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Axle weights and loading


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When I picked my tuck up, and with full tanks (275 gallons) here are the weighs I got.  

Steer 11,900 Drive 8,680. 

I am keeping my truck tandem and my wheel base is 265" if that matters.

I am not sure how much my deck will weigh, but I am guessing around 2,000lbs.  This will be a 8' x15' steel frame with aluminum decking.  

With my current trailer I have a pin weight of about 3,700. 

I plan on adding a 100-200 gallon fresh water tank (800-1600 lbs), a 60 gallon waste tank (about 500 lbs when full), some sort of "Job box" (500 lbs?) and carrying the SxS (1200 lbs) on the deck.  

 

Now that we have all of that out of the way let's talk about theoretical wights.  I say that because it is not practical to get it weighed first plus it is not built yet to weigh.  

My waste tank is mounted right behind the drivers side fuel tank.  It will only be filled occasionally and only for short travel periods.  

I am hoping to have the fresh water tank close to the back of the cab with the job box next followed by the ATV.  Obviously the trailer will attach just behind the rear axle. 

 

In theory, how much weight should I have on the front axle?

If I do not have the trailer attached, with my loading plan would that add too much weight to the front axle?

What else do I need to know/consider?

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Nwcid,

All that can be calculated with analogies to a simple fulcrum.  Force1 x Distance 1 = Force 2 x Distance 2.  I have a Power Point presentation I will try to send you that goes through bed building and effects on axle weights.  If you would like a copy, PM me with an email address.  It answers almost all your questions.

Edited by SuiteSuccess
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1 hour ago, Darryl&Rita said:

Less than it's rated for, or the weight rating of the tires, whichever is less. Do you know what the front axle is rated for?

I realize I should know the answer to that, but I do not yet since I have not started asking those kind of questions yet.  I will check next time I go down to the shop. 
 

Also, while I did not ask the question, and I am sure it is unlikely, how light is too light.  I keep reading about "unloading" the front axle too much. 

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49 minutes ago, Nwcid said:

I realize I should know the answer to that, but I do not yet since I have not started asking those kind of questions yet.  I will check next time I go down to the shop. 
 

Also, while I did not ask the question, and I am sure it is unlikely, how light is too light.  I keep reading about "unloading" the front axle too much. 

Staying tandem, it won't be an issue for you, unless you build a 10 foot tail overhang. If the steering wheel feels light or "squirrelly", time to bring some weight forward. I don't think there's a hard and fast number.

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If I remember, you have a pretty new Volvo. If so, there's a sticker in the door jam, driver's side.  Take a picture of it with your phone.  It'll come in handy.  The front axle rating is there.

Edited by rickeieio
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I did not assume I would have to worry about being too light, but it needed to be asked. 

Yes, my truck is a 2014.  I know where the info is, I just have not looked at it yet.  I have have a whole list of things to do. 

I have lots of pics of stuff for the truck, and other things.  I dont just keep them on my phone, I have them on a cloud service so I can access them from anywhere. 

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I made an Excel sheet based on info from a pdf files on weight formulas. It is on google drive and shared. There's a couple other files there fo trailer and truck weight.

File

https://drive.google.com/file/d/1yU8vJIOSqEYSThWmyhdEvo6wcOLo_4et/view?usp=sharing

 

Drive

https://drive.google.com/drive/folders/1XH6hCjmh-MdMjrwh4mFz0OcHKCkkp_Xe?usp=sharing

 

Maybe this will help,

Ken....

WEIGHTS AND CENTER OF GRAVITY CALCULATIONS.xlsx

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If you have a typical 12k front axle, you are already close to be overloaded. It will help if your hitch is mounted behind the rear axle by taking some weight off of the front axle. While every truck handles a little differently, our Freightliner Century is singled short. Our base front axle weight is only 9780#. When we weighed at the HDT rally, we offloaded about 2k off the front axle with our Toyhauler which that day had a 6250# pin weight. Our hitch at that time was around 72" behind the rear axle. I have since done a few changes and recently weighed our setup again, this time with a smart car on the bed, hitch moved as far forward as possible by 8", different loading in the Toyhauler which reduced pin weight to 5840#. All of these changes reduced our front axle offload to 1560#, at on axle is now at 8220#. We have not noticed any unusual handling in the truck with the lighter front axle weight and we put on around 18k miles with configuration. But we also avoid bad weather driving but have driven in heavy rain but slow our speed down. I don't think there is any actual good formulas that say how light the front axle can be, I would think it would be a total percentage of the truck weight but it could also be affected by how far the hitch is behind the rear axle. I am going to add some weight to my front end to help some just in case!

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Having enough weight on the front is greatly affected by how many axles you have in the rear.  I used to drive a tri-axle grain truck.  It was scary on a wet road with 12 tires wanting to go straight and only two trying to turn.  I would think if you're singled, weight wouldn't matter much.

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As I said in the beginning, this truck is staying tandem. 

If I only have the standard 12k front axle in the truck that may be a problem.  Again the truck was 100% stock with full tanks when I weighed it.  I do not plan on doing a lot of bobtailing, but enough that I need to make sure things are right.  

I will check out the links this evening.

 

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3 hours ago, Nwcid said:

As I said in the beginning, this truck is staying tandem. 

If I only have the standard 12k front axle in the truck that may be a problem.  Again the truck was 100% stock with full tanks when I weighed it.  I do not plan on doing a lot of bobtailing, but enough that I need to make sure things are right.  

I will check out the links this evening.

 

My front axle is 12.5k.  When weighed, I was 10650 on front axle.  I’m tandem with a 3/16”steel bed, 4000 lb pin weight and a smart car.  Bet you’ll be fine on your weights.  I don’t think you’ll offload enough from your front axle to make a difference unless your hitch is WAY back.  But again use the formulas to be sure.

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I was more worried about overloading if I only had the 12k axle as I am 11,900k unloaded.  Once I add 500-1000 lbs behind the cab that will add a lot of weight to the front.  

 

I checked the sticker and I do have the 13,2000 lb front. That will help for sure. 

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   If my memory serves right. The law is 600 pounds per inch of tire width. (11R22.5 =6,600 per tire 13,200 axle) 20,000lb. axles are available for the front.

   I have no proof, but my personal belief and experience is 75% of the axle weight rating is where the best ride and handling is.

   It is your truck and your final decision. good luck and may some answers help.

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20 hours ago, Nwcid said:

I was more worried about overloading if I only had the 12k axle as I am 11,900k unloaded.  Once I add 500-1000 lbs behind the cab that will add a lot of weight to the front.  

 

I checked the sticker and I do have the 13,2000 lb front. That will help for sure. 

Mount the Mother-in-Law seat behind the rear most axle:)

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I may be wrong in my thinking but if my truck was built to weight 38k on the rear and 12k on the front, when working, then that's approximately 30 percent on the front so I strive for nothing less and I dont like a heavy front light rear that's too much like bobtailing I think I am about 40/60 now when loaded. This seams to give me good traction, decent ride and good handling. I am singled short 182 inch wheel base.

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