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Jody Treadway

Jody Treadway

Croc wearing fool
Moderator
Joined
Mar 20, 2005
Location
Hendersonville, NC
Calling on the engineering geeks like @shawn, @jeepinmatt, @Ron and the rest of y'all.
Here is my dilemma. Lisa wants to start taking her ZJ along with my Ranger when we go wheel, so my current 22' Kaufman is way too short.

I am looking to get a gooseneck (either deckover or low boy) rated at 14-15k. My question is what length would you all suggest or is there a formula somewhere to calculate what length I need in order to make pin weight, axle weight, etc all kosher.

Here's what I'll be towing in terms of length and weight.
4500# Ranger 16.5' long from stem to stern (114" WB)
4000# ZJ 16' long from stem to stern (105" WB)

I'm *thinking* a 32' will work. With my truck at the tail end of the trailer so the ramps can set against my exposed rear tires (truck is dovetailed and full width). My concern is with approx 32' of cargo on a 32' trailer, and both rigs nearly identical in terms of weight and length, will I be high of tongue/pin weight.

Thoughts and wise cracking replies are welcome.
 
I've pulled similar to what your talking several times, shorter trailer. I have pulled a Toyota pickup and samurai or an early bronco and samurai on a 24' trailer. ramps were resting against samurai rear bumper both time. always loaded heavier of two on front and it pulled fine at 80mph plus.
 
I'm on a conference call (on mute), here you go:

If you know the weight and center of gravity (CG) location of both vehicles, and the cargo, it's all just simple math. Even if you only know the vehicle weight, you can make some assumptions about CG and be fairly close. It's all just weight and distance away from the point of load application; so distances from the pin and the axle.

This is basic static beam equilibrium, you can do it yourself. Pay attention to the plus and minus signs, those are important. If those are wrong than the load directions are wrong, and the answer will be wrong.


Starting at the pin as distance=0, and summing the moments about the pin:

(ZJ_weight x ZJ_CG_DistanceFromPin) - (Weight_on_Axle x Axle_DistanceFromPin) + (Ranger_weight x Ranger_CG_DistanceFromPin) = 0

Solve for Weight_on_Axle.

Notice it's just 3 weights, and 3 distances.


Then summing the Forces in the Y direction (which is vertically):

Weight_on_Pin + Weight_on_Axle - ZJ_weight - Ranger_weight = 0


Solve for Weight_on_Pin.


The weight on the pin should obviously be positive when you're done, else I'm not riding with you while you tow it..


Here's a free body diagram I drew while on that very same conference call (forgot the coord system, sorry engineers):

Trailer.jpg



Left-handed pencil smearing included for no additional charge.



There's also the weight of the trailer too, but you can make some assumptions about that as well, based on length above/behind the axles, and assuming the the deck is about the same weight per foot, etc. If you figure the CG distance and weight of the trailer from the pin, that can go into your pin weight calculation if you desire, the same as the Jeep and Range.
 
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ABadJeeper said:
You'll have to estimate a couple things on this calculator but it should help. I would think a trailer that has the axles slightly forward of standard would work out well.

Trailer Weight and Balance Equations and Calculator | Engineers Edge | www.engineersedge.com
Click to expand...
Fabrik8 said:
I'm on a conference call (on mute), here you go:

If you know the weight and center of gravity (CG) location of both vehicles, and the cargo, it's all just simple math. Even if you only know the vehicle weight, you can make some assumptions about CG and be fairly close. It's all just weight and distance away from the point of load application; so distances from the pin and the axle.

This is basic static beam equilibrium, you can do it yourself. Pay attention to the plus and minus signs, those are important. If those are wrong than the load directions are wrong, and the answer will be wrong.


Starting at the pin as distance=0, and summing the moments about the pin:

(ZJ_weight x ZJ_CG_DistanceFromPin) - (Weight_on_Axle x Axle_DistanceFromPin) + (Ranger_weight x Ranger_CG_DistanceFromPin) = 0

Solve for Weight_on_Axle.

Notice it's just 3 weights, and 3 distances.


Then summing the Forces in the Y direction (which is vertically):

Weight_on_Pin + Weight_on_Axle - ZJ_weight - Ranger_weight = 0


Solve for Weight_on_Pin.


The weight on the pin should obviously be positive when you're done, else I'm not riding with you while you tow it..


Here's a free body diagram I drew while on that very same conference call (forgot the coord system, sorry engineers):

View attachment 233451


Left-handed pencil smearing included for no additional charge.
Click to expand...
These guys pretty much covered it. It really comes down to where the wheels are located on the trailer relative to the center of gravity. Have you considered going bumper pull? That would gain you a foot or two of effective length because you could hang the ZJ over the stop bar in the front. With that you have to be a little more critical of the tongue weight, but you might could get away with a shorter trailer and less total towed weight.

Fabrik8 said:
I'm on a conference call (on mute), here you go:
Click to expand...
Haha, thats when I usually do my best thinking.
 
I'd go 36' if your total length of cargo is 32.5'. I mean, when you're already at 32' what's another 4'?

I had a 24' and it fit my Samurai and a TJ pretty well. I put Samurai and LJ or Toyota pickup on it a time or two but there was no additional room to adjust the load. I'd like to have a couple extra feet for adjustments. You could also turn your front vehicle around and have them nose to nose to move the cog back.
 
What's your rated tongue weight on the gooseneck and how much can your truck handle for a comfortable and safe tow?

with known weights of rigs and ideal tongue weight, by use of the vector diagram above, you should be able to figure it out.
 
LBarr2002 said:
I'd go 36' if your total length of cargo is 32.5'. I mean, when you're already at 32' what's another 4'?
Click to expand...

I'd do the same. Plus just leaves some extra room for hauling other things in the future.

