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Mounting a Flatbed

Discussion in 'The Garage' started by B_to_C, Jul 21, 2005.

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How To Mount a Flatbed

  1. Bolted directly to the frame

    14 vote(s)
    41.2%
  2. Use bushings!

    20 vote(s)
    58.8%
  1. B_to_C

    B_to_C 1/2 ton status Author

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    So how would you mount a flatbed on a blazer frame?

    Do you bolt the subframe of the bed directly to the frame rails or do you use the body mount bushings in between?
     
  2. 79k20350

    79k20350 3/4 ton status

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    I take it you mounted a pickup cab and now want a flat bed? I would either use just a thin strip of rubber or bolt it directly. If its wood i wouldnt bother, but if its a metal flat bed then id speend the time to put a little something there.
     
  3. 1-ton

    1-ton 1/2 ton status Premium Member

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    Make some steel stands that are welded (or bolted) to the frame, and then bolt the bed to the stands.
     
  4. B_to_C

    B_to_C 1/2 ton status Author

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    Yea putting a pickup cab on a blazer frame. It's going to be a metal bed, thanks.
     
  5. down4thakrown

    down4thakrown 1/2 ton status Premium Member GMOTM Winner

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    i'm goin to just bolt mine strainght to the frame. just goint o use some 1/8 thick steel plates and weld them to where the oem body mount holes are and use some 1/2" bolts. i dont plan on having anybody ride back there. so im not worried about the extra cushioning.
     
  6. camiswelding

    camiswelding 1/2 ton status

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    its not about passengers... its about distributing loads appropriately to the frame....

    the frame has flex... alot in off road situations...

    solid mounting anything is looking for trouble... the bed mounting points will crack ...or worse you will eventually stress the frame until it cracks

    I tried this for flatbed mounting several times and it works slick...

    I got 6 extra cab frame mounts and use them with appropiate height risers to make a "flat" mounting point for the flatbed... then I just used standard poly cab mount bushings... it looked factory... bushings were easy to get... and they provided plenty of flex ability/shock/load absorbtion... for a shortbed you would only need 4

    On heavy duty trucks they solid mount some applications of beds BUT they dont flex like our frames do... and normally are not subjected to severe off road usage....
    look at any military off road stuff... they all have bushings or shock mounts of some type for the beds///

    My aftermerket service body was mounted to the frame with standard doughnut bushings... even these werent good enough and the body stress cracked several brackets from flexing...

    my two cents

    cam :D
     
  7. down4thakrown

    down4thakrown 1/2 ton status Premium Member GMOTM Winner

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    i didnt think the frame flexing would be an issue because the bed isnt attached to the cab so it allows some movement between the two. but if you done this and seen the stuff crack and break maybe i should just get some oem bushings from the yard huh? or if some one is parting one out and the bushing are intact i'll just need the rear 6 mounts. with all the sleeves and bolts plz thx
     
  8. mrk5

    mrk5 The Sticker Guy Moderator Vendor GMOTM Winner Author

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    Don't suppose you have any pics?
     
  9. diesel4me

    diesel4me 1 ton status Premium Member

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    I broke all the rules I guess..

    The flatbed I had on my 74 K20 was made of 4" channel iron spaced 11" apart--they used to be pallet racks!--two of them welded together made a perfect 79" wide bed--exact same dimension of the width of the truck cab..weighs 900lbs empty,not counting the crane it has on it..

    I welded angle iron across the channel iron under the bed,right where the OEM front and rearmost bed bolts were,and used peices of pipe between the frame rail and flatbed to "level" it ,and the bolts went thru the pipe and into the top lip of the frame rail,just like original.only used 6 bolts!-( I put 2 in the center near the wheels for extra support)--no rubber cushions or wood blocks--metal to metal!--and only the pipe was touching the frame's top lip..the angle iron also laid on the frame rails in a few sopts..

    I hauled a LOT of weight in that truck,the flatbed has a heavy crane,and once I hauled a 4000lb detroit deisel bulldozer motor in it,and despite the rotted frame ,and those peices of pipe being paper thin from rust,it never hurt a thing...I was expecting the top rail of the frame to rip or crumble it was so crusty,but it lived!..

