truck rear suspension - air bags & Jounce springs

[WinterDeere]

Tow vehicle: 2015 Ram 1500 4x4 Hemi Outdoorsman with "HD" rear springs

Heaviest trailer: 2016 Big Tex 7000 lb. landscape trailer with winch and dual deep-cycle batteries mounted on tongue assembly

Problem: Tongue weight is a little higher than I would like for vehicle attitude, but offroad terrain and need for jacknife-sharp turns when backing into tight quarters makes weight distribution hitch (WDH) problematic

So, I've been looking at rear suspension enhancements, as the tongue weight is high, but not so high that I should really need a WDH on this rig. I'm leaning heavily toward just outfitting the truck with air springs or helpers in the rear, along with an on-board compressor for easy adjustment when retrieving log loads from remote locations (primary use of this trailer).

I know Timbren jounce springs can work very well at limiting travel, but they do nothing to help re-level the truck when loaded, they just limit sag. I'm leaning toward either full replacement air springs, or air helpers. The air helpers seem to fall into two categories, either air bags that go inside your existing coil springs (1000 - 2000 lb. class), or some that replace the Jounce (limiter) bushings (3000 lb. class).

Wondering what experience anyone has with any of these on a 1/2 ton truck.

Anyone with opinions on why no one should tow with a 1/2 ton truck, please just go whine somewhere else. No one wants to hear you, I'm well within the limits of the tow vehicle (GTWR = 10,150 lb), here.

 

[WinterDeere]

Had a little time to do a little more research on this today, and drawing toward some conclusions:

1. Air springs can correct ride height, but actually increase loading on rear axle even more than the tongue weight of the trailer. This will depend on drop hitch height, etc., but in general, you're pushing things the wrong way.

2. Inside-coil air helpers are garbage. They can stiffen ride, but don't correct height. At that point, you're better off going with Jounce springs.

3. WDH is the only way to correct ride height without adding load > tongue weight to rear axle. Of course we knew that, but I still have issues with turning ability... so now it's time to start looking at what WDH's allow greatest turn angle.

Of all the various articles and videos I've paged thru the last few days, this one may have done the best job in summarizing the effect of air bags vs. WDH:

My big issues with WDR:

1. I really need the ability to jack knife this trailer to almost 90 degrees in some locations, and do not want to be dealing with constantly removing / reinstalling the WDH arms.

2. I can do up to 3 - 4 trips in a single day, unloaded one direction (tongue ~ 400 lb) and loaded (tongue ~ 1000 lb) the other. I don't want to have to mess with removing/installing WDH arms for each trip, to account for the big discrepancy in tongue weights each direction.

 

[RjCorazza]

Had a little time to do a little more research on this today, and drawing toward some conclusions:

1. Air springs can correct ride height, but actually increase loading on rear axle even more than the tongue weight of the trailer. This will depend on drop hitch height, etc., but in general, you're pushing things the wrong way.

2. Inside-coil air helpers are garbage. They can stiffen ride, but don't correct height. At that point, you're better off going with Jounce springs.

3. WDH is the only way to correct ride height without adding load > tongue weight to rear axle. Of course we knew that, but I still have issues with turning ability... so now it's time to start looking at what WDH's allow greatest turn angle.

Of all the various articles and videos I've paged thru the last few days, this one may have done the best job in summarizing the effect of air bags vs. WDH:

My big issues with WDR:

1. I really need the ability to jack knife this trailer to almost 90 degrees in some locations, and do not want to be dealing with constantly removing / reinstalling the WDH arms.

2. I can do up to 3 - 4 trips in a single day, unloaded one direction (tongue ~ 400 lb) and loaded (tongue ~ 1000 lb) the other. I don't want to have to mess with removing/installing WDH arms for each trip, to account for the big discrepancy in tongue weights each direction.

In coil bags have some legit uses. I use them for plowing, 40 psi gets the front end up an inch or two, then 10-15 psi for the rest of the year. My truck has "2 up" springs from the factory for snow plowing, but these newer plows are HEAVY.

I'm not sure how much (if any) my WDH affects turning radius, but honestly, it's real quick and easy to take the bars off on my Reese hitch. Maybe a little more involved with the combined anti away I use on the RV, but the straight WDH on my equipment trailer is a 30 second job.

 

[alexpops]

Not sure how dodge does it, but could you throw on 2500 or 3500 springs to stiffen the rear against the sag & call it a day? I did that with an old Pontiac using buick springs when I was a kid. Was tired of the "jamming it into second look" & squirrelly cornering.

