Stop being so jealous and go out and get yourself an HDPP already! you know you want to

 

Ron, we agree that if a trailer is poorly designed and/or loaded it will misbehave behind a HDPP as much as a MT of the same configuration. The higher payload rating doesn’t magically fix this problem as some suggest. The main purpose of the SAE j2807 test is for direct comparison of trucks of the same class. One particular test requires the truck be loaded to its GVWR, RAWR, and GCWR simultaneously. If the HDPP was far superior it wouldn’t see a significant drop in TWR as a result.

 

8100hd - my question is this. Does the manufacturer choose the ratings to be tested, or does the procedure test to failure by gradually increasing the loads and testing over and over and over. I seriously doubt it is the latter. if I'm right, than ratings show that the manufacture chose a limit to test and the truck passed at that pre-specified limit. It is not a head to head. If I am wrong, please provide the documentation that contradicts my hypothesis.

The test you mentioned - simultaneously maxing out the GVWR, RAWR and GCWR would give the HDPP a less favorable weight distribution than the Max tow. In real life with big trailers, people are near max on the hitch... let's say 1200 pounds and people with max tows can put limited additional weight in the cab. People with HDPPs can put a lot of weight in the cab and often have the HDPP because they have a family and need the capacity for people in the cab. Apparently this is a comparison that isn't done, I think we'd both agree that having more actual weight on the front improves stability. I've already stated that loaded the same way, there should be little difference between identical wheel base / configuration Max Tows vrs. HDPP and that the bigger differences are when people compare the 145WB SCREW Max Tow to the 156" WB HDPP for reasons stated above. And due to the layout of the 145WB SCREW, the weight distribution just gets worse when you load it. I think we'd both agree on that too.

What we do not agree on is the impact of rigidity throughout the system and traction. At least the last time I brought this up you did not agree. I'll give an extreme example. IF the truck is on rails (literally) and locked into those rails, you could say it has infinite lateral traction. If it was rigid, the trailer could not move it side to side even if it were as light as a feather. So now assume tow trucks are equally rigid, but one has bad tires with 50% of the traction of another. A swaying trailer will overcome the traction limitation of the poor tires and wag the truck before the truck with good tires. Now assume one of the trucks have under inflated load C tires and one has appropriately inflated load rating E tires (i.e. on is less rigid than the other). Now the truck can start moving side to side before it even breaks traction. All of this matters, regardless of if it's included in the insurance equations or not.

 

I almost did when I found one with 4K miles on it, posted about it too as I was debating between it and the F350, but the F350 is better suited for my future plans. As far as WB is concerned, Absolutely! The longer it is, the more stable it is. Holds true for semis too. Used to drive a Mack Superliner, that was one long SOB, but was such a nice platform for long hauling compared to the short city Jimmies I also drove, hated those things.

We have hashed and rehashed the differences on the HDPP to ad nauseam. The differences are minor, and were pointed out above. Heavier axles, and stiffer springs pretty much sum it up. The thicker frame is also on the 145" Max Tow trucks. I do believe what makes the tow vehicle more capable in the tow guide are the 20" wheels, which have a short sidewall for more stability, other wise, Ford would footnote, 18" wheels with LT tires, which they don't, just with 20" wheels.

 

Testing? It’s a safe bet that Ford tests a few configurations then uses that data to calculate and simulate most others. The physics is very solid and not difficult to recreate out to many degrees of freedom.

 

If anyone actually read J2807, it states that the tested platform must be the one with 33% of sales. Hence why it is the XLT Screw LB 3.5EB with Max Tow.

Can pretty much guarantee that the HDPP is not 33% of sales.

 

It all comes down to the magical 20" wheels. If you look at any other configuration and compare max tow to hdpp they have the same GCVWR 17100 lbs total. Then when you put on the magical 20" wheels it jumps to "best in class" 18400 lbs. I'll take my 164" wheelbase over a 145" wheelbase for towing stability any day. Regardless of my non magical 18" wheels. The max tow with the 20" wheels is a good tow vehicle if you travel empty all the time. I can hook up my 1400 lbs pin 5th wheel with me the wife 2 dogs in the truck and still have payload for 500 lbs of cargo. Real world most people don't go camping by themselves.

 

While I sometimes poke at you (only because you poke at me). I think you're choice of an F350 was a good one. An F350 SRW with the 7.3 gas will likely be my next truck as I would like to do some overlanding across norther Canada and Alaska with a flat bed camper. The biggest consideration for me in getting the HDPP was that my job requires me to go into urban areas and park in garages that are as low as 6'6", and I really didn't want more than one vehicle to maintain. Hoping not to have a job by the time I need my next truck.

 

Just to clarify, as was mentioned by acii, no one here is saying you “need” a HDPP to tow heavy. The question was posed if the max tow tows as well as the heavy duty payload and the answer is yes... up until a certain point, than no. Sorry, but a maxed out max tow will handle like turds when an equally equipped HDPP still has 25% of its payload remaining. You can’t argue differently!

No one is saying you need a HDPP. But what we are saying is the HDPP tows heavy better, and heavier overall.

Lou

 

That about sums it up.