I have a 4.6L supercab with 3.55 gears. According to charts, my gvwr is 7000. With the addition of 4.10 gears, ATI procharger, rebuilt 4r70w transmission with shift kit, cat-back exhaust, and add an additional leaf spring on each side, will this increase my gvwr or am I just peeing in the wind? Any suggestions are welcome.

 

Your GVWR is written on the second line of the sticker on the driver's door pillar -- and is NOT the sum of the GAWR for the front and rear axles.

You will have logically increased the GAWR of your rear axle with the leaf springs; and you will have increased the GCWR of your truck with the 4.10 and additional HP.

From a practical standpoint -- yes, you have achieved both.

As for suggestions: Put your back against the wind.

 

Well, you still have to figure that you still have the same axle(s). So the GAWR has not increased at all.

Technically, you have made it “easier” for the truck to tow closer to it’s max rating, but you can’t claim any higher weights then what’s been documented for it’s GVWR and GCWR from the manufacturer.

The addition of the extra leaf springs (overload springs, as such), will only keep the truck from sagging as much in the rear when hauling the same amount of weight.

 

That depends...

...upon the component which was the weakest link in the GAWR calculation.

The axle is likely not the limiting factor -- springing and tires are usually the limiting factor, as the same axle housing is used for several GAWR ratings.

I didn't want to start splitting hairs -- (like pointing to the fact that brake power hadn't changed) -- but from an axle supplier's standpoint I can attest to the fact that a GAWR 'rating' is left to the vehicle OEM -- and/but as a rule of thumb, the axle supplier (at least in our case) will allow a higher GAWR for the same axle as long as the rated speed of the vehicle is reduced -- or the road conditions are more clearly controlled.

Nits aside -- he's on the right track.

 

I agree that he's helped his current power and load handling capibilities, no question. I guess I was just saying that just because you added the extra "stuff", he still has to adhear to the factory GWR figures...... You can't just claim that it now has a GVWR of x amount over stock because I added x to the suspension..... (Sure, you can now haul that much more, but just not "legally").

I added some #2500 overload springs and LT load range C tires, but I still have to maintain a GVWR of #6250 and a GCWR of #12700, even though it "could" handle more.....

If there's a way that he could 're-classify' his trucks GWR's by re-registering it with a the higher weights I suppose that would work too. Depends on how the state registers it's Light Trucks.

 

I agree.

I bet there are many people running their F-150 trucks with slide-in campers, too -- and the little easily-overlooked piece of paper that came with my '97 6250 GVW truck specifically said that it was not intended for slide in campers (but my 7700 series IS -- but only one weighing up to 1279# -- and that's for a 5550# (measured) truck with a 7700# GCW!

I wouldn't be surprized if there isn't less than 1 out of 50 light truck salesmen that have a clue as to how to properly spec a truck to a job -- and most trucks I've seen while walking around the campgrounds and BS'ng with owners appear to be overloaded.

 

Honestly, I wouldn't carry more weight myself than what the truck is rated for. Not because the axles couldnt handle more or anything, but to split a couple of those hairs, the truck just isnt designed for it overall. If you really want a higher load capacity, trading for a 3/4 ton truck would be the first logical choice. Adding springs, gears, power adders, and beefy trannys to a light truck will aid in handling the rated loads, but will not increase the overall capacity that much more. I assume that you are attatched to your truck in some form and this is why you havent bought a heavier model. BTW, light duty f-250's were sold in '97 with the 97+ f-150 body style. This might be a consideration if you really plan to carry heavier loads frequently.

Now for the hairs.

Like Y2K suggested, braking power has not increased. Even if you have trailer brakes, they can fail or their effectiveness may be limited depending on road conditions. I have added a leaf to my truck and it performs much better under loads, but I wouldnt say I have increased its capacity much, only improved how it handles it. Remember, heavier trucks not only use more springs, but they are often wider and thicker. HD shocks are in order for increased suspension mods. The frame will never be as strong (I have seen a trailer bend the frame of a truck that rear ended a semi. The frame/reciever was laying on the ground). U-joints and driveshaft, # of axle lugs, steering, transfer case (were aplicable) and front end components will never be as strong as a heavier model. Lastly, the truck will never have the overall beef (weight) in comparison to a trailer. It really will make a difference on if your truck pulls the trailer, or the trailer "pushes" the truck. Some of these differences are slight and will not necessarily be noticable however.

Now for your truck

If you are just looking to handle rated loads better, those mods would be a vast improvement.

Y2k is right, tires are the next thing I would look into. Load range D is in order for good load handling, both in the bed of the truck or pulling a trailer.

If you add leaves, consider buying a new set and adding leaves to them. A local spring shop will sell them reasonably. I had mine re-arched 2 different times after one broke (one either side each time). Within a year they were sagging once again. You just cant cold press thousands of miles of wear from your springs and expect them to hold thier shape. My new set has been in for almost 2 years now and ride at just the hieght they did originally. If your existing springs have little wear or decent arch to them, adding to them may be fine.

Gears are always a worthy mod for heavy loads, and you never can have too strong of a tranny or too much HP from a power adder.

You are on the right track, just consider that you really wont be able to safely handle a whole lot heavier loads IMO, and if you frequently handle heavy loads, a heavier truck is in order.

 

Thanks for all of the great replies! In all honesty, I have never really weighed my truck and trailer together. Will start there though.