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Body flex

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by dyeager535, Nov 9, 2001.

  1. dyeager535

    dyeager535 1 ton status Premium Member

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    Anyone else have problems when "wheelin" that the body panels flex enough that it sounds like someone is walking on your roof?

    Every time I did a creek crossing while hunting, easing over the bumps and holes, (I'm assuming it was) the roof would make that sound. I *know* what flexing sheet metal sounds like, and that is most definitely what it is.

    There was a picture (on here maybe) that showed the roof of a Chev truck when wheeling, and the roof had a nice crease in it from the body twist. (not permanent)

    I'd rather not let this keep happening, but without some real serious body off the frame work, is that possible? I'd think poly bushings, except the 1/2 ton frame is so flimsy, tying it to the body can't help much I'd expect.

    Thoughts or experiences on the same?

    (PS, not like its incredible or anything, but I was crossing water deep enough to be testing the doors water tight capabilities where the flexing was occurring. Not having carpet pays off big time! 24"+ depth. More concerned with being swept downstream than flooding it obviously. Nothing like a little excitement to a trip : )

    Dorian
    My tech/links page: <a target="_blank" href=http://www.dorianyeager.com/index2.html>www.dorianyeager.com/index2.html</a>
    Why insist on counting when the ring gear has the tooth counts stamped in?
     
  2. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    My roof doesn't flex...but it already has a crease from being rolled, so maybe that prevents the flexing? My hood flex's so much side to side it pushes the tops of the fenders outwards though. Both fenders have the spot welds broken at the top now. My floor under my feet 'oil cans' quite a bit...even just turning a corner in traffic. i don't know what you could do short of a full cage mounted to the frame to stiffen it up.

    Rene

    <font color=green>Dyslexics of the world...UNTIE!</font color=green>
    <a target="_blank" href=http://coloradok5.com/gallery/project_T2> tRusty pics...</a>
     
  3. dyeager535

    dyeager535 1 ton status Premium Member

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    I was thinking of perhaps a couple of the flat crossmembers for the tranny/t-case, but bolted to the TOP frame rail in a couple of places. But without looking, I'm thinking that will interfere with exhaust and such. I think there is enough room up against the body, and tying the frame rails together better couldn't hurt. Definitely no room for X bracing or anything without serious mods.

    My '83 didn't do this in the same stretch, so either the crossing is worse (likely) or there is some structural difference, which I highly doubt.

    It's just unnerving in a daily driven truck, to know that I'm probably accelerating the seperation of the topper joints, (near the rear window) and putting a lot of stress on all of the sheet metal attachment points, especially when I'm doing a whopping 2 weeks of off-road. No wonder fenders seem stretched sometimes when swapping from truck to truck.

    Dorian
    My tech/links page: <a target="_blank" href=http://www.dorianyeager.com/index2.html>www.dorianyeager.com/index2.html</a>
    Why insist on counting when the ring gear has the tooth counts stamped in?
     
  4. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Oh yeah, I've seen it. I think tying the body to the frame solid would be going the wrong direction. The frame on these trucks is built to twist and tying the body to it (especially with poly) would force them to move more as one, leading to more of what you saw. I think that the solution is to *isolate* the frame and body so they can move separately.

    One possibility is going to a single mount front and rear. By putting a single "pivot" mount in the center of the core support, the frame could twist as needed and the front cap would move with the body tub. Doing the same thing in the back would allow the frame in the rear to move without twisting the body too. You still have the 4 main body mounts to keep the body located in relation to the frame, but they are close enough together than I don't think there would be enough twist to cause trouble. You would also still have the option of tying the cage to the frame in that area (around the seats) without problems with the cage moving in relation to the body. The rear hoop could be mounted to the body (with a brace/plate) so that the frame could still flex but the body would be held rigid in relation to the forward mounts.

    Russ

    85 K30 CUCV, 350 TBI, TH400, 205, D60/C14, 4.56 Locked
    Some day: 4" lift, 44" tires, massive cutting, shorter wb and rear overhang.
     
  5. dyeager535

    dyeager535 1 ton status Premium Member

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    You are right of course about tying the body to the already "weak" frame, but without obvious visual mods (cage, etc) the only thing possible is strengthening the frame, and I'm not re-working a 30 series frame to fit under it : )


    Dorian
    My tech/links page: <a target="_blank" href=http://www.dorianyeager.com/index2.html>www.dorianyeager.com/index2.html</a>
    Why insist on counting when the ring gear has the tooth counts stamped in?
     
  6. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Hehe, you could always do like me. Start with a K30 and make it look sorta like a K5. Much cheaper in the long run I think... [​IMG]

    Anyway, what do you think about the idea of isolating in front and rear (single mount instead of two) so that the frame twist does not twist the body?

    Russ

    85 K30 CUCV, 350 TBI, TH400, 205, D60/C14, 4.56 Locked
    Some day: 4" lift, 44" tires, massive cutting, shorter wb and rear overhang.
     
  7. rock.monkey

    rock.monkey 1/2 ton status

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    I get the same thing when i twist up my truck.
    Im going to put longer bolts in the front body mounts and put heavy springs between the mount and the nut.
    This helps the body and frame seperate more when flexed and may get rid of the bowing in the roof and hopefully will keep the rad from twisting too.

    Bill Innes
    88' Jimmy

    Built for <font color=blue>Function</font color=blue> <font color=red>NOT</font color=red> <font color=blue>Fashion</font color=blue>
     
  8. jms

    jms 1/2 ton status Author

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    You mean like this? http://desertrider.net
     
  9. dyeager535

    dyeager535 1 ton status Premium Member

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    Yep thats exactly it. No wonder the paint is peeling on the trucks roof lol.
    Sure would like to prevent that. (easily) : (

    Dorian
    My tech/links page: <a target="_blank" href=http://www.dorianyeager.com/index2.html>www.dorianyeager.com/index2.html</a>
    Why insist on counting when the ring gear has the tooth counts stamped in?
     

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