How big of bed?????

[Vegas Teacher]

If I want to have a two door jeep and a 5th wheel how big of bed do I need to have put on for the trailer to be able to turn a 90 or more degree angle or more safely? What did you guys do, no I am not going to single mine.

[Darryl&Rita]

Length of vehicle, plus 60". Slightly less if you plan to angle the Jeep. 

[Alie&Jim's Carrilite]

Darryl is right again.... 😂

Take the overall length of the Jeep with any add-ons... stinger bumpers, gas can carrier, spare tires etc and add 60".  That is NOT from the back of the truck sleeper....  Allow another 2-3 inches for cab movement or a Drom box between the fairings etc.

[runaway parents]

Well lets see we just got  our bed finished this spring  we have 14 ft of flat deck space and 6 ft of beaver tail over all length just under 20 ft. We  put a exploder on it, to long. Put a four door jeep to  long by 2 inches .We are in the proses of looking for a 2 door jeep should work fine. Know keep in mind with out moving the axels back you are going to unload the front axel. We unloaded ours 1000 lbs seems to drive fine. It will drive better with the jeep on it. 

[Dollytrolley]

Teach......20 F E E T of deck is the Minimum....  Maybe 28 F E E T even better....   

As you drop into ...... Geezzerhood you will NEED to take more and more kamping "ESSENTIAL'$" with you as you become more ... ..re-fined in your needs to have kamping be EXACTLY like home with just closer nieghbors and shared water, sewer, and elec........

Remember the HDT Moto .....go big and then.....go even bigger....

 

Drive on.......( BIGGER bed iz better.....size matters)

[mrchips]

You need 21' from back of cab to center of hitch for a 4 door. a two door is 22" less WB. Here is some advice, don't go down that road unless you have a minimum of 265" WB truck and then it is iffy. Yes, I do know what I am talking about. Been there done and doing that. Then take into account how long your trailer is, and what the pin weight is. Trust me, it makes a huge difference. 

[Jack Mayer]

You don't want to single any truck that is going to carry a full-size vehicle like a Jeep or something similar.  And how successful you are with a combination with a long vehicle on it is totally dependent on a variety of factors - any one of which can cause you lots of headaches, and compromise driveability/safety. You can get away with a lot, using an HDT and light weight trailers/vehicles. But once you start putting on heavier stuff, or have an unbalanced, or not optimally balanced trailer, physics is going to prevail and you will start seeing issues. 

In particular, a long cantilever with the trailer hitch at the end can cause all kinds of issues. Not in EVERY case, but in a LOT of cases. It is all dependent on your particular circumstances. For others, if intending to carry a 4-door Jeep or something similar - you want a long wheelbase truck. Listen to Mr. Chips. You can debate it all you want, but physics generally tends to ignore "opinions".

[rickeieio]

1 hour ago, Jack Mayer said:

You can debate it all you want, but physics generally tends to ignore "opinions".

That's why we refer to them as  laws, not suggestions.

Edited June 28, 2019 by rickeieio

[Randyretired]

I extended the frame on my HDT 5' and the hitch is at the end.  We carry a Subaru Forester on the truck.  Our Teton has a relatively heavy tongue and I have carried more tongue weight than that.  We have been using this setup for about 14 years on this Volvo and it has been great.  It drives very nice and is stable.  I have not regretted it at all.  The ratio of the GAWR between the front axle and the rear axles is a smidge over 3 to 1.  That is what the truck is designed for and I stay within that ratio.  I never exceed 32,000 pounds for the trailer and usually less than that.  I certainly think you could carry a 2 door Jeep and stay safely within these weight ranges.

[Jack Mayer]

You can 

6 hours ago, Randyretired said:

  I certainly think you could carry a 2 door Jeep and stay safely within these weight ranges.

You can, depending on the required extension on the truck. It is not that it cannot be done - it can. But there is no "single answer" that works optimally, despite what you might read on Facebook or elsewhere. It depends on the specific weights and lengths involved. Taking a measured approach and working out all the numbers is a requirement for success IMO. That is the way we operate, and won't do it any other way.

[Darryl&Rita]

1 minute ago, Jack Mayer said:

You can 

You can, depending on the required extension on the truck. It is not that it cannot be done - it can. But there is no "single answer" that works optimally, despite what you might read on Facebook or elsewhere. It depends on the specific weights and lengths involved. Taking a measured approach and working out all the numbers is a requirement for success IMO. That is the way we operate, and won't do it any other way.

Given the availability of the many CAD programs, and the drop in CAD developer's time, there's no reason to build "by guess and by golly". Facebook seems to gloss over this,  in an attempt to portray builders as some kind of savant. It doesn't take long to learn the basics of any of the programs, to at least do a proof of concept on a design. A full, from scratch build can be fun to do, or can turn into an absolute mess. That's why programmers time can be a good investment. They have a whole filing cabinet of past projects to import data from, instead of running out to measure every time. 

[noteven]

I deleted my blah blah blah. 

 

 

Edited June 29, 2019 by noteven

[Randyretired]

35 minutes ago, Jack Mayer said:

You can 

You can, depending on the required extension on the truck. It is not that it cannot be done - it can. But there is no "single answer" that works optimally, despite what you might read on Facebook or elsewhere. It depends on the specific weights and lengths involved. Taking a measured approach and working out all the numbers is a requirement for success IMO. That is the way we operate, and won't do it any other way.

I am not on Facebook or any other internet sites but when I read that you need a wheelbase of 265" I know that isn't right.  We have a wheelbase of about 200".  While CAD and other programs are nice, simple math is all that is required.  It is a simple fulcrum.  