On the note of your question, trailer axle location is going to be a much more important factor for pin weight rather than trailer length. I would do what @rockcity is suggesting and solve for trailer axle location with a given pin weight and see whats out there on the market. If you post what pin weight you want I'm sure someone on here will figure it out for you.
 
rockcity said:
What's your rated tongue weight on the gooseneck and how much can your truck handle for a comfortable and safe tow?

with known weights of rigs and ideal tongue weight, by use of the vector diagram above, you should be able to figure it out.
Click to expand...

I don't have the bigger trailer yet, so the tongue weight is an unknown.
My truck is rated to tow 16.5k IIRC, so I'll be well enough under that not to lose much sleep.
 
Jody Treadway said:
I don't have the bigger trailer yet, so the tongue weight is an unknown.
My truck is rated to tow 16.5k IIRC, so I'll be well enough under that not to lose much sleep.
Click to expand...


You have the truck, right?

How much weight can you put on the gooseneck ball in your bed? That's a more appropriate question I guess since you don't have the trailer. Find that out and decide what you are comfortable with to keep from getting the Carolina squat going on and do the math as shown above.

Or do like Shawn said and just buy a stock 36-ish trailer and be done. :)
 
rockcity said:
How much weight can you put on the gooseneck ball in your bed? That's a more appropriate question I guess since you don't have the trailer. Find that out and decide what you are comfortable with to keep from getting the Carolina squat going on and do the math as shown above.
Click to expand...

He's got air bags and a B&W. So long as he's under the rating of the rear tires, he's fine.

If it were me, I wouldn't even stop to think about the pin weight until it was north of 4k.
 
shawn said:
He's got air bags and a B&W. So long as he's under the rating of the rear tires, he's fine.

If it were me, I wouldn't even stop to think about the pin weight until it was north of 4k.
Click to expand...


I was thinking the same thing but the dude in hippie town Asheville wearing crocs asked for some over the top technical data so I decided to play along, answering his question with a question and some other irrelevant smart ass responses.
 
@Jody Treadway the point I was making about getting a longer trailer has more to do with what "else" is going to end up on the trailer, other than the rigs. There's gonna be a toolbox, or a spare tire, or some axle that you're ferrying to a buddy of yours, or WTFever, and you're going to want somewhere to put it. I have two TJs on a 32ft deck, and if I had a couple extra feet, it wouldn't hurt my feelings one bit.

rockcity said:
I was thinking the same thing but the dude in hippie town Asheville wearing crocs asked for some over the top technical data so I decided to play along, answering his question with a question and some other irrelevant smart ass responses.
Click to expand...

Oh, I just figured your truck was a squatty bitch like that Ford we rented. We hooked a little trailer with a TJ to it, and it squatted like it was from Greenville.
 
As far as deck over or low boy... I'd go with a low boy with drive over fenders if you have the option. My 24' goose was a semi-deck over ( the fenders stuck through the deck about a foot). I didn't like how tall it was and was always a little nervous on the twisty mountain roads. My previous trailer was a 19' bumper pull with 4" drop spindles. It was insanely stable in the twistys... wish I could get it back.
 
shawn said:
Y'all are over thinking this.

1. Fuck a bumper pull.

2. Buy a gooseneck with 32-36ft of deck.
Click to expand...

#1. Fuck a goose neck (personal preference I hate the way they pull-empty or loaded).

#2. I Pull doubles with a tag along 24' deck over, you can pull the front tires to the header, essentially having the bumper over the tongue: can't do that with a goose.

#3. Keep my bed space

#4. I also haul many palleted items, easier with a deck over.

379b7777f0c08b4f89e3ba57ccd040c5.jpg


Cj5- 98 wb, 4000lb. Buggy 117 wb 4300lb. Trailer 3800lb, 2-7k braking axles. Pulls fantastic empty or loaded, behind my f450 and/ or 30' rv.


Matt

Edit; Both of these vehicles have a greater than 90° approach and departure angle.
 
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mcutler said:
#3. I also haul many palleted items, easier with a deck over.
Click to expand...

Yeah, I was on the fence, leaving towards low boy. But realized how much more versatile the deck over is.

As for the bumper pull, I had a couple of reasons that I didn't really elaborate on:
1. I'm the opposite way. I think goosenecks ride nicer. An empty bumper pull will beat you to death, and a loaded one pushes the truck around too much.

2. Finding matching heavy duty bumper pull stuff is a pain in the ass. Get a hitch that's rated for 16k, but then can't find hitch pins, draw bars, and balls to match. I have a combo pintle. The pintle is rated to 16k or something, but the ball is only rated to 10k, and damn if I can find a pintle draw bar that's rated for more than 10k. Once you do find something that has the correct ratings, you find out its too tall or too short, and now the trailer won't ride flat.

On a related note, I passed a wrecked Ford on the way home from URE a couple of weeks ago. He was towing an excursion on a bumper pull, tail started wagging the dog, spun the truck around and rolled the trailer. That's a lot harder to do with a gooseneck. For one thing, you're less sensitive to pin weight, so you can just load the trailer nose heavy. But the trailer also has a lot less leverage on the truck, both from gravity loads and from the lateral side to side stuff.

Tag trailers will back into all sorts of little holes that goosenecks only dream about, though.
 
Dead on, wth the backing a tag.

Tow rig selection makes a huge difference on trailer type as well. Goose lends to a lighter truck with ride and stability.

F450-550 don't give a damn how they're hooked, still ride like a wagon, but can haul the mail...and your brother's mail, and neighbor's mail... (speaking strictly from a chassis and brake standpoint)

Every family member or friend who has borrowed this trailer comes back raving on the ride, empty or full. It's all about axle placement and load management.


...and only paid $3800 for this jewel, new.

Matt
 
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