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Why Your CSM's Roof Rusts
http://www.4g61t.org/forum/viewtopic.php?f=22&t=29154		 Page 2 of 3
Author:  89Mirageman [ Sat May 15, 2010 6:19 pm ]
Post subject:  Re: Why Your CSM's Roof Rusts
On my colt you can see a small amount forming on each glue joint where the roof skin is glued to the braces. My car has no leaks at all and its just the glue joints. Luckily I only had one tiny place where it came through the top and even then the paint was just slightly bubbled. I have seen cars at the yard with holes, mostly on darker color cars it seems. In my opinion it doesn't come from a leak, probably just the humidity.
Author:  Coltsfan [ Sat May 15, 2010 6:32 pm ]
Post subject:  Re: Why Your CSM's Roof Rusts
I agree with Chris, it's just from the humidity. There are large strips of the roof that are literally bare steel on the inside. After twenty years it just rusts. Every time you get in your car with wet boots and turn on the heat, you're condensing water on the roof.
Author:  snowdevl [ Mon Jun 21, 2010 6:05 pm ]
Post subject:  Re: Why Your CSM's Roof Rusts
Quote:
I pose a question for everyone with roof rust to please respond.

Before you noticed the rust did you have an issue with water leaking inside the car? My theory is that it only happens on cars who take water into the inside. That would be the only way moisture on a regular basis could get inside the car to cause the rust.
My old Colt was completely dry on the inside, no leaks at all, and had pretty bad roof rust. My current one leaks in both the driver and passenger footwell (quite bad, haven't found where it's coming from yet, suspect it's a windscreen-out job to repair), and it also has bad roof rust. I've noticed with the leaky one, the rust is spreading alot more rapidly though, it has gotten quite bad over the past 6 months as it has been sitting outside in the weather, so it's being hit by both rain/sun on an almost daily basis (NZ weather - 4 seasons in 1 day :rolleyes: )

I need to fix this soon, as I don't think i'll pass my next half-yearly safety inspection. What would you guys do in this situation? I think it's gone beyond the stage where I can bring the rust back to bare metal and rustproof the inside. A roof swap would probably be the best (and most expensive) idea right? Would it be worth having it cut out and new metal welded in?

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Author:  Coltsfan [ Mon Jun 21, 2010 10:16 pm ]
Post subject:  Re: Why Your CSM's Roof Rusts
Mine was pretty close to what you have there, and I was really suprized not to have any obvious holes after I cleaned it up. I did the inside first, bonded it to the braces, then aggressively went after the outside rust. I fully expected to be looking at the urethane window weld through dozens of little pinholes, but it wasn't as bad as it looked.

That one on the side is going to be a bitch, but sourcing, and swapping a roof skin did not sound like something I would ever want to attempt with this model car. I just bought the best rustproof paint and metal re-enforced body filler money can buy. I figure if it holds up 5 more years I'm ahead of the game, but I think it could double that based on how the quickie patch job I did from the outside in 2005 held up. The spots that I noticed and patched back then were mostly still intact.
Author:  moidsm1 [ Fri Jul 23, 2010 4:45 pm ]
Post subject:  Re: Why Your CSM's Roof Rusts
Whats Rust? AZ Baby!
Author:  galant1517 [ Fri Jul 23, 2010 11:26 pm ]
Post subject:  Re: Why Your CSM's Roof Rusts
Quote:
Whats Rust? AZ Baby!
Yeah yeah yeah. You've got your own problems to deal with in Arizona. Does dry rot come to mind? And you'll never know the joy of pulling like hell in sub-freezing temperatures. It's so nice.
Author:  extreme4g63 [ Thu Jun 07, 2012 11:55 am ]
Post subject:  Re: Why Your CSM's Roof Rusts
I cut my cross beams out, sand blasted the inside (which was a mess) due to the rust progressing from one side to the other, installed Etching primer and Kitty Hair bondo on the inside from side to side (to strengthen the inside where the cross beams use to be), cut out two holes about 3 inches in diameter, Kitty Haired them back, bondo the exterior three times, and am waiting to paint now. Would like to paint a samurai sun on top, just to be different.
Author:  Ozyvr4 [ Mon Mar 11, 2013 2:19 pm ]
Post subject:  Re: Why Your CSM's Roof Rusts
Very good info. I inspected on the purchase and it only had 2 very small spots of brown through the paint so I will get on to this ASAP .
Author:  lancerman [ Wed Apr 29, 2015 1:09 pm ]
Post subject:  Re: Why Your CSM's Roof Rusts
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Author:  Mechacode [ Wed Apr 29, 2015 5:17 pm ]
Post subject:  Re: Why Your CSM's Roof Rusts
They still make replacement roofs? Lucky!
Author:  Flying Eagle [ Wed Apr 29, 2015 7:40 pm ]
Post subject:  Re: Why Your CSM's Roof Rusts
For better looking, and newer Mitsu's, apparently. Most Aussies/Kiwis drew off the last of the stock for the 2000 series cars, (C5/6/7/80's) last I heard. Could be more laying around, but you'd have to inquire.
Author:  pdxvr4 [ Thu Jun 11, 2015 6:16 pm ]
Post subject:  Re: Why Your CSM's Roof Rusts
Has anyone thought of using fiberglass on the bottom? My roof has 3mm or so sized holes from the rust now that I'm cleaning it up. I thought about putting some fiberglass up along the factory metal strip lines (removed factory braces already) to replace them. I would then use some bondo on top to fill the holes and smooth it out. However, I had the idea of using an epoxy such as JB weld to fill the holes, does it shrink?
Author:  89Mirageman [ Thu Jun 11, 2015 10:07 pm ]
Post subject:  Re: Why Your CSM's Roof Rusts
They actually make fiberglass or aluminum reinforced body fillers just for instances like this. I'd use either of those over JB Weld.
Author:  lancerman [ Fri Jun 12, 2015 2:32 am ]
Post subject:  Re: Why Your CSM's Roof Rusts
body filler is pretty much the cheapest plastic filler on the planet. not referring to purchase cost. should be used very sparingly cause it never stops shrinking. jb weld could be considered a very expensive but much more effective body filler. the panel glue I used looked and acted just like jb weld. it cost 40 just enough to glue the roof on. next time I think I would just use jp weld at 1/3 the cost. I would never use fiber reinforced plastic. rust always comes back with that stuff. and its not really stronger than the bondo that holds it all together. its just thicker so you can fill bigger holes quicker. it is much less adhesive than plastic filler itself and very porous. use plane bondo before that stuff. but yes jb weld is great stuff and certainly works very well for a no weld body filler. biggest key for any success with any material is proper removal of the rust. then a clean dry surface before any filler is applied.
Author:  89Mirageman [ Fri Jun 12, 2015 9:45 am ]
Post subject:  Re: Why Your CSM's Roof Rusts
Well you would want to grind away all the loose rust and use a rust converter before applying any type of filler but I assure you JB Weld was not meant to cover holes. Also the fiberglass or aluminum reinforced filler is made for these types of jobs. Sure they may shrink a little but you use regular body filler on top to get the surface perfect.

Also the aluminum body filler (called all metal) is meant to keep moisture out. We used it in class when replacing rocker panels and such. It's good stuff and hard as a rock when cured. Once its on there you won't have any issues as long as the prep work was done correctly. The roof on my 94 summit has these issues and I'll be using it to repair the damage once all the braces are removed and everything is clean and treated.

I can see where JB Weld would work to attach a new roof to the supports. Is that what you're talking about? And you could use it to fill the holes. But like I said, the other stuff is made with those repairs in mind.
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