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73-87 Chevy _ GMC Trucks => Brakes, Frame, Steering & Suspension => Topic started by: Dr_Snooz on January 07, 2018, 11:12:40 PM
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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?
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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.
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(https://uploads.tapatalk-cdn.com/20180109/d2443d84981de5998d3b164e1987191d.jpg)
It happened twice to me, to both sides. Not hard to make some that “strong” in my opinion.
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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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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.
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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?
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Fishplate along the inside of the c-channel?
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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? ;-)
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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 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?
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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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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.
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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.
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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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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.
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1986 C2500?
That's your issue if it isn't a typo, a 2500 frame is thinner and lighter then the 3500 frames.
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Again, unless someone can provide you destructive facts and figures it's a guessing game. For every action there is an equal and opposite reaction. The only thing anyone can offer you is an opinion.
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1) Why do you use/want a slide in vs. a travel trailer? Because the easy solution might be to get one of those trailers that is a camper AND has section in the back for tools/toys etc.......because you were thinking about getting a new camper anyways.......?
2) Even with 4.10 gear i think (not positive, but think) the highest GVWR is 8600 for 3/4 ton? So you'll be WAY over capacity anyways with a 4000 lbs slide in camper?
So why not just use the c-3500?
3) Doing further research, it appears that ALL the gm intermediate convertables got a boxed frame AND el caminos also did. But i suspect this was more for stiffening than to increase weight capacity?
Not sure what to tell ya.............
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Cool, thanks guys. Yes, the 2500 frame is a lighter frame, except for the crew cabs. Those got the 1-ton frames.
Since everyone keeps jumping ahead of my question. Here's the theoretical plan:
1. Box the C-channel frame. Fab up some beefed up crossmembers.
2. Replace the rear axle with a D80.
3. Replace the front axle with a D70 (yes, I intend to convert to 4x4).
4. Replace the 454 with a Ramjet 502 crate engine.
5. Replace the TH400 with a Supermatic 4L85
That should be plenty tough to do what I have in mind. Everything but #1 is easily do-able, "theoretically" speaking. It's #1 where things get tricky. A boxed 1-ton frame looks like it would be beefier than a 3500 HD frame. When I ask around amongst my redneck farmer and gearhead 4x4 friends, they seem to think it would be plenty stout. BUT I haven't crawled under a 3500 HD to measure frame heights or wall thicknesses. Also, given the difficulty of removing a frame to re-engineer it after failure, and the general expense level involved, a guy would really hate to be wrong. So I'm looking for a "multitude of counselors," if you will.
Mind you, this is all theoretical. Most likely, nothing will ever happen and the truck will return to dust sitting in my yard hundreds of years from now. I'll buy a used mall crawler and grouse about how much I dislike the new trucks every time I get in it, while realizing that I do like dome lights that turn themselves off when you leave the door open, and that backup cams are really helpful for hitching trailers. I'll drive it by the C2500 every day and wish for what might have been.
Still, I can dream...
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i think #3 may answer the question, but do you have to have a slide in camper, or will a travel trailer do?
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Has to be a slide in camper. I need to be able to pull a tool trailer. I need to be able to pull up to a disaster recovery site fully self-contained and ready to rock.
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I would start with some bolt on frame stiffeners or crossmembers. Make sure the bolts are snug in the hole-bets way to do this is to drill the hole undersized and ream to fit the bolt. Use 7/16" grade 8 hardware.
Frame stiffeners can be as simple as a 3x3 or even 4x4 angle iron, at least 16-18" long. Bolted to the outer edge of the frame.
If you want to add some rigid crossmembers, just move the frame stiffeners to the interior of the frame then create the crossmember.
Some big rigs use a double C frame rail (c-channel in a c-channel.) And extra crossmembers-all bolted in, to create a stronger frame.
The strongest crossmember to reduce flexing between frame rails is an 'x' pattern. A straight member will allow more twisting and movement.
