Troubleshooting Trailer Suspension to Reduce Porpoising

Updated 07/12/2016 | Published 07/11/2016

Question:

Hello, I am having trouble towing my RV specifically with what I call porpoising. Chucking on bad roads, especially older concrete roads with expansion joints. The kind that makes your kidneys hurt I have a 2012 Ram 1500 crew cab truck with a 5.7 hemi and my TT is a 25foot tandem axle Jayco. The GVWR of the TT is about 8100 lbs. I have measured the tongue weight at about 900 lbs. I use a Curt WD Hitch with an add on friction sway control. I have changed the truck shocks to Bilstiens, added Timbren overloads, and air bags in the rear coil springs. All combined, it has taken away about 1/2 of the porpoising but it can still be bad. What else can be done? Would Dexter EZ Flex equalizers help? Would an air ride receiver hitch help? Any suggestions would be appreciated. We are planning a longer vacation with the TT later this year and I am dreading the drive. Thank you in advance for your help.

asked by: Matthew H

Helpful Expert Reply:

It sounds like you have done everything possible on the tow vehicle side to reduce the up-and-down porpoising you noted, so I suggest checking out the trailer's suspension. Leaf springs do wear out and lose their weight-carrying capacity and this can lead to more motion from the overall system than with new springs. Also items like shackle straps can wear, their round holes becoming enlarged and/or egg-shaped. If many components in a trailer suspension are worn you can end up with excessive motion and reduced capacity to deal with road irregularities.

I suggest you pull one of the springs and its related hardware to check for obvious wear or damage. I linked our page for all trailer suspension components and also a video and article that will help you evaluate the condition of your trailer's suspension.

Another potential cause for the porpoising is the movement of water in the tanks. Water is pretty heavy and once set in motion it tends to keep moving. Also, if your total TW is near the maximum for your weight distribution system, then it may be unable to steady the trailer. Check that your actual TW is near the middle of the WD system's operating range.

expert reply by: Adam R