Author Topic: Theoretical Question  (Read 9635 times)

Offline Dr_Snooz

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Theoretical Question
« on: January 07, 2018, 11:12:40 PM »
If one boxed a 1-ton square body frame. Would the result be as strong as a new 3500 HD frame?

Put another way, could you make a square body frame as strong as a 3500 HD frame, and if so, how?
1989 Chevy Suburban V-2500, 5.7L, TH400

1990 Chevy C-3500 Ext. Cab, 7.4L, 3L80

2009 Chevy Silverado 1500 WT 4WD, 4.8L, 4L60

Offline Big Chip

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Re: Theoretical Question
« Reply #1 on: January 09, 2018, 05:19:18 PM »
I am not sure what year HD truck you are asking about but the frames break on the HD trucks right behind the A-arms.  I guess it's  about the same without boxing it.  It is an easier repair to fix the breakage caused by the steering box in my opinion. 

Offline Big Chip

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Re: Theoretical Question
« Reply #2 on: January 09, 2018, 05:21:29 PM »


It happened twice to me, to both sides. Not hard to make some that “strong” in my opinion.


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Offline VileZambonie

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Re: Theoretical Question
« Reply #3 on: January 09, 2018, 05:24:10 PM »
I have seen the boxed frames break and turn to dust like the cookies my buddy's wife made for Christmas. The frame on these trucks seem to have done a good job over the years proving their worth. Sure they have weak points but easily remedied
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Offline Willy Lee

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Re: Theoretical Question
« Reply #4 on: January 09, 2018, 06:34:28 PM »
A boxed frame is a crap collector and will rot out. Just ask the brakelines and fuel lines on a GMT400. The last decent frame Chevy made was in a Square. And the new trucks don’t know don’t care the faggoty Luke Bryant mobiles. They are for people with no imagination to create something of their own so they buy what the factory thinks they want. I guess they know because these sheep keep buy the big shiny wheeled , overpriced, couldn’t traverse a mud puddle, mall crawling turds.

Offline Dr_Snooz

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Re: Theoretical Question
« Reply #5 on: January 09, 2018, 10:13:37 PM »
Fair enough, let me clarify. I love my square, but let's be honest, it can't hold a candle to the HP and payload ratings of the new trucks. I have a Lance camper that I like a lot, but it doesn't quite meet my needs. I'd like to replace it with a newer camper, but the new ones are quite a bit heavier. The Lance I have puts my truck about 200# under GVWR, which doesn't leave a lot of room for cargo or a tool trailer. If I want a newer camper, I either have to buy a new truck, which I don't want to do, or find a way to beef up the old truck. Any ideas?
1989 Chevy Suburban V-2500, 5.7L, TH400

1990 Chevy C-3500 Ext. Cab, 7.4L, 3L80

2009 Chevy Silverado 1500 WT 4WD, 4.8L, 4L60

Offline Jason S

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Re: Theoretical Question
« Reply #6 on: January 10, 2018, 11:13:14 AM »
Fishplate along the inside of the c-channel? 
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1974 Chevrolet K10, Custom Deluxe, 350, SM465, NP203, 3.73's

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Offline Dr_Snooz

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Re: Theoretical Question
« Reply #7 on: January 10, 2018, 06:24:33 PM »
Just to amplify, I'd need to build a truck that can handle a ~4000 lb camper + a ~3500 lb trailer. Anyway to engineer that into a square-body or do I need a mall-crawler?  ;-)
1989 Chevy Suburban V-2500, 5.7L, TH400

1990 Chevy C-3500 Ext. Cab, 7.4L, 3L80

2009 Chevy Silverado 1500 WT 4WD, 4.8L, 4L60

Offline 1967KaiserM715

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Re: Theoretical Question
« Reply #8 on: January 11, 2018, 06:58:59 AM »
Cucv military trucks were rated at 1-1/4 ton, used same 1-ton frame civilian trucks used. Your frame is fine. Add a few more crossmembers and bolt on a few frame stiffeners if your really worried. Frame stiffeners can be made from 2" angle iron.

