Fifth Wheel Overhang: Quantifying the Ideal Truck Bed Clearance with a Gooseneck Hitch

In this detailed analysis, Big Truck Big RV dives deep into the critical topic of fifth wheel overhang and truck bed clearance when using a gooseneck hitch. The video explores the nuances of achieving optimal clearance to prevent potential damage, evaluating different hitch systems and their impact on overall towing safety and performance. Learn how to measure and adjust your setup for a worry-free RV experience.

The WaySafe Safe Load Hitch: A Scientific Tool, Not a Towing Solution

The initial focus is on the WaySafe Safe Load hitch, previously featured in towing evaluations. However, after experiencing concerning movement during a 700-mile tow, the presenter now views it primarily as a scientific tool. While rated for up to 30,000 lbs of towing capacity and 7,500 lbs of vertical hitch weight capacity, the observed rocking motion made it unsuitable for continued towing. Instead, its value lies in its ability to facilitate precise scaling and weight measurements in a static environment.

"I actually really like this for the same purpose, but in a static environment where it's not moving. To be able to essentially use this as a scientific tool versus a towing tool will work out really well for me." - Big Truck Big RV

The height difference between the WaySafe Safe Load and the BMW OEM gooseneck ball is also measured, with the WaySafe offering a significant increase of approximately 2.5 inches, a difference of 5.75" versus 8.25". This height advantage, however, doesn't necessarily translate to improved bed rail clearance, which is the core issue explored in the video.

Measuring Bed Rail Clearance: BMW vs. WaySafe

The presenter meticulously compares bed rail clearance using both the BMW OEM gooseneck ball and the WaySafe Safe Load. The process involves hitching up to the fifth wheel with each ball and measuring the distance between the RV's overhang and the truck bed rails. Initial measurements on uneven ground proved unreliable, highlighting the importance of a level surface for accurate assessment. After moving to a level area, measurements revealed a clearance of approximately 7 inches at the front and 6.25 inches at the rear with the BMW ball. The passenger side had a clearance of 4.375" up front and 3.75" in the back, indicating the fifth wheel was leaning slightly.

The WaySafe ball provides even greater clearance. On the driver's side it measured 9.25" at the front and 8.5" in the rear. On the passenger side measurements were 7" at the front and 6.25" in the rear. While these clearances might seem adequate, the presenter emphasizes the need for ample space, particularly when navigating steep inclines or uneven terrain.

The Gen-Y Executive Hitch: Considerations and Concerns

The Gen-Y Executive hitch is a key component in this setup, providing shock dampening and contributing to overall towing comfort. However, the presenter addresses concerns about potentially lowering the hitch by one set of bolts to gain additional clearance. While this might seem like a simple solution, it raises questions about the structural integrity of the setup. The presenter cautions against deviating from the manufacturer's instructions, which specify using the same number of bolts as the original hitch. This setup used 5 bolts.

"Gen Y's instructions say use the same number of bolts of the hitch that you removed... I'm worried more about possibly the wings right there that the hitch goes into possibly deflecting or compromising or even moving if the clamping force of just four bolts isn't enough to prevent any type of possible movement or shifting."

The concern is that reducing the number of bolts could compromise the clamping force, potentially leading to deflection or movement within the hitch assembly. This highlights the importance of adhering to engineering specifications and prioritizing safety over marginal gains in clearance.

Weight Distribution and Pin Weight Analysis

The video also delves into weight distribution, revealing a pin weight of approximately 3,200 lbs when the fifth wheel is fully loaded. The truck's suspension drops about 1.75 inches under this weight, illustrating the importance of proper weight distribution and adequate truck capacity. The presenter also discusses the specific configuration of his Brookstone 398MBL, which includes heavy additions like a Moride slide-out tray, an Onan 5500-watt generator, a Splendid washer and dryer, and a heavy king-size bed. These factors contribute to a higher-than-average pin weight, emphasizing the need to consider these variables when assessing towing capacity.

The presenter estimates that a typical Brookstone configuration might have a pin weight closer to 2,500-2,700 lbs. By lifting the trailer off the hitch, it was determined that the rig had approximately 3,100 lbs worth of tongue weight. This discrepancy highlights the importance of understanding your RV's specific weight profile to ensure safe and compliant towing.

Alternative Hitch Solutions and Recommendations

Ultimately, the presenter concludes that the WaySafe Safe Load hitch is not suitable for his towing needs due to the excessive movement experienced. While the BMW OEM gooseneck ball offers better stability, it still lacks the desired bed rail clearance. As a result, he plans to explore alternative solutions, specifically mentioning a Reese puck-mounted gooseneck ball designed to provide approximately 7 inches of overall height. This option strikes a balance between stability and clearance, potentially offering the ideal solution for his setup. He also expresses continued enthusiasm for the Gen-Y Executive hitches, highlighting recent design changes that improve compliance with Lippert frame specifications.

"I am anti-bolting on a gooseeneck adapter to your kingpin and dropping that straight down onto your goose ball. I am totally anti that. The measurements are wrong in my opinion. It creates a crazy lever arm against the front of your RV."

Furthermore, the presenter reiterates his long-standing opposition to using gooseeneck adapters that bolt onto the kingpin. He believes this approach compromises the structural integrity of the RV and creates an unsafe towing situation. Instead, he advocates for using pin box replacements from reputable manufacturers who have thoroughly researched and engineered their products.

Key Takeaways

Bed Rail Clearance is Critical: Insufficient clearance can lead to costly damage and compromise towing safety.
Hitch Height Matters: Different hitch systems offer varying heights, impacting overall clearance and levelness.
Weight Distribution is Key: Proper weight distribution is essential for safe towing and optimal truck performance.
Adhere to Manufacturer's Instructions: Modifying hitch systems beyond specified parameters can compromise structural integrity.
Consider Alternative Hitch Solutions: Explore different hitch options to find the best balance between stability, clearance, and weight distribution.
Gooseneck Adapters are Risky: Avoid using gooseeneck adapters that bolt onto the kingpin; opt for engineered pin box replacements instead.

Conclusion

This video provides a comprehensive look at the complexities of achieving optimal fifth wheel overhang and truck bed clearance. By meticulously measuring and evaluating different hitch systems, the presenter offers valuable insights for RVers seeking to improve their towing setup. Be sure to watch the full video from Big Truck Big RV for a complete understanding of the concepts discussed and to see the measurements in action.