Increasing GVWR

[LTZ C20]

Hey all, I'm just pondering ideas on how to increase the GVWR of my truck. Its a C20 Camper Special, 14 bolt corporate, 4.10s gears and it has 9 leafs per spring pack. The entire suspension of the truck is all except for the shocks which I replaced about 5 years ago with yellow bodied monroe gas magnums for 3/4 ton trucks.

I've looked at air adjustable shocks, I've looked at air bag helper springs, I've also had a quote from a local spring shop to re arc my current springs and I've also looked at just replacing the packs with new sets.

I can't decide which to do. My current GVWR is 8200, I'de like to push it to at least 10,000. I like the air helper spring idea, I'm wondering if it would be easy to replace the spring pack with a 1 ton set?

I can post picks of suspension if needed. As always, experience welcome, thanks for looking.

[Irish_Alley]

From what I understand 8600 is the max for 3/4 tons. If you wanted anything higher you would have to go to 1 ton with the taller frame and they start at 8700 and end with 11000. Don't know for sure but I think you need a new frame to up the gvwr.

What are your plans?
How many springs in the rear?

[LTZ C20]

You are correct about the 8600 rating, my 8200 is a typo, I ment 8600. I'm not trying to register it as a higher weight rated truck, I'm just wanting to up my towing ability.

I have a 30 foot travel trailer, another tent trailer, the shop trailer at work and the trailer for my go kart buggy to tow. Plus any time I may need to tow something heavy unexpectedly, like another vehicle on the shop flat bed trailer.

I have 18 springs in the rear, 9 per side, no over load springs.

[Irish_Alley]

http://www.equipmentworld.com/understanding-your-pickups-max-payload-capacity-and-how-helper-springs-make-a-smooth-ride-of-a-heavy-load/

[LTZ C20]

That was a good read, I think I get the subtle point I suspect your trying to make.

[Irish_Alley]

Maybe lol. Air bags and helper springs don't increase the gvwr. They will improve the ride quality and make the ride safer. You could always increase the amount of springs but you will bounce all over and break your back

[Dr_Snooz]

Box the frame and put a Dana 80 under it.

I'm still trying to figure out what they did with the CUCV's that got them up to 9400 GVWR. Anyone know?

[LTZ C20]

Box the frame and put a Dana 80 under it.

I'm still trying to figure out what they did with the CUCV's that got them up to 9400 GVWR. Anyone know?

That's not going to happen. Lol

[LTZ C20]

I found that Air Lift's newest product is available for my truck. I like the kit, it's price seams good for what I want. Where it gets expensive is that I like the idea of onboard inflation/deflation.

[Irish_Alley]

Think the cucvs just got an overload spring that boost the gvwr up

[LTZ C20]

Ok so hears a thougt. Replace my old springs with a new spring pack for a 1 ton non-dually, then add air lift helper springs. Does that sound like it should be sufficient? Also, how many leafs are in a spring pack for 1 ton camper special, is it 9 like a 3/4 ton or more/less? 1 ton springs should fit no problem right, just be a remove and replace deal, as long as they are for the same year and are for a fleet side 2wd like my truck is? Or should I stick with a 3/4 ton set and just add the helpers?

[Dr_Snooz]

Well, 8600 is the 1-ton GVWR, so you're already maxed out with your current setup. That's as high as the square bodies go, or anything else before the 3500 HDs (with the exception of the CUCVs).

Different springs aren't going to take you any higher because other components are still rated at 8600. The 14-bolt is rated at 8600 and it's the heaviest rated axle for that time, to my knowledge. The frame is also rated at 8600. If you want to have 11,000 GVWR, then you're talking about a 1-ton HD frame and a heavy axle like a Dana 80.

So the answer to the theoretical question you asked, how to get to 11k GVWR, is to beef up the frame (like boxing it) and put a higher rated axle underneath (like a Dana 80). Not a simple or cheap proposition.

If you're asking a more practical question, (what spring setup will keep me from sagging when I tow heavy loads), then the answer is more simple. I have three trucks from that time period. One is a 1-ton and two are 3/4-tons. All are rated at 8600 GVWR (1-ton GVWR rating). My '89 Sub has 7 leaves. The '86 crew has 8 leaves. My '90 1-ton (new body style) has been modified to carry my Lance camper. It has 6 thicker leaves, plus a set of healthy overload springs. It also has some airbags that no longer hold air. When I stack the camper on it, the frame gets very wiggly. Mind you, this is the new body style which had a partially boxed frame from the factory, and it's still wiggly. The square body frames had no boxing of any kind. This is why I say to box the frame. The brakes also have a tendency to get hot, which is why I say to put a heavier axle under the truck. Even then, bushings and shocks blow out with much greater frequency on the '90 than the other trucks. C'est la vie.

