I had always been satisfied with the Rancho 9000 shocks on my 2020 F350, until I started towing my 29', 7500 lbs Keystone travel trailer. The porpoising has been bad and getting worse. I'm on a 3 month cross country trip and sure would like to change these suckers out. Any suggestions for a good shock to tow my trailer with my 2020 F350 with stock suspension?

Thanks!

 

I don't think there's any good way to mitigate that with a shock swap. Certain roads are just like a bucking bronco...

 

I would tend to agree... I doubt a shock change is going to fix the problem. While I am definitely not a fan of Ranchos' or twin tube shock designs in general, I doubt the shocks are the problem. Going to a monotube like a Bilstein might help a little as they will not fade nearly as quickly as the Rancho's but, hours on a rough road with a load on is going to fatigue even the best shocks.

Often it is the road in my experience. My friend rode along to pick up some equipment in SLC. He tends to badly overload his truck with tongue weight because he thinks it fixes this problem. I loaded the machine and we hit the road. It was porpoising a little at first and he started in on his diatribe about how I had the machine too far back. Within a few minutes the road surface changed and no porpoising for the rest of the 6 hour drive. without making any load adjustments.

You can try moving weight around in the trailer but not many options with a travel trailer. You could try a set of monotube shocks. You could make adjustments to your weight distributing hitch if using one. Good Luck

 

I have an 18' trailer that bounces no matter what I do. I am not sure if it is the design, or if it is just the incorrect length of the hitch to axles. Rough roads certainly enhance the issue.

 

Porpoiseing is just an interaction between the pavement and the vehicle’s suspension. When the vehicle travels over jointed pavement at a particular speed, the vehicles suspension will always react to the profile of the pavement at the joint. At a particular speed and the particular dynamics of the vehicle’s suspension will sometimes be excited in a sinusoidal manner that effectively amplifies the effect.

there is no amount of suspension tuning you can do that will eliminate it completely on any jointed concrete road. The only thing you can do is travel at a speed that eliminates the resonance between the suspension and the profile of the joints on that road at that time of day. Try traveling at slower speeds and you will likely find a speed that doesn’t resonate with the road.

FWIW, we are currently kicking off a big research project at work directly related to this phenomenon. This is not an unknown problem for DOT’s but the ultimate solution is not readily apparent. This is because the profile of the road actually changes from hour to hour and day to day. Our research project is focused on developing a way to accurately measure the road profile, determine how it will react to heavier vehicles and develop a treatment method to help mitigate the effects of what we call “warp and curl”.

if successful, we will be able to predict what roads are going to be a problem before they generate complaints and treat them proactively rather than reactively as we currently do.

hate to say it, but all you can do is slow down. Sometimes you can speed up and get above the resonance, but usually that speed will end up in excess of the posted speed limit.

shifting the load can help also as stated above because it changes the tuning frequency of the vehicle’s suspension. But as above, there is only so much you can do with a travel trailer.

 

So true, there is a 10 mile section of I40 in AZ. If I tow the horse trailer with the excursion 55 to 60 mph max, tow it with any of my trucks no problem, tow the car trailer or the dump trailer with the excursion no problem.
doesn't matter how the horse trailer is loaded either or even empty.

 

I agree that there are some roads that so bad, no amount of tuning can eliminate poor handling.

That said, a couple of questions:
1. What setting do you have the front Ranch 9000XL shocks on?
2. What WDH do you have and how confident are you that it is setup properly?
3. How well is the weight distributed within the trailer?

I can reduce porpoising by increasing the setting on my Rancho 9000XL shocks. It won't eliminate it but it does help. If my WDH isn't setup right I'll get more porpoising. I'm satisfied with how my Rancho shocks perform. I recently developed a vibration that I'm trying to figure out. Changing the shock setting didn't help. The tires were rebalanced, but I haven't had a chance to test that. However, since the tech said three tires were OK and one was off by only 1 oz, I suspect that the tire balance isn't the issue.

