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Old 07-22-2013, 12:44 PM   #1
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Default Conversion Weight on Semi back ?

Hi, im new to the site and green at doing this sort of thing. what im trying to figure out is how do i determine how much weight i can put on the back of the 1997 Kenworth T2000 im going to be building. the truck was a tractor but after the Chassis was streched a little to hold a 16' box and a power tailgate. what i want to do is put a 22' box on it and after the diff area lower the frame down about 20" so i can make a 6-7' toy hauler section with a side door.

knowing the truck was set up for 80,000lbs 1st does anyone know how much of the trailer weigh would be on the 5th wheel ?

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Old 07-22-2013, 05:50 PM   #2
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Welcome to the forum, I love the garage, we carry a Smart Car , someone should be along soon who can help you with those calculations....
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Old 07-22-2013, 08:44 PM   #3
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At the high end the tractor would weigh 20,000lb total.

Most steering axles carry about 11,000lb unhooked leaving about 9,000lb on the drives.

Commercial regulation (not really applicable but good reference) put tandem drives at 34,000lb max in most states, leaving you with 25,000lb of rear axle carrying capacity.

I don't think there is any way you could build a 16ft or even 22ft conversion that heavy.

For reference my Haulmark with a 35ft box with 2slides has my rear axles at about 25,000lb dry.
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Old 07-22-2013, 09:41 PM   #4
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Yes, you're not going to be able to put anything in a 22' box that's too heavy for tandem drive axles. My truck has a single rear axle, 295" wheelbase, front axle is 12k with full fuel tanks and two 200 lb. guys in the front seats, rear axle is 17k lbs. with full water. 26' living quarters, one smallish slide.
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Old 07-23-2013, 12:36 AM   #5
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I don't think a 1000 Gal hot tub (about 8800 lbsloaded) would put a damper on your truck.

My truck build is kinda odd. 10K front axle (empty weight 5500 lbs) My new air ride Rear axle is rated at 20K (curb weight about 8000 lbs right now) And this is just a single rear axle truck. So you can see I can add just about anything I could ever want and not over load my vehicle.
Total weight Truck trailer and Jeep in the below pic is about 20K
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Old 07-23-2013, 07:51 AM   #6
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Wow thanks for all the input, i was kinda thinking it would hold it. i am putting 2 slides and the over hang will hold about 2000lbs when the bikes are in there. i was going to make sure most of the weight was between the cab and the front the rear axle and split from side to side. im weighing the buy a box and later it or make one thing right now.
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Old 07-23-2013, 07:54 AM   #7
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Quote:
Originally Posted by mekanic View Post
I don't think a 1000 Gal hot tub (about 8800 lbsloaded) would put a damper on your truck.

My truck build is kinda odd. 10K front axle (empty weight 5500 lbs) My new air ride Rear axle is rated at 20K (curb weight about 8000 lbs right now) And this is just a single rear axle truck. So you can see I can add just about anything I could ever want and not over load my vehicle.
Total weight Truck trailer and Jeep in the below pic is about 20K

with your set up you dont get any issues with that tongue weight, i was afraid if i pulled a heavy trailer i may get that pogo effect.
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Old 07-23-2013, 11:32 AM   #8
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You've got a good looking rig to start with.

There should be a sticker on the truck somewhere, usually in the doorjamb or glovebox with the weight rating for each axle. Then go to the truck stop and weigh each axle to see where you are at right now, and how much excess capacity you have left. As others have mentioned, I am sure you have more than enough capacity, my only concern would be balance since everything you will be adding will be behind the axles, and all the weight you add there will take weight OFF the front axle. In an extreme situation that could make the handling very poor. There are a few threads out there that tell you how to calculate all that with the weight you are adding and the distance from the axle centerline. A semi tractor is set up to handle a bunch of trailer weight on the fifth wheel, but it is all centered directly over the drive axles. Not saying what you are doing won't work, just might want to do some calculations on the weights. Also, that 80000# gvw is combined with the trailer, the gvw for the tractor alone would be the weight rating for each of the 3 axles added together.

