brulaz

My Ford manual says to return the front 1/2 of the way with the WDH. My Equal-I-Zer manual says anywhere from 1/2 to all the way with the WDH.

I follow the Equal-I-Zer instructions and aim for "all the way" as my rear axle is over loaded, and this will remove the maximum weight off of it.

These recommendations are fairly recent, as some engineers noted that many users were over- tightening their WDH causing steering issues. Theoretically you can lift the rear tires right off the ground with enough WDH.

So instead of saying "return all the weight to the front axle", Equal-I-Zer is saying "return 1/2 to all", and Ford is saying "aim for 1/2". Take your pick.

Martiangod

My goal and instructions to customers is always, if your steering feels the same as unloaded, your good, if it feels heavy, back off on the WDH, if steering is light, give the bars take another chain link up, if you push too much to the front you will have premature front bearing wear.
and I always want to see front and rear wheel well height within 1/2" of each other

brulaz

Found it:
This from JBarca's post in this thread (about middle of first page). The following posts by Ron Gratz are also helpful:
http://www.rv.net/forum/index.cfm/fu...d/26767689.cfm

11screw50

Yeah, I forgot that the manual said half way for my 2011, honestly, have not looked at that section for the 2015 since it will be another month or more before I tow (mostly depending on my son's baseball schedule...might not make it out camping until the end of July this year)

Easy enough to cut the numbers in half so as to return the front halfway back to unhitched level. The numbers are great but they don't help you set it up properly (per the manufacturer's recommendations), they just let you see what is (should) be happening with the weight and even then that only works if you can wrap your head around the numbers in a meaningful way.

*edit* sure enough, I just looked and the 2015 manual does say to bring it back down a quarter and not half like the previous gen. Definitely interesting. Based on previous example, that would only have 112# shifted back to the front and only 55# to the trailer leaving 1280# added to the rear axle. This seems almost pointless...

Montol

In response to your excellent work, I made this somewhat rudimentary spreadsheet, which attempts to recreate some of your formulae, and some of Ron Gratz's formulae.

Hopefully it isn't a total piece of garbage. I'd like your feedback and comment, if you care to do so.


Also, I was wondering - how do I know what WDH rating I should be using? According to the guys at Hitch Experts, the setup in that spreadsheet should put me at a 600lb or 800lb WDH (I'm guessing 800lb is probably 'ideal' since the total weight behind the rear axle is around 775 with a 105lb WDH).

However, as you've said . Is it possible to 'back off' the WDH bars a bit? If so, there's a spanking good deal on a 10,000lb/1,000lb WDH hitch that I was looking at, and would like to buy...so long as they are not going to damage my system in some way. How do I learn how to 'back off' the WDH?

Thanks!

ColbyL

Well, to me, it looks pretty good so far. Thanks for doing it. My first thought is, what if you had it show the weight removed from front before WDH, and then an input for the percentage of that weight to return to the front, which would result in "force applied by WDH bars.

For example, Ford wants the front end on a '16 F150 to come back 1/4 of the way. I know it isn't linear because it is force against a spring, but lets say it is, so if a tongue weight of 1100 lbs results in 400 lbs removed from front TV axle, I want to put 100 lbs back, or 25% of 400, and the spreadsheet would calculate that, say, 900 lbs will be applied by the WDH bars. And it would also make all the other important calculations, such as weight transferred to TT axle and TV rear axle.

In this case, I would be able to see that WDH bars rated for 1000 lbs would be safe to use for this setup.

ncz

The problem you may run into is that the bars are too stiff for the tongue weight you are dealing with. The bars are designed to flex. If your tongue weight is not enough to "flex" the bars, you will end up with a ride that will shake the dishes out of your cabinets and the fillings from your teeth. It will work for WD and ride control purposes but may not be the most comfortable

ColbyL

I'm taking another look at the spreadsheet. I've weighed the truck axles unhitched and hitched, and also the tongue weight unhitched. No cargo, full tank, just me in driver seat.
The predicted RAW comes out 440 lbs heavier than actual, and the predicted FAW is 135 lbs heavier than actual.
MONTOL, could you please review the formulae that you used to predict these weights?

Montol

The one thing that is 'bad data' in this spreadsheet is the CAT Scale measurements for the starting FAW and RAW. I totally fudged those numbers, since I suspect my truck is around 6,000 curb weight, but I don't know how that is distributed. All of those initial truck inputs were based on the sticker and specs for a 2013 F150 XLT SuperCrew w/ 157" wheelbase. I also did a little fudging on the cargo weight in the cab versus the bed (but in front of RA). I don't know how those weights would distribute out to the axles.

What was your FAW and RAW on your rig? If you change all of those initial truck values and the CAT Scale inputs, is it any closer to reality?

Also, these were the calcs entered. I'm just about to upload the new spreadsheet:

When the trailer is lowered onto the hitch ball, the rear axle is the pivot point:
X is removed from the front axle: Loaded Weight * (Rear Axle to Hitch Ball Length / Wheelbase Length)
Y is added to the rear axle: X + Loaded Weight

If using WDH with info as given:
A is shifted to the TT axle: WD Spring Bar Load * (Spring Bar Length / Hitch Ball to TT Axle Length)
B is shifted to the front axle: A * (TT Axle to RA Length / Wheelbase Length)
C is removed from the rear axle: A * (TT Axle to FA Length / Wheelbase Length)

ColbyL

I input my actual scale weights unhitched- 3150 front and 2350 rear. I left the 1000 bar force alone (it doesn't change anything much by varying by 100 lbs either way). I am wondering if full tongue weight AND weight removed from front axle should both be part of the equation for predicted RAW. I'll attach my spreadsheet....