Porpoising on highway with Hawk shell

[GPAY]

Hi all,
I have had my Hawk shell with some options on my 2014 Ford F150 for 5 weeks now.
No mods to the suspension and it handled well when it was initally installed. I was pleasantly surprised when driving the 300 miles home as it handled quite well.
Just took it on a 500 mile trip for a couple of days and it drove differently and not very well. I think the term is porpoising. The truck would buck (a feeling of going back and forth I guess is a way of putting it).
There was some added weight since its maiden voyage 5 weeks ago but not much, maybe a hundred pounds or so. Any ideas..tire pressure? Too much weight? Any ideas would be appreciated.
Thanks

 

[John D]

Do you have a short bed truck, 6 1/2 foot bed, maybe an extended cab? Watch your weight and balance and you should resolve the problem. Many short bed rigs benefit from suspension help. With your light weight camper, you should have little trouble correcting the porpoising, or get use to it. Many truck owners feel the need to go up to a 3/4 ton truck. I have had every kind of truck, S-10, Ford and Chevy half ton, 3/4 ton Dodge 4x4, one ton dually, I even own a US Army Deuce and a half. I much prefer a 1/2 ton truck with light weight popup campers.

I'm a little different from most as I think you can make almost anything work. I'm 73 and have been doing this camping gig since the 1950s and I have seen just about everything in the RV business. For 10 years, I owned a camp ground and can tell you some stories! Everyone has their favorite truck and camper, etc. You can make anything work and I recommend you take the approach of refining your existing rig. With your light weight camper, you will have very little problem. Just drive conservatively with whatever your rig may be. As they say, the nut behind the wheel is the most important one.

I am commenting because one of my present trucks is an F150 with a long bed and an ATC. I have little trouble with it but I work to prepare it for every trip and I use a check list. I pay attention to my rig. John D

 

[snuffy]

i would invest in a set of ride rite air bags and a set of high end gas shocks , also load range D tires, it makes a half ton truck drive so much better imo..

 

[super doody]

Also rear sway bar if you don't already have one.

 

[PaulT]

You should check your turnbuckles. If they are a little loose, they can allow some front to back movement relative to the truck bed that may give an oscillating feeling. They can loosen from time to time especially on a recent installation. Worth checking out anyway.

Paul

 

[camper357]

If the swaying is side to side you need stiffer tires with more air and maybe a sway bar. If the bucking is the weight of your camper commpressing your rear susupension to the point it lightens your front suspension then you need stiffer rear springs. I used the cheap add a leafs on my last half ton and it completely got rid of the front to back bucking, but it already had "e" rated tires before that.

 

[Beach]

I would guess that you added at least a few hundred pounds to the rig when you took the trip. since you were already near or at the max load for the 150 with the empty camper, that added weight probably is the difference in ride quality. Get some add on springs or air bags for the rear, H.D. shocks and e rated tires. I have super springs but if I had it to do over I would get custom H.D. spring packs on the rear.

 

[GPAY]

Thanks everyone, I emailed Sean Dempsey at the WI dealership. He suggested I take the tires up to the max pressure listed on the sidewall and now all is well!

 

[GPAY]

On a trip today and the truck and camper are doing the porpoising-bucking thing still. I had thought the problem solved with inflating the tires to the max pressure but apparently not. So...ordered the Firestone Ride Rite mode l2525 kit today from Amazon tonight and having it installed locally on Wednesday ( have another short road trip on Thursday). Wish me luck...I hope this solves the problem as it is driving me a little crazy!
Any thoughts are welcomed!

 

[Squatch]

I'd upgrade the rear shocks as well. The more spring and load you have the more shock you need to control it.

 

[Lighthawk]

I have full Hawk on first gen Tundra, so not exactly your setup. I beefed the stock suspension with Ride-rites, a Helwig swaybar, and new Bilsteen 5100 shocks.

I think the swaybar only addresses side to side forces, so not relevant unless on uneven trail or in cornering situations on pavement. In bouncy, off trail conditions, I'm very happy I've got the extra control the swaybar affords.

When I first got my BFG AT tires I tried max psi @ 80 psi and it just about rattled my teeth out. Even on our local concrete highway.
I detuned to 45psi on the front at 55psi on the rear for the highway, and drop 10psi all around (35F/45R)when hitting the dirt road.
I go yet another 10psi lower (25F/35R) for slow, rocky terrain.

Bottom line: I've never experienced the porpoising with my setup, but would not advise running max psi on your tires, assuming they are E rated.

 

[huckfinn]

I believe I had something like porpoising at first using a SuperSpring helper spring on my Tacoma/Fleet. Your combo seems much less stressed than mine.

Probably the airbags will do the trick. My solution was to have a local spring specialist rebuild the leafpack for less than $500.

He said: forget the shocks till they wear out. I believe him—since he wasn't busy and could have easily taken my money.

 

[Stromtrooper]

HELLO,

Porpoising is a good way to describe the "bronco bucking" problem that we HAD (on 2007 Tacoma TRD 4X4 with FWC Eagle - before the following remedies were applied:

Replaced all 4 stock TRD shocks with Bilstein 5100's WITHOUT optional spacers,

ADDED Firestone Ride Rite Heavy Duty air bag helper springs to existing bolt on helper spring kit.

Highway ride is 90% better after about $1500 of parts and labor, with both bags at 40psi. We bought the bags online and had them installed at 4wheelparts when we had the shocks replaced.

Truck was driveable, but sketch before adding shocks and bags, now it is 3" taller and 1" taller in the front, and level(able). Totally worth the $$.

 

[RC Pilot Jim]

I too have occasionally experienced "porpoising". Worst case on a stretch of road about 20 miles south of Florence, Oregon on the coast highway. Slowing down eliminated most of it...Thank goodness.

 

[photohc]

I have almost the same setup as you. Hawk on 2013 F150 FX4. Short bed. I agree with most of the comments so far. I've installed, Firestone Air bags, upgraded the tires to E rating, and have Helwig sway bars. Never experienced "porpoising" with this setup. With the camper, the air bags are at 32#'s, tires at 50 front, 55 rear. With the camper removed, I lower the air bags to 8#'s, tires to 45 front, 50 rear.