    I noticed immediately after I installed the bed,it felt MUCH more roadworthy,and the truck felt like it was more "rigid" than before,it steered better and rode better due to the weight..felt like the frame could not flex around as much--when its as rusty as mine was,thats a GOOD thing!..

    I probably could have invented a better way to bolt the bed on,but it worked fine for me--I think simple is better...many OEM flatbeds simply use blocks of oak wood cut to match the frame rails and clamp the bed to the truck with long "U" bolts and flat stock..even the bigger "straight job" moving trucks...not too complicated.... :crazy:
     
  10. camiswelding

    camiswelding 1/2 ton status

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    sorry..project trucks long since sold....
    I am getting ready to do a trailer sometime in the next couple of months using this exact method for bushings

    some good info might be gained from project turtle 1 and 2 in floorwheeler magazine..... the articles address just this concern and the author tells the story of how his chassis cab camper mounts were insufficient and cracked while they were trekking though mexico...

    yes wood and long u-bolts (more to make a flat mounting point than any cushion) have been used for many years... but I would still suggest that most of these vehicles do not see severe service that most ck5ers subject their trucks to....
    so... my suggestion again is... if you want it to flex and not crack the frame some bushing is necessary...
    look at any sano truggy mount and you will see the fabber has designed in bushings for the frame outback just for this reason... rarely do I see well engineered setups weld directly to the frame or metal to metal....

    On my service body there was one place the body manufacturer had the body metal to metal with the frame.... it wore the frame down nicely in that area...
    my 4 cents :D

    cam

    A good resource to look at is a publication called "Truck and Trailer Body Builder's" ....but even most of those guys dont design trucks for moab or the rubicon
     
  11. cow killer

    cow killer Registered Member

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    bull, ever see a semi twist bad? the frames on the semis are made to twist more than a passenger vehicle. they are made to twist cause of all the torque the engines make, it would snap a frame so quick it aint funny. thats why they are only c channel frames with maybe 4 crossmembers. alot of flatbeds on heavy duty trucks are either solid mounted (sorta like a dump truck) or mounted ontop of oak wood.

    and sever off road conditions? ha, you should see some of the **** they put them trucks threw in the quarrys around us. we replace crossmembers so much due to over twisting.
     
  12. sweetk30

    sweetk30 professional hooker Premium Member

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    simple mount and still have flex. 2-3" wide section of angle iron. bolted or welded to flat bed. then matching peice bolted or welded to truck frame to set flat bed on at the said mounts. drill hole and install big bolt and have extra length and space it with rubber of somekind if wanted. then install old dana 60 king pin springs or others that size and secure with washer and lock nut. this will hold tight and still give some flex if needed in the flat bed to frame. some rock crawlers also do this to the body mounts for extra flex with out riping off the body from the frame.
     
  13. jekbrown

    jekbrown I am CK5 Premium Member GMOTM Winner Author

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    I planned on solid-mounting the one on my tow rig. its never gonna see offroad abuse... so I'm not particularly worried about over-flexing the frame...

    j
     
  14. wildmouse216

    wildmouse216 1/2 ton status

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    Blazer frames are notorious for flex and even busting body mounts. If yours never has you should go look at all of them and you might be wrong. You cannot draw any similarities in frames from semis to passenger vehicles. The loads and stress they are designed for are a totally different thing. Most of the big flatbeds that I see are dumpbeds and a dumpbed has only one solid mounting point to the frame. If you look at a box truck they have bushings.
     
  15. B_to_C

    B_to_C 1/2 ton status Author

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    Ha, forgot I even made this pole. Here is how we ended up doing it... 4 body mount bushings. We used what he had lying around, so it got two poly ones for the front and two rubber ones for the back.

    [​IMG]
    [​IMG]
     
  16. M-1028

    M-1028 1/2 ton status

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    I welded mine directly to the frame. Before I did the flat bed I had a little frame flex, but now there is none. Mine gets tested pretty hard since everyone seems to think its a mobile RTI.
    [​IMG]
     
  17. Dallin

    Dallin 1/2 ton status

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    M-1028 that looks awesome! What diameter tube did you use? I'm trying to decide between 1.75" and 2".

    I voted solid mount. It's been working for me. My bed is welded to the frame.
     
  18. M-1028

    M-1028 1/2 ton status

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    Its 1.5 sch. 40, so around 2" od
     

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