Firestone Air Bags on 2003 F250

[Dean A Van Peursem]

I just installed Firestone Air bags on the rear axle of my 2003 F250 Super Duty TV. I did it myself. It didn't go quite as expected but I guess that could be expected. These are rated for 5000 lbs and do not require drilling for installation and assume a 5th wheel hitch is being used. I had to install them twice due to one side of the TV being slightly different than the other. I had to find a bolt hole combination on the lower axle brackets that didn't interfere with the spur that normally limits over travel of the spring. One side allowed a 1" lower fit than the other. Also I had a left brake line in the way and a Shock abosorber axle bracket that had to be moved to install the left lower bracket. I don't know if these difficulties are normal or not. But they are now installed.I haven't done a test run with the RV hooked up yet.

Now the question. It appears there is only about 4 to 5" of distance between the upper and lower plates that hold the air bags. Does that provide enough compression room for the air bag? It seems to me that the air bags will not compress enough to allow the top overload spring to ever come into play. Is this normal?

There is just no way to install these any other way than what I have them unless I do some real modifications (cutting, bending and welding).

Anyone else have experience installing these? How much clearance do you have between plates when empty? Any pictures. I just don't feel comfortable these are right. Maybe they are.

[Wrenchtraveller]

I installed a set of these Firestone Ride Rite air bags on my 00 F350 but that truck did not have the factory overloads. That is 6 years ago so my memory has faded but I am sure there were special instructions converning overload springs so make sure you did not miss that part.

I do know that you must experiment with the air pressure in the bags to get the best handling.
Too much air can take too much weight off of the truck springs and make the ride mushy .
Good luck and I am sorry I could not help you more.

[Charlie]

Dean-
I assume by the description that the bags you installed are the Firestone's part #2330. If so, I have these on my 2001 F-250. I also with the help of a friend did the installation. Prior to installing the bags the Montana would squat the truck enough to be down on the overload springs. I don't know if they touch during travel after air bag installation but I feel more comfortable knowing I have more support.

The way the bag on the passenger side is made allows the heat shield to placed in two different positions, I opted for the forward position as I think it is a bit closer to the exhaust pipe and have not had any problems. During installation I did have to move the brake line on the driver's side, but did not have to change any shock brackets.

Firestone's instructions state max. pressure is 100#. I don't remember if this was unloaded or loaded, but think this should be a compressed pressure. I did not install the onboard gauges and compressor. I carry a 12V compressor and use a digital air guage for accuracy. I started out with about 25# empty and when loaded, this is compressed to about 45#. Since I have decreased the unloaded pressure to 15# and this is plenty to hold the truck and trailer level. You will have to experiment to determine what is good for your rig.

Here are some photos as requested. The pics taken with a min. pressure of 5#, where I run them when not in a tow mode. Hope all this helps.

[Dean A Van Peursem]

Don/Charlie:

Thanks for the quick response. I didn't completely describe the TV properly. It is a 2003 F250 SC LB 4 x 4 Lariat with an overload leaf spring. The 4 x 4 probably sets up a little higher in the rear than a 4 x 2. Yes, I installed the Firestone # 2330 air bags. On the right side (passenger) I too positioned the heat shield forward closest to the exhaust pipe to give a maximum heat shield.There were other positions possible but I thought this would provide the most heat protection. On the drivers side where the brake line interfered I just moved the line out of the way and riding up against a non-moving part attached to the frame. The left Shock absorber bracket was installed about a quarter inch too close to the springs which just didn't quite allow enough room for the Firestone lower air bag bracket. I loosened the shock bracket U bolt and slid that bracket toward the center of the truck just enough to allow the air bag bracket to slip in between. I made sure the shock bracket was mounted at the same angle as it was before. I interpreted that shock bracket interference as just normal manufacturing installation tolerances.

What bothers me a bit is I first installed the right side with the top part of the lower axle bracket in a position that just gave a little bit more than head room for the bolt going up into the center of the bottom plate of the air bag per Firestone instructions. This head needs to have a slight amount of clearance above the cast iron jounce tongue. When I tried to install the left hand one with the same bolt setting on the lower bracket the bolt head interfered with the cast iron jounce tongue on that side. I then had to go to the next hole pattern higher on the lower axle braket assembly. This reduces the space between the upper and lower plates by about an inch or so. Of course then I had to go back to re-do the right side so they were assembled equally. I still do not know why one side was different than the other. The lower bracket is not assembled to it's highest postion however. Maybe again just manufacturing installation tolerances but it reduces the amoubnt of travel the airbag can compress.

