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Open Roads Forum  >  Towing

 > Trailer Bounce oscillations

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ApexAZ

Gilbert, AZ

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Posted: 09/23/21 11:54am Link  |  Quote  |  Print  |  Notify Moderator

Hi all,

I have some experience towing small toy trailers < 3k lbs, but never anything as big or heavy as our new toyhauler.

Is it normal to feel the back end bouncing / oscillating up and down when you go over bumps? It doesn't feel extreme, but after the initial bump, it kind of has this mild, diminishing bouncing sensation that happens 2-3 times.

We have a WD hitch that I believe I set up properly, but wondering if this is considered normal on a conventional hitch setup.

Thanks,

Brian

TurnThePage

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Posted: 09/23/21 01:39pm Link  |  Quote  |  Print  |  Notify Moderator

Most trailers don't come with shocks, which would correct that behavior. If it's really bouncing that much, the springs might be undersized too.


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Posted: 09/23/21 02:51pm Link  |  Quote  |  Print  |  Notify Moderator

More specifics plz. Is the trailer bouncing or is the nose/tail feel and/or look in the mirror like it’s teetering on the axles. Is the truck staying pretty much steady while the trailer is bouncing?
If the trailer is bouncing on its own, then putting shocks on the trailer would definitely help. If your whole rig is porpoising that’s a matter of getting stiffer shocks on the tow rig. Btdt


2017 Ram 2500 w/stuff
2016 ORV Timber Ridge 240rks w/more stuff

fj12ryder

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Posted: 09/23/21 02:57pm Link  |  Quote  |  Print  |  Notify Moderator

Size/weight of trailer, and size of truck would be helpful too.


Howard and Peggy

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ApexAZ

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Posted: 09/23/21 02:58pm Link  |  Quote  |  Print  |  Notify Moderator

Over here wrote:

More specifics plz. Is the trailer bouncing or is the nose/tail feel and/or look in the mirror like it’s teetering on the axles. Is the truck staying pretty much steady while the trailer is bouncing?
If the trailer is bouncing on its own, then putting shocks on the trailer would definitely help. If your whole rig is porpoising that’s a matter of getting stiffer shocks on the tow rig. Btdt


It's a 2020 GMC 3500 SRW with a 4" lift (blocks between springs and axle). The trailer is a 36' conventional hitch with 2 axles / leaf springs.

I don't actually know the weight of the trailer yet, but dry it's rated at 1400 TW and around 8700. It's a toyhauler so it is a bit tongue heavy.

When I go over a bump, it feels like the nose of the trailer is pitching down and it feels like my rear end compresses and softly bounces a few times. Bounce may be the wrong word too. More like waves of compression, or soft bounce. I guess it sort of seems normal since the trailer is pivoting at the hitch, which is between the wheels, I'm just not sure how much is considered normal.

theoldwizard1

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Posted: 09/24/21 06:16am Link  |  Quote  |  Print  |  Notify Moderator

A lot depends if you have a single axle or dual axle.

Dual axle with independent suspension is supposed to be the best.

ApexAZ

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Posted: 09/24/21 09:45am Link  |  Quote  |  Print  |  Notify Moderator

theoldwizard1 wrote:

A lot depends if you have a single axle or dual axle.

Dual axle with independent suspension is supposed to be the best.


The trailer has 2 axles.

Fuel F-287
36'9"

Tow vehicle: 2020 GMC 3500 SRW standard bed with 4" lift (blocks in the rear)

I went to the scales last night and here is what I got:

Trailer was dry with the exception of 2 full 30 gal LP tanks. No toy loaded.

Trailer: 9180
TW: 1500

TV Front: 4580 (down from 4900)
TV Rear: 5440 (up from 3620)
Trailer Axle: 7680

Gross weight: 17,770

I'm not sure if a 6.5% weight reduction in the front is that concerning, but I can still do a couple things on the hitch to try and push more weight forward. I may also add some bags in the future to reduce the rear end sag a bit. The truck is lifted, so that makes it difficult to get it more level.

Sjm9911

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Posted: 09/24/21 10:34am Link  |  Quote  |  Print  |  Notify Moderator

Is it happening when your loaded up or not loaded? The toy in the back will reduce the tongue weight. When i had a pop up the porposing was either from not enough tounge weight or the trailer toung was too high. So is it level or a little bit toung down when you tow? And thats when its loaded. If you set up un loaded and add a toy it will change stuff depending on how much weight you add. So empty may need to be a bit more toung down. Also some concreate highways can cause a vibration at certian speeds, so it kind of resonates throughout. You need to change the speed when that happens to break the cycle. Play with it a bit , you'll get it better.


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Grit dog

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Posted: 09/24/21 10:40am Link  |  Quote  |  Print  |  Notify Moderator

ApexAZ wrote:

Hi all,

I have some experience towing small toy trailers < 3k lbs, but never anything as big or heavy as our new toyhauler.

Is it normal to feel the back end bouncing / oscillating up and down when you go over bumps?


I'll say 100% normal. She's a big piggy, and your 1 ton springs and whatever the wdh is pulling off for weight is just fine with your truck.
Toyhaulers are (obviously) tongue heavy and axles further rearward to handle the weight of "toys."
The result is a trailer that especially with no significant weight back in the garage area, pulls very straight but also has a large cantilever from the axles to the tongue. So you're going to feel it more in the ass end of the truck. But that's why trucks have springs and shocks.

Like me, you're lifted and probably have a 6/4 lift so it's level unloaded.
Loosing a few hundred lbs off the front axle makes ZERO difference. Already got a diesel anchoring the front end and it's probably still heavier on the FA than a gas truck. I call all but guarantee the front end doesn't feel light or wander.

I installed bags, but I'm not using a wdh and I have coil spring Ram 2500 so the bare tongue weight of the trailer was dropping the back of the truck alot. Looked like the Carolina squat.
The bags not only level the truck but take out the bounce of having a significant load on the springs.


2016 Ram 2500, MotorOps.ca EFIlive tuned, 5” turbo back, 6" lift on 37s
2017 Heartland Torque T29

Grit dog

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Posted: 09/24/21 10:52am Link  |  Quote  |  Print  |  Notify Moderator

You can simulate a little help from a suspension aid real easy.
If you have time, do this.
Cut some wood wedges or buy 4 hockey pucks or plastic felling wedges.
Insert them in your leaf pack above the bottom overload spring. So the springs get into the overload as soon as load is applied. Secure with hose clamps or even a good cinch with baling wire/tie wire.
That will stiffen your rear suspension under load.
Leave the wdh at home. Hook up and take a spin down the highway. Will give you a good idea what Stable Loads/helper springs/air bags with moderate pressure would do.
Stiffer rear springs will reduce the bounce you’re feeling.

Again, your truck is 100% capable and safe, actually ideal, for a trailer this size.

If you want send me a PM and we can talk. That trailer should pull like a dream with only minor tweaks.

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