280Z 2+2 Rust damage on interior floor pans - how severe/bad is this?

[Paulytunes]

As I posted in my build/project thread, I recently discovered some rust on the floor of my 280Z 2+2 when I lifted the carpets.  The damage went previously unnoticed because the exterior frame and panels are undercoated.  The worst of it is on the driver side, where there is a hole large enough that I can poke my finger through in between the foot rest and clutch pedal.  There is also a long perforation and signs of deterioration running fore to aft in the approximate location of the frame rail, and a pencil sized hole just in front of the seat rail.  It is hard to determine the damage from under the car because it is undercoated.  The passenger side looks like it was repaired previously, as the drain plugs have all been filled in, and it looks like a plate or something was attached in the area of the frame rail.  My questions are:

1. Is this damage severe enough to be a structural concern?  Should I not drive the 280Z until I can make repairs?
2. Is the appropriate repair new floor board(s) and/or rail(s) or just a remove rusted area and patch?
3. If I do need new floor boards, I have a 2+2.  I believe the front of the floor board (where all of the evidence of rust is located) to the seat rail is the same for the coupes as it is for my car.  I understand some additional cutting might be needed to make it fit, but otherwise it should work and is probably a better solution that just replacing the floorboard with a flat piece of metal.
4. When I mention the word "rust," most body shops in my area (Baltimore, MD) tell me they don't do rust repair and I feel like I have terminal cancer.  Does anyone have a recommendation for someone that can do this work that would be somewhat local to me?  I have limited space, no access to a welder, and very rudimentary welding skills at best (I did a very small amount of welding way back when in college as part of the SAE baja team, but I don't trust my skills or ability on my car).  

Thanks to all and any that can provide guidance.  Please talk me off the ledge - I was pretty sick to my stomach when I discovered the rust.  I'm worried of how much more damage there is hidden beneath the undercoating.  

[grannyknot]

Mmmmm, that's not looking so good, you can see on both the P/S and D/S the floor pan has collapsed into the the rail running underneath. The only way to be sure is get a putty knife and start chipping out all of the tar mat, once you've removed that you will be able to see the extent of the damage.

Chances are you will have to replace the floor pans and rails but being a 2+2 is going to add some complexity to the job.  It doesn't look like https://kfvintagejdm.com/product-category/datsun-280z/ 

make a 2+2 floor pan but you might get away with the standard 280 pans with an custom extension welded in. https://kfvintagejdm.com/shop/datsun-280z/complete-floor-pans-datsun-280z/

Body shops make their money by getting a damaged car in and out as fast as possible, modern uni body cars with rust take a lot of work to repair properly and so they avoid them, the Z series from 69-78 were some of the first uni body cars and they are much simpler and easier to repair than a modern car.  If you aren't going to do the work yourself you will need to hunt for a shop that is experienced repairing older classic cars, a standard collision shop shouldn't be your first choice.

[Patcon]

I replied in your other thread

[Paulytunes]

1 hour ago, grannyknot said:

Mmmmm, that's not looking so good, you can see on both the P/S and D/S the floor pan has collapsed into the the rail running underneath. The only way to be sure is get a putty knife and start chipping out all of the tar mat, once you've removed that you will be able to see the extent of the damage.

Chances are you will have to replace the floor pans and rails but being a 2+2 is going to add some complexity to the job.  It doesn't look like https://kfvintagejdm.com/product-category/datsun-280z/ 

make a 2+2 floor pan but you might get away with the standard 280 pans with an custom extension welded in. https://kfvintagejdm.com/shop/datsun-280z/complete-floor-pans-datsun-280z/

Body shops make their money by getting a damaged car in and out as fast as possible, modern uni body cars with rust take a lot of work to repair properly and so they avoid them, the Z series from 69-78 were some of the first uni body cars and they are much simpler and easier to repair than a modern car.  If you aren't going to do the work yourself you will need to hunt for a shop that is experienced repairing older classic cars, a standard collision shop shouldn't be your first choice.

grannyknot,

Thanks for the quick response.  I did reach out to a floor replacement seller already.  If the only the front section is bad, couldn't I in theory I have the front section welded to my original back floor pans?  