[Jack Mayer]

No one needs CAD to figure out this stuff. In fact, I'm not sure how CAD would actually help. What you need to do is have accurate measurements and weight of all items.  And then calculate the numbers for the truck. But you also have to have some reasonable experience or you are just rolling the dice. For example, how do you think a trailer with 15% pin weight (with the axles well forward) and the kingpin 7' behind the truck axle is going to handle. You have to consider everything.

[Darryl&Rita]

I only mentioned CAD because some guys can't deal with spreadsheets too well. SolidWorks, for example, gives a real world diagram of the truck, with weight vectors called out in different colours. Depending on how the parameters were entered, 1000 lbs can be represented by a green, orange, or red zone. Or 5000 lbs, or 10k. Of course, garbage in will give a garbage output, so the same numbers Jack is referring to, still need to be gathered with the same accuracy. 

ETA: SolidWorks also lets you change applied vectors quickly. Change trailers? Easy prediction how the new tounge will affect the truck. Add wind forces, with the click of a mouse. Too heavy on the front, move the fuel tanks a 1/16" at a time. 

Edited June 29, 2019 by Darryl&Rita

[runaway parents]

Hi teach my advice to you is check all advice given on this. Consult someone you can trust to confirm that advice given on this is legit. when I started my build  .I was told buy a well known individual  on this forum that what I was building would work fine . Two years later and several thousand dollars latter this person did an about face and said it would not work. Needles to say i was extremely pissed. This caused  a lot of sleepless nights thinking what have i done to my truck. Having no choice but to push ahead I finished the build any way . I remained tandem  yes it did unload the front axel a little. Truck seems to handle fine. Once I get jeep onboard should handle  even better .If push comes to shove i will hang tractor weights on the front bumper. ha Don't think i will have to go that far.

[Mark and Dale Bruss]

Interesting, spreadsheets are hard but CAD is easy?

[Darryl&Rita]

49 minutes ago, Mark and Dale Bruss said:

Interesting, spreadsheets are hard but CAD is easy?

To wrap your head around, yes. Some guys like a colour coded picture, vs. the numbers in a spreadsheet. The initial work is the same, gathering measurements and weights, just the end result is different.

PS: I like SolidWorks.

[rickeieio]

3 hours ago, Darryl&Rita said:

PS: I like SolidWorks.

I like Whenitworks. 🤔

[noteven]

 

Whenitworks:

Of the 5 or 7 hundred KW’s I had a part in laying out for about 20 or 50 vocations the builds always began with tape measure, pen, paper, applicable weight and dimension regulations. Initial concepts were sketched by hand. Next step was spec’ing software spreadsheets, collaboration with the fab shop engineer and KW engineers. 

But step 1 was get out the tape measure and the weight and dimensions regs and sketch pad  to see what fits. Then work with KW factory engineering and equipment factory engineering to ensure the concept will stay within the correct vehicle dynamics, weight distribution  and braking compliance requirements.

If a truck from stock was being considered for sure physical “tape measure engineering” and base line weight distribution came first. 

Of course specing software, spreadsheets, and CAD were brought in as the work progressed. 

Building a truck mounted service unit with pumps, drawworks, and a 70ft mast on a twin steer tri drive worth $1million started with a tape measure...

The owners goal was a unit that could be easily configured to meet spring thaw reduced axle loading law and not have to be hauled to well sites. 

Truck 1 was ordered with frame drilling pre-done by KW.

7 months later on completion we had missed our initial calculated weight distribution by 180lbs  heavy on the front and 400lbs light on the rear. 

2 more units were built

We didn’t sit in meetings arguing about spreadsheets vs CAD vs what someone said “should work.” 🤣 All of the above were used.

Just to see If tape measures still worked I just set up a bed on a truck mounting to some existing frame holes. Measure twice drill once and the bolts went in with fingers. 

Anyway long story short you have to start with weight and dimensions regs vs what you want, ( I.e. will it fit?), consider dynamics and braking, (often kind of brushed over in RV world) then go to the details...

 

[Scrap]

I've become addicted to my metric tape....anything else and I screw it up.  I owe my tech $100 for every hole he has to drill that could've been done factory. 😟  I got him down to $50 if I get it on the wrong side! 🤣

[noteven]

Scrap- the dimension units on a KW frame layout drawing is our secret shhhhhh ... mm ‘s the word...

[Jack Mayer]

What works and won't work is determined by a wide variety of factors. You have to know them all to determine the final result, and even then it can change based on the trailer that you use. In general long overhangs (cantilevers) have to be scrutinized very carefully. It does not mean they won't work. But the longer out you go, the more you have to be careful. In general on our builds we don't like to go over 6'. Not that it can't work, but what works in one configuration may not work in others, and owners HAVE been known to make changes in their equipment along the way. If we build it for a specific situation and it is used in a different situation and causes issues, we don't want to carry that liability. Pushing things to the "edge" leaves little room for contingencies.

If you work your numbers and understand them, then you have done your homework....and what you build will likely work for you.  It is up to YOU to understand all your numbers, which I'm sure you will. One thing to point out - on ALL long cantilevers the trailer is far more "twitchy" than shorter overhangs....which is easy to understand if you think about it. This can vary from "not too bad" to "unmanageable" depending on the trailer characteristics - NOT just pin weight. For example the ratio of the king-pin-to-axles vs. the overall length is a major contributor to  "non optimal" handling. Yet the actual pin weight may be the same as a trailer that has a "better" ratio. So there are a lot of considerations. Also, heavily loading the rear can set up a teeter-totter effect that can contribute to poor handling on a very long cantilever rig.