 

[kozal01]

Ive run airbags on the last two F-150's I've had, Airlift on my 2005 and Firestone on my current 2015 and I will not own another truck without them now. Sounds like you understand that airbags cannot replace a WDH if you're exceeding the free hanging weight limit on the hitch and that bags do not add capacity but they are really great for adjusting ride height and helping stabilize the load on the truck. I used to use them in conjunction with my WDH on my old truck when I pulled my camper to help control the trailer better over bumps, usually 10-15 PSI was enough to settle things down.

 

[5030]

I've never cared for air bags inside coil springs because the springs will eventually rub a hole in the bag..

I take it your Ram has coils in the back correct? I have leaves but my truck is a 1 ton Ford. If I were you, I'd look at a set of air assist shocks. One nice thing about my air bags on the Ford and that is, no matter what I'm hauling or the weight, I can always level the truck. I've overloaded it in the past and I can level it no matter what.

 

[hiddentacocatneddih]

I have the air lift system on my ram 3500 dually

It's nice with the remote control to adjust it but the truck is on leafs not coils.

Has a 12V compressor you hide under the bed plus Schrader valves out the back in case the pump goes out

My buddy has the same system with just the manual fill on the same truck. Get the pump

 

[WinterDeere]

Ive run airbags on the last two F-150's I've had, Airlift on my 2005 and Firestone on my current 2015 and I will not own another truck without them now. Sounds like you understand that airbags cannot replace a WDH if you're exceeding the free hanging weight limit on the hitch and that bags do not add capacity but they are really great for adjusting ride height and helping stabilize the load on the truck. I used to use them in conjunction with my WDH on my old truck when I pulled my camper to help control the trailer better over bumps, usually 10-15 PSI was enough to settle things down.

Yeah, I was looking at the Firestone and Airlift systems, as well. The Firestone has a bit more appeal, if I go that direction. They have the added benefit of correcting ride height and handling when I just have a load in the bed, no trailer. Of course, Timbrens jounce bumpers could also do a lot of that.

I'm not sure how much (if any) my WDH affects turning radius, but honestly, it's real quick and easy to take the bars off on my Reese hitch. Maybe a little more involved with the combined anti away I use on the RV, but the straight WDH on my equipment trailer is a 30 second job.

yeah, maybe I'm making too big a deal of it. But I basically have to jack knife the trailer just to get around one bend in my driveway, so it'd be a constant on/off thing, if the WDH can't make a tight turn.

I was looking at the style with chain link to the arms, rather than resting on tabs, thinking they'd be less likely to "pop off" in a tight turn. Of course, some of those models come with sway control links that would cause the same problem, but some do not. Thinking one like this:

https://www.etrailer.com/Weight-Distribution-Hitch/Reese/RP66022.html

I've never cared for air bags inside coil springs because the springs will eventually rub a hole in the bag..

Yeah, I've seen some blown bag videos. But most have been due to over-inflation or damage during installation. Haven't seen one that's due to wear/age, yet.

Not sure how dodge does it, but could you throw on 2500 or 3500 springs to stiffen the rear against the sag & call it a day?

I'm not sure if the 2500 springs are direct fit, probably not, but I'm sure someone makes stiffer stock-height springs for the 1500. But if I were going to do that, I'd might as well just do the air bag spring replacements, as they give the ability to adjust firmness and correct height. Main trouble is that reducing the sag actually increases load on rear axle, possible past design point.

My buddy has the same system with just the manual fill on the same truck. Get the pump

Oh, definitely! I wouldn't even consider a manual fill system, since I leave home with a 2k lb. trailer and then return home with 7k. I need the ability to adjust in the field... and I do mean literally, "in a field".

 

[5030]

I have the AirLift system on my F350 and it has the on board 12 volt compressor and keeps a certain amount of air in the bags all the time (when the ignition is on of course).

All bags eventually wear out, fact of life and rubber and ozone. They usually fail right at the stool as well. Put mine on in 2002 and they are still fine, but I keep an eye on them anyway. Just starting to check a bit but then the truck is inside when I'm not using it so little ozone to impact them.

 

[dodge man]

Look at Anderson weight distribution hitch. I have no experience with it but I think it eliminates the backing problem. It uses chains instead of the bars.

 

[RjCorazza]

...
I was looking at the style with chain link to the arms, rather than resting on tabs, thinking they'd be less likely to "pop off" in a tight turn. Of course, some of those models come with sway control links that would cause the same problem, but some do not. Thinking one like this:

https://www.etrailer.com/Weight-Distribution-Hitch/Reese/RP66022.html

...

That is the same WDH I use on my equipment trailer. I like it.

