New 2018 42' Sandpiper has the F250 sagging a bit

[Tide Guy]

Think you got more trailer than truck. You didn't specify weight, but recommend a larger truck.

[Airmech]

Dababysdaddy, thank you for your and your wife's service so we can have our freedom and have our little argument online as we do. Glad you are happy with the results of your work and enjoy the results. Sounds like you won't be racing down the interstate anytime soon, no reason to anyway. Life is a journey, so enjoy it. Once again thank you both.

[xrated]

Originally Posted by fvstringpicker

I not arguing the downside of overloading a truck. You can overload an 18 yard dump truck. My argument is that a 3/4 pickup and a 1 ton pickup has the same chassis and drive train with the exception of the rear springs, wheels and tires. With the same rear spring, wheels and tires a 3/4 ton can handle the same load as a 1 ton, at least in your pre-2011 models. If they changed recently, I don't know.
If you know of any other mechanical differences, I hope you share the information. It would keep folks like me making this mistake. I know the door tag sez different things, but when the parts are interchangeable, I mean.

I pulled up a 2015 Ford spec chart and for example...the F250 rear axle spec is 6200 lbs. The F350 (SRW, not dually) is 7280 lbs....so almost 1100 lbs difference in the axle weight rating. So of course, by the chart the axle spline size is bigger in the F350. The brakes....rotor diameter is the same on both, but the F250 is vacuum operated and the F350 is hydro.....whatever that means. Also, the brake master cylinder on the F350 is bigger. I guess all of that stuff accounts for the F350 being able to carry more weight and obviousliy have more payload capacity.....and remember, all the above info is in reference to the F250 and the Single Rear Wheel F350...not the dually. So, as it turns out, it's more than springs, wheels, and tires.

[fvstringpicker]

I don't know about Fords X but I have hydro boost on my 2500HD Duramax. Its my understanding that diesels use hydro boost (off the power steering pump) because they lack the vacuum to operate vacuum brakes. I'm surprised to hear Ford use vacuum assisted brakes on more than 1/2 tons;especially the HD models.
Hydros do have more than double the braking force as vacuum assist and if a 250 Ford has vacuum, that's a whole different ball game. The hydro would account for the larger master cylinder because of the much greater braking force. I still say the RAWR of 6,200 or 7,280 comes from the tire weight capacity which is the weakest component of the system. (at least I hope the tires are the weakest component.)

[Gordon Dewald]

Originally Posted by fvstringpicker

I don't know about Fords X but I have hydro boost on my 2500HD Duramax. Its my understanding that diesels use hydro boost (off the power steering pump) because they lack the vacuum to operate vacuum brakes. I'm surprised to hear Ford use vacuum assisted brakes on more than 1/2 tons;especially the HD models.
Hydros do have more than double the braking force as vacuum assist and if a 250 Ford has vacuum, that's a whole different ball game. The hydro would account for the larger master cylinder because of the much greater braking force. I still say the RAWR of 6,200 or 7,280 comes from the tire weight capacity which is the weakest component of the system. (at least I hope the tires are the weakest component.)

IMO it would not be the tires that are the weak link as they would not be part of the design. Tires are disposable and would be sourced after the design was complete. Of course they would be looking for the cheapest tire supply that met the design criteria.

[Ricatic]

Originally Posted by xrated

I pulled up a 2015 Ford spec chart and for example...the F250 rear axle spec is 6200 lbs. The F350 (SRW, not dually) is 7280 lbs....so almost 1100 lbs difference in the axle weight rating. So of course, by the chart the axle spline size is bigger in the F350. The brakes....rotor diameter is the same on both, but the F250 is vacuum operated and the F350 is hydro.....whatever that means. Also, the brake master cylinder on the F350 is bigger. I guess all of that stuff accounts for the F350 being able to carry more weight and obviousliy have more payload capacity.....and remember, all the above info is in reference to the F250 and the Single Rear Wheel F350...not the dually. So, as it turns out, it's more than springs, wheels, and tires.

In a time long since passed, I was a huge supporter of the new Ford 6.7 F
series trucks...I knew the specs inside and out...at that time, this discussion regarding the "differences between the rear axle assemblies in the F250 and F350 SRW raged for months and years...simply put...the spec book is wrong regarding the F350 SRW axle diameter...the spec book does not differentiate between the F350 SRW and the differently equipped F 350 Dually.