Thanks for the pictures Charlie. They are more helpful than you can imagine. It appears that your installation ended up with maybe even less compression room than mine provides. However, my lower brackets are one bolt hole pattern higher than yours. Yours are currently set at where I started but ran into an interference on one side with the jounce. It appears that maybe yours didn't have the jounce bracket. That may be one of the differences between a 4 x 2 vs 4 x 4. But looking at your installation compression room unloaded, mine appears to have about the same or slightly more. The space unloaded between the overload spring and its cast bracket also appears to be similar. So, due to your pictures I'm feeling a bit better about the way mine came out. It does appear to me that the air bags will seldomly compress enough to allow the single upper overload spring to play much of a role anymore.

The Firestone instruction sheets (Air Spring Technical Data) show what the expected distance should be by part number of the air bag part number. Of course the 2330 isn't listed. However, a part number 0335 is listed for the 5000 lb bags and 4 1/2 - 6 1/2" space between the upper and lower plate is specified. I am closer to the 4 1/2" than the 6 1/2" unloaded. Firestone doesn't clearly state whether this is an unloaded measurement or not. But I would think it has to be.

I too am assuming the air pressure reading of a maximum of 100 lbs is under full load and loaded compression of the air bag. I have been advised to try to run around 50lbs loaded. But I'm sure this is different for every combination of TV and RV.

Thanks to your inputs I am more confident that mine now may work properly. Once I hook up to the RV and get a few miles under my belt I'll have a better feel. Thanks for all the help.

[Dean A Van Peursem]

Wanted to follow up on this topic as we now have taken a trip with the air bags installed. Drove a couple hundred miles to a state park on the Pacific Coast with 50 lbs loaded in the bags. Truck oriented a little too high with 50lbs in the bags, now trying 40 lbs which seems about right. Bags have solved the tail end too low on the TV.

But still have a little bob in the TV when going over rough roads. Don't know if this is normal or my rear shocks need a checkup. Only 45,000 miles on the TV so wouldn't think they are worn out already.

[CountryGuy]

Different vehicle, but our OEM shocks on Big Butt were toast at 18,000. Replaced with Bilsteins, very happy with that solution, made HUGE difference in ride solo and with Tana hooked up. No air bags, just commenting on the shocks.

Carol

[sreigle]

I had the bags put on a '99 F350 superduty 4x2. I also have them on this '05 F250 superduty 4x4. In both cases because of the strength of the rear suspension when unloaded I felt comfortable dropping pressure to zero or near zero when unloaded. Never a problem. The purpose of 5 psi is to keep them from being damaged if the suspension bottoms enough. But that suspension never came close to that.

With 3300 lbs of pinweight I run the bags at 50 psi unloaded, which compresses to 70 when I drop the pin on it. On the road when we hit pavement that wants to make you play horsey I'll adjust the bags while driving (onboard compressor). Usually somewhere between 60 and 75 works well on just about all kinds of pavement. Nothing eliminates all movement, though.

[sheiba1]

Hi Dean I have air ride air bags on my dodge that when I over fill them (40/50 psi) makes the 5er a 3600re pin bounce a lot. I installed the on board compressor and in cab air gauge which keeps the bags at 10 psi no load, just hooking up the 5er puts the air pressure at 25 psi which keeps every thing level and rides great.

Hope this helps.
Rich and Marita

[Dean A Van Peursem]

Hi Rich: I'm learning to find the appropriate air pressure. I started out with a loaded pressure of 50, that was to much purely because the rear of the TV was too high. Tried 40 and that is when I really noticed the bobbing. Last try was at 35 at it didn't seem to be bobbing as much. Next try will test at even lower pressures.

But... I have come to the conclusion that my 2003 Ford OEM rear shocks (Rancho) are shot. So am contemplating putting Bilsteins on. I was told today that Rancho shocks are oriented more for off roading. My truck did have the Off Road option.