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diesel swap/frame stress for 86

Discussion in 'Chevy Trucks' started by welj31, Jan 30, 2009.

  1. welj31

    welj31 Member
    Messages: 58

    As I said in other thread I plan on a diesel swap for my 86 3/4 sub
    I have seen some co's on web offering this swap but they say nothing about the added stress on the frame. I know there will be some from a past swap of a 454 into a 86 full size jimmy. First time out ripped a 6 inch chunk out of frame where tcase cross member mounts. I think this frame is thicker but i will try to beef it up anyway. Has anyone done this type of swap? If so what problems did you run into? Thanks
  2. Detroitdan

    Detroitdan PlowSite.com Addict
    Messages: 1,937

    If you ripped the frame with a 454, it wasn't the weight that did it. 1/2 and 3/4 tons shared much of the same frames, even 1 tons were mostly the same. You could get a 454 in a 1/2, 3/4 or 1 ton, if you have the motor and tranny mounts put together properly and you don't drive off a cliff with it, it will be fine.
    I don't know what a 12v weighs, but I will bet it is a lot. You are right to be worried about the weight, but all you should need to address is front springs. There are places you can add gussets for strength on the 90s trucks, but I wouldn't even worry about boxing the frame on your year.
  3. welj31

    welj31 Member
    Messages: 58


    it was not the weight it happened when i hit the gas a little to hard kinda twisted it

    NICHOLS LANDSCA PlowSite Veteran
    Messages: 4,362

    I can't believe you could rip a sound frame, I would think there was something wrong with it before you put the motor in it. I've done plenty of motor swaps some in excess of 900HP and never had anything like that happen.
  5. aeronutt

    aeronutt Senior Member
    Messages: 262

    The 12v weighs about 1000 lbs. That's several hundred more than a 454 so the front springs are going to need help. It's not an easy swap and you will spend a lot of time fabricating brackets and squeezing 10 pounds into a 5 pound bucket. I've seen it done to where it looks factory and I've seen it done... well... it never actually got done because he gave up after a year and sold the pile of parts for 1/4 what he had into them. :cry:

    Without having seen your 86 Jimmy, it tough to say what went wrong. If I had to venture a guess I'd say the problem with frame strength was likely due to amateur custom welding and/or failure to engineer custom mounts with proper attention to torque & weight stresses. It's amazing how much strength a 5-ounce diagonal gusset can add when properly placed. It's equally amazing how easy a 5-lb bracket can rip loose when improperly placed or poorly welded.
  6. Joe D

    Joe D Senior Member
    Messages: 605

    While I agree about the weight of the 5.9 Cummins, your off a little on the big block. I think there is a 400lb difference max.