Air bags do not hold up over time. Mine are full of cracks and I'm scared to use them. Admittedly, they could be over 20 years old too. They do reduce sway much more than the overload springs alone, however, so if that's an issue, consider them. In addition, the overload springs give the truck a rake, so if you don't want the back to sit higher than the front when unloaded, air bags are your natural choice.

Bottom line, I'd say overload springs would be your best, longest-lasting and cheapest option. Air bags have other advantages.

[LTZ C20]

Ok, I looked at my camper special emblems, the GVWR is 8200, not 8600. With 8600 being the 1 ton GVWR, that's only an increase of 400 pounds. I was only looking to break 10,000 lbs anyway.

Dr, your statement "(what spring setup will keep me from sagging when I tow heavy loads)" is probably the really question I was trying to ask. I think is was looking at it the wrong way. Sagging and 40 year old springs is what I'm wanting to correct. I do like the truck have a rake when unloaded, it's a big truck, it should have a rake, so that when loaded it rides level.

I'm open to either overload springs or air bags, I like the air bag idea because you can adjust each side as necessary, it sounds like once an overload spring is pushed down, it doesn't have the ability to push back up like an air bag. My truck rides pretty smooth now, not a Cadillac floating on clouds but for an old truck it's very comfortable. How does on of these trucks with bags ride compared to one with overload springs?

Dr Snooz, I found your info very helpful. Your right, because right now boxing the frame and swapping axles is not a good route for the intended use, cost and frequency of use.

I like that my truck is heavier duty than a regular 3/4 because of the camper special option, I'de like to keep that by using 9 springs again if I replace the rears with new. It's one of those factory original options that I would like to keep with the truck as that is what makes it kind of special.

I just looked at truck we have on the lot here at work, it's a 2015 Chevy 2wd standard cab, long bed 3500 HD with a gas 6.0 liter engine, it has 6 leafs with 2 overload leafs in the rear and has a GVWR of 10,400. That's 8 total per side. Still less then my 9 leaf set. My truck is also 2wd, standard cab, long bed, with a 355 TBI. My hp compared to the new 6.0's is comparable, my current engine puts out over 400 ftlbs of torque so I have enough muscle to tow.

For cost comparison sake, a set of 1 or 2 over load springs for my truck, compared to an air bag set up with no onboard inflation system, price about the same or is one cheaper than the other? If I use over loads, should I use a factory type set up or a new aftermarket kit?

What affects will a rear sway bar have on all of this also, as I want to put one of those on and I don't currently have one.

I also plan to replace the front coil springs with new HD springs, which I think it came with from the factory anyway via the Camper Special option. One of my springs is slightly collapsed just a little but. Right now, unloaded the truck rides dead level, the shop trailer at work, empty makes it start to squat.

Thanks all again for your wisdom.

[Irish_Alley]

i agree with everything dr. said but something else to add on is your gvwr is how much your truck can weight with the driver and tongue weight of a trailer. that being said your truck is rated at 8600 lbs. your curb weight is close to 4k. so you can have 4k (or so) extra weight. if your hauling a trailer and you have 4k in tongue weight then you might be having other problems. helper springs should be good but like said it will lift the rear up

[LTZ C20]

One of the guys at work recommended I call a curtain spring shop in the area. I did, spent about 30 min on the phone with them. Told him what I had, what I wanted, what I have to tow, the guy was really knowledgeable. Sounded like he'd been doin this kinda thing for a very long time. He told me to take some measurements, along with hooking up my heaviest trailer and taking some other measurements and use a floor jack on the rear to figure out exactly what I want for ride height and how much I will need to go up. He said he also might have a set of new springs already made so check back when I'm ready to do the work. He also recommended that before I do anything to the rear, I do whatever it is to the front first that I want. This is because the rear is adjustable (the springs can be arced to the desired spec) front springs or not (that's without cutting springs of course, there won't be any of that going on here).

So I'm gonna go take some measurements and see what I come up with. Probably going to end up doing the front first. Then do the rear. At this point it's gonna be a hold on any helpers of any kind, wait till I get the stock suspension back to where I want it and then evaluate the situation again. He also said, unless I'm going to being using one of those in bed campers or driving around alot with loads above the roof of the cab, don't worry about a rear sway bar, it won't be needed unless I've got alot of weight above the roof line and the truck becomes top heavy.