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  1. 5th Wheel Pin Box
  2. CURT
  3. Lippert Rhino
  4. 24000 lbs GTW
  5. Upgraded Pin Box
  6. Absorbs Road Shock and Reduces Chucking
Curt Helux Shock-Absorbing 5th Wheel Pin Box - Lippert Rhino - 24K GTW - 4,000 lbs TW
CURT

Curt Helux Shock-Absorbing 5th Wheel Pin Box - Lippert Rhino - 24K GTW - 4,000 lbs TW

Part Number: C65MJ
$1,595.95
Retail:$2,103.95
You Save: $508.00
5th Wheel Pin Box
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Tired of your trailer tossing you around? Curt's Helux pin box smooths things out with a tough coil spring that beats air bags and torsion setups. It's maintenance-free, easy to use, and won't put your RV's frame warranty at risk. 1-800-940-8924 to order CURT 5th wheel pin box part number C65MJ or order online at etrailer.com. Free expert support on all CURT products. Great prices and Fastest Shipping for Curt Helux Shock-Absorbing 5th Wheel Pin Box - Lippert Rhino - 24K GTW - 4,000 lbs TW. 5th Wheel Pin Box reviews from real customers.
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  • Reviews (9)
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CURT 5th Wheel Pin Box - C65MJ

  • Lippert Rhino
  • 24000 lbs GTW
  • Upgraded Pin Box
  • Absorbs Road Shock and Reduces Chucking
  • CURT
  • Rubber Spring Suspension
  • Fixed Turret

Tired of your trailer tossing you around? Curt's Helux pin box smooths things out with a tough coil spring that beats air bags and torsion setups. It's maintenance-free, easy to use, and won't put your RV's frame warranty at risk.


Highlights

  • Smooth, Cushioned Ride: Internal spring helps absorb road shock and reduce aggressive bouncing and chucking.
  • Ultimate Comfort and Protection: Eases fatigue, minimizes wear on your RV and cargo, and helps your trailer ride smoother every time.
  • Zero Maintenance: No airbags, bearings, or bushings to service, just hitch up and go.
  • Built to Last: Fully welded steel with a triple-layer powder coat stands up to rust and wear.
  • Trusted in the Industry: Approved for Lippert RV frames, so it won't void your trailer's warranty like some aftermarket pin boxes.

Made in USA

Features to know about

Smoother Ride, Better Protection

Helux in use

The Helux coil spring system absorbs road shock, jerking, and the back-and-forth chucking that wears you out on long drives. It keeps things steady through starts, stops, and uneven roads so your ride feels calmer, your cargo stays safer, and your trailer takes less of a beating.

Durable and Maintenance-Free

Built from fully welded steel with a triple-layer powder coat, this pin box is made to handle years of towing and all kinds of weather. And with no airbags, bearings, or bushings to service, you won't have to think about upkeep.

Lippert Approved Upgrade

Unlike some aftermarket pin boxes, this one is approved for use on Lippert RV frames. That means you get a smoother ride without risking your trailer's warranty.

Specs

Application:

  • Compatible with Lippert Rhino pin box bolt pattern
  • Approved for use on Lippert RV frames

Weight Capacity:

  • Gross towing weight (GTW): 24,000 lbs
  • Minimum pin weight: 2,120 lbs
  • Maximum pin weight: 4,000 lbs
  • Optimal pin weight range: 3,166 lbs to 3,712 lbs

Construction and Color:

  • Material: carbon steel with powder coat
  • Color: black

Warranty:

  • Pin box: limited lifetime warranty
  • Finish: 1-year
  • Parts: 1-year

Notes:

  • Not compatible with offset 5th wheel hitches.
  • Your trailer's pin weight must be between 2,120 lbs and 4,000 lbs for the shock absorption to function as designed.

What is Pin Weight and Why Does it Matter?

Your trailer's pin weight is the amount of weight pressing down on your truck through the king pin. It's the key factor in choosing the right Curt Helux pin box since each model is tuned to a specific pin-weight range. If it's too light, the coil springs won't engage correctly, but if it's too heavy, you'll overstress the system. When this number is accurate, the pin box performs the way it was designed and gives you the smoothest ride possible.

How to Accurately Measure Pin Weight

The most reliable method is to use a set of certified vehicle scales (like CAT scales).


pin box measurements

  • Step 1: Weigh your truck and trailer together with the trailer hitched (truck front axle on Scale 1, truck rear axle on Scale 2, and trailer axles on Scale 3).
  • Step 2: Record the weights from Scales 1 and 2, then add them together. This is Weight A.
  • Step 3: Unhitch the trailer and weigh the truck alone (front axle on Scale 1 and rear axle on Scale 2).
  • Step 4: Record the weights from Scales 1 and 2, then add them together. This is Weight B.
  • Step 5: Subtract Weight A from Weight B. The difference is your actual pin weight.

This process accounts for how your trailer is actually loaded, which includes cargo and water tanks, so you know you're picking a pin box that matches the conditions you're using it with.

How to Estimate Pin Weight

If you don't have access to a scale, you can get a ballpark figure with your trailer's GVWR:


  • Step 1: Find the GVWR on the trailer's specification sticker.
  • Step 2: Multiply that number by 0.22.
  • Step 3: The result is your estimated pin weight.

This method gives you a starting point, but remember it's only an estimate. The actual pin weight can change depending on how you fill tanks and distribute weight in the trailer.