 

Good comments and questions, thanks. I have the Ranchos dialed all the way up to the max. I am using a weigh safe WDH ( https://www.weigh-safe.com/product/t...ibution-hitch/ ) I know the tongue weight and have been to the CAT scales a few times. I have also calculated the forces manually, and those calculations correspond to the CAT scales, so I am confident of the WDH setting. I used to run a Huskey Center Line, and the porpoising was slightly worse.

The setup isn't achieving resonance frequency because it does dampen out, but it is definitely under damped. The problem has become worse, so I'm thinking that maybe the Ranchos have worn out, even though they are only three years old. That's why I was thinking a heavier shock would help, one that isn't overworked and wears quickly. I admit that I have little experience with different types of shocks. Stiffer and more shock should improve the damping, but maybe sacrificing ride when not towing. It would seem that adding shocks to the TT would help, but without knowing for sure, I'm probably not going to start an experiment of welding shackles to the TT. With shocks being a big debate on the main forum, I was hoping you guys might have a preference.

Thanks!

 

There is a bolt-on solution for trailer shocks. I've seen it, but never really looked into it. I would rather have a welded solution. That's what my toy hauler has. I don't know that the trailer shocks make that much of a difference in porpoising. I do know that Lipper trailer shocks are incredibly light on resistance. I thought my shocks (probably OEM) were shot. But when I received my exact fit Lippert trailer shocks they performed exactly the same. I spent a bunch of time to find a set of Monroe Magnums that were the same size and had the right fittings.

 

Just something to think about regarding your comment above. Obviously, I'm not there to drive or ride with you, but it is still possible that you are seeing ride affects from the road profile. The profile of the joints, and the resulting ride, is not a constant for any given section of road. The warp/curl profile of the road will change from segment to segment within the same project. If it rained the night before that segment was paved, that will change the profile of the road in a specific way. If they didn't get enough curing compound on that segment, it will affect the profile in a specific way. If it hadn't rained in a while and the granular section started to lose it's moisture, that will affect the profile in a specific way.

I say all of this just to indicate that you could have vastly different ride characteristics within any roadway segment that would give the same ride effect as a problem with damping. It could very well feel like your truck was bouncing forever from a roadway defect, then come out of it, then go back into that same underdamped feeling several times within a mile or two all because of the changing profile of a jointed concrete pavement.

Now, all of that said, your shocks could also just be worn out and unable to control the load. If that's the case, get new shocks and replace them when you start seeing the same problem again.

I've never tried the adjustable Ranchos. I've got Bilstiens on my expedition and all-in-all, I'm not that happy with them. They ride good. they offer good control, but they weren't the night and day difference i was expecting compared to the stock units. They both rode good and offered good control. The factory struts were still good at 90k when I replaced them (except one leaker in the front). Now with about 75k on the bilstiens, i can tell the fronts are losing their ability to control the wheels under sharp inputs. I paid a premium for the bilstiens under the assumption (and sales pitch) that the mono-tube design would last longer than a twin-tube design. I have not found that to be the case. So i spent $1200 on struts and installation for units that rode as good as the factory struts and didn't last as long. Not exactly a win IMO. I could have gotten the Gabriel Ultras that ride as good, and cost half as much (installation is still a killer on an expedition). I will not buy bilstiens again. I recently put shocks on our F250 and i got the Gabriels. No need to spend the extra IMO.

So, get what you think will work for you and replace them when you start seeing a problem.

JMHO

 

There is a section of road north of Fort Collins, Colorado on I-25 in the right hand lane, going both north and south, that is absolutely terrible when towing. But the left hand lane is quite nice. It's like two different companies, crews and methods where used in the left and right lanes. Going south of E-470 on I-25 towards Castle Rock, Colorado there is a section that I call the boob jiggler. That section convinced my wife that new/different shocks were in order. The Rancho 9000XL shocks made a difference in this section but not so much in the section north of Fort Collins. Sometimes a bad road cannot be handled well by any shock.

