Community Forums

immortl · 05-21-2021, 10:36 AM

Different set up here than my last question, same tow vehicle but now a 15.5k GVWR Fifth Wheel Toy Hauler.

Tow Vehicle - 2009 Dodge Ram 3500 4x4, quad cab, long bed, dual rear wheels, 4.10 rear, with the 6.7l cummins diesel engine.

Trailer - Keystone Alpine 3900RE, dry weight of about 12,970, GVWR of 15,500, hitch weight 2955, all per posted specs. Bought the trailer 2 months ago and had it shipped up to family on the east coast. We'll be at the trailer early to mid summer. At that time I'll take it over the scales to get actual weights and such as we get it all set up for our full timing adventure.

Just had a bunch of work done on the new to us tow vehicle to get it set up how I wanted it mechanically.

I plan on swapping the trailer's hitch out from an Air Ride 5th Wheel over to a Goosebox. We want to have full use of the bed and not have to lug a fifth wheel hitch in and out of it. I have not added an onboard air system nor air bags to the truck yet. I'm pretty certain at least on board air is in the cards for the near future with a 5g resevoir. Not sure yet about air bags.

What do you folks think about air bags on the rear axle of the truck for this set up? Absolutely necessary? Eh, nice to have? What sort of improvements to the ride quality would be seen with airbags? What should I be asking but am not because I don't know yet what I don't know?

Thanks,
Joe

Old-Biscuit · 05-21-2021, 11:06 AM

Trailer - Keystone Alpine 3900RE, dry weight of about 12,970, GVWR of 15,500, hitch weight 2955

Hitch weight listed is DRY pin based on the DRY weight---roughly 23% ratio
GVWR 15,500 at 23% = WET pin of 3520#

Dually.....shouldn't need air bags for that WET pin
RAWR 9350#

cfowler55 · 05-21-2021, 12:14 PM

I had a 2017 and now have a 2020 RAM dually. I had plenty of ccc with either. Air bags improved the ride of both when towing. I run the bags at 28 psi with a remote controlled onboard compressor. That lifts the rear back up to level and picks it up off of the overload springs. Do I have to have them? No. But the improvement in ride quality made them worthwhile to me.
Charlie

immortl · 05-21-2021, 05:00 PM

ccc - something carrying capacity something?

So probably not needed, makes sense, I tried to keep everything within capacity when making our selections. That said, they would perhaps be beneficial to ride quality. In the nice to have list then, which to me equals, yup we're getting them. DW will crucify me if I add the air horns to the setup too, but I think that would be fun.

Thanks,
Joe

xc-mark · 05-22-2021, 05:34 AM

I would say No air bags needed. Air bags reduce the amount of travel up and down on the rear axle. The only reason I could see if you needed to raise the bed of the truck higher to make the trailer sit level (in 99.9% of the time newer trucks are to high).

Palmeris · 05-22-2021, 07:41 AM

ccc= cargo carrying capacity

Air bags work by reducing the amount of suspension travel...shock absorbers work by reducing the amount of suspension travel...springs work by reducing the amount of suspension travel...

When you add weigh to the rear of the vehicle the suspension compresses the springs, shocks and air bags, thus reducing the amount the suspension can travel, this is reffered to as squat ... Adding air to the bag reduces that compression by bringing the suspension back to the height prior to the weight being added, thus reducing or eliminating the amount of squat induced by the added weight , thus restoring the amount of suspension travel. Some of that additional weight is then transferred through the vehicles frame to the front suspension componets

In a perfect world adding weight to the bed would compress the rear and front suspensions equally thus lowering the entire vehicle and making the vehicle level. In reality , to accomplish a level vehicle rear airbags are required to do this. A level vehicle vs vehicle height are 2 different things

Now how much weight vs how much squat for a specific vehicle and trailer combo

If you do add bags to your truck suggest to use the ones with the internal jounce bumper as the factory one is removed when installing the bags

immortl · 06-09-2021, 11:17 AM

Thanks folks for the thoughts and feedback, I appreciate it. Sounds like air bags probably aren't going to be necessary, but I'll check everything over when I can get it all hooked up together in a month or so.

