Bouncing when towing travel trailer

[Joe Merchak]

Hey Guys

I have a 2018 Express with 5.7 and 3.21 axle. My travel trailer is a Spirit 2758RB empty weight of 6000lb and gross of 7500. I have WDH and have a 1/4 increase in front and 1" lower in rear when hooked.

My issues is I get this bounce or wave feeling when towing. It does not bother me but its making my wife sick. I was thinking need to stiffen up the rear to help counter this motion. I dont want to replace the springs because I like the ride when not towing. Would air bags help with this? If so which ones do you guys recommend?

Thanks
Joe

 

[Charles Saucier]

I have a 2018 quad cab exactly like yours, 5.7 and 3.21 axle. I had the same issue when pulling our 2019 23' 6200 lb travel trailer plus some what I refer to as flutter when semis passed us on the Interstate. Tried to get it out by changing the adjustment on the WDH but I couldn't achieve what I was trying to accomplish, my wife was also getting motion sickness. I installed some Air Lift 2500 lb bags and with 35 lbs of air in them it seems to have really helped, truck wave/bounce is gone. I dropped the ball to the lowest height and then just aired the bags up until the trailer was level. It is probably as good as its going to get until I wear out these OEM tires and get tires with a stiffer side wall. Still a small amount of flutter but bounce is definitely gone. Good luck.

 

[crash68]

Airbags can help fine tuning your trailer WDH set up. Sounds like need to tighten the WDH up, putting more weight on the front end. At minimum you want to put all the weight back on the front end, with it being higher it's light. Ideally take the truck to a set of CAT scales to check and set up the WDH.
Search out posts by VernDiesel on this site for tips on setting up a WDH.
https://www.ramforum.com/threads/looking-at-the-numbers.123099/

 

[joshuaeb09]

Dialing in your WDH should help as noted, but I would get the same issue with light utility trailers sometimes on my truck. I swapped the springs with the TTC-1211 XHD's and replaced my worn out sway bar end links with moogs which pretty much killed all of that. I prefer the firmer ride since its closer to what I'm used to in a truck and it's not really all that harsh. I'll eventually get a hellwig if I start towing more frequently, but the springs and better end-links are fairly cheap. You can also get stronger variable rate springs if you wish to keep that softer OE ride when unloaded.

 

[sandawilliams]

Hey Guys

I have a 2018 Express with 5.7 and 3.21 axle. My travel trailer is a Spirit 2758RB empty weight of 6000lb and gross of 7500. I have WDH and have a 1/4 increase in front and 1" lower in rear when hooked.

My issues is I get this bounce or wave feeling when towing. It does not bother me but its making my wife sick. I was thinking need to stiffen up the rear to help counter this motion. I dont want to replace the springs because I like the ride when not towing. Would air bags help with this? If so which ones do you guys recommend?

Thanks
Joe

Bags will help but I would try HD tires first. Those car tires aren't really made for towing much.

 

[Joe Merchak]

Based on my WDH instructions my setting is dead on. I will take it to a cat scale and get it weighed but I dont feel the steering is light or heavy so I dont think I have an issue with the weight distribution. I did forget to put down I have the 20" rims if that has anything to do with it.

I did read all the tips under the link you posted prior to asking the question.


The feel is definitely in the rear but this is my first truck with coil springs in the rear as well.

I guess I go to the scales this weekend to get a print out of weight and go from there.

Thank you for some guidance.

 

[cmac7203]

Double check your tires. 1500s tend to use P rated tires (sometimes D or kE) and my guess you have either P or D. As a result you have softer sidewalls which will create a LOT of bounce and flex. Upgrade to a load range E which have more belts, are stiffer, and require much higher PSI. That change alone will make a huge difference in the bounce factor.

The problem with air bags alone is they only level, and don’t do anything for weight distribution. That’s a pretty common misconception. You can run bags only, be nice and level, no WDH, and scale it and be shocked how much weight has shifted FROM the front axle to the rear axle. Challenge there is a floaty front end that won’t steer or brake the way it needs to. Optimum is WDH to keep weight distributed correctly across ALL axles, and if you want run bags to fine tune the level. Don’t depend on them alone.

