How to replace your roof skin.

Discussion in 'Body Restoration' started by POS71RS, Nov 22, 2010.

  1. POS71RS

    POS71RS Moderator Staff Member Lifetime Gold Member

    10,318
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    Aug 21, 2002
    Central Coast, CA
    Instead of a 'How to, by professional'... I'd like to consider this a 'How to... by the amateur hobbiest that can't afford to pay a professional to do it for him.'
    But the second is just too long for the title bar. So, here's my take on replacing the roof skin on my 71 Camaro.

    I spent the better part of the day trying to get the windshield out in 1 piece... but that was time wasted... as I later ended up just kicking it out.

    Then, with air chisel in hand, I cut out around the edge of the roof.
    [​IMG]

    That was the easy part. The hard part comes with trying to seperate the glue sections! I started with a prybar, then came up with this:

    [​IMG]

    It's a thin piece of angle sheetmetal I had. It was 20 or 22ga and about 4 foot or so long. I flattened the end of it and hammered it through the glue. It was long enough to reach the inner glue stacks, and thin enough to cut through.

    Here it is, nevermind the foam... your car should NEVER have that.. :innocent:
    [​IMG]


    Roof off, the inner working:
    [​IMG]
     
    Last edited: Nov 22, 2010
  2. POS71RS

    POS71RS Moderator Staff Member Lifetime Gold Member

    10,318
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    Aug 21, 2002
    Central Coast, CA
    After cutting and seperating the majority of the skin, I had these crimped on pieces left over. They're pretty simple to get off. In fact, I'd liken the whole job to similar to a big door skin replacement.

    [​IMG]

    I used my putty knife to bend the skin away from the frame, and smacked it downward to peel it off.
    [​IMG]
    [​IMG]

    Then I took the time to remove and neutralize the rust on the inner structure. It was also imperative to strengthen the inner structure as it exhibited a lot of flex from being weakened.
    In my case, some idiot (;)) sprayed foam inside the roof structure, which rusted and thinned the metal extensively. That's the reason for the skin replacement, but the inner structure wont be replaced, and since it will never be visible... I should hope... I didn't bother with aesthetics. Just welded some sheetmetal over the rust weakened metal...
    [​IMG]
     
    Last edited: Nov 22, 2010
  3. POS71RS

    POS71RS Moderator Staff Member Lifetime Gold Member

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    Aug 21, 2002
    Central Coast, CA
    Gotta make sure you protect/rustproof the structure! Don't want to do this job ever again... I used POR15, just what I had on the shelf. Make sure to fix any rust/damage in the structure now! (then rustproof)
    [​IMG]

    And it's imperative to check all the joints MANY times, but don't forget to compare the window trim. If you don't have the window trim... BUY IT; and fit it. My stuff lined up pretty decent. But I did adjust the fore/aft of the skin to make sure the curvatures matched.

    [​IMG]

    This blurry shot is where I decided to offset flange the new skin under the old A-frame. Makes it a little easier to match up, and once welded, a very strong joint. Being a totally invisible joint, I figured it wouldn't be seen until...well.. the roof is off again. ;)
    [​IMG]

    Here I'm just showing one of the ways I pulled the skin down to fit. The repop roof skin has a crease where the roof skin is to be creased up and under the structure as the stock roof was. You'll want to get the edge of the inner structure lined up with the inside of this crease. If you don't... I dunno how you will ever get that door-glass crease in there and look half decent.
    [​IMG]
     
  4. POS71RS

    POS71RS Moderator Staff Member Lifetime Gold Member

    10,318
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    Aug 21, 2002
    Central Coast, CA
    I also tied a ratchet strap to the subframe, and looped the strap around the front of the roof to achieve the fit I wanted.

    There's probably a hundred tools, etc you can find to use to roll the edge up.
    These vise grips were great for begining the straight part of the roof... but worthless for the curved portion.

    [​IMG]

    One of my body-dollies was great for rolling the curved portion. I hammered onto it, hammered with it, and even ran it across the edge while exerting as much pressure as I could.
    [​IMG]

    I spent the better part of an entire day crimping the edge in while trying to reduce the amount of wrinkles in the outer skin. Patience is key here!

