Need help selecting hitch spring bar 'weight'

[RFP]

As the proud owner of a new-to-us 23D International Serenity, I am trying to get all rigged up and ready for a spring and summer drama-free, safe enjoyment of this beauty.

The previous owner was using a 'generic' version of the Equil-i-zer hitch which I find very unappealing due to the virtual lack of 'spring' in the trunion bars and the resulting harshness transfered to our trailer.

I am leaning toward either the Reese 'SC' (friction sway control, tapered bars) or he Husky 'Center Line' ('active' sway control in the head, NOT the 'TC' version).

Reese: http://www.reeseprod.com/products/we...a3X3%7CrlxitHa

Husky: http://www.huskytow.com/product/husk...towing-system/

Of course, both are available with a range of spring bars.

The 23D has a 'brochure' tongue weight of 720-pounds.

Our tow vehicle is a new Ford F150 3.5 EcoBoost with Max Tow package.

Now, finally to my question: The 720-pound advertised tongue weight seems to be right at the break point of the spring bar 'weights.' So, do I choose a bar with a rating higher than, say, 800-pounds, or lower.

Obviously, I want adequate weight equalization, but also want to avoid my hitch set up beating up my Airstream.

By the way, we pack and travel light... very light!

Thanks in advance for your help!

Rob

[HowieE]

You want the lightest bars that will allow you to bring the front axle of the TV back to near original height.

Heavier bars will get you there but will result in a harsh ride and strain on the trailer.

[RFP]

Originally Posted by HowieE

You want the lightest bars that will allow you to bring the front axle of the TV back to near original height.

Heavier bars will get you there but will result in a harsh ride and strain on the trailer.

Thanks, Howie

I guess that gets to the heart of the question... how is it possible to know in advance what bars that would be. Of course, I suppose this is only a problem if I am ordering the hitch and setting it up myself. I assume a dealer might have an assortment of bars on hand to try during installation.

I am planning on ordering and installing it myself.

Rob

[HowieE]

Yes selection is tough with all the variables.

Maybe someone with a like set up will chine in with their results.

As for a dealer having a selection yes, they may have them, but in general very few dealers have any idea at all in how to set up a WD hitch. The problem is it takes time or have the space to do correctly and they are generally not interested in spending that time.

[dkottum]

https://www.etrailer.com/faq-weightdistribution.aspx

[RFP]

Originally Posted by HowieE

<<< snip >>> but in general very few dealers have any idea at all in how to set up a WD hitch. <<< snip >>>

Yikes... another bubble busted!

My local; RV dealer is United RV... they have a big ship and do a lot of service work. I just assumed that they would have the know-how, and the interest, to do this right. Probably a crummy assumption.

Rob

[wkerfoot]

I don't know the engineering answer to your questions, but here is my experience.

I have a 2014 Dodge Durango with a tow rating of 7,200 lbs and use the 800 lb bars to tow either my 1979 23' Safari (5,000 lbs) or my 1954 29' Liner (5,500 lbs) and 1200 lb bars when towing with my 1977 Lincoln Continental. I have no idea what the tow rating is for the Lincoln.

I believe that suspension stiffness is as important as tongue weight when choosing bar ratings.

Bill

[xrvr]

Originally Posted by HowieE

You want the lightest bars that will allow you to bring the front axle of the TV back to near original height.

Heavier bars will get you there but will result in a harsh ride and strain on the trailer.

Exactly. Try the lighter bars first and see how that works.

[m.hony]

Spring bar rates should be correlated to trailer tongue weight.
The first thing to know when choosing is the tongue weight of the trailer I would think.

[dznf0g]

Originally Posted by m.hony

Spring bar rates should be correlated to trailer tongue weight.
The first thing to know when choosing is the tongue weight of the trailer I would think.

I'm not sure I agree with that for the simple fact that there is no standard between hitch manufacturers for how they rate their bars. For example, refer to Inland Andy's spring bar flex rates experiment from several years ago.

[fwjumper]

Your new truck likely has heavier springs with the tow package. I seriously doubt that you will need anything more than 800 pound bars. This will sound inane, but is worth a try. On level ground, hook the trailer to the truck. Measure carefully, how much the truck drops. Then with two or three strong friends, try to lift the truck. If you can lift it to the original height, 6oo # bars will probably be enough. If you have a way to weigh the load to lift it back to normal, that would be even better. (picture a bathroom scale under the bumper with a jack on the scale lifting the truck.) Obviously, this won't work because you would destroy the bathroom scale, but if you could borrow something heavier or a load cell, that would work great. Anyway, the lifting trick will just give you a general idea of how much it will take. I would be surprised if 3 healthy guys couldn't bring it back to level.

[RFP]

Originally Posted by fwjumper

<<< snip >>> Measure carefully, how much the truck drops. Then with two or three strong friends, try to lift the truck. If you can lift it to the original height, 6oo # bars will probably be enough. <<< snip >>>

Interesting experiment... sounds like it would be worth a try.

It's interesting that the new truck's manual says to measure the front height and then adjust the WD hitch so that the front height returns [only] 1/4th the distance to the original. I've read that several times and sure 'nuff that's what it says! In other words, the WD hitch allows the front to rise 3/4th as much as it would without the hitch.

