Troubleshooting Severe Chucking At Low Speeds When Towing A Trailer

Question:

2016 GMC 3500 HD 4x4 Dually. 40k miles. BandW turn over ball hitch. Breaking good but when it gets to about 10mph irradiated non normal chucking of the truck only and I mean you better have your seat belt on. Things fly off the seats. It happens when breaks are hit hard and when gradually stopping as well. More when downhill stopping. Ive had a new interstates controller installed and GMC dealer says all is working properly on the trucks end. Ive hauled the trailer with friends trucks and it is fine. Ive adjusted trailer brakes from nothing to screeching. Any suggestions? I note again This is NOT normal chucking. Truck/Trailer/Pin weights are all within range. Does not do it with light trailers.

asked by: Sheri

Expert Reply:

When adjusting the brakes on the trailer do you mean just adjusting the braking output on the brake controller or did you actually adjust the brake shoes on the trailer brake assemblies? I would start by taking apart the hubs and checking the brake assemblies to ensure they're properly adjusted and then repack your bearings to make sure they aren't getting stuck and causing the chucking.

From there I would test the output of the trailer brake controller at the 7-way with a voltmeter # PT89ZR. If you have output set low and the voltage is the same as when the output is set high then we know the brake controller is the issue and is sending too much power out to the brakes. Typically at low speeds you'll want to have the brake output a bit lower to prevent it from jerking you back. Jerking when the brakes are hit hard can be normal to an extent. The Curt RockerBall Shock Absorbing Gooseneck Hitch Ball # C67DR can be used in place of your B&W hitch ball to get some cushioning to help absorb the chucking you're experiencing.

Now would also be a good time to check your trailer's suspension to see if anything else is damaged or sticking that could be more noticeable at low speeds but hard to feel at higher speeds. There's definitely something strange going on but without seeing the truck and trailer in person it's a bit hard to diagnose. If you live near our Wenztville, MO location and would like to setup and appointment to get it checked out then you can reach us at 1-800-940-8924.

expert reply by: Kevin C