Targa Roof Repair Guide - Leaks, rust, and seals. Pics Included
Thread Starter
Senior Member

Joined: Feb 2009
Posts: 874
Likes: 18
From: Brisbane, Australia
Car: 1985 Pontiac TransAM
Engine: 400SBC 24x conversion
Transmission: T700r Stage2 Shiftkitted
Axle/Gears: 2.77 9 Bolt
Targa Roof Repair Guide - Leaks, rust, and seals. Pics Included
Hey guys,
I purchased my '85 TransAM just over a year ago now, and this site has been invaluable to me, and I though it's time to give something back.
My purchase came with the good and the bad, new motor, new 700hp+ durable trans, koni adj. suspension and $5k of alpine audio.
But the roof leaked, the doors sagged, and the a/c didn't work.
Thanks to my mate with his panel beating skills and huge shed of tools, we got it done it 1&1/2 days. If we had to do it again, it'd probably take about 8hours start to finish, any extra time was just exploration.
Unfortunately my phone with the pics on it was stolen and I lost the first days, but 1 day was the rear, and the next was the front, so it's all good.
Here's what we started with:


We started by removing the headliner, and all triming around the area, remove the targa tops and looked at what we had to deal with.
The centre-piece was beyond repair and was rusted most of the way through, so it was thrown out and had to buy a new one.
The tracks had rust through them, underneath them, and starting to eat through the body.
I contacted a metal fabrication place and gave them the length of metal i needed, and the bends required, they made up both rails for me for $50.
I gave them the overall width, then the height (1st bend) and the lip length( 2nd bend). This gave us an exact replica of the [ shape of the weatherseal track.
Also if possible ask for the metal type to be the rust-proof one, something with additional zinc or cobalt or something that prevents rust.

Once we had the parts, it was time to take off the rails.
GM apparently wanted to make sure their biggest fault with these cars was secured, as the tack welds were abundant.
We started with the rear rail and cleared all the seam sealer out of the tracks, and silicon crap previous owners had squeezed in there, and then gave the tracks a buzz with a light sand to show where the welds were.
We then used a drill bit and put a small divit in the welds, and then used a spot weld remover drill bit (don't remember the name for them) and cut the metal around the weld, just on the seal rail.
The welds were mainly in pairs, about 1/2" apart, and then 1-2" to the next pair.
We removed these, and lifted the rail as we went to help detect any hard to see spotwelds.
Once all spot welds were removed the seal lifted right off.

We then took the new rail, and used the old one to get the length right.
We flattened it out best we could, cut the new rail to size, and then cut out the section for the center piece to slot in.
Then we went along and drilled out spots to weld the new rail onto the roof. Despite what GM might suggest, one hole every 2 inches should be more than enough, just make sure your first weld on each end is close to the edge, about 5mm-10mm in.
We cleaned all of the metal up that was underneath the rail, and cut out any bits that were too far gone. We cut some small bits of metal and welded them in place of the rusted bits, and made sure everything was rust free. Also ground down all of the weld spots to get it all smooth again.


We then gave the bare metal a spray with some etch primer and let it dry.
We then place the rail in place ready to go on. Naturally the ends we pointing up as the roof is curved. Luckily the metal would bend as we went.
One step we didn't do that you may or may not want to do is to apply some seam sealer to the underneath of the new rail. This might stop a bit more water later in the cars life, but might cause some fire if the sealant isn't fireproof.
We clamped the first end to the same spot it came off, and put the first weld in, then continue to weld in the other holes as you clamp it down and it will fall(press) nicely into shape.
Then just place the centre bar in to make sure it fits ok, and remove.
Once in, all welds were ground down flush and etch primer sprayed on.

Next comes the front rail...
This one is pretty much the same, but with one big difference, the front rail also curves round the windscreen.
Hence a second day for that one.
We hired an Oxy/Acetylene & torch, and then heated the rail and applied pressure to bend to shape. It s a bit of trial and error to get it right, but so long as its relative close, the last of the shaping can be done when welding and clamping the rail in place.

Follow the same procedure as before, remove old rail, flatten, measure new rail, drill holes, cut center bar gap, etc.
Then clamp the first corner, and weld into place, as before, each time you clamp give a bit of hit with a piece of wood and hammer to get the bend as close as possible. We spent a bit of time getting it right to make sjure the new seals still fit properly.
Once its all done, etch prime and let dry.
When we finished, the new center bar didn't quite line up to the rails, which was to be expected, the factory one didn't seem to either.
We then ran a bead of automotive seam sealer into the outer side of the tracks to seal the rail to the rest of the roof on both rails. Then used the seam sealer to fill in the areas around the centerbar.
Once done you're right to paint, apply a primer, dry, then apply your layers of paint.