Weird!

[nvestysly]

Our used 29' Classic and 2500 Suburban came equipped with 1000# bars. The hitch connection was way too stiff!

I agree that lighter bars are probably the way to go. We changed to 600# bars and the ride is much better. Plenty of weight is transferred back to the front on the Suburban with the 600# bars. The lighter bars are flexed a noticeable but reasonable amount.

I like the hands-on idea suggested above - just lift the back of the truck and see what is required to get it back to level.

Inland Andy posed an interesting thought in the past... paraphrasing - if you select bars simply based on tongue weight that means the same bars are used on a small car, a 1/2 ton truck, a 3/4 ton truck, or a Mack truck. Does that really make sense?

on edit: I've seen several hitches installed by dealers that were not set correctly. The bars were too heavy, the bars were not flexed, the head angle was wrong, etc. Not all dealers are clueless but it seems a great many don't understand hitches.

[ajnz]

It does make sense to use the same spring bars regardless of what the tow vehicle is. Remember, the purpose of the bars is to transfer the load the tow vehicle sees at the hitch evenly to the front and rear axles. The effect of the transfer will be less pronounced if the tow vehicle has a stiffer rear suspension as would be seen in a 1 ton truck vs SUV. The actual change in weight distribution between front and rear axles will be identical however.

[KJRitchie]

This owner is using 800lb bars.
http://www.airforums.com/forums/f238...ml#post1515209

Kelvin

[Siegmann]

Originally Posted by RFP

Interesting experiment... sounds like it would be worth a try.

It's interesting that the new truck's manual says to measure the front height and then adjust the WD hitch so that the front height returns [only] 1/4th the distance to the original. I've read that several times and sure 'nuff that's what it says! In other words, the WD hitch allows the front to rise 3/4th as much as it would without the hitch.

Weird!

Can you provide more info on your truck manual guidance on WD hitch adjustment.

Everything I have read for all the manufacturers (Ford/GM/Chrysler) is anywhere from 100% FALR to 50% FALR. While height returns are not exactly the same as measuring the loads on a scale, I have got to assume that a 1/4 height return would be less than 50% FALR. Now maybe a height return to within 1/4 inch of the original height was what they were specifying?

[RFP]

Originally Posted by Siegmann

Can you provide more info on your truck manual guidance on WD hitch adjustment.

Everything I have read for all the manufacturers (Ford/GM/Chrysler) is anywhere from 100% FALR to 50% FALR. While height returns are not exactly the same as measuring the loads on a scale, I have got to assume that a 1/4 height return would be less than 50% FALR. Now maybe a height return to within 1/4 inch of the original height was what they were specifying?

OK... Here's the exact text from page 262 of the Owner's Manual
----------

When hooking up a trailer using a weight-distributing hitch, always use the following procedure:

1. Park the loaded vehicle, without the trailer on a level surface.

2. Measure the height to the top of your vehicle's front wheel opening on the fender. This is H1

3. Attach the loaded trailer to your vehicle without the weight-distributing bars attached.

4. Measure the height to the top of your vehicle's front wheel opening on the fender a second time. This is H2

5. Install and adjust the tension in the weight-distributing bars so that the height of your vehicle's front wheel opening on the front fender is approximately a quarter the way down from H1 toward H2

6. Check that the trailer is level or slightly nose down toward your vehicle. If not, adjust the ball height accordingly and repeat steps 2 - 6

Once the trailer is level or slightly nose down toward the vehicle:

- Lock the bar tension adjuster in place

- Check that the trailer tongue securely attaches and locks onto the hitch

- Install safety chains, lighting, and trailer brake controls as required by law or the trailer manufacturer.

[m.hony]

Originally Posted by dznf0g

I'm not sure I agree with that for the simple fact that there is no standard between hitch manufacturers for how they rate their bars. For example, refer to Inland Andy's spring bar flex rates experiment from several years ago.

Tongue weight is a starting point anyway.
I have 1,000# bars for my Classic 30-
Still have a hard time transferring enough weight back to front axle.
I think the reason for that is I have a half ton truck.
I wonder if 600# bars would make it even more difficult to transfer weight to front axle...


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[RFP]

OK, here's some more grist for the mill:

I just went out and hooked up the Airstream to the F150 (for the first time) using the generic 'Equal-i-zer' hitch from the previous owner.

The surface isn't level... slight downward slope to the driveway. The rig is pointed down-driveway, slightly downhill.

The bottom of the shank is only 5 3/4" from the concrete; I don't think it would get out of the driveway and into the street without dragging... do I care about that?

No load heights:

Front = 35 3/4"
Rear = 38"

Full trailer load with no bars attached:

Front = 36 1/2" (Front raised only 3/4" !)
Rear = 35 3/4" (Rear dropped 2 1/4")

With bars (square, non-tapered, MARKED 800 POUNDS):

Front = 35 15/16" (Now, front is raised only not quite 1/4" )
Rear = 36" ( Rear is still down 2" )

Everything looks level, for whatever that's worth.

I don't really know what I just "learned"

All of this just me feel like a complete doufus!

Rob

[m.hony]

Your rig seems to be set right already.


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