Boat Trailer Hwy Bounce

[Skipper21]

Have a trailer bounce problem on concrete Hwy only 50-65 mph. Tow vehicle 2011 Dakota quad cab V8 magnum, trailer 1999 Bayliner Capri 18 ft fish/ski boat, only happens over concrete hwy not asphalt. It has done this when I had my 2001 Dakota SLT and with my 2011. Had 4 different brands of tires over the years all balanced and same issue. Is this a wheel base issue or tongue weight, newer Hwy tar lines?? Have tried strapping the boat vertical to the trailer at the front with no difference. Heard this is a common problem and try putting 200lbs in back but haven't tried that yet. Not thrilled about that option every time boat goes out. Tongue weight drops hitch about 1 1/2 inches. Any input appreciated would like to take longer trips but this can't be good for the truck or trailer & boat.​

 

[M2HB]

You have covered several reasons for it. Concrete freeways are notorious for expanding and creating bumps.
I assume it is a single axle trailer since tandems with leaf springs have an equalizer that minimize this issue.
I also assume that it has leaf springs. If they are too stiff, you can get a trailer to bounce.
I would check your tongue weight. You want from 10 to 15% weight on the tongue. The longer the tongue, the more stable the trailer will usually be.
You don’t want to put more weight in the back. That can create some serious stability issues.

 

[MTboatguy]

There is really nothing you can do, concrete slabs are poured at a fixed interval and you are running into the seams, asphalt is much easier to make a smooth seam with, you are just bouncing over the seems, slow down a bit and it will be far less noticeable, or add weight to your trailer.

 

[Skipper21]

Yes single axle leaf springs. Guessing by dead lift, tongue weight to be about 200lbs. Boat weight about aprox 2,100lbs.
Wondering if the shorter wheel base of a Dakota verses full size truck makes this a bigger issue. A trailer expert told me if the wheel base of the tow vehicle is the same as the tongue to axle wheel base sometimes can make the bounce much worse. Thinking of trying a friends F150 as a tow vehicle on the next trip to see if there is a difference. I meant to say adding weight to the back of the tow vehicle bed not back of boat for a test that would most likely create a hazardous sway good point. What if I tried a couple of concrete blocks in the bow of the boat for a test to see if there is a difference on that stretch?

Appreciate the comments!

 

[MTboatguy]

It is amazing how much those joints on concrete can vary, especially on a single axle trailer with short springs.. My Dad was a contractor and we built a lot of concrete pad roadways and by there nature they cause weird things to happen to trailers. Remember just because the speed limit sign says 75 does not mean you have to do 75! When towing, vary your speed and find out on your combination what rides the best and then stick to it.

 

[Scott Danforth]

many times, too heavy of a spring on the trailer will induce bounce.

 

[tpenfield]

you could name your trailer 'Bouncy'

Check the actual tongue weight and determine if you are within 5-10% of the total weight of the boat/trailer. If you are closer to 5%, then increase tongue weight towards 10%

 

[poconojoe]

I'm no expert on trailers, tongue weight, etc. But you said "tongue weight drops hitch about 1 1/2 inches". Is that a lot of drop? Are your truck's rear springs weak? I don't really know, just throwing out the idea because I don't think mine drops at all. Mine is a 2016 Chevy Colorado and boat is 18 foot bow rider approximately 3,000 pounds.
Another thought would be the condition of your truck's shock absorbers. Maybe they are worn and are not dampening the "bounce".
Has anyone suggested that the truck's suspension could be the problem?
Just some ideas that came to me.

 

[ahicks]

What kind of tires are you using? If they are the ST type, you have to run them at max inflation. However, if you changed to radial or bias ply that were NOT ST rated, you could run an air pressure established by your load. Sometimes way less pressure than the ST tire requires, resulting in a dramatic difference in ride....

 

[poconojoe]

On the subject of types of tires....when I switched from bias ply to radials, the feedback from the trailer became smooth like a cushion. My old bias were harsh and bouncy.

 

[Redfred1]

Probably the road. Don't think it's a tow vehicle problem either. I thinking excessive tongue weight; others have too. (1 1/2" drop). I have a '89 Bayliner 1700 Capri; weight around 2200; is towed by a '07 Ford Explorer 4.0. Tongue weight (bathroom scale is 110lbs). Very little drop. I would also check the tire pressure. My 2.

 

[tpenfield]

Anyone put shock absorbers on their trailer axle(s)?

 

[bigdee]

Anyone put shock absorbers on their trailer axle(s)?

I have not but I know of trailers with them. That is the only way to stop/limit bounce. Since people don't ride back there bounce doesn't really hurt anything but shock will dampen bounce significantly. There is a guy in town who took shocks off his car for kicks and it is unreal to see how high his car jumps off the ground! He can pump the gas pedal up and down and do wheelies.

 

[NYBo]

I wonder if this has something to do with the relationship between the length of the concrete slabs and the distance from the truck's rear axle to the trailer's axle.

 

[ahicks]

High end travel trailers and 5'ers are sometimes equipped with shocks, but as a rule, most will not. Generally, they just don't need them.

It's mostly about a lightly loaded trailer on a really stiff set of tires and springs. It's like pulling a roller skate down the road. There isn't enough weight to make those springs and tires flex enough to smooth things out/do their job.

As mentioned, if tires are used that don't have to be run at max psi, you can adjust the tire pressure to the load and eliminate this issue....

 

[bigdee]

As mentioned, if tires are used that don't have to be run at max psi, you can adjust the tire pressure to the load and eliminate this issue....

Transfer that energy to the tire sidewalls and you will beat the heck out of those tires.....don't do it!

 

[GA_Boater]

Does this happen on the same stretch of road?

I used to drive regularly on an interstate and when I hit one miles long section, the car started bucking like a rodeo bronco every time. The semi's bounced like yoyos, too. Next time look at the vehicles around you.

 

[Leardriver]

My F350 bounces on concrete when empty. Every single axle trailer I have does also.

 

[ahicks]

Transfer that energy to the tire sidewalls and you will beat the heck out of those tires.....don't do it!

Unless you're speaking of ST rated tires, that is absolute hogwash. Many types of tires are DESIGNED to flex in the sidewall - without overheating or long term damage. Inflation tables are based on the amount of heat being generated by that flex, and when followed, allow a tire to work as designed at well below it's max rated pressure.

 

[bigdee]

Unless you're speaking of ST rated tires, that is absolute hogwash. Many types of tires are DESIGNED to flex in the sidewall - without overheating or long term damage. Inflation tables are based on the amount of heat being generated by that flex, and when followed, allow a tire to work as designed at well below it's max rated pressure.

Not hogwash from Tire rack

"Your trailer is a follower, which often makes tire sidewall flexing a negative. Sidewall flexing on trailers, especially those with a high center of gravity (enclosed/travel trailers) or that carry heavy loads, is a primary cause of trailer sway. Typical passenger radial tires with flexible sidewalls can accentuate trailer sway problems. The stiffer sidewalls and higher operating pressures common with Special Trailer (ST) designated tires help reduce trailer sway".

After pulling all types of trailers for over 50 years I have learned that lowering pressure is a no-no. A fully inflated tire will be trouble free. Bounce will not hurt a thing....trailer will follow you as long as you drive sensible. BTW lowering pressure does very little to alleviate bounce anyway.