Mike@Asheville wrote:
I have a 2004 F450 (original cab/chasis) that I plan to use for a truck camper. The 2004 F450 has a GVWR of 15K while the F550 is 17.5K. Other than the springs what components would be different between the two?
My Truck Camper loaded is going to put me a little over my 15K GVWR. I had the Kelderman AirRide system installed when I first purchased the truck. It has a compressor and is self leveling. The stock spring pack remains in place. Will the airbags in the pic below compensate for the extra weight?
This is just an opinion, but my answer would be "NO, the airbags will
not compensate for the extra weight." The airbags in that particular Kelderman system replace the rear leaf spring shackles, to add comfort, not add capacity, to the suspension system. They also work to lower and raise bed deck height for easier 5th wheel hitching, and for re-leveling the rear when loaded. They do not increase the rear axle's GAWR, nor the chassis's GVWR.
In fact, I was surprised to see that Kelderman system on a Fontaine, but when you said that you had it installed, it then made sense. You ordered your Classic Traveler without the air ride, and had the less expensive Kelderman system installed after the fact. Right?
That system does not turn an F-450 into an F-550. Nor does any of the other air suspension systems, whether full air ride replacements that delete the springs altogether, or the load leveling airbags typically added directly over the axle in between the spring hangars, or the hybrid system like the Kelderman, which works like MorRyde's RL system, retaining the factory spring pack, but replacing the non damped rear shackle with an airbag support. (MorRyde uses 3 rubber shear springs instead of an airbag to perform the shackle duty).
What is different between an F-450 and an F-550?
1. The Rear Axle
In your case, this would be a bit hard to believe, since you just happen to have the first year that Ford started trying out the then brand new just developed Dana 110 axle, whereas the F-450 chassis cabs built prior to (and off and on since) were equipped with the Dana 80 axle. While this new Dana 110 axle was eventually fitted in both F-450's and F-550's, it was initially tested in just the F-450s, while the F-550's carried on with the much larger Dana 135 axle. For comparison's sake, the Dana 135 axle has 14.25" ring gear, versus an 11.8" ring gear size in the Dana 110.
Now, it is true that in years subsequent to your model year, the F-550's began receiving a version of this new Dana 110 axle, while the F-450's also had the 110 axle for a period of time. (F-450's have toggled back and forth between Dana 80 and 110 over the years). However, there are several different variants of the 110 axle, with different GAWR ratings matched to the appropriate application. In other words, not all Dana 110 axles are rated the same. For example, the Dana 110 in an F450 might be more aptly described as a Dana S11-110, versus a Dana S14-110. Both are called Dana 110 for short, but the former is rated to 11,000 lbs, and the later is rated to 14,000 lbs.
What physically makes the same axle rated differently? The physical distinctions might be as subtle as a 1mm difference in the thickness of the axle housing material... not something you can really see from the outside. The axle distinction gets even more complicated in later model year F-550's with the higher 19,500 GVWR, which have yet another model of Dana axle called the S130. This is distinct from the former S135 axle fitted in the F-550's of your vintage. The difference is the S135 was discontinued, because it was replaced by the lighter weight, ovalized housing, smaller ring gear, "high power density" design of which both the 110 and 130 are both descendants of. The ring gear size of the 130 is 12.2" (versus the older, rounder Dana 135's 14.25" ring gear).
2. The Rear Springs
The F450 rear spring pack is rated to 11,000 lbs, whereas the F-550 spring pack is rated to 13,500 lbs. Again, like the Dana 110 axle and housings above, the physical difference between the 450 and 550 springs are really hard to see.
Both models have the same number of leaves (11), that are the same width (3"), and are the same length (55.06"). Yet the F450's rear springs have a deflection rate of 949 lbs per inch per spring (1,675 lbs per inch per spring after the overload leaf engages), whereas the F550's rear springs have a deflection rate of 1,210 lbs per inch per spring (1,935 lbs per inch per spring after the overload leaf engages).
So if it is the same number of springs in the pack, that are the same width and the same length, how is it that the deflection rates are different? Spring thickness. The total thickness at the pad on the F-450 is 4.59", and on the F-550 it is 5.02". Very subtle difference visually, which is why we must rely on the ratings on the door plates of our trucks, and not second guess what the manufacture has calculated based on what we see.
3. The Rear Brakes
Sometimes, the ratings and specs might be the same, but the equipment might still be different. Such was the case with the rear disc brakes between the F450 and F550 during certain model years. This may not be applicable to your specific truck, because you were one of the first to get the Dana 110, but in previous years of F-450 and F-550 models, the rear brake rotors had the same diameter and swept area, but were oriented differently. In the F-550, both calipers used to be on the forward end, while the F-450 had a staggered caliper arrangement, one forward, the other rearward. You asked for physical differences, hence the comment.
4. The Rear Spring Shackle Hangars
Most F-550s came with cast rear spring hangars that hug and are bolted through the web and the lower flange of the frame. By contrast, the F-450 rearmost rear spring shackle hangar is a thinner stamped piece that is only riveted to the web of the frame, and does not hug the bottom of the web like the F-550's rearmost shackle hangar does. The rear shackle hangar in the F-450 looks more similar to the way spring hangars are on the F-350 frames, albeit presumably the F-450 stamping is more robust than the pickups, but not nearly as robust as the F-550's cast shackle hangar that is bolted to the frame on two planes.
Ironically, some F-550's slipped through the barn with the F-450 stamped rear hangar. I haven't seen this in person, but I have seen pictures, where someone was showing their frame for some other reason (mounting a bed or a hitch) and I said "wait a second, that's not an F-550, that's an F-450" based on what I recognized as an F-450 shackle hangar. They in turn showed me the vin plate that confirmed they had an F-550, and I had to believe them. They apparently got jipped on the high dollar rear shackle hangar.
The foward rear spring hangars to both the F450 and F550 are the same huge all cast spring eyelet anchors that are bolted to the frame through the web and the lower flange.
5. The Rear Driveline
Depending on wheelbase, cab axle distance, cab configuration, rear axle, and drive (4x2 vs. 4x4), there may be a difference in U Joint sizes, with the F-550 having the larger U joints. I want to say 1480's or 1510's... but I honestly do not remember what size they were. I still have my originals.
6. The Front Axle...
Contrary to what was posted above, one thing that ISN'T different between the F450 and F550 is the AVAILABILITY of a 6,000 lbs front axle rating in the F-450 with the Snow Plow Prep package. So while your F-450 may only have a 5,600 lb front axle rating, it was certainly possible for it to have a 6,000 lbs rating just like the F-550, if it were so equipped. The difference there would be the front springs. Keep in mind, this discussion is related only to the vintage of the OP's truck. Later F-550's were equipped with 7K lbs front axles.
7. The Frame
For your particular cab configuration, cab axle, and wheelbase, in your year, there is no difference in frames between the F450 and F550. However, in later years, a sleeved frame became available for the F-550 in the same WB, CA, CC, that doubled the frame thickness to .600 and increased the section modulus from 10.1 to 17.8, which resulted in an increase in GVWR from 17,500 lbs. to 19,500 lbs. During your year (and earlier years), these L plate frame sleeves were only available on longer wheelbases.
Those are some of the physical differences that come to mind between the F-450 and F-550.
