I have 2019 Limited 3.5 turbo with 40k miles and just towed a new 6300 Lb Rv trailer. It now bounces (like bad shocks ) in regular and towing mode. Much better in sport mode. Any recommendations? Thanks.

 

Put some Bilestein 5100 shocks on the rear. (or others in the great shock debate close to the oil thread debate section, lol)
Original shocks are garbage.

 

Did you pump up the tires for towing?
I always used maximum sidewall pressure when towing to cut down squirm when towing on previous vehicles with P metric tires.
My truck doesn’t need that.
I also used to keep my unladen tire pressure about halfway or above between factory sticker and sidewall markings, for slightly better milage and tire wear.
I found my truck beat the hell out of the passengers on our PA country and most city roads especially rear seat passengers, at the higher pressures. Now I keep them close to the factory recommended value.

 

Hitch height (too high actually can lead to excessive tongue weight with dual axle trailers) can lead to a porpoising or bouncing effect. Or hitch at proper height but no weight distribution or insufficient weight distribution.... I'd start with those two and if that's not it look at tires/shocks etc. Truck isn't lifted?

In my understanding sport and tow/haul will work the same while accelerating - truck will hold lower gears to provide necessary torque. Tow/haul will do the same on downhills to save brakes vs. sport I think would not.

 

Since the rear end suspension has no idea what drive mode the truck is in, I do not see how one mode can be more bouncy than others.

I am sometimes wrong, so if I am please enlighten me.

 

I have no idea and wont assume that you are talking about the truck bouncing or the trailer bouncing or both bouncing and what the conditions are that trigger the bouncing.

It would be great if you could explain in greater detail what is happening and when it happens.

 

Sport mode shouldn't change how the suspension feels. You likely need new shocks. Like said above, go with the bilsteins.

 

You can upgrade shocks or add some products to firm up the rear suspension like Roadactive Suspension or Add-a-Leaf. Before you do any of that make sure your truck and trailer are properly calibrated. Trailer should be close to level and not substantially nose down or nose up. Weight distribution hitch (WDH) should be configured to restore at least 50% of lost weight back on to the front axle which will reduce weight on the rear axle and suspension. You can watch some videos on how to calibrate a WDH. You can also take your truck and trailer to a CAT Scale and get readings for the steer, drive, and trailer axles when connected, again with WDH spring/trunion bars disengaged, and again with just the truck. This will tell you a lot about the unique characteristics of your particular setup.

 

If its the rear bouncing, he's probably got worn out shocks that cannot take the additional load and stress of a trailer. Replacement is easy and should be done. Fronts are a bit complicated.

 

Thanks guys.