ford f 150 25% return with wdh

[TheGerman]

Circling back to the OP's question of "why": The "combination handling" section of SAE J2807 basically wants the tow vehicle to understeer when reaching the limits. This makes sense as understeer is considered easier to manage for most people and oversteer with a trailer typically ends up in jackknifing. SAE J2807 calls for three different tests: No WDH, 50% front axle load restoration and 100% FALR. The first two are performed with 0.4g on a circular test pad, with 100% FALR the speed is reduced to reach only 0.3g. Increasing the weight distribution forward reduces understeer, effectively the WDH is making the rear suspension stiffer and if you're familiar with setting up race cars that increases the tendencies to slide over that axle.

Ford probably decided on 25% FALR based on their testing and the fact that current half-ton suspensions tend to be soft for ride quality. Trying to get close to 100% FALR likely makes the rear way too stiff and prone to oversteer.

[DieselDrax]

Originally Posted by TheGerman

Circling back to the OP's question of "why": The "combination handling" section of SAE J2807 basically wants the tow vehicle to understeer when reaching the limits. This makes sense as understeer is considered easier to manage for most people and oversteer with a trailer typically ends up in jackknifing. SAE J2807 calls for three different tests: No WDH, 50% front axle load restoration and 100% FALR. The first two are performed with 0.4g on a circular test pad, with 100% FALR the speed is reduced to reach only 0.3g. Increasing the weight distribution forward reduces understeer, effectively the WDH is making the rear suspension stiffer and if you're familiar with setting up race cars that increases the tendencies to slide over that axle.

Ford probably decided on 25% FALR based on their testing and the fact that current half-ton suspensions tend to be soft for ride quality. Trying to get close to 100% FALR likely makes the rear way too stiff and prone to oversteer.

Awesome info, thanks!

[Dustyhd]

Originally Posted by TheGerman

Circling back to the OP's question of "why": The "combination handling" section of SAE J2807 basically wants the tow vehicle to understeer when reaching the limits. This makes sense as understeer is considered easier to manage for most people and oversteer with a trailer typically ends up in jackknifing. SAE J2807 calls for three different tests: No WDH, 50% front axle load restoration and 100% FALR. The first two are performed with 0.4g on a circular test pad, with 100% FALR the speed is reduced to reach only 0.3g. Increasing the weight distribution forward reduces understeer, effectively the WDH is making the rear suspension stiffer and if you're familiar with setting up race cars that increases the tendencies to slide over that axle.

Ford probably decided on 25% FALR based on their testing and the fact that current half-ton suspensions tend to be soft for ride quality. Trying to get close to 100% FALR likely makes the rear way too stiff and prone to oversteer.

I see in SAE j2807 that they test weight carrying and with weight distribution set at vehicle manufactures recommendations. I don’t see that third test at 50% and then at 100%. They will test with a WDH at 100% if the manufacture doesn’t specify a %.