Just my $0.02 worth.


Sent from my iPad using Tapatalk

 

[Joe Merchak]

What tires do you guys recommend? I have the goodyear P275/60R20 now

 

[TMyers]

What tires do you guys recommend? I have the goodyear P275/60R20 now

As stated above, that "P" rated tire is a lot of your problem. You can get the same tire in a "LT" or light truck 10 ply (E load range) tire. LT275/60R20

Side Note: Back in the early 90's we ran a Top Alcohol Dragster. We came to Englishtown every year.

 

[Joe Merchak]

Thanks guys. Sucks as they are brand new. It is becoming winter here in NJ so we wont be taking the trailer out anymore this year so I guess I start shopping in the spring for LT tires. I will still get it weighed at the scales just to make sure my WDH is set correctly.

Again, thanks for all your help.

 

[OC455]

Thanks guys. Sucks as they are brand new. It is becoming winter here in NJ so we wont be taking the trailer out anymore this year so I guess I start shopping in the spring for LT tires. I will still get it weighed at the scales just to make sure my WDH is set correctly.

Again, thanks for all your help.

What kind of WDH do you have? I thought I had mine set for my truck per the instructions. Had to re-set mine twice. Going to a CAT scale will tell you more about what you need to do for setting your hitch. Getting your tongue weight between 10-15% is where you'd want to be. aka: VernDeisel's post.

Timber Grove air springs are great for getting everything dialed in too. Once you get your hitch set, then put enough air in to stabilize and eliminate the porpoising back and forth. ( I only run about 12 to 15 psi in my air springs depending on how my camper is loaded.)
https://timbergroveenterprises.com/old-home

I would start with the hitch and air assist springs before tires. If you look at tires next, look into XL rated tires. They will have a better side wall and higher load rating. Probably won't change your ride quality very much if you like the ride as it is now.

 

[Riccochet]

Had same issue with my current and last Ram. I added AirLift 1000 helper bags to both. For normal, non-towing they're aired down and you'd never know they are there. While towing the travel trailer I air them up to 30 PSI after hooking up. No more bounce. Cheap and very effective.

 

[Joe Merchak]

This is the WDH I have:
https://www.etrailer.com/Weight-Distribution/Equal-i-zer/EQ37100ET.html

 

[cody mummert]

i have the same hitch. and timber grove air bags i have been putting about 11 lbs in them and my hitch brackets are set to the highest setting it seem i want to go to a good shop to help me fine tune it i still get the floating feeling my tt is 6600 lbs dry

 

[Mcgruff]

Thanks guys. Sucks as they are brand new. It is becoming winter here in NJ so we wont be taking the trailer out anymore this year so I guess I start shopping in the spring for LT tires. I will still get it weighed at the scales just to make sure my WDH is set correctly.

Again, thanks for all your help.

If tires are close to new you can sell them on Craigslist, Facebook, etc. or see if tire store will buy/credit toward new tires. I bought my 1500 used from a dealership who put new Sailun (Chinese) P rated highway tires on it. Not bad tires really, but wanted AT for traction and E rated for towing. Discount tire gave me a couple hundred dollars credit toward some BFG KO2s. Not much but it helped a little. Just don’t wait too long as the more tread you use the less they’ll give you. You’ll make more selling them yourself but of course, you take a risk and it can be a pain finding a buyer.

 

[Mcgruff]

Had same issue with my current and last Ram. I added AirLift 1000 helper bags to both. For normal, non-towing they're aired down and you'd never know they are there. While towing the travel trailer I air them up to 30 PSI after hooking up. No more bounce. Cheap and very effective.

“After hooking up”? Supposed to be aired up before adding weight. That’s what I do.

 

[Joe Merchak]

Well we are going to do 1 more trip. The weather looks like it going to be ok for thanksgiving so we are going to take it to a place in PA for a 4 day weekend. I am going to try to get to the CAT scales this weekend to see what the weight on the rig is so to verify I have my WDH setup right.

