Frame Stiffing to reduce Porpoising?
Got a question for you seasoned drivers with older rigs. I have a 1999 F350 Dually Quad Cab Long Bed. I've been driving it for thousands of miles and for the most part, it's been fine. However, while ...
Forum Discussion
At issue is that it is impossible to add rigidity to the existing frame design without also adding weight.
Ford has reinforced Super Duty chassis cab frames using L reinforcements, which are split, angled along the web, and inversed at the cab to bed junction.
Let's pretend that the pickup frame is also conducive in shape to add similar frame reinforcements, and roughly estimate, using a reasonably derived example to demonstrate the added weight of material that frame stiffening reinforcement might impose.
And by the way, all of the reasonably derived estimates in my prior post were clearly identified as "EXAMPLE" assumptions, to again, demonstrate a process of estimation where the actual facts are not known.
Thanks to your clarification of the Federal Certification Label GVWR (11,200 49 state instead of 11,000 CA) and CAT Scale ticket when the truck was empty (caveat: if weight was for registering the TX truck in CA for purposes of determining fees, then most folks make every effort to make the truck as light as possible for "empty" weighings... ie, little fuel, no tools behind seat, etc), we still do not know what your actual camper weight is, beyond the dry weight of your BigFoot 25C10.6B of 2,734 lbs at manufacture.
Does that weight include the jack system? It does not appear to include the rooftop air conditioner shown in your photo, as the BigFoot label states N/A for both the air conditioner and the generator you said you added. The collective experience of truck camper owners culminates into the common understanding that there can be a signficant gap between the as manufactured weights of a camper, versus the as useable in the real world weight of the camper.
I think those of us focusing on the rig combination as typically deployed in your actual usage in the real world first, are focused on the porpoising you reported, which you stated was the principle problem you perceived and were trying to solve. One solution you proposed to solve that problem involved a question regarding the use of frame reinforcements. We are looking past that proposed solution first, in order to assess what you surmised was the root problem you were trying to solve with the frame reinforcement proposal.
But that proposal adds weight. To estimate that weight, we can use a 3" x 7" rectangular tube of 0.250" steel material thickness, which in mild A36 steel weights about 15.62 lbs per foot, and assuming we can split this tubing twice longitudinally into two L shaped reinforcements that we later split again cross-sectionally in order to invert the L at the cab transition point to retain some frame flexibilty while optimizing the placement of horizontal flange of the L to mitigate where the original frame flange is under the greatest tensile stress on the bottom flange, and the greatest compressive stress on the top flange, we might need to buy about 5 feet of this material to cut up, and hydraulically contour into a conforming shape. So that is almost 80 lbs of added material.
Because it might be best to avoid welding on the frame, we would need some hardware to mount the frame reinforcements. Whether we chose Grade 8 bolts and hardened flat washers, or Class 10.9 flange bolts and prevailing torque flange nuts, or better yet, huck bolts that are less likely to loosen over time... all that hardware will add some additional weight, say another 10 lbs. It all adds up.
As an example, from Truck Camper Magazine:
"Bigfoot 25C10.6: dry weight, 3,180 pounds + 50 gallons fresh, 417 pounds + 6 gallon water heater, 50 pounds + 2x 20-pound full propane tanks, 40 pounds + 2 batteries, 130 pounds + stuff, 500 pounds = 4,317 pounds"
Your 2000 model year 25C10.6B may start off with a lower dry weight, but the AC unit, the generator, the camper jacks, perhaps a solar panel, etc, pile the weight right back on again. In the TCMAG reported example, their actual BigFoot camper wet weight exceeded the dry weight rating on the label by 1,137 lbs, which is a 36% increase over the as manufactured dry weight on the label.
Without even considering the weights of your added generator, AC unit, and camper jack system, and instead just simply adding 36% of your dry weight to your dry weight to come up with a rough estimate of your wet weight with your pots and pans, yields a result of 3,718 lbs, which is consistent with what you are already sure of... that you are running over the 3,600 lbs capacity that you have determined from the difference between your GVWR and empty scale weight.
Now add passengers x 150 lbs each, and a full tank of diesel at an estimated 277 lbs (38 gallons x 7.3 lbs per gallon)
Along with 90 lbs of frame reinforcement, added weight that could be the final straw that might exacerbate, say, a driveshaft U joint failure from having already been pushed to a bit over maximum capacity.
You have an ideal camper, and a nearly ideal truck to haul it with. You have reported what you perceive to be a porpoising problem, and have proposed a solution. Obtaining the actual facts of the circumstances helps provide proper perspective on the problem, and may lead to a different solution than what was previously proposed.