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Offline Dr_Snooz

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Re: Theoretical Question
« Reply #9 on: January 19, 2018, 08:37:49 PM »
The CUCVs were rated at 9400# GVWR. I don't know what they did to achieve that, but I assume they put in some heavier leaf springs and called it good. I have some pretty beefy overload springs on my truck now, so let's just assume that a 9400# GVWR is appropriate. The truck weighs 5600# empty. A new camper, dead empty, will put my GVW at 9600#, which is already 200# overweight. Then if I put in my stuff and fill the water tank, I'll be way, way over GVWR. Then I would connect a 3500# trailer on a 48" hitch extension and drive off? I get that you can go way over GVWR and be okay, but doing it as a matter of course seems like begging for a lot of catastrophic breakdowns. I'd rather engineer it to be tougher.

Right now, the truck is not tough enough to carry the older, lighter camper. Fully loaded, it feels flexy and ponderous. The brakes overheat on extended grades. It's simply isn't tough enough to handle an additional 2 tons of weight.

Nobody can answer my original question? "If one boxed a 1-ton square body frame. Would the result be as strong as a new 3500 HD frame?" My gut feeling is that it would be stronger than a 3500 HD frame, but what do I know?
1989 Chevy Suburban V-2500, 5.7L, TH400

1990 Chevy C-3500 Ext. Cab, 7.4L, 3L80

2009 Chevy Silverado 1500 WT 4WD, 4.8L, 4L60

Offline VileZambonie

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Re: Theoretical Question
« Reply #10 on: January 20, 2018, 08:26:55 AM »
I would ask you, how would boxing the entire frame benefit your pulling and braking if that is what your concern is? If you boxed the entire frame, it would be heavier, have an uneven temper and where is the structural weak point now? What would be the gain in towing and braking? I don't think anyone can answer your theoretical question unless they have an R&D lab to give you the outcome data.

Look at what these one tons, cab and chassis trucks and other modified rigs have done with upgraded suspension and brakes over the years.

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              ⌠¯¯¯¯¯'   [☼===☼]
              `()_);-;()_)--o--)_)

74 GMC, 75 K5, 84 GMC, 85 K20, 86 k20, 79 K10

Offline Stewart G Griffin

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Re: Theoretical Question
« Reply #11 on: January 20, 2018, 09:13:28 AM »
i was flipping channels the other day and briefly saw Barrett-Jackson Auctions and apparently the factory boxed the frames on the 69 Chevelle SS convertable, to "provide extra rigidity due to the added flex of the body due to the missing roof."   So maybe there is something to this?   (Did the other gm convertables also have this extra feature?)

2) Is the truck in question the 90 c-3500?    What is your rear axle ratio?  GVWR is more than just frame and springs.

Offline hatzie

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Re: Theoretical Question
« Reply #12 on: January 20, 2018, 10:13:04 AM »
Cucv military trucks were rated at 1-1/4 ton, used same 1-ton frame civilian trucks used. Your frame is fine. Add a few more crossmembers and bolt on a few frame stiffeners if your really worried. Frame stiffeners can be made from 2" angle iron.

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The M1008 & M1010 are 8800 GVW with open Dana 60 Front axles and NP208 transfer cases.
The M1028 & M1031 are 9400 GVW with Limited slip Dana 60 front axles and NP205 transfer cases.

The M1008 is just a 1-1/4 ton pickup with the standard CUCV package.
The M1010 is a CUCV with a tactical Ambulance box mounted on the frame.
The M1028 had a slide in tactical box
The M1031 had a frame mounted tactical box
Both the M1028 & M1031 had pintle hitches to tow big heavy things like the military generator sets.

They were all based on the 1984 K30 chassis with uprated springs and heavy brakes.  None of them had boxed frames.