Here is reality...the Ford manufactured Sterling rear axle assembly is built 20 minutes from my house...my BIL is the Assistant Plant Manager...I asked him about the axle assemblies and the possible differences...His reply was "no differences at all...in fact when the assemblies are completed at Sterling Axle, they are palletized for shipment to the Truck Assembly Plant with no identification whatsoever as to whether they would be placed under an F250 or a F350 SRW...axles, brakes, bearings, circlips, differential gears...all the same...the F350 SRW does get the taller spacer block at the springs but that is not part of the axle assembly shipped from Sterling Axle.

The F350 Dually gets a totally different axle assembly built by Dana Corp and it has the larger diameter axles and subsequenly different sized support components...

You would think that after all these years, this axle discrepancy predates the 6.7 Model years, Ford would fix their spec book...but alas...we are talking about Ford...

Earlier in the thread, the GVW ratings between the F350 SRW and the F250 were compared. The F250 has been 10,000 pounds since I bought my problem child back in model year 2011. My F350 SRW was rated at 11,500 pounds...the heaviest SRW rating available. A little known fact though is at that time, Ford offered an optional F350 package that derated the 11,500 gvw down to 10,000 pounds...gasp...the dupliciousness...one may ask why...it was simple...in some states, a GVW of over 10,000 pound earns the owner commercial plates and much higher wheel taxes...the difference in the two trucks components that make up that 1500 pounds of GVW loss...the door sticker...all axle components remain the same...FAIK, Ford still offers this option...

Hope this only causes a little bit more confusion...

Regards

[Airmech]

Thank you ricatic for some facts in a sea of speculation. It's interesting, but not surprising.

[Wundertaker]

Originally Posted by Ricatic

In a time long since passed, I was a huge supporter of the new Ford 6.7 F
series trucks...I knew the specs inside and out...at that time, this discussion regarding the "differences between the rear axle assemblies in the F250 and F350 SRW raged for months and years...simply put...the spec book is wrong regarding the F350 SRW axle diameter...the spec book does not differentiate between the F350 SRW and the differently equipped F 350 Dually.

Here is reality...the Ford manufactured Sterling rear axle assembly is built 20 minutes from my house...my BIL is the Assistant Plant Manager...I asked him about the axle assemblies and the possible differences...His reply was "no differences at all...in fact when the assemblies are completed at Sterling Axle, they are palletized for shipment to the Truck Assembly Plant with no identification whatsoever as to whether they would be placed under an F250 or a F350 SRW...axles, brakes, bearings, circlips, differential gears...all the same...the F350 SRW does get the taller spacer block at the springs but that is not part of the axle assembly shipped from Sterling Axle.

The F350 Dually gets a totally different axle assembly built by Dana Corp and it has the larger diameter axles and subsequenly different sized support components...

You would think that after all these years, this axle discrepancy predates the 6.7 Model years, Ford would fix their spec book...but alas...we are talking about Ford...

Earlier in the thread, the GVW ratings between the F350 SRW and the F250 were compared. The F250 has been 10,000 pounds since I bought my problem child back in model year 2011. My F350 SRW was rated at 11,500 pounds...the heaviest SRW rating available. A little known fact though is at that time, Ford offered an optional F350 package that derated the 11,500 gvw down to 10,000 pounds...gasp...the dupliciousness...one may ask why...it was simple...in some states, a GVW of over 10,000 pound earns the owner commercial plates and much higher wheel taxes...the difference in the two trucks components that make up that 1500 pounds of GVW loss...the door sticker...all axle components remain the same...FAIK, Ford still offers this option...

Hope this only causes a little bit more confusion...

Regards

what was the question again???

[mrgrayaz]

I still see zero point in saving $1000 in buying a F-250 over a F-350, and then spending $1000 to modify the suspension to...gasp...handle F-350 loads.

Why? Why not run the OEM suspension? Sway-away add-a-leafs still doesn't get you a sway bar like the camper package does. and that does actually matter with a big heavy 5th wheel. I'd much much rather have the the Ford Engineer approved suspension for the loads I'm carrying them some aftermarket stuff...possibly junk...possibly not? Who knows. Some F-250's come with lower capacity wheels as well, though I doubt that is a problem with the newer truck as everything seems to have 20's....

Either way - my 350 SRW w/ camper package runs its stock suspension with a 16k GVWR 5th with no issues. Level, as designed - within GAWR. no F-250 is going to touch that.

