Sway question

[huskyrunnr]

Regarding my '02 F350 short bed with an 8' nco Alaskan (1400 lbs), fairly new Bilstein shocks. Front swaybar has new drop links. Rear drop links to the rear sway look OK with no visible slop when I rock the camper. Overload leaf on the rear spring pack is not in play at all when I rock the camper by hand. E rated tires are about 60 psi and they don't bulge much at all when I rock the camper.

Driving around a curve feels very good with no sway. What is annoying me is when I turn off or on to a steep ramp, like a parking lot entrance, the truck sways with about 1.5 maybe 2 oscillations and enough amplitude to throw me around a bit.

Is there anything I can do to tone down this rocking motion? Maybe bring the overload leaf into play somehow? Some shock other than Bilstein? I don't remember this issue with my old F150 which was longbed and had Hellwig helper springs. I also don't remember it with an old F150 shortbed with same helper springs.

Thanks for any advice.

 

[huskyrunnr]

Just for closure, internet searches led me to DIY solutions like wooden blocks and felling wedges and commercial solutions that mostly pointed toward Torklift "Stable Loads". I tried the Stable Loads for just the upper overload springs and that brought down the amplitude of the rocking tremendously. Very pleased. Nice to be able to tune that rocking motion out of the suspension.

 

[Vic Harder]

Glad that worked for you. From your description, it sounded like your shocks are being overwhelmed and unable to control the oscillations.

 

[allanb]

I have the same annoying "sway". Was hoping the airbags would cut it out. They help, but going over a bump or swale, can sure feel it.
Maybe i'll have to try the stable loads or different shocks

 

[huskyrunnr]

I agree that more damping would help. I'll have to check which Bilsteins I put on there and see what is out there with more damping. The oscillations are still there, just higher frequency and less amplitude, from my seat of the pants impression.

 

[smlobx]

What jumped out for me in your description is that you are running your tires at 60 psi..

First, do you have E rated tires? If you do you your tire pressure seems low. On the F-350's I've owned the tire pressures from the placard in the door jamb ranged from 65/75 to 70/80 depending on year...

 

[Foy]

i installed the Torklift Stable-Loads (upper only) on my old F350 SRW in 2014 at which point I'd towed my A-Frame popup enough to feel the need to engage the single leaf upper overload more quickly and reduce sag. They worked, but the ride got rougher than a buckboard. My then 5 year-old ProComp shocks were shot, and my rear leaf main springs had sagged with age (2002 model), and that combination had the Stable-Loads within 1/2" or less of suspension travel before contacting the overload leaf and the shocks weren't dampening that little bit of travel effectively. I would guess an installation where there was still (at rest, unloaded) a goodly amount (1.5 to 2.0 inches, at least?) between the Stable-Load and the spring leaf would allow for "normal" shock-dampened spring travel before the butt-kickin' Stable-Loads contact the overload leaf and stop the travel for good.

With flattened main springs front and rear, and worn out shocks, I'm biting the bullet and installing new leaf springs all the way around, new Bilstein 5100s, and replacing the Stable-Loads with stock bump-stops. I hope and believe that will restore my highway ride quality, which with the ultra-long wheelbase of the CrewCab longbed, has been very enjoyable for most of the 12 years I've had the truck.

Foy

 

[huskyrunnr]

smlobx, wow, thanks! Looked inside the gas door and the psi is 55/80 for front/rear. My tires are Toyo AT Open Country II and they give max load @ 80 psi. They are E rated. Thing is, I remember reading the pressure should be that high on the web somewhere a couple years ago, and I went in to Les Schwab and asked them to go up to 80 psi on the rears. I was told I shouldn't do that because then there is no margin for pressure variation going over bumps. Maybe they're trying to sell more tires. I never know who to trust but in this case I trust you and the damn fuel door placard!

Foy, what is the diagnostic or measurement to make to determine whether the spring pack is shot? I bought this truck with 90K on it so I have no baseline.

I really appreciate folks sharing their knowledge and experiences. This should really help me dial in this ride.

ETA: went back in to Les Schwab awhile ago and asked about the low pressures. They had put 55 psi all around yesterday after a rotation. His answer to why so low was that 55 is fine for the 10 ply tire and my little camper. I got him to go 65/75 and the truck feels more responsive to me.

