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NOW W/ PICS! a few snags encountered during body mount swap

Discussion in '1969-1972 K5 Blazer | Truck | Suburban' started by tp85, Jun 10, 2002.

  1. tp85

    tp85 1/2 ton status Premium Member

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    Take a look at these pics of body mount rust areas. I think the position #1 mount is solid (even w/ the floor pan rust since bolt goes through a tube support). However, I need to repair the rear most mount location. You'll see in the pictures that the bed floor metal is in perfect condition...meaning the rust occurred from the bottom up. You may want to check your trucks. On the LH side I need to replace the entire box which is welded to the underside of the bed.

    Any ideas or comments would be greatly appreciated!
    Tom

    body mount rust areas


    Getting to know my 72 blazer…. /forums/images/icons/grin.gif

    I started the job to replace all of my truck’s body mounts. I ran into a few snags /forums/images/icons/mad.gif that I was hoping for some input. My factory body mounts were complete deteriorated, and, in some cases missing.

    1. Most of the factory cushion washers/shims were rusted and fused to the body or frame. So what is the best way to deal with the rusted areas after I scrape off the loose stuff? I was going to paint the frame and body mounting surface areas with POR-15. Does this sound like a good idea? /forums/images/icons/confused.gif It just doesn’t seem wise to install the new mounts onto the rusted surfaces.

    2. My floor pans had been replaced long ago, and the PO just had them installed over /forums/images/icons/mad.gif the position #1 bolt heads. I used a hole saw and cut through the new floor pan to find the factory hex bolt tack welded to the original floor pan (factory standard). No big deal to cut the weld and remove the bolt, but I am concerned about the condition of the body metal around the bolt that is supposed to carry the load of the body at this point. The recessed hole was filled with rust bits, and the metal was torn up quite a bit. I really can’t see what is around and beneath the recessed hole. Does anyone know how this is supposed to look…from a side profile? I recall an old thread that seemed to suggest that some housing under the recess carried the load. What should I look for to determine if it is structurally sound?

    3. My worst problem is the rear most mount, position #5. FYI, I have a very small amount of rust at the rear corners of the bed, but nothing extreme. There are two fairly serious problems at this body mount location. First, the frame is rather thin at the mounting point. It looks like the body mount cushion retained water, etc. around the frame…causing heavy rusting. In fact, the ~1” diameter hole on the frame that is supposed to hold a raised ring of the cushion has rusted into a much larger hole. So I need to weld something to this area to strengthen the frame, and provide a proper sized hole to secure the cushion. Has anyone done this, or have any ideas on the frame repair? The second problem with this rear-most body mount position is on the body side of the mount. The bed is solid (as well as the funky washers), but the ~3’ body extension piece (down to the cushion) is heavily rusted where it contacted the metal washer of the cushion. I need to repair the lower portion of this body extension. I will probably just weld a square washer to the base of the extension, but I am looking for other ideas.
     
  2. 70~K5

    70~K5 1/2 ton status

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    Re: a few snags encountered during body mount swap

    I don't know what to do about the #2 position mount on top. But LMC sells replacement lower mounts.
     
  3. JoshA

    JoshA 1/2 ton status

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    Re: a few snags encountered during body mount swap

    I have a pic of the floor pan area with the floor pan removed. I will e-mail it to you. it should show you what you need to know
     
  4. 70jimmy

    70jimmy 3/4 ton status Premium Member GMOTM Winner

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    Re: a few snags encountered during body mount swap

    I am planning on changing my mounts soon too. Heard a lot of different opinions on poly vs. rubber. What are you guys using and what are some of the pros and cons. Also best place to buy them. Thanks.
     
  5. Steve_Chin

    Steve_Chin 1/2 ton status

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    Re: a few snags encountered during body mount swap

    Oh, joy. That was one of the worst things I have done to my Blazer, replacing the body mounts. It wasn't all that hard or time-consuming, but it required a lot of acrobatics to get around the hitch and gas tank around the #5 mounts.

    I didn't have rusted mount tabs, so I can't comment on a good way to fix those.

    I can't see where putting POR-15 on the mounting tabs would be problematic. I just sprayed mine with some engine paint and let 'em dry a while. It's all worn off now, I think... Anyhow, I would suggest that wne you install the new hardware, you put a thin ring of 3M strip-caulk under the head of each bolt so that the bolts are sealed to the floor. This will prevent any water that leaks into the Blazer from travelling down the bolts and also prevent any exhaust fumes under the Blazer from entering the cab.
     
  6. tp85

    tp85 1/2 ton status Premium Member

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    Re: a few snags encountered during body mount swap

    Take a look at these pics of body mount rust areas. I think the position #1 mount is solid (even w/ the floor pan rust since bolt goes through a tube support). However, I need to repair the rear most mount location. You'll see in the pictures that the bed floor metal is in perfect condition...meaning the rust occurred from the bottom up. You may want to check your trucks. On the LH side I need to replace the entire box which is welded to the underside of the bed.

    Any ideas or comments would be greatly appreciated!
    Tom

    body mount rust areas
     
  7. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    Tom,

    Boy I feel your pain...! /forums/images/icons/crazy.gif

    I grew up in New Hampshire most of my life, and it's tough being a car/truck enthusiast on the East Coast with all the salt they use on the roads. The passenger side is always rustier than the drivers side from the slushy & salty piles on the side of the road, and ALL the bolts are rusted solid....ALWAYS! Every job seems to require an "EZ Out" to remove broken off bolt threads......

    From a purist perspective, you can graft in new metal from a good donor truck....but it will take LOTS of time (...and time is $$$). I don't know what the overall condition of the truck is, and if this level of committment is justified.

    I think it's probably reasonable to try a combination of wire-wheel cleaning, POR15, and metal patches where needed as a good compromise (effort vs. results) to solve your problem. On that one rusted frame area, you might try welding in an angled plate that runs along the top of the framerail and then down the vertical frame surface.

    The only thing to keep in mind though is that the body mounts determine the "gaps" on your doors, etc. If you add metal there it's going to tweak the body slightly out of position. If that location had a square "shim" already installed there (factory used shims in the different spots to set the gaps right) you could remove it, and use a metal patch of the same thickness to repair the frame. That way, you would still have the same overall bodymount thickness as before.

    Just some ideas.....I applaud you for fighting to keep a 1st Gen alive and running in such a hostile environment. It's a labor of love. /forums/images/icons/smile.gif
     
  8. tp85

    tp85 1/2 ton status Premium Member

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    Thanks Greg. I do plan to weld a 2" X 1" X 1/8" angle on the under side of the rusted frame hole. This should avoid changing the height of the body. On the frame, the rust is VERY localized to where the cushion was smashed. The frame seems to be normal thickness just 1/4" from the hole.

    I am also going to replace the 'box and bolt tube' that extends down from the bed to the body cushion with 3" X 3" X 1/4" square tubing. I really need 2 3/4" in height, so will have to be creative and modify the tube somehow. I'll try to remember to post pics.

    Luckily, the blazer is actually not too badly rusted. The floor pans and rockers were replaced. The rocker boxes and windshield frame look good with the factory paint. A little surface rust at other spots. The only really bad spot is the rear most body mounting points. The PO claims that truck was 'treated' several times. Apparently, in his town, they fill the doors and tailgate with used hydrolic fluid/oil, spray the underside, etc.. and just let is drip off. He said it was real messy when you parked your vehicle in the garage/barn as the doors and tailgate drained. I have never heard of this type of rust-proofing...it may be just a local thing. All I know is that I have oily black soot all over the underside of the truck. I'll probably power wash it to see what is underneath the coating.
     

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