We Cant Wait wrote:
Ron sorry but the truck mfr. has no idea about weight distribution etc.---
I think you should try to convince Ford, Chevrolet/GMC, and Ram of your opinion.
---Read the manuals for the hitches and they say to ensure that the height before aand after hitching is the same, thus no unloading of the front axle.---
The manual for the OP's ReCurve R3 WDH calls for approximately equal added load on TV's front and rear axles.
If you read all of the WDH manuals, you'll see recommendations which range from adding equal load to front and rear TV axles (making the front and rear axle loads perhaps 300# heavier than unhitched), to making the front axle load the same as unhitched, to restoring only 50% of the removed load.
---Taking 220 lbs. off the front axle when hooked with the distribution hitch hooked also will cause steering issues especially on a wet road, he'll hydroplane in a heart beat and loose steering control.
Many people report towing with the WDH adjusted to restore less than 100% of load to the front axle -- in compliance with TV manufacturer specifications. I've seen no reports of that causing loss of steering control.
I believe the reason Ford, GMC/Chevrolet, Ram, Equal-i-zer, and others now are specifying less than 100% load restoration is pretty well summed up in this
Letter to Editor by Richard H Klein, P E printed in TRAILER BODY BUILDERS Magazine. The comment which specifically addresses WDH adjustment is:
QUOTE
2. The statement “too much tongue weight can force the truck down in the back, causing the front wheels to lift to the point where steering response and braking can be severely decreased” is not the real issue with heavy tongue weights. The real problem is that the tow vehicle's yaw stability, as measured by “understeer gradient”, is severely decreased. This increases the propensity of the tow vehicle to jackknife in turning maneuvers. Specifically, recent full scale testing conducted by the SAE Tow Vehicle Trailer Rating Committee (and now published in SAE J2807), determined that the use of weight distributing hitch torque should be minimized. In fact they recommend that the Front Axle Load Restoration (FALR) not exceed 100% (100% means that the front axle weight is brought back, via weight distribution, to a weight equal to its “no trailer” condition).
UNQUOTE
A related explanation from a representative of the company which manufactures the Equal-i-zer hitch was first posted
here . It says:
QUOTE
In the past we had suggested that you should see a small drop on the front suspension. We are always trying to improve things here at Progress – our motto is “Safe and Happy Customers,” and so we are always reviewing our instructions and installation process. Recently, as part of this constant effort our engineers looked more deeply into this aspect of installation. We had always felt that a small drop was a sign that the trailer’s weight was being transferred to the front axle, and that this was essentially a good thing.
As our engineers reviewed the instructions for the last round of renewal of our instructions, the found research results that contradicted our prior thinking. There has been a substantial amount of testing conducted by experts from SAE and the RV Industry Association to find out what will produce the best stability when towing. This towing suggests that you want your front axle’s compression to be close to, but not lower than your free-standing height.
UNQUOTE
Those statements were made around 2010. Progress Mfg (Equal-I-zer) then changed their WDH-adjustment spec to state that load restoration could be in the range of 50-100%.
Since then, major TV and WDH manufacturers have made front axle load restoration specifications of 50%, 33%, 25% and 0% depending on tongue weight and tow vehicle capacity.
Ron