Good luck! Dave
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Old 07-23-2013, 01:15 PM   #9
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Dave
thanks for the input, im trying to get most in front of the rear axle, the kitchen bathroom and one set of beds will be there along with all the tanks. i even had the fuel tanks moved forward to help. ill look for the tags
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Old 07-23-2013, 06:05 PM   #10
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Quote:
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with your set up you dont get any issues with that tongue weight, i was afraid if i pulled a heavy trailer i may get that pogo effect.
Well mine is quite different. Last year it had its stock Rear axle a 22.7K leaf spring rear axle. According to fors with a spring rate of 4000 lbsPER INCH
And no shocks either.

When I bought the trailer The previous owner towed it with his 1/2 ton truck.
He told me it towed it best (Stability) when the hitch ball dropped 2 inches from its unloaded height as he loaded it.
On my truck Not matter the load it has Never dropped more than 1/4 inch.
I can NOT honestly feel it back there. There certainly is no po-go effect.

I now have a 20K Air ride Rear axle and suspension and of course it has shocks as well.
Haven't drove it with the trailer, But it is better already.
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Old 07-23-2013, 08:58 PM   #11
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I have a w900L that i built a 30' box and a 12' slide the garage is 8'x8'6" in the picture i have 3 motorcycles inside pulling my car trailer with a mustang It rides great loaded or not it you really dont know the trailer is back there
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Old 07-24-2013, 07:54 AM   #12
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nice build, im thinking i may have the roll the diffs back a bit to make this have the proper balance. im heading out to look for a box today. thanks for all your input. it really helps.
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Old 07-24-2013, 07:36 PM   #13
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As a previous poster noted, weigh each axle now. Then use weight and balance calcs to determine how the various stuff you put on the truck will impact the load on each axle. Anyone with a private pilots license should be able to help you with the math. Very simple once you've done it a few times.
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Old 07-25-2013, 04:44 PM   #14
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Thank, ill do that i have a buddy that fly's
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Old 07-26-2013, 04:21 PM   #15
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Most class 8 tractors are factory rated for 44,000 lbs for the rear tandems. Most states limit a pair of tandems to 34,000 lbs for the pair (17,000 lbs each axle) it would take an awful lot to max a pair out.
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Old 07-29-2013, 07:52 AM   #16
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Quote:
Originally Posted by Driveshaft Shop View Post
Hi, im new to the site and green at doing this sort of thing. what im trying to figure out is how do i determine how much weight i can put on the back of the 1997 Kenworth T2000 im going to be building. the truck was a tractor but after the Chassis was streched a little to hold a 16' box and a power tailgate. what i want to do is put a 22' box on it and after the diff area lower the frame down about 20" so i can make a 6-7' toy hauler section with a side door.

knowing the truck was set up for 80,000lbs 1st does anyone know how much of the trailer weigh would be on the 5th wheel ?


Great looking rig... you should start with a wish list of you want... figure out the weight and how you would distribute it. Then get you axle weights and figure out what you need... good luck with your build... post pics and let us share in your build.
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Old 06-05-2014, 07:34 AM   #17
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i kinda changed direction with the truck, i bought a 24' stacker and installed it (with the help of Bagshaw fabrication) a few weeks ago






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Old 06-06-2014, 09:10 AM   #18
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Wow... looks great!
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Old 06-09-2014, 02:32 PM   #19
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That is awesome! I would have never thought to do that! The top and bottom line up perfect!! What height is the bottom of the trailer, now box at below the entry door? I am building my t2000 conversion now and am curious how low I should build the skirts down to. Yours looks just right.

Steve
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Old 06-10-2014, 04:01 PM   #20
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Default Hats off to you!

Nice job on your truck conversion! Its great to see someone staying true to the lines and looks of a "truck." I like it!
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