[fvstringpicker]

Rest assured you ain't gonna break no axle with the pin weight of 5th wheel; neither will you break it with the entire weight of 5th wheel. Besides it ain't the size of the axle, in and of itself, but the alloy and heat treatment. Your stock axle is likely the cheaper 1039 alloy. 1541 alloy is a least 20% stronger (using the term loosely)
Duallys with the typical larger axles are not because of the vertical load, well not entirely, but because of the increased torsional forces do to the lack of tire slips relative to the road. The torsional forces put far more stress on an axle than vertical load. With a diesel generating well over 700 pounds of torque, calculate the torque at the rear wheels in first gear. Hint: its likely in excess of 12,000 ft pounds. My duramax is close to 14,000.

But I agree if you don't already have a 3/4 ton, go ahead and just get a 1 ton and save yourself the upgrade work.

[RoadrunnerII]

Hi I own a 2016 F250 screw 6.5 box lariat with 5th wheel prep and camper option
I pull a 34 Ft 5th MA Gvwr on trailer is 11,300lbs
In doing my research on my truck the weakess link in the rear gawr is the tires. Truck came with Lt 275/70R - 18 inch load range E tires
Load range E tires have max inflation of 80 psi and max load at that pressure of 3640 lbs. On srw that is 3640 x2 or 7280 lbs
Here is the gotcha. Door sticker is 65 psi for all 4 tires
At 65 psi the tires fall into load range D and per the tire manufacturers load to psi chart at 65 psi max load per tire is 3050 lbs
For srw means 3050 x2 or 6100 lbs which is the GAWR on the door sticker. Coincidence? I think not.
So to the OP check your tire sidewall and if you have LR E tires up the pressure appropriately. For my rig the 65 psi I am within my weight ratings for my trailer and truck.
Oh and for the sag on the truck loaded
Ford does not have any lift from level (rake) with the empty truck. I put a level on my box rail
They use a set of helper springs on the rear. I hit the helper springs when the rear of the truck drops 2-3 inches. Those helpers springs are very stiff.
I don't like the rear looking squatted like the original OP Truck
so I added airbags. Air up to level and go. Ride is better as the helpers are no longer touching. It also puts the truck back level for headlight aim and for braking.
The F350 with the 4 inch spacer blocks has a rake to the truck of 2-3 inches before you add load.
Go figure what the engineers where thinking
Just my 2 Canadian cents but the logic and math add up to me.
I am willing to bet my two cents the F350 equipped the same as my F250 comes with same tires just aired up to 80 psi for the extra load capacity or at least a big portion of it.

RoadrunnerII

[918jeeper]

I had an 01 f250 and pulled my 33 ft big country with no sag. Bought a new 2011 f250 and towed the same trailer and the rear end sagged.

I did some research and found that Ford actually removed one of the leaf springs on the f250 starting in 2011 to improve the smoothness of the ride. It didn't take much to make the truck sag.

I loved the truck! Had lot's of power until I started loosing antifreeze and it wasn't leaking. I got rid of it and bought a 2015 Chevy Duramax DRW and tow a 40ft Cardinal I call Pretty Turd because it's a pretty looking POS.😁

Anyway thanks for you and your wife's service and have fun! Good luck with your new rigs!

[Top_Speed1]

Originally Posted by DaBabysDaddy

I knew people were gonna say that... but it is well within the weight and tow limits. That truck pulls over 18k pounds. The tongue weight is fine too. And no... I can't "take the truck back", it's not new. It's a 2015. I'm not sure why, when people on this forum see a suspension sag a bit, they automatically assume "it's too much" for the truck.

You will be fine. Fords are notorious for the sag as soon as you sit some hefty weight on them.

Here's what I did on my brand new F350 dually;
Air Lift 5000 Air Bags
Air Lift 72000 Wireless/controller compressor

The bags (install) in about 2-3 hrs, about the same for the compressor system. Firestone also makes a system for your truck as well.

Good luck, and you will have no/zero sag and your truck will now look like it's meant to be with mated with your trailer!

Here's a Ford Truck post I made on it

[Wundertaker]

I will guarantee you that I will double and triple check "before" I buy "any 5er" that I have a TV that will "easily handle the new load"! Many folks will go to great lengths to justify errors that they realize too late that they've made in their selection process.


I can see we're still..."beatin' the poor horse"!!! I guess that includes me also...darn!