I am also going to try to get to my tire place and see if I can get money for the tires for some LT tire since I only have 3K on the truck.

Thanks for all the info guys, you have been a great help.

Joe

 

[OC455]

From VernDiesel:

I've never been in the habit of weighing the unloaded truck with passengers but can't say that it is wrong or will dramatically change the unloaded steer weight. If anything it will just set the bar a little higher for replacing the unloaded steer weight and make your window to reaching max steer axle weight a little bit smaller. Which using max steer axle weight is rare anyway. Thinking about that it should actually make calculating your seen tongue weight a little more accurate as well. check

Weigh loaded truck and trailer with no weight distribution. check mostly to see what progress you make.

Weigh loaded truck and trailer with the weight distribution. check This is where I was saying to lower your stress you can simulate passengers weight with other weight so that they are not waiting on you and you have whatever time you need.

Adjust as necessary to get optimal weight transfer, then adjust air in the TG air springs. check



Follow hitch Mfg instructions and adjust WDH, you can also rearrange the load in your truck, and the load in your TT. Then re-weigh until you have at minimum replaced the unloaded steer weight and gotten the drive axle weight down to max axle rating or below. A closer to 50/50 bias is generally ideal.

Subtract unloaded truck weight from the loaded truck weight for accurate TW. (tongue weight) (This is because when using a WDH TW is no longer static weight but rather dynamic weight IE it affects steer drive & TT axle weights) That number divided into the gross trailer weight will be your TW percentage. This needs to be between 10 & 15 percent.

Now you have a safe tow with maximum stability for emergency swerve around for accident avoidance and maximum stopping power. You should still review your scale slips for CVW, (combined vehicle weight) GVW, (gross vehicle weight).

Note by adjusting hitch & load you can raise or lower your TW and truck GVW. Sometimes with heavier trailers for warranty & such people want the TW down to where they are below the trucks GVWR. Other times the priority is a little more TW for maximum stability. Physics wise on a bumper pull its preferable to have more weight on the TV axles than on the TT axles so the tail can't wag the dog as they say.

Lets do a worse case scenario 10k trailer kind of stuff. Say you have moved what weight you can forward in your truck and cranked the WDH for all it can give you and rearranged some of the heavier items back into the trailer above the axles or perhaps even some behind the axles and you are still light on steer & heavy on the drive. You can still remove the 60 pound tailgate & replace with a net or relocate the 60 pound spare from behind the rear axle of the truck that is 120 pounds off the rear axle right? Not so fast taking this 120 off the drive axle may have also allowed the WDH to take an additional 20 pounds off the drive axle and transfer it to the steer axle. Also lets say you relocated that 60 spare to the back of the trailer on the rear bumper or under the trailer behind the axles. Now that 60 pounds helps the WDH to take say another 20 pounds off the drive axle and either steer axle or perhaps off the truck entirely and back to the trailer axles. So you might have transferred 20 to the steer and 140 to the TT by taking 160 off the drive. Granted this is sort of an over the top example to help understand how it works. BTW you might also be able to get a stronger swing bar hitch for that kind of extreme weight.

To some guys its kind of a fun challenge not so much just to be in spec and or in the zone so to speak but to get the best numbers they can. Anyway let me know when you get your numbers. Vern

 

[Gary McOrmond]

Hey Guys

I have a 2018 Express with 5.7 and 3.21 axle. My travel trailer is a Spirit 2758RB empty weight of 6000lb and gross of 7500. I have WDH and have a 1/4 increase in front and 1" lower in rear when hooked.

My issues is I get this bounce or wave feeling when towing. It does not bother me but its making my wife sick. I was thinking need to stiffen up the rear to help counter this motion. I dont want to replace the springs because I like the ride when not towing. Would air bags help with this? If so which ones do you guys recommend?

Thanks
Joe

 

[Gary McOrmond]

Check your tow brake unit. I had the same issue and it was the unit applying the brakes rapidly and creating the waves. The dealer re-flashed the unit and it has worked perfectly ever since.