Rear hatch slam lid rust question

[brianZortiz]

Hello All,

 

fixing rust on my 72 240z and found a good amount of pitting under the rear slam lid after removing spot welds. There was a hole which my welder fixed (third picture) but not sure if I should fix whole pitted areas or just prep and Por-15 it. 

[grannyknot]

That is the kind of pitting that has gone too far, you'll never stop the rust from coming back and and trying to weld on to that rotted metal will be very difficult. If it was me I would be cutting those pieces out and making new ones.

[AydinZ71]

Brian,

 

I just went through this nightmare. You will need to cut it all out. The rear hatch slam lid is actually four pieces of metal spot welded together. Two vertical pieces that flare out in opposite directions, one lower “backing” which is what bends and creates your hatch mounding life. The LAST piece is what is visible and available for $130 Online. I attached some photos of my cut and rebuild. It took 2-3 weekends. I don’t have a metal brake, so I had to weld the 90’s. 

[Sanchez]

I’m doing my slam plate and I’ve been considering using panel bond adhesive for my mine. I have pitting similar to yours in a few areas and already cut out and patched the few area that had holes all they way through. I was thinking of using panel bond extensively over the potted areas and doing a few plug welds around the edges and on the two brackets that go above the license plate. I think the PB should help the rust from returning and some well placed seam sealer should keep water from getting back under there.

[jhm]

There's a company in the UK that's producing hard-to-find replacement body panels, and the rear slam panel is one of them.  Looks like they do pretty nice work.  There may be other vendors doing similar work; but I just happened to notice their ad the other day on FB:  username was "Kim Mays" on the "Datsun Parts and Needs" FB page.

 

Here's a link; but may not work for you if you're not a member of the group:  https://www.facebook.com/photo?fbid=1661652560538618&set=pcb.1655145461187252

[AydinZ71]

On 11/10/2020 at 6:06 AM, Sanchez said:

I’m doing my slam plate and I’ve been considering using panel bond adhesive for my mine. I have pitting similar to yours in a few areas and already cut out and patched the few area that had holes all they way through. I was thinking of using panel bond extensively over the potted areas and doing a few plug welds around the edges and on the two brackets that go above the license plate. I think the PB should help the rust from returning and some well placed seam sealer should keep water from getting back under there.

Por-15 sells a seam sealer on amazon. It’s made from a. Thicker formulation of thier standard product. It’s non-porous and will encapsulate the metal when used on a degreased prepared metal surface. 
 

you can try to plug weld the holes but in my experience the steel necks-down where there is significant enough corrosion to cause a hole. Therefore, the second you zap it, the surrounding metal melts away, making a mess and a much larger hole. Still. If you are skilled you can very slowly add metal to the diameter of the hole, fill-in the hole, then grind flush from both sides.

 

honestly, in the end I was happy I cut and replaced the whole thing. 

[AydinZ71]

one thing I recall, is there was a TON of rust stuck between the spot welded panels. This is something you just dont see unless you start cutting into it. I bought the car with what seems to be 50 years of "temporary" fixes. I saw silicone, brazing, all sorts of stuff. None of it helped prevent the corrosion forming between the panels. When I separated them, id say 20-50% of the metal had corroded between, and so the surface metal was much thinner than you could see from the outside. 

[brianZortiz]

Thanks all for suggestion. I will go with cutting the potted rust and putting fresh metal. Plan on having this car for a long time. 

On 11/11/2020 at 7:12 AM, jhm said:

There's a company in the UK that's producing hard-to-find replacement body panels, and the rear slam panel is one of them.  Looks like they do pretty nice work.  There may be other vendors doing similar work; but I just happened to notice their ad the other day on FB:  username was "Kim Mays" on the "Datsun Parts and Needs" FB page.

 

Here's a link; but may not work for you if you're not a member of the group:  https://www.facebook.com/photo?fbid=1661652560538618&set=pcb.1655145461187252

I’m in Datsun parts and needs. Thanks for the link, but it seems they don’t advertise the bottom side of slam panel which is pictured. The top I got from MSA

[AydinZ71]

yeah 😕 I had to fab the bottom part myself with 18-gauge stock. I think 19 or 20 is the right gauge for this part, but nothing wrong with a little more steel.