What Stops Porpoising on Tow Vehicle that is Using Weight Distribution with Trailer

Updated 09/17/2025 | Published 10/28/2016

Question:

We own a 2016 Silverado LTZ, 4x4 crew-cab short box, with factory Max Trailering Packageinch and big 6.2 liter V-8 rated to pull 12,000 lbs. Just purchased a 2017 Keystone Outlook 32 ft travel trailer 8,615 lbs weight with 1,075 lbs hitch weight. We use an Equalizer Weight Distribution System with 4-point sway control. When towing the trailer it feels like it is porpoisinginch as we go along the road or highway. Would the Timbren Rubber Springs reduce this? Thank you.

asked by: William S

Expert Reply:

Most of the time when a tow setup is porpoising with a weight distribution system all you have to do is add a bit more spring bar tension to minimize the porpoising. With an Equalizer system you would need to angle the spring bars down further to add the additional tension.

Suspension enhancement like the Timbren part # TGMRCK15S would help but you should be able to solve the problem with the WD system.

expert reply by: Jameson C

Ed F.

2/2/2020

I have the exact situation with my 2019 F150. Airstream with 1050 tongue weight I added the Timbren springs which helped immensely. However, not completely. Ive spoken to Equalizer, been to Cat scale multiple times, and my setup is correct. Im now waiting for the Roadmaster RAS3611-YHD that I have on order. Had those on a F250 towing a 5th wheel and know they worked great. Was trying to save a little money but now will have bought both! It looks as though the bottom plate on the Timbren springs may interfere with the RAS attachment pieces. Any experience with people having both on their truck? Thanks!

Jason S.

2/3/2020

On your 2019 Ford F-150, the RAS # RAS3611-YHD install around your leaf springs to give additional support and stability by mechanically enhancing the factory suspension. I haven't seen anyone try the Timbren # TFR1504E in conjunction with the RAS, but I do believe the bottom bracket would interfere so you will likely need to choose between them. The benefit of the RAS is adjustability so you can adjust your ride to your preference.

Leland M.

7/28/2020

Hello.I have a problem when towing my trailer that over bumps and dips in the road. my truck bounces or floats in the front end. I have a f-150 Lariat with 7600# towing capacity. my trailer is a 26ft ultralite dry weight of 4585#. i have equalizer bars and i have air bags on the rear set at 75#. the whole unit seems to be level. any suggestions? thank you

Jon G.

8/5/2020

There are a couple of things you can check to make sure that everything it setup correctly. First make sure that your trailer suspension is in good working order as a worn out suspension could cause more play. Second is to look at the tongue weight of your trailer and shoot for it to be 10-15% of the loaded weight. You can also double check that your weight distribution system is rated properly because anything that is rated too low won't be effective.

Jay F.

12/4/2021

We have a 2021 F-350 long bed with Airlift 7500 air bags and we pull a 2021 Gatormade 24.9k, 35+5 flatbed with mega ramps. We have a Shocker Hitch on the trailer and we’re getting porpoising on the highway. What can be done to prevent this? I’ve heard that with this setup, load lifters would help. What’s you recommendation?@JonG

Les D.

12/6/2021

@JayF Our Comment system strips out some punctuation. Are you saying that you have a 35 foot plus 5 foot trailer that can weigh up to 24,900 pounds fully loaded? What kind of hitch are we using? Fifth wheel, Gooseneck, or conventional bumper pull? Having the load properly distributed will have the most affect on how it rides. What are you hauling?

See All (5) Replies to Leland M. ∨

Kim

9/15/2025

I thought tension is added by raising the L brackets—is that not the case? How would I angle the spring bars down?

Jameson C.

9/15/2025

@Kim Which WD system do you have? Some of them have different ways to change the spring bar tension.

Kim

9/17/2025

@JamesonC Equalizer 14,000. We have significant porpoising. The dealer set it up with 5 washers. Wondering if there should be 6. They didn’t give us any extra. I’m confused about when to adjust the number of washers and when to adjust the L bracket height. Thanks!

Jameson C.

9/17/2025

@Kim I just read through the owners manual on the amount of washers to use and here's what I found: Start with 5 spacer washers for most setups. If your actual tongue weight is higher than 90% of the hitch’s max tongue weight rating, you may want to start with 6 spacer washers or more as the tongue weight approaches the maximum hitch rating. Some setups with lighter tongue weights may only need 4 spacer washers.