To be solution oriented, it is strongly suggested to have your camper actually weighed as currently equipped with how you travel with it.
Ford has reinforced Super Duty chassis cab frames using L reinforcements, which are split, angled along the web, and inversed at the cab to bed junction.
Let's pretend that the pickup frame is also conducive in shape to add similar frame reinforcements, and roughly estimate, using a reasonably derived example to demonstrate the added weight of material that frame stiffening reinforcement might impose.
And by the way, all of the reasonably derived estimates in my prior post were clearly identified as "EXAMPLE" assumptions, to again, demonstrate a process of estimation where the actual facts are not known.
Thanks to your clarification of the Federal Certification Label GVWR (11,200 49 state instead of 11,000 CA) and CAT Scale ticket when the truck was empty (caveat: if weight was for registering the TX truck in CA for purposes of determining fees, then most folks make every effort to make the truck as light as possible for "empty" weighings... ie, little fuel, no tools behind seat, etc), we still do not know what your actual camper weight is, beyond the dry weight of your BigFoot 25C10.6B of 2,734 lbs at manufacture.
Does that weight include the jack system? It does not appear to include the rooftop air conditioner shown in your photo, as the BigFoot label states N/A for both the air conditioner and the generator you said you added. The collective experience of truck camper owners culminates into the common understanding that there can be a signficant gap between the as manufactured weights of a camper, versus the as useable in the real world weight of the camper.
I think those of us focusing on the rig combination as typically deployed in your actual usage in the real world first, are focused on the porpoising you reported, which you stated was the principle problem you perceived and were trying to solve. One solution you proposed to solve that problem involved a question regarding the use of frame reinforcements. We are looking past that proposed solution first, in order to assess what you surmised was the root problem you were trying to solve with the frame reinforcement proposal.
But that proposal adds weight. To estimate that weight, we can use a 3" x 7" rectangular tube of 0.250" steel material thickness, which in mild A36 steel weights about 15.62 lbs per foot, and assuming we can split this tubing twice longitudinally into two L shaped reinforcements that we later split again cross-sectionally in order to invert the L at the cab transition point to retain some frame flexibilty while optimizing the placement of horizontal flange of the L to mitigate where the original frame flange is under the greatest tensile stress on the bottom flange, and the greatest compressive stress on the top flange, we might need to buy about 5 feet of this material to cut up, and hydraulically contour into a conforming shape. So that is almost 80 lbs of added material.
Because it might be best to avoid welding on the frame, we would need some hardware to mount the frame reinforcements. Whether we chose Grade 8 bolts and hardened flat washers, or Class 10.9 flange bolts and prevailing torque flange nuts, or better yet, huck bolts that are less likely to loosen over time... all that hardware will add some additional weight, say another 10 lbs. It all adds up.
As an example, from Truck Camper Magazine:
"Bigfoot 25C10.6: dry weight, 3,180 pounds + 50 gallons fresh, 417 pounds + 6 gallon water heater, 50 pounds + 2x 20-pound full propane tanks, 40 pounds + 2 batteries, 130 pounds + stuff, 500 pounds = 4,317 pounds"
Your 2000 model year 25C10.6B may start off with a lower dry weight, but the AC unit, the generator, the camper jacks, perhaps a solar panel, etc, pile the weight right back on again. In the TCMAG reported example, their actual BigFoot camper wet weight exceeded the dry weight rating on the label by 1,137 lbs, which is a 36% increase over the as manufactured dry weight on the label.
Without even considering the weights of your added generator, AC unit, and camper jack system, and instead just simply adding 36% of your dry weight to your dry weight to come up with a rough estimate of your wet weight with your pots and pans, yields a result of 3,718 lbs, which is consistent with what you are already sure of... that you are running over the 3,600 lbs capacity that you have determined from the difference between your GVWR and empty scale weight.
Now add passengers x 150 lbs each, and a full tank of diesel at an estimated 277 lbs (38 gallons x 7.3 lbs per gallon)
Along with 90 lbs of frame reinforcement, added weight that could be the final straw that might exacerbate, say, a driveshaft U joint failure from having already been pushed to a bit over maximum capacity.
You have an ideal camper, and a nearly ideal truck to haul it with. You have reported what you perceive to be a porpoising problem, and have proposed a solution. Obtaining the actual facts of the circumstances helps provide proper perspective on the problem, and may lead to a different solution than what was previously proposed.
To be solution oriented, it is strongly suggested to have your camper actually weighed as currently equipped with how you travel with it.