Thanks,
Joe

Cumminsfan · 06-09-2021, 01:29 PM

Air bags won't hurt. If after hitching up the whole setup feels a little sloppy or not rock solid then air bags will help tighten things up.
It's all about how you want the truck to perform. No different than a race car driver needing more control. They will change springs, tires, shocks, etc to enhance the handling.
Same can be done with a truck and trailer. Just because the factory built it one way doesn't mean an owner can't make some mods for improvement.
Mods to the truck won't change it's ratings but will improve the handling.

Jshopes81 · 06-12-2021, 12:35 PM

Quote:

Originally Posted by Palmeris

ccc= cargo carrying capacity

Air bags work by reducing the amount of suspension travel...shock absorbers work by reducing the amount of suspension travel...springs work by reducing the amount of suspension travel...

When you add weigh to the rear of the vehicle the suspension compresses the springs, shocks and air bags, thus reducing the amount the suspension can travel, this is reffered to as squat ... Adding air to the bag reduces that compression by bringing the suspension back to the height prior to the weight being added, thus reducing or eliminating the amount of squat induced by the added weight , thus restoring the amount of suspension travel. Some of that additional weight is then transferred through the vehicles frame to the front suspension componets

In a perfect world adding weight to the bed would compress the rear and front suspensions equally thus lowering the entire vehicle and making the vehicle level. In reality , to accomplish a level vehicle rear airbags are required to do this. A level vehicle vs vehicle height are 2 different things

Now how much weight vs how much squat for a specific vehicle and trailer combo

If you do add bags to your truck suggest to use the ones with the internal jounce bumper as the factory one is removed when installing the bags

I find the statement in here about compressing front and rear equally to be level to be wrong. Trucks have built in rake. The front rides lower than the rear empty. You have to compress the rear more to be level.

Rhagfo · 06-13-2021, 06:27 AM

Quote:

Originally Posted by cfowler55

I had a 2017 and now have a 2020 RAM dually. I had plenty of ccc with either. Air bags improved the ride of both when towing. I run the bags at 28 psi with a remote controlled onboard compressor. That lifts the rear back up to level and picks it up off of the overload springs. Do I have to have them? No. But the improvement in ride quality made them worthwhile to me.
Charlie
__________________
2019 310GK-R
2017 RAM DRW - sold
2020 RAM Longhorn DRW

Did you level your TV? you likely have a 3,300# pin on that 5er, before I added air bags to improve ride I would add a set of Bilstein shocks. That is all I needed on our 2001 Ram 2500 pulling/carrying a 5er with a 2,700# pin.

consolenut · 06-13-2021, 07:06 PM

If your thinking you may need air bags. Think more truck.

immortl · 06-13-2021, 10:59 PM

Thanks for the additional feedback. I'm taking a wait and see approach, we'll see how it all sits and rides when we get to the trailer in a few more weeks and I'll go from there. The truck definitely has a rake to it, good bit higher in the rear when empty so we'll see how much it settles down with the fifth wheel. Weight wise, looking (on paper so far) to be under the limits for CCC and overall CGVW. I definitely want onboard air whether or not we do the airbags and I'll be putting a sealed viair compressor and 5g tank on the truck.

I did just have a set of Bilstein 5100 shocks installed all around. An aside - has anyone tried to buy Bilsteins lately? They're not available for the rears just about anywhere (at least for the Dodges). Few diesel mechanic friends up mine came up empty. I finally found a set on ebay where the seller only listed one vehicle they were compatible with (Hummer). Using part numbers for search queries, they came up and were the right ones for the Dodge pickup too.

That and a tire balancing were the final, for now, things for the truck. It now runs smoothly, drives/coasts in a straight line, has gobs of power with no black smoke, and is an absolute pleasure to drive. Unloaded fuel mileage is even up to a hand calculated 15-16 at 80mph+ compared to the original 11-12. It's ready for it's first task of towing a loaded 24' cargo trailer across the country (at a lower rate of speed of course).

Thanks,
Joe