2024122233 Curt Helux Pin Box - Coil Spring Shock Absorption - 4,000 lbs Pin Weight

Installation Details C65MJ Installation instructions


California residents: click here


Ratings & Reviews

4.9

9 reviews
Tired of your trailer tossing you around? Curt's Helux pin box smooths things out with a tough coil spring that beats air bags and torsion setups. It's maintenance-free, easy to use, and won't put your RV's frame warranty at risk.

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Easy to install. Works great. There is a noticeable reduction in chunking.



by:

Glad the pin box was good. The box and pallet were damaged badly. Will be installing it tomorrow. I think it will enhance our ride while towing.



by:

I received this curt helux pin box very quickly. I was impressed with how fast and how the shipment was handled. I've installed the pin box but haven't yet towed our 5th wheel yet. 1st camping trip later this month possibly. Maine weather needs to be a bit nicer. Anyway. So far very impressed with the product.



by:

This pin box is absolutely amazing. Way smoother pull way less chucking ! Highly recommended this over any stock pin box.



by:

I’ve only had my toy hauler out one since installing the hitch but went over a set of RR tracks and 3 bridges and it definitely makes a difference. Greatly soften the blows to the truck so you know it’s taking a lot of stress off the fifth wheel. Watched it workings through the rear view mirror. Simple design that someone should have come up with long ago. Took a friend of mine and I exactly 1 hour to install withe the help of his motorcycle jack on the tailgate of the truck. It’s heavy and well built. They are a little pricey but I feel well worth it for the longevity of the frame. Most importantly know the weight of your trailer loaded to pick the right one


9
9

See what our Experts say about this CURT 5th Wheel Pin Box

  • Identifying Pin Box on 2025 Eclipse Attitude 2919SAG
    Hey Luis! I can help you identify your pin box but you will need to send me a picture of the sticker on the pin box itself. It will have something like an LCI number and S/N which can be used to identify it. You can email me a picture by responding to the email with the link for this page, there is no way to attach it if you respond below. If you don't have a sticker the only way to identify the bolt pattern is to measure. See the help article further down on this page which explains how...
    view full answer...
  • Recommended Curt Helux Pin Box for a Rhino Bolt Pattern
    Hey Russel, thanks for the pictures. The Curt Helux Shock-Absorbing 5th Wheel Pin Box item # C65MJ is the correct one to replace your Rota-Flex with a Lippert Rhino bolt pattern. It has a standard 5th wheel kingpin. There are no gooseneck options. You can continue to use your B&W Companion 5th wheel hitch with the Curt Helux Pin Box item # C65MJ. You won't need the Curt Spyder item # 16085 at all so no need for 5th wheel rails. We do not have the MorRyde Independent Suspension system...
    view full answer...
  • Will The Curt Helux Pin Box Work With My Lippert 1621 Pin Box?
    Hey Lee, For your specific pin box and bolt pattern we do not have a Curt Helux for it yet. Based off of your photo the pin box on your trailer is going to be the Lippert 1621 model, or the Lippert 1621 bolt pattern. We do have a # LC369535, Curt Flex Air, pin box available for that bolt pattern. This is not going to be up to the the 24,000lb, but offers a 21,000lb capacity on it. There is a Gen-Y option for you as well, # GY68GR, for a 30,000lb capacity. Like the Curt Hellux internal...
    view full answer...
  • Do I Need a Locking Plate to Use a Curt Helux Pin Box w/ a Demco Autoslide?
    Yes, they are Martin and thanks for the picture. You will need a locking plate to use a Demco Autoslide 5th Wheel Hitch like item # DM8550024 with a Curt Helux pin box. The correct one is the Demco Autoslide Locking Plate for Lippert Helux Pin Boxes item # DM53KV. This will keep the king pin from rotating inside your Demco Autoslide 5th wheel hitch. I attached a screenshot from the instructions so you can see how to get it setup. The Demco Autoslide 5th Wheel Hitch w/ Slider item #...
    view full answer...
  • What Is The Difference Between Curt Helux Pin Box With Black Spring Vs. Orange Spring?
    Hello Lee, thanks for reaching out. It sounds to me like you have the correct pin box for your camper. It sounds like you did your homework and calculated your pin weight correctly, and the 4K Helux Pin Box # C65MJ would be exactly correct for 3,100-3,400 lb pin weight. For the Helux pin box, the orange spring indicates a factory pin box, and the black spring is aftermarket. There would be no physical differences aside from the color of the spring. You are totally fine to stick with the...
    view full answer...
  • Cushioned Pin Box Recommendation for 2026 KZ Sportster 3411x That Won't Void Warranty
    Hey Kris, the Curt Helux cushioned pin box part # C65MJ that you referenced is approved for use on Lippert RV frames so it would work great and not void any warranties. This is designed to replace the Lippert Rhino pin box. Is that what you have? I wasn't able to determine for sure that is the style pin box your KZ would have came with.
    view full answer...
  • Looking for Cushioned Pin Box for 2005 Alpenlite 5th Wheel
    Hey Gary, it most likely does not since the Rhino Pin Box type that the # C65MJ is designed to fit is a newer design that wouldn't have been around in 2005 but if you can let me know what pin box you do have I can see what would work for you. On the pin box you have there will be a sticker that has its model number listed. Most likely it's a Lippert 1621 but due to the age of your trailer it could be a few others as well.
    view full answer...

Do you have a question about this 5th Wheel Pin Box?


Info for this part was:

Employee Lindsey S
Updated by:
Lindsey S
Employee Wilson B
Updated by:
Wilson B
Employee Alex H
Updated by:
Alex H
Employee Jameson C
Expert Research:
Jameson C
Employee Katherine B
Edited by:
Katherine B
Employee Andy C
Installed by:
Andy C
Employee Kim H
Written by:
Kim H

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