I have seen CUCV trucks with Dually rears but IDK if these were A2 A3 etc variants, a handful of motor pool modified chassis, or modification after they changed hands to civilian ownership.  Knee jerk says the civilian owner decided they wanted a dually.
« Last Edit: January 20, 2018, 10:34:38 AM by hatzie »
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Offline 1967KaiserM715

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Re: Theoretical Question
« Reply #13 on: January 20, 2018, 12:02:16 PM »
Cucv military trucks were rated at 1-1/4 ton, used same 1-ton frame civilian trucks used. Your frame is fine. Add a few more crossmembers and bolt on a few frame stiffeners if your really worried. Frame stiffeners can be made from 2" angle iron.

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The M1008 & M1010 are 8800 GVW with open Dana 60 Front axles and NP208 transfer cases.
The M1028 & M1031 are 9400 GVW with Limited slip Dana 60 front axles and NP205 transfer cases.

The M1008 is just a 1-1/4 ton pickup with the standard CUCV package.
The M1010 is a CUCV with a tactical Ambulance box mounted on the frame.
The M1028 had a slide in tactical box
The M1031 had a frame mounted tactical box
Both the M1028 & M1031 had pintle hitches to tow big heavy things like the military generator sets.

They were all based on the 1984 K30 chassis with uprated springs and heavy brakes.  None of them had boxed frames.

I have seen CUCV trucks with Dually rears but IDK if these were A2 A3 etc variants, a handful of motor pool modified chassis, or modification after they changed hands to civilian ownership.  Knee jerk says the civilian owner decided they wanted a dually.
The dually trucks are m1028 a2 and a3 variants. There is possibly 1031 variants with duals, but the only ones specifically specced for dual rears was the 1028.

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Current Vehicles:1985 GMC K10(Daily) 1991 GMC K2500(Daily) 1975 Beetle(not running) 1985 Mercedes 300D(not running) 1952 M35    1967 M715(not running)
 1986 Chevy K30(under repair)

Offline Dr_Snooz

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Re: Theoretical Question
« Reply #14 on: January 21, 2018, 11:35:21 AM »
I would ask you, how would boxing the entire frame benefit your pulling and braking if that is what your concern is?

It doesn't. But that's not my concern (at least for the purposes of this thread). My concern, and the question I'm asking in this thread, is how to consistently overload a frame by ~51%-133% without breaking it. My mention of the brakes (and the frame wiggliness) was to make the point that my truck is already maxed out with the old camper, and it's clear to me that some serious modifications are going to be needed before another 2 tons can be placed on it reliably. Obviously, extensive modification will be needed from the powerplant to the axles before I can do that. I was only trying to keep the thread from becoming any more confusing than it is already by confining my question to the frame itself. I'm not trying to be disrespectful, but the "oh it'll be fine" answers above are not satisfactory. It's an easy thing to say, but I'm pretty certain that no one is going to come help me bend the frame back when it turns out they're wrong. If no one knows, then that's fine, just say so. If it's impossible, then tell me to buy a mall crawler, but please don't be dismissive.

If you boxed the entire frame, it would be heavier, have an uneven temper and where is the structural weak point now? What would be the gain in towing and braking? I don't think anyone can answer your theoretical question unless they have an R&D lab to give you the outcome data.

These are the kinds of questions I'm trying to get answered. I have no idea, which is why I posted the thread. The hotrod and pirate4x4 crowd have been boxing frames since forever and seem to be pretty sold on the idea. They're mostly concerned about frame flex, however, where I'm more concerned about weight and towing. It's a somewhat different application that isn't well covered by those communities. I just thought someone here would have some additional insight. Sorry if I had that wrong.

And yes, the '90 C3500 is the truck currently carrying the camper, but the '86 C2500 is the frame I would be boxing. I'm pretty sure the rear end is a 4.10.
« Last Edit: January 21, 2018, 11:45:34 AM by Dr_Snooz »
1989 Chevy Suburban V-2500, 5.7L, TH400

1990 Chevy C-3500 Ext. Cab, 7.4L, 3L80

2009 Chevy Silverado 1500 WT 4WD, 4.8L, 4L60