Dealer saying the payload is a "suggestion"
#51
The salesman I was working with did the same thing via text. I'm nearly certain it was an honest mistake and what he did was just quote me the max possible payload for the 2015 F-150 that we bought, which was like 2200 lbs or whatever. I was hoping it might be a gem and would be a HDPP truck, but checked the sticker when we got there to confirm actual payload was 17xx pounds or so. Was still pretty happy with that.
#52
I found a thesis that compares a model to real world testing and it looks like some interesting weekend reading. From what I've read so far, the understeer gradient is only a measure of the impact of speed / load on steering on a given vehicle compared to the same vehicle at low speed / no load. So to I'm not sure how I would do a cross vehicle comparison - but as I said, more reading to do.
I also prefer oversteer but understand why understeer is the safety standard and appropriate for 99% of people.
I also prefer oversteer but understand why understeer is the safety standard and appropriate for 99% of people.
#53
Regarding Andy T. I wish he would post test results!
Regarding SAE, I wish they would post test results!
#54
Meh, Andy T also setup a Honda Odyssey to tow a triple-axle airstream. I really liked our Odyssey as a tow vehicle and thought it was very capable with both our pop up and my enclosed utility trailer, but the triple-axle airstream is just silly.
#55
Empty, yes. Loaded for a trip, no. GVWR diff of 800 pounds. Ability to swing the TV to TT weight difference by 1,600 pounds through proper loading - and that will make a difference where the tires meet the road.
Regarding Andy T. I wish he would post test results!
Regarding SAE, I wish they would post test results!
Regarding Andy T. I wish he would post test results!
Regarding SAE, I wish they would post test results!
Increasing hitch load will increase sway stability, in contrast it will also reduce understeer gradient and adding more payload in the bed reduces it more. Placing weight as forward as possible in the bed will help but it’s still adding to rear axle load. This principle will apply to any vehicle of course regardless of its weight but a high payload with hitch weight and a light front axle deserves caution not confidence.
#56
And it follows that adding mass forward of the center point between the axles should increase understeer. I did some reading and think I have my arms wrapped around the inertia around the axles and understand your initial comment regarding the balance between trailer stability and cornering.
This once again gets me wondering about ultimate cornering ability. Since friction between the tire and the road does not tend to keep up with inertia with added mass, ultimate corning ability should decrease with increased mass. As such, I wouldn't be surprised if the lighter HDPP truck can out corner any 3/4 ton with the same trailer. The heavier 3/4 ton truck may have a more positive understeer gradient, especially if it's a diesel due to a more forward weight bias. But ultimately it will let go earlier than the lighter truck especially given the higher mass and that these trucks tend to have about the same size contact patch.
This is why I would love to see actual results from the SAE and Andy T's tests. I would not be surprised if the BMW X5 he set up with an 8,000 pound TT would indeed put a 3/4 ton to shame on a handling coarse with the same trailer. I'm not saying I agree with everything he does. There are definitely liability issues and structural strength issues. But it seems there is a trade off with a high mass tow vehicle. Yes, it's more stable. But it also might not be able to avoid an accident when a lighter tow vehicle could.
This once again gets me wondering about ultimate cornering ability. Since friction between the tire and the road does not tend to keep up with inertia with added mass, ultimate corning ability should decrease with increased mass. As such, I wouldn't be surprised if the lighter HDPP truck can out corner any 3/4 ton with the same trailer. The heavier 3/4 ton truck may have a more positive understeer gradient, especially if it's a diesel due to a more forward weight bias. But ultimately it will let go earlier than the lighter truck especially given the higher mass and that these trucks tend to have about the same size contact patch.
This is why I would love to see actual results from the SAE and Andy T's tests. I would not be surprised if the BMW X5 he set up with an 8,000 pound TT would indeed put a 3/4 ton to shame on a handling coarse with the same trailer. I'm not saying I agree with everything he does. There are definitely liability issues and structural strength issues. But it seems there is a trade off with a high mass tow vehicle. Yes, it's more stable. But it also might not be able to avoid an accident when a lighter tow vehicle could.
