found in front of cabinetry or inside walk-in closets in modern fifth-wheel trailers.

For additional support on this product, please visit: https://support.lci1.com/lippert-pin-boxes

Note: Images in this document are for reference during assembly, installation, and operation. Actual parts and assemblies may differ.

Safety

Read and understand all instructions before installing or operating this product. Adhere to all safety labels. This manual provides general instructions, acknowledging that variables in task difficulty, operation, and individual ability may alter circumstances. Failure to follow instructions may result in death, serious personal injury, severe product and/or property damage, including voiding of the LCI limited warranty.

▲ WARNING: The "WARNING" symbol indicates a safety risk that may cause death or serious personal injury if not performed safely and within the parameters set forth in this manual.

▲ WARNING: Failure to follow instructions provided in this manual may result in death, serious personal injury and/or severe product and property damage, including voiding of the component warranty.

▲ WARNING: The trailer MUST be supported per manufacturer's recommendations before working underneath. Failure to do so may result in death or serious personal injury.

▲ WARNING: Due to the weight of the pin box, it is recommended that at least two people install this system.

▲ CAUTION: The "CAUTION" symbol indicates a safety risk that may cause personal injury and/or product or property damage if not adhered to safely and within the parameters set forth in this manual.

▲ CAUTION: Always wear eye protection when performing service, maintenance, or installation. Consider other safety equipment such as hearing protection, gloves, and a full face shield depending on the task.

▲ CAUTION: Failure to check and follow tow ratings could result in tow vehicle damage or separation while towing. Ensure the trailer and its contents do not exceed tow vehicle, hitch, and/or trailer tow ratings.

▲ CAUTION: Moving parts can pinch, crush, or cut. Keep clear and use caution.

Resources Required

• Two to three people, depending on task
• Cordless or electric drill or screw gun
• Appropriate drive bits
• Torque wrench
• Impact wrench or ratchet
• Open end wrenches
• Sockets
• Drift/centering pin
• Hammer (optional)
• Tape measure

Factory Pin Box Removal

1. Level the 5th wheel front to back.
2. Measure the distance from the bottom of the factory-installed pin box's kingpin plate (Fig. 1A) to a flat surface directly below (Fig. 1B).
3. Note the bolt hole locations of the factory-installed pin box and the mounting frame. The new pin box system will be remounted in the same hole settings.
4. Properly support the pin box assembly. Note: The pin box assembly weighs several hundred pounds; a minimum of two people are required. A forklift may be used to lift the pin box into position. Ensure the pin box is sufficiently and properly supported before removing mounting hardware.
5. Remove fasteners that hold the original pin box in place.
6. Remove the factory pin box from the mounting frame.

Fig. 1 Description: Diagram illustrating the 5th wheel pin box mounting area. Point A indicates the kingpin plate, and Point B indicates a flat surface below for measurement.

Installation

Install New Pin Box

1. Hoist the new pin box into place.
2. Use a second person to align the pin box with the bolt holes in the mounting plate.
3. Using a drift/centering pin (or screwdriver), center the holes and install a bolt in both top and bottom positions. Note: Bolts can be inserted from either side. The attachment sequence is one washer on the bolt head side and one washer and nut on the threaded side. Serrated washer teeth should face inward toward the pin box wings (Fig. 2).
4. Verify the distance from the bottom of the kingpin plate to a flat surface is within +/- 1½" of the ground-to-plate measurement from the removal section. Make height adjustments if necessary.
5. Using the remaining hardware from the pin box kit, install bolts, washers, and nuts in the remaining pin box holes.
6. With a torque wrench, torque all nuts to 120 ft-lbs.

Fig. 2 Description: Diagram showing the installation of a bolt, washer, and nut. It highlights that washer teeth should face inward towards the pin box wings.

Operation

Hitching Procedure

Note: Grease may be applied around the kingpin and on the skid plate surface to assist the hitching procedure. Refer to recommended grease specifications.

Approved Sources - Bearing Grease

▲ WARNING: Do not mix lithium, calcium, sodium, or barium complex greases. Mixing incompatible compounds can create corrosive or toxic chemicals. Ensure all old grease is removed completely before applying new grease.

▲ WARNING: Working between the tow vehicle and trailer is dangerous. Failure to properly secure them from movement can result in serious personal injury, death, or product damage. Ensure all safety precautions are followed.

1. Place chocks firmly against the front and rear of each trailer wheel to prevent movement.
2. If necessary, lower the tow vehicle's tailgate. Note: Monitor tailgate clearance to the trailer during hookups.
3. Using the trailer landing gear, adjust trailer height so the bottom of the trailer's pin box (Fig. 3A) is 1/2" to 1" below the top portion of the hitch skid plate (Fig. 3B). Note: During hitching, the bottom of the pin box should contact the hitch skid plate ramp.
4. Open the jaw on the 5th wheel head. Refer to the hitch manufacturer's instructions for proper latch operation.
5. Back the tow vehicle slowly toward the trailer until the hitch contacts the bottom of the pin box and the kingpin slides into the receiver.
6. Latch the 5th wheel hitch in the closed position per the hitch manufacturer's instructions.
7. With the trailer wheels still chocked, verify:
   • The landing gear is on firm, level ground.
   • The landing gear fully supports the trailer's weight.
   • The tow vehicle is stationary, in park, with the emergency brake engaged.
   • The bottom of the pin box is resting on top of the hitch.
   • There is no space between the mating surfaces.
8. If space exists between the pin box and hitch, the trailer is not properly hitched. Do not tow. Repeat hitching steps 1-7.
9. Connect previously disconnected electrical cables between the tow vehicle and trailer.
10. Raise the tailgate of the truck.
11. Do not tow the trailer until a Pull Test has been conducted. Proceed to the Pull Test section.

Fig. 3 Description: Diagram showing the connection point between the trailer's pin box (A) and the tow vehicle's hitch (B) during the hitching process.

Pull Test

▲ WARNING: Failure to perform a pull test may result in severe property damage, serious personal injury, or death. Failure to secure the tow vehicle and trailer from movement during the procedure could also result in severe property damage, serious personal injury, or death. Ensure the tow vehicle and trailer are properly secured against movement during the procedure.

1. Ensure trailer wheels are chocked, trailer landing gear is on firm ground supporting the trailer, and the tow vehicle is in park with the emergency brake engaged.
2. Return to the tow vehicle cab, release the emergency brake, and then apply the trailer brakes.
3. Slowly pull the trailer forward with the tow vehicle.
4. If properly hitched, the wheel chocks and trailer brakes should prevent the truck from moving forward.
5. If not properly hitched, the trailer will separate from the hitch, and the truck will move forward while the trailer remains behind. If this occurs, repeat the Hitching Procedure.
6. After a successful Pull Test, fully raise the landing gear per manufacturer's recommendations.
7. Check and inspect all electrical circuits for proper operation, including clearance lights, turn signals, and stop lights.
8. Remove and store all trailer wheel chocks.

The contents of this manual are proprietary and copyright protected by Lippert Components, Inc. (LCI). LCI prohibits the copying or dissemination of portions of this manual without prior written consent from an authorized LCI representative. Any unauthorized use shall void any applicable warranty. The information contained in this manual is subject to change without notice and at the sole discretion of LCI. Revised editions are available for free download from lci1.com.

Please recycle all obsolete materials.

For all concerns or questions, please contact Lippert Components, Inc.

Ph: (574) 537-8900 | Web: lci1.com | Email: customerservice@lci1.com