Trans tunnel cracks and underbody paint/coating
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Car: 1986 Camaro
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Trans tunnel cracks and underbody paint/coating
So I have been slowly rebuilding my transmission, and about done with that (had some issues that took some extra parts and time). But before I put it back in I have been cleaning up the underside of the car, and I found some tiny cracks in the metal of the transmission tunnel. I am not sure how to take care of them, I don’t have access to a welder and I was hoping to just get the car on the road before pulling out the interior since it needs some work and I don’t have the money for that now.
So other than these little cracks the metal looks good, just some rust on the outside edges and beteew where the heat shields didn’t cover near the cat. So my question is what would be the best to paint the undercarriage with? I was thinking rustolium with rust converter then covering it with some kind of under carriage paint (any recommendations?), and maybe one with some insulation vale in is since it always seemed like the transmission tunnel had heat radiating off of it on long drives.
So other than these little cracks the metal looks good, just some rust on the outside edges and beteew where the heat shields didn’t cover near the cat. So my question is what would be the best to paint the undercarriage with? I was thinking rustolium with rust converter then covering it with some kind of under carriage paint (any recommendations?), and maybe one with some insulation vale in is since it always seemed like the transmission tunnel had heat radiating off of it on long drives.
Last edited by david86camaro; 09-16-2018 at 08:49 PM.
#2
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Re: Trans tunnel cracks and underbody paint/coating
It looks like that metal may have been hit, which bent them, and cracked. You want to bend them back smooth and drill a 1/8" hole in either end to stop the propagation of the cracks. Find someone to then v-notch them and weld them up. Welding is the only fix for these. You can band-aid them by covering them up but you'll regret it later.
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Re: Trans tunnel cracks and underbody paint/coating
It looks like that metal may have been hit, which bent them, and cracked. You want to bend them back smooth and drill a 1/8" hole in either end to stop the propagation of the cracks. Find someone to then v-notch them and weld them up. Welding is the only fix for these. You can band-aid them by covering them up but you'll regret it later.
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Re: Trans tunnel cracks and underbody paint/coating
I’m trying to think what would have coused this, back in high school and college I did have a few accidents but I’m surprised that I have damage there. I’m the second owner and bought it when it was only 7 years old and was not told of any previous accidents so I only have myself to blame!
The acidents were minor front end and one rear ending, the only one that it was hit hard enough would have been when it got backed into (I wasn’t in it), got hit in front of the front wheel pretty hard. The rest were a dog, a coyote and a construction sign, nothing besides fender and bumper replacement!
The acidents were minor front end and one rear ending, the only one that it was hit hard enough would have been when it got backed into (I wasn’t in it), got hit in front of the front wheel pretty hard. The rest were a dog, a coyote and a construction sign, nothing besides fender and bumper replacement!
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Re: Trans tunnel cracks and underbody paint/coating
Yep, needs welded. A good weld will burn right into that sheetmetal, no need to V it out. Just clean the surface with a light grinding and weld it up. Prime and paint both sides.
Hit in the rear huh? I'm curious, are there slight pressure buckles in either outer sail panel?
Hit in the rear huh? I'm curious, are there slight pressure buckles in either outer sail panel?
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Re: Trans tunnel cracks and underbody paint/coating
Not that I have seen, but it was a such a light hit that, the bumper cover was not replaced, just repainted. There is some slight misalignment in the fitting of the bumper, I wish I forced them to fix that, but at 20 I didn’t know better, and was being nice!
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Re: Trans tunnel cracks and underbody paint/coating
Anyone have any suggestions as to what would be the best undercoating/paint? I’m thinking of painting any rust spots with a good rust converter, then paint everything with some rustoliom, and then some sort of rubberized coating for some sound and heat insulation. But want make sure that doesn’t case issues, I have heard that sometimes the rubberized coating can cause issues with trapping water, but that is why I was thinking a good coat of paint first will help prevent that.
Also my rear end looks pretty rusty, it’s only surface rust, so I was thinking of painting that, any suggestions as to what kind of paint? Was thinking just black for the axle, then a gray or red for the cover since I have to pull it off anyway (it started to leak after I cleaned it off, was covered in a pretty thick layer of road grime).
Also my rear end looks pretty rusty, it’s only surface rust, so I was thinking of painting that, any suggestions as to what kind of paint? Was thinking just black for the axle, then a gray or red for the cover since I have to pull it off anyway (it started to leak after I cleaned it off, was covered in a pretty thick layer of road grime).
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Re: Trans tunnel cracks and underbody paint/coating
Undercoating doesn't really have any sound deadening or insulating qualities. But it does resist chipping which is nice in wheelwells. It's kind of ugly though, imho.
I always use engine enamel on rear axle housings and such.
I always use engine enamel on rear axle housings and such.
#9
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Re: Trans tunnel cracks and underbody paint/coating
Clean the area thoroughly, apply seam sealer, let cure before driving.
To weld those areas, you'll need to get the carpet up off the floor, or it'll melt or worse catch fire. Unless you really feel comfortable removing the seats, console, and a bunch of trim, not to mention finding someone to do the welding... It's probably from being jacked wrong, slipping off a jack/stands/lift, or driving over a foreign object. If it's from structural stress, a weld will probably create a stress point and it'll just crack again anyway. Clean it up and cover the gap/bare edges with seam sealer, it'll close up the hole, keep water out, prevent it from rusting. It'll also flex just enough that it probably won't need further attention unless you decide you dig into it.