#57
Once you add any substantial hitch weight to the vehicle getting back to the unloaded understeer value won’t happen. As you are starting to get an understanding of the concept you will see that adding any WD at all lowers the understeer gradient. I still have my confidence in the F250 just for the fact that Ford lowered the FALR on the f150 to 25%. Theres only one reason they would do that and that’s to get the truck to pass the cornering stability test. Since the f250 can still take 50% FALR that puts the odds in its favor.
Andy Thompson is a smart man and he can indeed create a combo that can do a slalom at a higher rate of speed then a pickup. There’s nothing magical about his methods, he uses vehicles with very short rear overhangs and a wide stance. The trailers are almost always low CG Airstreams and I am willing to bet he has lowered the hitch weight to 10% or lower on most of these rigs. He almost always has to modify both vehicle and trailer and in turn he makes money doing so which is his primary motivation. In my opinion he focuses to narrowly on this slalom handling, but it makes for a great sales pitch though. He doesn’t like it when you ask or question him about engine, transmission, and transaxle cooling, and vehicle manufactures warranty. Read his articles, there’s some good information there but it’s mixed in with the BS sales pitch.
Andy Thompson is a smart man and he can indeed create a combo that can do a slalom at a higher rate of speed then a pickup. There’s nothing magical about his methods, he uses vehicles with very short rear overhangs and a wide stance. The trailers are almost always low CG Airstreams and I am willing to bet he has lowered the hitch weight to 10% or lower on most of these rigs. He almost always has to modify both vehicle and trailer and in turn he makes money doing so which is his primary motivation. In my opinion he focuses to narrowly on this slalom handling, but it makes for a great sales pitch though. He doesn’t like it when you ask or question him about engine, transmission, and transaxle cooling, and vehicle manufactures warranty. Read his articles, there’s some good information there but it’s mixed in with the BS sales pitch.
#58
In case this is helpful to someone else - my ah hah moment was when I realized I had to think of weight and mass separately. A WD hitch redistributes weight but it does not change the distribution of mass. This is critical when you think about set up. Where the mass is determines the effects of inertia. Where the weight is impacts traction to resist inertia at the tire / road surface interface. You have to think of both of these separately and then put them together to get the full picture of what is going on.
It is very interesting to think about and will change where I pack things. For example, heavy items (like my tools and jacks) that easily fit under the seats in the cab will go there instead of in the bed near the tail gate. Kayaks will go more forward over the cab instead of over the bed. More central mass distribution and less weight distribution through the WD spring bars should result an less pronounced oversteer bias at the limits of traction.
Last edited by Gladehound; 02-17-2018 at 10:05 AM. Reason: add reasoning for benefit of others
#59
4 seasons trailer
Thank you so much for your response! No one was in the car at all. We kicked around the idea of loading it with the whole family, four car seats (our kids are all young) and dog just to see how much the truck plus us weighed but decided to go with the empty weight instead. I even made my husband take out his headphones so as not to throw off the weight ha!
I am not opposed to a smaller trailer or an ultralite but my fear now is that as our family gets older and we have four teenagers (did I mention they are very closely aged?) we will not have the option to upgrade our trailer without upgrading the truck. Of course we now have buyers remorse and wish we would have maybe gone for a 250. The Army is sending us to Alaska for the next three years so just to make things a little more fun we need a four seasons trailer as well. The low payload and towing capacity are scaring me!
I am not opposed to a smaller trailer or an ultralite but my fear now is that as our family gets older and we have four teenagers (did I mention they are very closely aged?) we will not have the option to upgrade our trailer without upgrading the truck. Of course we now have buyers remorse and wish we would have maybe gone for a 250. The Army is sending us to Alaska for the next three years so just to make things a little more fun we need a four seasons trailer as well. The low payload and towing capacity are scaring me!
#60
Senior Member