I'm still waiting for my seals to arrive, but once they do we'll install them and then run another bead of seam sealer between the seals and the roof to ensure no water gets through or trapped.
I purchased my '85 TransAM just over a year ago now, and this site has been invaluable to me, and I though it's time to give something back.
My purchase came with the good and the bad, new motor, new 700hp+ durable trans, koni adj. suspension and $5k of alpine audio.
But the roof leaked, the doors sagged, and the a/c didn't work.
Thanks to my mate with his panel beating skills and huge shed of tools, we got it done it 1&1/2 days. If we had to do it again, it'd probably take about 8hours start to finish, any extra time was just exploration.
Unfortunately my phone with the pics on it was stolen and I lost the first days, but 1 day was the rear, and the next was the front, so it's all good.
Here's what we started with:


We started by removing the headliner, and all triming around the area, remove the targa tops and looked at what we had to deal with.
The centre-piece was beyond repair and was rusted most of the way through, so it was thrown out and had to buy a new one.
The tracks had rust through them, underneath them, and starting to eat through the body.
I contacted a metal fabrication place and gave them the length of metal i needed, and the bends required, they made up both rails for me for $50.
I gave them the overall width, then the height (1st bend) and the lip length( 2nd bend). This gave us an exact replica of the [ shape of the weatherseal track.
Also if possible ask for the metal type to be the rust-proof one, something with additional zinc or cobalt or something that prevents rust.

Once we had the parts, it was time to take off the rails.
GM apparently wanted to make sure their biggest fault with these cars was secured, as the tack welds were abundant.
We started with the rear rail and cleared all the seam sealer out of the tracks, and silicon crap previous owners had squeezed in there, and then gave the tracks a buzz with a light sand to show where the welds were.
We then used a drill bit and put a small divit in the welds, and then used a spot weld remover drill bit (don't remember the name for them) and cut the metal around the weld, just on the seal rail.
The welds were mainly in pairs, about 1/2" apart, and then 1-2" to the next pair.
We removed these, and lifted the rail as we went to help detect any hard to see spotwelds.
Once all spot welds were removed the seal lifted right off.

We then took the new rail, and used the old one to get the length right.
We flattened it out best we could, cut the new rail to size, and then cut out the section for the center piece to slot in.
Then we went along and drilled out spots to weld the new rail onto the roof. Despite what GM might suggest, one hole every 2 inches should be more than enough, just make sure your first weld on each end is close to the edge, about 5mm-10mm in.
We cleaned all of the metal up that was underneath the rail, and cut out any bits that were too far gone. We cut some small bits of metal and welded them in place of the rusted bits, and made sure everything was rust free. Also ground down all of the weld spots to get it all smooth again.


We then gave the bare metal a spray with some etch primer and let it dry.
We then place the rail in place ready to go on. Naturally the ends we pointing up as the roof is curved. Luckily the metal would bend as we went.
One step we didn't do that you may or may not want to do is to apply some seam sealer to the underneath of the new rail. This might stop a bit more water later in the cars life, but might cause some fire if the sealant isn't fireproof.
We clamped the first end to the same spot it came off, and put the first weld in, then continue to weld in the other holes as you clamp it down and it will fall(press) nicely into shape.
Then just place the centre bar in to make sure it fits ok, and remove.
Once in, all welds were ground down flush and etch primer sprayed on.

Next comes the front rail...
This one is pretty much the same, but with one big difference, the front rail also curves round the windscreen.
Hence a second day for that one.
We hired an Oxy/Acetylene & torch, and then heated the rail and applied pressure to bend to shape. It s a bit of trial and error to get it right, but so long as its relative close, the last of the shaping can be done when welding and clamping the rail in place.

Follow the same procedure as before, remove old rail, flatten, measure new rail, drill holes, cut center bar gap, etc.
Then clamp the first corner, and weld into place, as before, each time you clamp give a bit of hit with a piece of wood and hammer to get the bend as close as possible. We spent a bit of time getting it right to make sjure the new seals still fit properly.
Once its all done, etch prime and let dry.
When we finished, the new center bar didn't quite line up to the rails, which was to be expected, the factory one didn't seem to either.
We then ran a bead of automotive seam sealer into the outer side of the tracks to seal the rail to the rest of the roof on both rails. Then used the seam sealer to fill in the areas around the centerbar.
Once done you're right to paint, apply a primer, dry, then apply your layers of paint.