 

I don't have experience towing big stuff, but wonder if any type of air bag system would help dampen out the problem.

 

I agree that that I am seeing ride affects from the road profile. Thanks for all the comments. Also, thanks for saving me cost of trying Bilstiens. That was going to be my next move, but now I'm going to look into camper shocks a little more.

 

I'd say the issue is more with your trailer suspension than it is the shocks on the truck. Late in 2021 my wife and I bought a 36' TT. On the two lane going to the main highway from our house there are several bridges. The truck would porpoise every time I hit the bridge joints at 50 MPH which is the posted limit. It was rough enough that I would slow to about 40 MPH every time I approached one of the bridges, irritating to the drivers behind me I'm sure.

Fast forward a year. The wife complains about "her stuff" inside the RV being bumped and moved around when we travel. I watch a few YouTube videos and see people reporting how dampened equalizers make a huge difference in the smoothness of the RV ride. After watching several videos describing the differences between the various types I decided to buy the Lippert Road Armor equalizers. Hey, while you're there you may as well get rid of the crappy nylon bushings and dry bolts holding the leaf springs and equalizers and install a wet bolt kit with the proper length shackles and bronze bushings. Off to etrailer.com I go.

The Lippert Road Armor kit has rubber dampeners on both sides of the equalizer. The MORryde kit only has rubber on the upper side of the equalizer. Hmmm. I opted for the Road Armor, thinking that rubber on both sides would offer better dampening of spring and axle movement. Now to get the wet bolt kit with shackles and bronze bushings to hold it all together. Hmmm - the Lippert kit is $300 and it doesn't include the bronze bushings to replace the nylon crap from the factory - they are an extra $60. Wait - MORryde sells a kit with the bronze bushings for $150. SOLD. I install the kits with my RV friend, hook up the Super Duty and we take it on the road for a test drive.

Lippert Road Armor Equalizers: https://www.etrailer.com/Trailer-Lea.../LC696740.html

MORryde Suspension Upgrade Kit: https://www.etrailer.com/Trailer-Lea...de/MR76ZR.html

Lippert Road Armor dampened equalizer. Note the heavy rubber cushions on both sides of the equalizer and the bronze bushings it comes with:



MORryde shackle & wet bolt kit with bronze bushings:


Road Armor and wet bolt kit installed on the RV:


As I tow the RV on the twisty road from my house to the two lane we noticed immediately that the RV suspension is silent because of the bronze bushings and wet bolts. Nice. I pull onto the two lane and take off. I am talking with my RV buddy about how quiet it made the RV axle movement when I realize we are approaching the 1st bridge. I don't have time to really slow so I just cross it at 50 MPH, bracing for the porpoise event. We crossed the bridge and ZERO porpoising occurs. Huh. I anxiously await the next bridge - it's about 3 miles up the road. We hit it at 50 MPH - same result. Next bridge - no porpoising. We continue on to the main highway, where there is a stretch that always causes the RV / truck to porpoise for about 1/2 mile or so and generally just feel less stable than preferred. WOW !!! It is so much better I can't believe it. For $500 and 3 hours of my time to install the kits I can't think of a bigger bang for the buck investment I've ever made in a vehicle.

This is one of the few times I can honestly say that a suspension "upgrade" actually made a real difference in the ride of the vehicle. I guess the rubber dampens the suspension movement enough to reduce or eliminate the resonance between the truck / RV combo and the highway joints. Whatever the case it is amazing how much better the RV tows with the change in suspension hardware. A bonus is now I can grease the RV to help keep it all moving smoothly. I am currently debating if adding shocks to the RV will help further with ride quality and RV longevity.

And yes, it did help with the amount of "stuff movement" in the RV that my wife was complaining about. I'm more excited by the towing improvement but we both got a win so I'll take it.

 

I doubt that I am towing as big as you, but can say I put Bilstein 5100s on my truck rears this spring, took all the extra bounce out. Took the wind effect out as well.