Tuesday, January 31, 2023


Ask Dave: Can weight distribution hitch bars get weak?

Dear Dave,
Do the bars on an equalizer hitch lose their carrying capacity over time? My old hitch had 1000# bars and the rig would porpoise a lot going over seams and humps in the road. I switched to newer 1200# bars and the ride is much better. —Larry, 2006 Vortex 224 FB TT

Dear Larry,
I cringed when I first thought about using your question for Ask Dave, as the topic of “weight distribution” fills my comment box every time! However, I thought it might be nice to go into the weekend pulling the knives out of my backside as I have not explained how a weight distribution hitch works very well in past articles. So, I’m not even going to attempt to discuss that, but rather maintenance and some advice from the companies that make the hitches.

Types of weight distribution hitches

There are several different companies that offer a weight distribution or equalizing hitch system. They include Equal-i-zer®, Blue Ox, Roadmaster, PullRite, and CURT™ (owned by Lippert).

According to my CURT Technical Advisor, there are two types of weight distribution hitches: the round bar and the trunnion spring bar types. The round bars attach to the underside of the hitch, while the trunnion bar attaches to the face. They are similar in operation; however, the round bar has less clearance to the road as it protrudes underneath.

Round bar
Trunnion bar

He went on to state that technically the spring bar in both situations could lose some tensile strength or weight carrying capacity if it is being operated at maximum load or more for a period of time. However, it would be so minimal that you would not notice it in the ride.

The hitch does not create “porpoising”

The technical adviser went on to say that the hitch cannot create porpoising. It is only reacting to what is happening at the suspension of the truck or trailer. He suggested having the shocks and springs of your tow vehicle inspected and getting the trailer weighed to find out what the actual tongue weight is. It may be that your rig is at the maximum 1,000-lb. tongue weight and your old hitch worked well, but then the shocks or leaf springs became weak and the result was the porpoise effect. It is also possible that you have loaded the coach differently, such as with more water in a forward-located fresh water tank. Getting weights will help tell the story.

Other technicians I have talked to indicate the connecting points will wear before the spring bars lose weight-carrying capacity. Sometimes you will see enlarged holes or loose pins. If your trailer brakes are set too low, the starting and stopping will cause the trailer weight to push and pull hard against the connecting points and elongate the holes as well.

 You might also enjoy this from Dave 

How does a weight distribution hitch work?

Dear Dave,
How does a load-leveling hitch work? I can’t seem to get my head around it. —Gary

Read Dave’s answer.

Dave Solberg is a leading expert in the RV industry and the author of the “RV Handbook.”

Read more from Dave here


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Bob M
1 month ago

It would be nice if RV travel could get a expert to explain what causes porpoising and how to stop it. I ‘ve had two different travel trailers. One 28’ with no porpoising. Presently a 34’ Jayflight 29RKS that porpoises on some Pa concrete highways. Same WD bars used on both travel trailers. One Jayco dealer said WD bars were to heavy. Went to lighter bars still porpoised. Another rv owner said there’s nothing that can be done. Was told I need a longer bed truck. Went to F150 with 6’ bed. Still porpoised. Another guy said I need airbags on rear. Yesterday I asked another RV technician and 5th wheel owner.about the airbags. He said they don’t work. That there’s nothing that can be done about it. He even told me what road does it to him which is the same road & area I have problems. Help

Larry with the 2006 Vortex
1 month ago

I am pulling my Vortex with a 2004 Ram 2wd 3/4 ton Cummins. I have Bilstein shocks on all 4 corners with new ones in the rear. My “old” truck has 160K miles and I love the truck. My old bars were the round bar type and have been around for a while. The new bars are the trunnion type. Both hitches were made by Reese. I have had my rig on the scales loaded and nothing seems out of range. The newer hitch really seems to make a more enjoyable ride.

Jim Johnson
1 month ago

Not entirely on topic, but I am using a Curt “Rockerball” and loving it. Likely won’t work for many weight distribution hitches, but sure is good for our single axle camper. The design all but eliminates the shove/pull surge from the trailer when passing over less than ideal surfaces.

My only complaint is Curt did not release a series of receiver draw bars to specifically offset the added height of the new ball. I was forced to buy a new draw bar from a competitor.

Tom E
1 month ago

As to “porpoising”, it took 3 modifications to eliminate most of my “porpoising”. I went from 6000 lb to 10000 lb bars, added shocks to the trailer, and replaced my 1/2 ton truck shocks with more heavy duty shocks. A 4th modification, adding an anti-sway bar to the rear of my truck, significantly reduced that “wiggle” you get when passed by a bus or motorhome. With these 4 modifications, the bumper pull trailer experience with the 1/2 ton was close to that of my 1 ton dually pulling a 5th wheel.

1 month ago
Reply to  Tom E

Was the “… anti-sway bar to the rear of my truck, …” actually added to the truck or was it between the truck and the trailer? Thanks.

Tom E
1 month ago
Reply to  volnavy007

Added to the truck. It also significantly reduced cornering issues when not towing the trailer – especially in wet conditions.

Tom E
1 month ago

Usually the damage to the steel bars comes in the form of micro fractures. Yes, those steel bars can weaken with use, just like your trailer springs flatten out with time. Bend a piece of metal back and forth enough times and it forms micro fractures & eventually it will break, just like your trailer springs. That said, pulling a 6000 lb trailer, I switched out my 6000 lb Equalizer bars for 10000 lb bars and it made a world of difference.

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