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Is the bed supposed to look like it's flexing a lot going down rough road?

Discussion in '6.9L IH & 7.3L IDI Diesels' started by Detroit80, Sep 18, 2020.

  1. u2slow

    u2slow bilge rat

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    Dodge and GM did their 2wd A-arm suspension without boxing the frame... for decades. And 94+ Dodge boxed the frame with a solid axle.

    The other thing that happens with boxed frames is they crack when pushed beyond their limits. C-channels just tended to flex a little more.
     
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  2. david85

    david85 Full Access Member

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    I stand corrected. Looking at later ford and GM (1990s) A-arm suspension, the general solution was a more complex boxed frame to support the front end. But like you say, older trucks seem to just use the cross member to contain the torsional stress.
     
  3. IDIBRONCO

    IDIBRONCO IDIBRONCO

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    Here's something that's stood out to me from the reading the first post. Detroit was judging frame flex by watching the headache rack move. Assuming that he's watching it in the windshield mounted mirror, it's probably 2-3 feet above the frame and any movement at this point would be multiplied over the amount that the frame is actually moving.
     
  4. Black dawg

    Black dawg Registered User

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    that 6.5 should pull a 5k trailer easily.

    A 7.3 with a turbo that is turned up some does pull better than a 6.5, but it doesnt really show up until like twice that weight.....where the 7.3 shines is its longevity being used that way.

    And yes these frames are pretty flexible.
     
  5. Detroit80

    Detroit80 Full Access Member

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    True. Which makes it that much harder to really determine just how much is too much, seeing as how I also don't have a good way of actually measuring the movement that I'm seeing either. I was actually considering mounting up my GoPro in the cab, facing the rear, to get some video of what's happening that I can later reference to measure against something like the rear glass. But then, without having accurate information on load, speed, how the suspension is moving, etc..it's all gonna be wild-butt-guesses anyways, lol.

    On paper, yes. Half of the reason why I gave this truck a shot when I bought it - on paper, the HP/torque numbers are similar to what the 7.3 puts out (the other half being that I know from prior experience that I found the Chevys of this era to be FAR more comfortable inside than the Fords and Dodges). My usual haul + tow weight IS more than twice that weight too. camper weighs 3,500-4,000 pounds loaded up for a weekend, and my trailer loaded weight could be anywhere from 5,500-9,000 pounds depending on what vehicle/tools/spare parts I have loaded up (highly modified Suzuki Samura, Suzuki Grand Vitara, or Chevy K5 Blazer). Plus I'm kind of stuck with my current set up, as there aren't many toy hauler type trailers that can handle a full size vehicle well (Samurai is on full width truck axles too). Even if I switch to hillbilly hauler with the camper on a gooseneck, my trailer weight would still be about the same as my current combined, just with less of it over the rear axle of the truck.

    In practice, however, it feels like the difference between running a 4.3L V6 and a 454/460 when hauling/towing, and I've seen tons of similar reports even on the Chevy specific forums - that if you intend to tow over 5K on even a semi regular basis, you want a big block gas truck or get a Ford/Dodge diesel, period. Don't even consider a 6.2/6.5 diesel truck. I figured part of that was the usual internet exaggeration, and even if it wasn't quite up to the task of hauling the camper and trailer together, it would be good enough to at least be a stand in tow rig for the car hauler alone. But I didn't think it would be this bad...

    It almost feels as if the power drops off much faster past peak torque with this motor, so while peak numbers are similar, the USABLE power on the freeway is much less compared to the 7.3, but I've never found 100% bone stock dyno graphs to really compare (though admittedly, I never really tried looking all that hard either..a graph online isn't gonna suddenly make MY truck make any more power, lol).

    Regardless, end story is that even if I somehow made this Chevy make more power, it isn't going to realistically be a full replacement for the Ford anyways as it just isn't going to handle the load of the camper + trailer. Sure, I could likely make some upgrades in both the drivetrain and suspension departments to get it there, but the cost of doing so would likely exceed what it would cost just to rehab my current Ford, or even buy a bigger truck instead. Hell, I even have a fresh stout 489ci big block in the Blazer now that I built last year that I could easily yank, and pop in the Chevy truck instead. But then I'm back to questioning if the rest of the truck is really going to stand up to my needs long term, and I have my doubts there too.
     
  6. Enginerd

    Enginerd Full Access Member

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    To answer your first question, I have a flatbed welded to the frame and the headache rack moves quite a bit since as IDIBRONCO said the top of the headache rack is like 4' off the frame. The frame can flex a pretty incredible amount. It is no issue though because it's fairly smooth offroad and still handles weight just fine. I just let my brother borrow the truck to haul 5,300 pounds of sheetmetal... on the flatbed. It looks like it's broke cuz it's squating so bad lol
    0913201536.jpg
     
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  7. Detroit80

    Detroit80 Full Access Member

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    Oh wow, glad you posted that picture. I had been thinking about doing a stack type exhaust on my truck as well, trying to get the soot to go skyward instead of on my trailers, but was wondering what it would look like...and trying to find pictures of trucks with "normal" sized exhaust in stack form instead of big enough to drop a basketball down on douche-bro trucks has been impossible so far. Hell, even saying/typing "stack" in this form makes me feel dirty in a not good way, lol.

    Although, occasionally hauling a truck camper as well could present some issues doing this too...I might just be moving soot from my trailers to the side of my camper, and I'm not sure I'd want a 12 foot tall pipe on the truck either, lol.
     
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  8. Philip1

    Philip1 Supporting Member Supporting Member

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    Did somebody say stacks? Lol
    46772d1477168607-what-stacks-image.jpeg
     
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  9. Detroit80

    Detroit80 Full Access Member

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    Yes... That... Not wanted, lol.
     
  10. david85

    david85 Full Access Member

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    Wow...good for a laugh I guess! Reminds me of some of the crazy builds they do in Japan. Just because they can (doesn't mean they should)LOL.
     
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  11. Black dawg

    Black dawg Registered User

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    I wasn't talking on paper.....I have towed with both enough to know how they act...……with heavy trailers the 7.3 will do everything better, but a 5k trailer pulls fine. You are right though in planning to use the ford for that bigger load.
     
  12. Enginerd

    Enginerd Full Access Member

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    Well here's some more stack pictures. It's an ugly sukka lol. Dual 3" straight pipes sound AWESOME but it's loud as can be. It's pretty cool because it sounds like the pipes "talk" to each other. I just put some big mufflers on this weekend though. It's my work/farm/hunting/daily do it all truck. Definitely nice having the soot go up instead of out.
    0822200759a.jpg 0822200758.jpg
     
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  13. Detroit80

    Detroit80 Full Access Member

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    I was actually surprised as just how quiet my truck is now on open exhaust, though it's just a single, dumping right behind the cab. Definitely know it's there, but it's not at all what I'd consider to be loud. Though I think I could likely benefit from having my exhaust shop replace all the tubing from the turbo back, along with a larger diameter crossover. Pretty sure it's all factory tubing now, probably just cut off where the factory muffler would have been.

    But I do like the general idea....
     
    Last edited: Sep 21, 2020
  14. u2slow

    u2slow bilge rat

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    @Detroit80 the turbo is doing some silencing. Open pipe on a NA is choppy. Increasing the pipe size (post turbo) tends to drop the tone some, less raspy.


    I dig it! Plan to have my W250 looking like that from the pass side. 4" single up against the headache rack and cab corner.
     
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  15. IDIBRONCO

    IDIBRONCO IDIBRONCO

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    Completely accurate. Those turbos do act as a muffler.
     

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