He found another stamp on the front door that said 80 psi all around. I was looking on the rear half-door.

 

[Foy]

Husky,

My truck is an '02 and I'd sought to remove the "down in front" rake provided by the stock springs which include a 2" spacer block in the rear. By 2010, the stock front springs were noticably flattened out I made a poor and un-researched decision and bought a pair of front springs as part of a so-called "leveling kit" allegedly made for my truck and its (ridiculously) heavy diesel engine. For a while, the new front springs and 4 new shocks brought a great ride and I was happy. For most of the last couple of years, the ride has gone to heck and the front springs are noticably flattened out again. At the rear, the single leaf overload spring is noticably closer to the bump stops which engage it. All 4 shocks are obviously shot in that I get little dampening either up or down. On that evidence, I decided to replace the whole kit and kaboodle and be done with it. I made the decision as part and parcel of a decision to keep the truck for at least the next 5-7 years, after which time I'll be in my late 60s and may or may not want or need to run an oversized truck. It'll also have over 300,000 miles by that time.

As to tire pressures to run, there is much discussion here about exactly that. My take has always been that tires of any rating achieve their maximum rated load-carrying ability at their maximum rated pressure. My E-rated rubber (Michelin LTX AT/2, 285/75R16 on stock wheels) carries something like a 3,800 lbs capacity rating @ 80 psi. While I never have it loaded down anywhere in that range, I normally run them at 70 psi front and rear. When towing the camper to Montana and back in 2015, I ran the rears at 80 psi. That obviously contributes to the tightly-sprung ride, but the stiffened sidewalls make for better handling, if one can even speak of "handling" when the subject vehicle is 20' long, 6.5' tall, and weighs over 8,000 lbs with its normal fiberglass topper, tools, outdoor power equipment, and "fun gear" like coolers and fishing tackle.

Foy

 

[craig333]

And since air is free, its an easy thing to experiment with before trying pricier solutions. I'd rather have my truck handle well than give me a cushy ride and I get that running closer to the max air pressure.

 

[smlobx]

Husky-
I'm glad I was able to give back to this great community. As someone else stated it won't cost you anything. Also, I have a hard time relying on a tire jockey over the engineers at Ford when they designed and built the truck.

 

[Wallowa]

Tire pressure does factor into "handling" [subjective term] but more importantly in our case traveling off road; more pressure gives added protection of the sidewalls when crawling through large sharp rocks..

Weight rating is mostly an issue of not over heating the sidewalls due to under inflation for the load carried...resulting in separation of material or easier punctures/tears and catastrophic failure.

Phil

 

[ntsqd]

The tire mfg has designed-in allowance (Engineer-speak: "Factor of Safety") for hitting a sharp bump while at their max psi rating and at their max load rating in Death Valley in August. That Factor of Safety is decreased as the tire ages and/or accumulates miles (heat cycles), so pay more attention to older or higher mileage tires in that kind of scenario but don't be afraid to run the max psi rating on the sidewall if that is what works best.

Lots of discussion here and elsewhere about how to determine the "ideal" tire pressure for your specific vehicle and loading. I've been known to exceed that ideal pressure (while still under the mfg's max rating) when I know that the next leg or legs of the drive are purely pavement and is just something to slog thru, but I mostly stay at the ideal pressure for our rig. I usually only drop the pressure by 10 psi for long stretches of wash-board (i.e. Harry Wade Rd. etc.) and can not recall ever intentionally dropping lower than that.

 

[huskyrunnr]

Learning a lot here. Thanks all. I'll look into the ideal tire pressure threads here. If you air down, will those little compressors that folks carry get you back up to 75-80 psi?

 

[Foy]

Learning a lot here. Thanks all. I'll look into the ideal tire pressure threads here. If you air down, will those little compressors that folks carry get you back up to 75-80 psi?

Mine will, and PDQ. The cheap jump-box add-on compressors are useless, IMHO. I have a 5.4 CFM unit from Smittybuilt and have yet to burn it up.

Foy

 

[ntsqd]

I carry an MV-50 compressor (there are clones and variants of the model name out there) as either the primary or the back-up compressor in all three trucks. By far the best little compressor that I've ever had. If you search the net for this model you'll find all sorts of stuff about them. I'd call them the best starting point with the performance and cost of better options increasing from there.