    For the final crimp, I walked a piece of wood on the skin side while crimping with a large set of locking pliers.
     
  5. POS71RS

    POS71RS Moderator Staff Member Lifetime Gold Member

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    Aug 21, 2002
    Central Coast, CA
    I put holes in the roof skin and protected the insides the same way I did the quarter panels. Ground off the primer, primed with weldable primer, punched holes. I'm taking every precaution I can afford to prevent future problems with rust.

    [​IMG]
    [​IMG]
    [​IMG]

    I welded the holes punched into the roof to quarter seam, but also added welds from skin to skin for reinforcement. I also made sure to weld and beef up the B-pillar... ie, the area prone to cracking on 2nd gens.
    [​IMG]

    I also added a few tack welds on each side, inside the roof skin to inner structure, where the roof skin was crimped.
     
  6. POS71RS

    POS71RS Moderator Staff Member Lifetime Gold Member

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    Aug 21, 2002
    Central Coast, CA
    And the roof replacement (metal work) is nearly done. There was a step that I 'skipped'.. it was the adhesive or anti-flutter/rattle dots that go inbetween the roof skin and structure. I believe the factory pooped out the adhesive on the structure then welded the skin over the adhesive piles. I was planning on doing the same, but it dawned on me that I could achieve the same end result by injecting the adhesive through the perforations/holes in the inner structure after the welding was complete. Doing so would give me more time to adjust and get the welding/fitting/etc done before the adhesive set too.

    And onto the adhesive... I have seen a product online that was supposed to be specifically for this application, but I couldn't find it anywhere. And the local body shops either couldn't help me... or gave me advice that I was too weary to follow.

    Obviously the roof skin is on there pretty solid. It's crimped above the glass, tacked, and spot welded all around. So the main reason for the adhesive is to prevent the inner roof and outer roof from contacting.. or as I think SEM products puts it "flutters".
    Several paint shops told me to use door skin adhesive. The same adhesive that cures near rock hard. In my personal opinion, this seems like it could lead to issues when the temperature changes, and the sheetmetal expands/contracts, and the glue does not. My fear would be to have dimples form everywhere the adhesive holds it in place. Maybe I'm wrong, but I didn't want to chance it.

    The anti flutter stuff I saw at one store was a VERY soft foam. In my opinion... too soft. So I got to thinking.. what has a strong bond... and stays pliable?... Well, I saw both attributes in the urethane holding my windshield in! And in it's dried form.. I think that's VERY similar to what I pulled out that the factory applied 40 years ago.

    So, instead, I injected a couple dozen spots of this adhesive into the crevice between the roof structure and roof skin through the stamped/perforated holes in the inner structure.

    After complete, the skin took on a dead-thud when you tap on it instead of a hollow ring as before the urethane was injected. I am thinking that I am happy with this outcome!
     
    Last edited: Nov 22, 2010
  7. Double R Restorations

    Double R Restorations Veteran Member Gold Member

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    Jan 11, 2002
    VA
    That sure was alot of work, but it looks great and I know you must feel great knowing its almost done. Thanks for the write up. This is one area that I hope my car is OK.
     
  8. Twisted_Metal

    Twisted_Metal Moderator Staff Member Lifetime Gold Member

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    Feb 26, 2004
    Bloomington, MN
    Great job on the pics and description of the process! :D

    The roof...... Ya done good there too! :cool:
     
  9. Done Yet?

    Done Yet? Veteran Member

    1,305
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    Mar 5, 2010
    Fort Pierce, Florida
    Excellent how to thread... Im sure this will help many people that need to do the same type of repair. Your roof came out very nice great job. :bowtie:
     
  10. boardog

    boardog Veteran Member

    839
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    Dec 8, 2006
    north ga
    a couple of tricks i use. use a small butane torch to seperate the skin from the adhesive spots. i take a small 2 foot pry bar heat the area around the adhesive work from the outside edges toward the middle. most of the time the roof will seperate from the adhesive with just heating the area, if not, after it is heated gently pry on it to seperate the skin. on the edges where the skin is folded over take a small grinder and grind thru just the skin this will leave just the small aprox 1/2 inch strip of metal. use a sharp chisel to take it off.
     

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