 

[zzvyb6]

Here's the problem you face (technically from a Vehicle Dynamcs Authority: Me). With that much extra rear load and with trim height maintained, you face a potentially dangerous condition where the lateral stiffness of the rear tires is insufficient to manage the higher vertical load you've added with the trailer tongue weight when turning at speed. The solution is simple: You need a much larger rear tire size with much higher load capacity AND you need a much larger front anti-roll bar. This is to maintain the Stability Margin that all vehicles must have in order to complete safe turning/cornering at moderate speed AND more importantly, safe recovery if you have to make a moderately severe lane change or object avoidance maneuver. Otherwise, you will probably jack-knife the rig at at expressway exit, leave the roadway and roll over. That's how the physics goes. It's called 'balance' and the cornering balance you need is forward biased. The bigger rear tires will manage the side loading more successfully while the larger front bar (or you can even put a second one on) will keep the front tires from dominating the rears. That's what causes a jack-knife. The bigger rear tires will also need less air pressure to produce a good balance, too. Cornering force goes DOWN with pressure in truck tires after about 30 psi, BUT you probably will need 35 to 45 psi just the handle the load on them. For extra safety, use a wider rim, to. That helps generate more needed rear side force. This is the advantage of dually rear axles. Each of the 4 rear tires have 1/2 of the load on them that a single tire would struggle with. Plus you can get by with 1 spare for any of the other 6 tires (although the Fords use a different inside wheel on their duallys than the outside one).

 

[CalG]

Road Master!

 

[BlueKnife]

Anyone with opinions on why no one should tow with a 1/2 ton truck, please just go whine somewhere else. No one wants to hear you, I'm well within the limits of the tow vehicle (GTWR = 10,150 lb), here.

The tow ratings on 1/2 ton trucks these days are very optimistic and seem to be based on towing in absolutely ideal conditions. That said, if you don't want a different pickup, perhaps consider a different trailer. A gooseneck can be turned around in places where you wouldn't have a ghost of a chance with a tag trailer and it can safely carry considerably more weight without overloading the tow vehicle.

 

[WinterDeere]

With that much extra rear load and with trim height maintained, you face a potentially dangerous condition where the lateral stiffness of the rear tires is insufficient to manage the higher vertical load you've added with the trailer tongue weight when turning at speed. The solution is simple: You need a much larger rear tire size with much higher load capacity AND you need a much larger front anti-roll bar.

Two notes:

1. Tires have already been upgraded from OEM P-rated crap to 10-ply rated LT's, which are a little overkill for a 1/2 ton truck. I'm not operating anywhere even close to the rating of these tires.

2. My heavy hauling is all low speed / local roads, not highway travel. Only time I ever use this trailer at highway speeds is when hauling lumber, which is comparatively light.

I've never experienced any side roll when towing this trailer, which has been used quite a lot over the last 8 years. But again, I'm rarely ever exceeding 45 mph when loaded near GTWR, and more often a good bit slower than that.

The tow ratings on 1/2 ton trucks these days are very optimistic and seem to be based on towing in absolutely ideal conditions. That said, if you don't want a different pickup, perhaps consider a different trailer. A gooseneck can be turned around in places where you wouldn't have a ghost of a chance with a tag trailer and it can safely carry considerably more weight without overloading the tow vehicle.

You're probably right, but I'm so far below the load rating, that I don't think it's a big concern here. The truck is rated for GTWR = 10,150 lb, as configured, but my trailers GTWR is only 7000 lb.

That said, Ram "recommends" a WDH for any trailer over 5k. Not "required", but "recommended".

 

[WinterDeere]

That is the same WDH I use on my equipment trailer. I like it.

I think this is going to be my solution. Have you tried backing into near-jacknife with it, or do you always take it off before such maneuvers?

 

[jyoutz]

Not sure how dodge does it, but could you throw on 2500 or 3500 springs to stiffen the rear against the sag & call it a day? I did that with an old Pontiac using buick springs when I was a kid. Was tired of the "jamming it into second look" & squirrelly cornering.

I have a Dodge 2500 and when I had a cabover camper, I had a spring shop add another leaf to each rear spring. If a 1500 has rear leaf springs, this is the easiest and most permanent option. Obviously this isn’t a solution if the truck has coil springs.

 

[RjCorazza]

I think this is going to be my solution. Have you tried backing into near-jacknife with it, or do you always take it off before such maneuvers?

My normal use is in relatively open areas. The few times I've been in tight quarters I have removed the bars.

 

[Hughman]

I put air bags on the rear of a 96 bronco. Love them. I never towed too heavy. Mostly boats and utility trailers and the like. The air bags really helped keeping the front end planted and the headlights pointing in the right direction when I got a little heavy with the tongue weight.

 

[nisaacs]

I think this is going to be my solution. Have you tried backing into near-jacknife with it, or do you always take it off before such maneuvers?

Why do you have to jack knife your maneuver with such a big bite? Can you take smaller bytes?