So I have been going down the road towing my 32ft TT just as happy as you please. Last time I got something wrong because it towed very poorly. Thankfully we were only going a short distance. So we are going out again this weekend and I have some time to try to get it right. I took distance measurements to the center of the fender lip unhooked and hooked up to see what was happening. I hooked up and found I had about 1.5" of drop in the rear so I added air to the air bags until I got about 1" of drop then adjusted the WDH

Unhooked with 10 PSI in the air bags
LF 35.75
RF 35.5
LR 37
RR 36.75

Hooked with 10 PSI in the air bags and NO WDH
LF 36.5
RF 36
LR 35.5
RR 35.25

Hooked with 30 PSI in the air bags WITH WDH
LF 36.25
RF 36
LR 36.25
RR 35.75

I can't believe I am not getting more leverage to the front considering my bars are already a little past horizontal. I have one more washer to add to tilt the head more so I am going to add that and take it fully loaded for the weekend to the scales and see what I have.

It seems I may need more bars or I may find out I have way too much tongue weight.

Any other thoughts before the scales?

 

If you stand back with it hooked up and 10 psi in the bags, what does it look like?


If your combo looks level with either the 10 or 30 psi then try it.


when you say it towed poorly what do you mean? Was it wagging the tail? Excessive bouncing or what?

 

"Last time I got something wrong because it towed very poorly"
Wags, did you change something on your setup this time out?
It does seem odd that your front end measurements don't change with and without WD hooked up. Unless airing up the bags is changing the front measurements then the WD is taking up that change. Do you have a front comparison with and w/o WD with the air bags at the same pressure in both scenarios?
Any idea on trailer weight? (Listed GVWR of trailer)
Do you know what size spring bars are on the WD hitch?

 

Standing back and looking it looks like the front is up a little but that may be me not seeing the normal rake. That is why I am measuring and trying to take judgement out of it and using only data. What I mean by different is the trailer seemed to be pushing me around and was porpoising something fierce.

I must have changed something but I don't know what which is why I am taking my time and trying to get it right, then document, then reproduce forever more. I was trying to adjust the WDH after airing up the bags so I wouldn't think the bags would change anything, if I set the WDH then aired up I could see change. I don't remember trailer weight exactly but think it is about 8500 lbs loaded. I am going to include that after the scales in my documentation. The bars are 1000 lbs each.

I have towed with this TV and TT several times even from SoCal to the Grand Canyon with out issue so I am confident it is a set up issue.

 

Bars first then air bags. Bars transfer weight to the front axle, not so with air bags.

The current standard is measure at the front fender and height should be the same as slightly lower than when unhitched. If you have that, according to the manufacturers you should be good.

Steve

 

I will try with minimum air in the bags tonight.

Question #1: Why would it matter how much air is in the bags (within reason) as long as measurements are taken with the air at the same psi, filled or not? Shouldn't the WDH transfer regardless of where the rear is?

Question #2: I am starting off with about 1 1/2" of drop at the rear. How much drop is considered acceptable?

 

I am sure someone from one of the manufacturers can articulate this better than I, but I believe the reason the "point of measurement" standard was changed came about to deal with the number of folks running air bags.

Air bags are not intended to transfer weight to the front axle. It used to be the case that measurement was at the rear wheel wells, but when air bags are aired up, it changes the measurable impact of the hitch weight and it is the effect of weight on the hitch unloading the front axle that you are attempting to ameliorate with the bars. In this regards, to the best of my knowledge, manufacturers have always taken the position bars first, then air bags. If you air up first, you transfer weight to the rear axle and reduce the role of the bars.

I don't think I have ever seen documented a maximum acceptable drop, although I am sure at some point your tongue weigh would exceed the weight rating of the hitch and/or other components.

