#1  
Old 01-22-2018, 08:53 PM
65Bonnie389 65Bonnie389 is offline
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Default Firewall Seam Rust

I have rust along the entire length of the upper firewall seam, where the firewall meets the cowl panel. It has rusted right through.

Upon cutting out a section and cleaning away all the sealer etc I can see there are three layers of metal all sandwiched/spot-welded in together at this seam.

What is the best way to approach this repair? I am competent with welding and bodywork (self taught, not an expert!) and have done many repairs before, but have not encountered a repair like this.

I could simply butt weld in a patch to join the top layers together, grind the welds down and re-seal the join and could make it look almost factory to the point that no-one would probably notice, but I don't know if this is an acceptable repair as I would still be leaving the two layers of metal unjoined behind the repair which could cause further problems. How important is this area structurally? Do I need to weld all three layers together somehow?

Any advice appreciated. Car is a 1965 Bonneville.

Thanks
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  #2  
Old 01-24-2018, 08:29 AM
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Greg Reid Greg Reid is offline
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Bumping this to the top because I want to know the correct answer. I know how I would do it but I'm not a professional.

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  #3  
Old 01-24-2018, 08:58 PM
dhutton dhutton is offline
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Pretty sure you have to fix/incorporate that third piece into the repair or you will get water leaking into the car. Cut it open and rebuild as original.

Don

  #4  
Old 09-12-2021, 04:14 PM
1965 Pontiac Parisienne's Avatar
1965 Pontiac Parisienne 1965 Pontiac Parisienne is offline
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Default Cowl panel rust repair

Had the same rust issue at my 65 Bonneville convertible ..bought sheet metal pieces from a donar car and weld in ..is looking great now ..
have tons of pics how I done ..
You can use the 65/66 cowl section sheet impala so you will be fine too ..that's now available
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1965 canandian Parisienne custome sport convertible AZ car. „Sold“
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  #5  
Old 09-12-2021, 11:30 PM
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ZeGermanHam ZeGermanHam is offline
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I had a few areas of rot along my firewall seam, too. We cut back the layers and welded in fresh metal for each layer until it was back to normal. With a minuscule amount of filler, it's now undetectable.




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  #6  
Old 09-13-2021, 12:33 AM
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Default 65 Big car cowl panel repair

Some more pics ..sheet metal are from a parting car to use in my 65 Bonneville convertible
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1965 Bonneville 2 door coupe nightwatch blue AZ car
1965 Bonneville convertible starlight black
1966 Star Chief Coupé
1965 canandian Parisienne custome sport convertible AZ car. „Sold“
1977 california Firebird Esprit [/SIZE][/FONT]

  #7  
Old 09-13-2021, 12:34 AM
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Some more pics
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1965 Bonneville 2 door coupe nightwatch blue AZ car
1965 Bonneville convertible starlight black
1966 Star Chief Coupé
1965 canandian Parisienne custome sport convertible AZ car. „Sold“
1977 california Firebird Esprit [/SIZE][/FONT]

  #8  
Old 09-13-2021, 12:45 PM
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One thing to consider is how it got to rust, Right there.
Obviously welding dis tempers the metal, and really can allow faster rust. That said, look at location. There is the air horn/ wiper transmission area. Any clogs down the sides or rockers stopping air, will keep this area more moist. It has to be sealed right when done.
My repair on a full frame car in this area is done with new metal, but I glue the metal in. All 3 pieces. Glue? Really?
Yes, There is No distemper of the metal, NO AIR between panels, AND THE GLUE HAS Anti Rust Inhibitors. This is how a new car is built. A bit more time pre fitting, but WAY LESS finish time. Stronger than plug welds, spot welds, or a seam that might be welded.

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  #9  
Old 09-16-2021, 03:15 AM
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1965 Pontiac Parisienne 1965 Pontiac Parisienne is offline
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Default Cowl repair

I didn't would glue anything .. I have a convertible and the cowl needs a lot of strength at this windshield area ...
it's rusty from inner because it's factory not good rust proofed ..pure sheet metal without any paint on ..3 layers of sheet welded factory at this point together and it's started to rust from first day ..my car runs in Florida .. less miles on odo.. salty water ..
Same to the lower windshield area ...

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1965 Bonneville 2 door coupe nightwatch blue AZ car
1965 Bonneville convertible starlight black
1966 Star Chief Coupé
1965 canandian Parisienne custome sport convertible AZ car. „Sold“
1977 california Firebird Esprit [/SIZE][/FONT]

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