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im going to add to whats been said, your springs, brakes and axles are the weak point to these trucks. take my crew cab 350/4l80e 205 1 ton with single rear axle, its gvwr is 9400 my buddies a dually 454 th400/205 that has the same frame but different axles with bigger pads. its gvwr is around 11000.
the weight of a goose neck is going to be over the rear axle so the frame will have little impact there. the gvwr is also biased on the trans/engine. take i believe its a 79 1 ton they also came with an inline 6. but its gvwr is lower than the 350. so more springs+more power+better trans will give you a higher gvwr but DOT wont care unless you been re-certified to haul that much more weight.
if you want the best answer go to a spring shop they'll tell you what you need to know and will tell you what is needed
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also keep in mind the difference in GAWR, GVWR and GVCW.
http://forum.73-87chevytrucks.com/smforum/index.php?topic=33169.msg282039#msg282039
the trailer will be hauling most of the weight your truck is only pulling its weight + the tongue weight. my crew cab 1 ton is 9400 LBS but my curb weight with the cummins and tools is 7300. so i can effectively haul 2000 lbs in tongue weight and still be ok by GVWR
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Updating thread with some new data. I went truck shopping with my brother last week and had a chance to crawl under a 2008 Ford F-350 Super Duty. The truck is listed with a GVWR of ~11k and a GCWR of up to ~33k depending on engine and axle ratio. The surprising thing for me was that the frame was a plain old ordinary C-channel. It was as thick as my 1-ton frame and not as tall. Basically, it wasn't as strong as what I have, but still rated for waaay more weight. So that would confirm what you guys are saying, that the frame isn't really the big issue here.
Only recently have the 3500 HDs gone to a fully boxed frame, but even there, I think the cab and chassis configurations still have a C-channel in the rear for bolting up aftermarket box beds and the like. So again, the frame isn't the big concern.
I know on my '90, the brakes are my BIG limiting factor. They heat right up under load. The frame gets wiggly under load and the suspension bushings wear out quickly, but the frame hasn't had any trouble at all.
Time to rant:
Why were we shopping for trucks you ask? A few years ago, my brother lost his mind and bought a Ford. Specifically, he bought a 95 Ford F-350 Power Stroke (with the Int'l engine). He thinks it's all that, and most owners do love that engine. It IS impressive: a giant 7.3L diesel with 400+ ft-lbs of torque that still gets 16-20 MPG. The ENGINE is great, but the thing burned up 4 [manual] transmissions in one year hauling a heavy travel trailer. So he's doing without the travel trailer while he gives it all a re-think. He's looking for a trans that won't burn up under heavy load, aaaaaaannnndddd... He ain't finding one. Everyone on every discussion board knows that the much vaunted Power Stroke likes to blow up whatever transmission you put behind it. Which makes me wonder how Ford's engineers did not know what every guy on every discussion board seems to know? Of course they knew! It's so typical for Ford to spec something they knew would not hold up under normal use, just to save a few dollars. They think nothing of making you remove the intake manifold to change a coolant hose, or pull the body to change head gaskets, or spec'ing an engine that grenades transmissions, or a gas tank that blows up on impact, or a car that rolls over and kills people after a routine blowout. When their wickedness gets into the papers, they throw lawyers and PR flacks at the problem. What a disgusting company. How does a business with such total contempt for its customers keep from going broke???
The best part is that for vacations, my brother's driving the wife's Suburban and staying at motels. In so doing, he finds out that he can drive almost twice as long because the Suburban is so much quieter, whereas the noisy, stinky Power Stroke beats him into submission in a relatively short time.
The moral of the story: never buy a Ford.
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BTW, does anyone know if any kind of tempering or heat-treating was done to these old frames at the factory? How about on the new HD frames?
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I was driving past the Chevy dealership last week when I slammed on the brakes and flipped a quick illegal U-turn. They finally had a 3500 HD pickup on the lot. It was not a cab and chassis, which still uses C-channel frames, but a pickup with the boxed frame. I can confirm that the new, fully boxed 3500 HD frame is basically just a boxed K3500 frame. Now I didn't spend a lot of time under there, and I didn't have a dial calipers with me. I didn't take any measurements, or look at all the brackets or anything. I just eyeballed the frame rails, and those are essentially the same dimensions as a K3500 frame but with a full box.
So if you're hankering for a 3500 HD that you can actually see out of, then box the frame on your K or C.
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Honestly, I don't understand why they haven't been boxing these frames for a long, long time. I looked under a 2500 HD a few years ago. It was just a beefed up C-channel frame. There was so much extra metal under that thing, it was crazy. The boxing is a much better use of materials.
Anyway, as far as I'm concerned, the answer to my original question is that YES, boxing a square body frame will make it as strong as one of the new 3500 HD truck frames.
Thanks guys!