Steve

 

"Ameliorate" Great word

a·me·lio·rate
əˈmēlyəˌrāt/Submit
verb
make (something bad or unsatisfactory) better.
"the reform did much to ameliorate living standards"
synonyms: improve, make better, better, make improvements to, enhance, help, benefit, boost, amend; More

I had to look it up so for anyone else that is having their education tested I posted the definition.

As to your answers I understand the description you gave but I am having a hard time getting my head around why it would matter if I set the bars after the bags. If I upgrade my springs so there is less sag in the rear I would have the same situation wouldn't I? Help me understand. I don't do well when I don't.

 

Here is what I was trying to say, I guess not so well. I am sorry for the word choice. I did not mean it as a test.

The bars are supposed to deal with weight transfer. The bags stabilize, but are not to transfer weight. If you take some of the weight off with the bags, the bars will transfer less.

I am not trying to tell you what to do, just passing on what the manufacturers have had to say, in the past. One thing I might suggest is simply calling customer support for your hitch manufacturer and discussing your situation. I am entirely willing to be wrong, just trying to pass on what I have been taught.

In the past I have posted about the trouble I have had setting bars when a truck has heavier springs as they take away the drop and there is no way to know how much weight I transfer when I bring up the bars. So, yes, it would be the same as having heavier springs, but it still makes it hard to know what the bars are doing.

If you can do all this on a scale, your goal is to keep no less weight on the front axle when hitched than you had before you were hitched.

Steve

 

Okay, I have an additional thought because it may sound like we are saying something different, when we may be close to the same.

Normally when you use spring bars, you are returning the tow vehicle to it to the same degree of level as it is when it is not hitched. That is why the manufacturers have changed their focus to basically say "when hitched the front fender height should be the same or a little lower" than it was before you hitched. You simply put weight back on the front axle.

My thinking was then that your vehicle is level without the air bags pressurized.
If, in your normal running configuration" you have 10 pounds of pressure in the bags, I think it would be reasonable to set your bars with 10 psi in the bags or any other pressure that was your normal running configuration, as long as you put the weight back on the front axle so it is the same as it was before you hitched and your vehicle handles well at that pressure in normal driving.

When I go back to your initial post it looks to me like your front fenders are higher than they are unhitched. I believe the usual thought would be that your front axle is lighter when hitched based on it elevation and I think the usual suggestion would be you need more help from the bars.

 

That is what I was trying to say. I am glad you figured out how to say what I was thinking. I too now realize that I did my measurements wrong because I measured, added air and trailer and WDH and tried to achieve the same measurement as before. You make a very good point that the air needs to be the same. That is what I was thinking but it didn't dawn on me that I ultimately didn't do that. Amazing how hard only verbal communication can be without any visual cues. Anyway you are right that my front fenders are a little higher with the bars pulled beyond horizontal. My understanding is to keep the bars horizontal. I am going to angle the hitch head more and see what happens. The final determination will be on the scales in the morning.

So now that we are saying the same, if I can't get the front down and the tongue weight is not too high then I need more bar right?

 

Yes, that is exactly right, more bar to get the front down.

Man, I am glad they are not all this hard and yes, it is really hard sometimes to say things clearly.

Steve

 

Well WE3ZS, you said it early and Steve kept telling me until I understood and I finally did. I was trying to compare measurements with different amounts of air in the bags. I decided to see what would happen if I trusted Ford to get it right and lowered the bags to 10 PSI ((just to have some air in them to protect them)(I bought the vehicle with them on it)), angled my head more and hooked up...guess what?

LF 35.5
LR 36
RF 36
RR 36.25

Just right at what it was unhooked, TV level and TT at "0" bubble level checked inside the door on the floor.

Again scales will tell but it looks like I am very close.

Yay

Can't wait to drag my trailer around tomorrow and see how it does.

Thanks again guys

 

That certainly look encouraging. I hope all goes well for you from this point forward.

Steve

 

Looks much better.


Now if it passes the eye test and looks level then all that is left is the scales.


Probably not needed but I would like to know where I stand anyway, at least once.