Any bare areas that are starting to rust would best be stripped to bare shiny steel, then sealed with something like epoxy primer. The lazy way is to remove as much rust as possible and hit it with some kind of rust converter, or encapsulator, which pretty much just means you're painting over the rust, and hoping it slows the rate of corrosion. No easy answers there...
For heat, the stock cat converter heatshields should be all you need.
To weld those areas, you'll need to get the carpet up off the floor, or it'll melt or worse catch fire. Unless you really feel comfortable removing the seats, console, and a bunch of trim, not to mention finding someone to do the welding... It's probably from being jacked wrong, slipping off a jack/stands/lift, or driving over a foreign object. If it's from structural stress, a weld will probably create a stress point and it'll just crack again anyway. Clean it up and cover the gap/bare edges with seam sealer, it'll close up the hole, keep water out, prevent it from rusting. It'll also flex just enough that it probably won't need further attention unless you decide you dig into it.
Any bare areas that are starting to rust would best be stripped to bare shiny steel, then sealed with something like epoxy primer. The lazy way is to remove as much rust as possible and hit it with some kind of rust converter, or encapsulator, which pretty much just means you're painting over the rust, and hoping it slows the rate of corrosion. No easy answers there...
For heat, the stock cat converter heatshields should be all you need.
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Re: Trans tunnel cracks and underbody paint/coating
Clean the area thoroughly, apply seam sealer, let cure before driving.
To weld those areas, you'll need to get the carpet up off the floor, or it'll melt or worse catch fire. Unless you really feel comfortable removing the seats, console, and a bunch of trim, not to mention finding someone to do the welding... It's probably from being jacked wrong, slipping off a jack/stands/lift, or driving over a foreign object. If it's from structural stress, a weld will probably create a stress point and it'll just crack again anyway. Clean it up and cover the gap/bare edges with seam sealer, it'll close up the hole, keep water out, prevent it from rusting. It'll also flex just enough that it probably won't need further attention unless you decide you dig into it.
Any bare areas that are starting to rust would best be stripped to bare shiny steel, then sealed with something like epoxy primer. The lazy way is to remove as much rust as possible and hit it with some kind of rust converter, or encapsulator, which pretty much just means you're painting over the rust, and hoping it slows the rate of corrosion. No easy answers there...
For heat, the stock cat converter heatshields should be all you need.
To weld those areas, you'll need to get the carpet up off the floor, or it'll melt or worse catch fire. Unless you really feel comfortable removing the seats, console, and a bunch of trim, not to mention finding someone to do the welding... It's probably from being jacked wrong, slipping off a jack/stands/lift, or driving over a foreign object. If it's from structural stress, a weld will probably create a stress point and it'll just crack again anyway. Clean it up and cover the gap/bare edges with seam sealer, it'll close up the hole, keep water out, prevent it from rusting. It'll also flex just enough that it probably won't need further attention unless you decide you dig into it.
Any bare areas that are starting to rust would best be stripped to bare shiny steel, then sealed with something like epoxy primer. The lazy way is to remove as much rust as possible and hit it with some kind of rust converter, or encapsulator, which pretty much just means you're painting over the rust, and hoping it slows the rate of corrosion. No easy answers there...
For heat, the stock cat converter heatshields should be all you need.
As far as the paint, there is one part of the floor pan that got cooked (around where the heat shields came together), and is a little corroded and rusty then there is only a little rust at the edges (likely from gravel and rock chips). I was planning on cleaning, wire brushing and a little sanding before any paint, but want to still coat with rust converter to make sure I get it all. It sounds like I may just paint and wait till I replace the carpet to deal with sound deading and insulation, since it sounds like anything underneath would not do much good.
Last edited by david86camaro; 09-23-2018 at 11:40 PM.
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Re: Trans tunnel cracks and underbody paint/coating
Tearing a car down after being down for a year already is how projects spiral out of control, and your car becomes a lawn ornament instead of something you actually drive and enjoy. Put it back together, seal up the cracks and when you're ready to do the carpet next spring, get a welder lined up to fix the cracks. But that's just my perspective.
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Re: Trans tunnel cracks and underbody paint/coating
Tearing a car down after being down for a year already is how projects spiral out of control, and your car becomes a lawn ornament instead of something you actually drive and enjoy. Put it back together, seal up the cracks and when you're ready to do the carpet next spring, get a welder lined up to fix the cracks. But that's just my perspective.
The fun I have to deal with, was not leaking until I cleaned off the dirt and grease about a year ago.
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Re: Trans tunnel cracks and underbody paint/coating
Hard to tell where exactly this is located based on the photos, but possibly this could be from a bad transmission mount causing the transmission to slam into the tunnel. This could be especially violent with a manual transmission and a high rpm clutch dump (torque arm pushes the back of the transmission upward during acceleration). Best fix is to hammer/dolly back to shape, drill relief holes at each end of the crack and weld. As Drew said though, if the car were actively being driven, just drill the relief holes, seam seal and drive it. Not worth tearing the interior apart for this, unless you are going to do that anyway.
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Re: Trans tunnel cracks and underbody paint/coating
Hard to tell where exactly this is located based on the photos, but possibly this could be from a bad transmission mount causing the transmission to slam into the tunnel. This could be especially violent with a manual transmission and a high rpm clutch dump (torque arm pushes the back of the transmission upward during acceleration). Best fix is to hammer/dolly back to shape, drill relief holes at each end of the crack and weld. As Drew said though, if the car were actively being driven, just drill the relief holes, seam seal and drive it. Not worth tearing the interior apart for this, unless you are going to do that anyway.
Thanks for your input.
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