I'm still waiting for my seals to arrive, but once they do we'll install them and then run another bead of seam sealer between the seals and the roof to ensure no water gets through or trapped.
Last edited by evilstuie; Jan 23, 2010 at 04:24 PM.
Thread Starter
Senior Member

Joined: Feb 2009
Posts: 874
Likes: 18
From: Brisbane, Australia
Car: 1985 Pontiac TransAM
Engine: 400SBC 24x conversion
Transmission: T700r Stage2 Shiftkitted
Axle/Gears: 2.77 9 Bolt
Re: Targa Roof Repairs - Leaks, rust, and seals. Pics Included
I'll add more pics next week, and show all of the seam sealer bits, and seals in.
Next will be the door hinges.
I'm not sure if this is sticky-worthy or not, who do i talk to about it?
Next will be the door hinges.
I'm not sure if this is sticky-worthy or not, who do i talk to about it?
Junior Member
Joined: Jul 2009
Posts: 5
Likes: 0
From: Houston, Tx
Car: 1984 Z-28/iroc clone
Engine: 305
Transmission: 700r4
Re: Targa Roof Repair Guide - Leaks, rust, and seals. Pics Included
good topic. I'm doing this to my car now but my rust isn't as bad as yours. I only have to replace the whole center piece.
Senior Member
iTrader: (4)
Joined: Feb 2009
Posts: 588
Likes: 0
From: Camdenton, Mo/ St. Joseph, Mo
Car: 97 Cummins 92 CamaroZ28, 94 GSXR750
Engine: Modded 5.9 , carbed sbc358, modded
Transmission: Nv4500, 700R4 (for now)
Axle/Gears: stock
Re: Targa Roof Repair Guide - Leaks, rust, and seals. Pics Included
Quick question: not that it really matters since I dnt have t-top. But I'm just wonderin does t-top stand for targa top? I thought t top was what was on our thirdgens while targa top was when the entire roof part came off. Such as in fast and the furious with the supra at the end? Thanks for clearing this up for me
Member
Joined: Jan 2004
Posts: 108
Likes: 0
From: Murfreesboro TN
Car: 91' Z28 T-TOP
Engine: 305 TPI
Transmission: 700r4
Re: Targa Roof Repair Guide - Leaks, rust, and seals. Pics Included
That looks really good. I like it when I see someone take the time to do a job right. I am tearing mine completely apart to get rid of all the rust in mine.
Thread Starter
Senior Member

Joined: Feb 2009
Posts: 874
Likes: 18
From: Brisbane, Australia
Car: 1985 Pontiac TransAM
Engine: 400SBC 24x conversion
Transmission: T700r Stage2 Shiftkitted
Axle/Gears: 2.77 9 Bolt
Re: Targa Roof Repair Guide - Leaks, rust, and seals. Pics Included
hey guys, had a few requests for the dimensions for the new pieces, so here they are.
I just went to the first metal fabrication place i could find with the dimensiosn and they made them up, think it cost $40 for 2x2metre lengths.

Yes it's a very professional and pretty drawing isn't it :P
Also incase you're no good at math, the fold is a 4mm fold, add 1mm for each side and that gives you your total height of 6mm.
I'm also glad to note that after owning the car for just over a year, it is now 100% leak proof, thanks to the glory of sikaflex.
After all the repairs were done, I ordered a set of the cheap( they never work) targa seals, installed them as the guide said, and use copious amounts of sikaflex(sealant) and it worked like a charm.
I did have a slight leak with where the t-tops sit in the centre bar, but all i did there was run a line of sealant in where the glass sits, put a piece of clingwrap over the length of glass, pushed it in and locked it in place, wiped the excess off and let it set for 48 hours.
When I came back, i just took the t-top off, peeled the clingwrap off, put it back on, and no more leaks.
This is a remarkable effort considering the doors are extremely sagged, and the windows alignment is off.
The only other thing i did was spend a bit of time aligning the t-tops to correct the door sag.
I just went to the first metal fabrication place i could find with the dimensiosn and they made them up, think it cost $40 for 2x2metre lengths.

Yes it's a very professional and pretty drawing isn't it :P
Also incase you're no good at math, the fold is a 4mm fold, add 1mm for each side and that gives you your total height of 6mm.
I'm also glad to note that after owning the car for just over a year, it is now 100% leak proof, thanks to the glory of sikaflex.
After all the repairs were done, I ordered a set of the cheap( they never work) targa seals, installed them as the guide said, and use copious amounts of sikaflex(sealant) and it worked like a charm.
I did have a slight leak with where the t-tops sit in the centre bar, but all i did there was run a line of sealant in where the glass sits, put a piece of clingwrap over the length of glass, pushed it in and locked it in place, wiped the excess off and let it set for 48 hours.
When I came back, i just took the t-top off, peeled the clingwrap off, put it back on, and no more leaks.
This is a remarkable effort considering the doors are extremely sagged, and the windows alignment is off.
The only other thing i did was spend a bit of time aligning the t-tops to correct the door sag.
Last edited by evilstuie; Dec 16, 2010 at 02:02 PM.
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