The classic car community is pretty strong here, so I think I have a number of places to try any hunt down and contact.  I'll get to work at seeing if I can determine the further extent of the damage in the mean time.  Looks like I am out of the simple patch and repair world and more into the full floor pan and possibly rail replacement ballpark.

[grannyknot]

4 hours ago, Paulytunes said:

grannyknot,

Thanks for the quick response.  I did reach out to a floor replacement seller already.  If the only the front section is bad, couldn't I in theory I have the front section welded to my original back floor pans?  

The classic car community is pretty strong here, so I think I have a number of places to try any hunt down and contact.  I'll get to work at seeing if I can determine the further extent of the damage in the mean time.  Looks like I am out of the simple patch and repair world and more into the full floor pan and possibly rail replacement ballpark.

Yes, it is very possible to only use a portion of the new panel, quite often the entire panel doesn't need to be replaced and doing so just brings you a lot more work and expense.  Someone on your other thread mentioned using dry ice to help remove the tar mat, it does work well but so does a sharpened putty knife.

Looking forward to your pics.

[Paulytunes]

Made some progress today before I had to deal with another automotive emergency with the family minivan.  I pulled up all of the loose pieces and vacuumed up the small pieces of rust.  I didn't get a chance to get much of the tar mat up. 

[iscnetwork]

New floor pans, would be my recommendation.

I can't really see the rails to know for sure on those.

[Paulytunes]

3 hours ago, iscnetwork said:

New floor pans, would be my recommendation.

I can't really see the rails to know for sure on those.

After performing more minor surgery and digging deeper today, I concur.  It turns out the reason the passenger side looked so uneven was that the floorpans were indeed rusted and separated from the rails.  One of the previous owners used some pretty sketchy techniques to perform the repair.  On the driver side, there is a thin square of aluminum that was screwed into the rusty floorpan, to cover up a rust hole.  On the passenger side, they used a combination of tar, what looks like rubber, maybe some bondo, and wait for it... a cut up Maxwell House Coffee Can!!  I guess the repair really was good until the last find!  This has got to be one of the worst repairs I have ever come across.  It's funny, I was talking to a fellow Cub Scout Parent at Camporee this weekend, and he was telling me about his Mustang that he bought to restore and his rusty floors had been replaced with road signs!  I guess this was a somewhat common quick and dirty rust repair for owners who wanted to hide rust from unsuspecting future owners?  SMH.  Looks like I will be buying new floors and rails.  On a postive note, the same Camporee Parent is a professor of Automobile Mechanics at the local community college, and he recommended a former student that does rust repairs, so I will be reaching out to him.  

Edited October 23, 2023 by Paulytunes
corrections

[Patcon]

Thats a great connection to make!!

[Paulytunes]

So I made a little more progress today and found more coffee can bottoms.  It's clear that the more I chip away, the more suspect repairs I am finding.  I'm scared to rip out whatever is inserted into the passenger side frame rail, which appears to be some sort of rubber strip and long pieces of metal, held together with Bondo or something else.  Looks like whichever PO did this repair decided that no welding was the way to go.  Searching on YouTube for non-welding floor pan repair also yielded lots of other interesting results, although I have yet to see someone recommending coffee cans or a similar circumstance to my repair.  

I am also struggling a bit with looking at images of the floor pans in Grannyknot's link and other ones on Amazon, eBay, Z Car Depot, and Motorsport Auto and comparing them to my floors.  It looks like the drain pan holes are in the wrong places.  I assume that the end that bends up is the front, and would replace where the second coffee can bottom is on the passenger side photo at the top of the image.  Is that correct?  

I guess the other question that I have is what can I do from prevent this from happening again once the rusty metal is replaced with all new sheet metal?  Is the root cause of the rust years of rainwater getting into a body seam, weep holes getting clogged with debris, water pooling and eventually causing rust formation?  Is the best and only preventative measure to avoid any precipitation and keep the Z in the garage, or is there something else I should be doing to eliminate the source of water infiltration?  

[grannyknot]

9 hours ago, Paulytunes said:

So I made a little more progress today and found more coffee can bottoms.  It's clear that the more I chip away, the more suspect repairs I am finding.  I'm scared to rip out whatever is inserted into the passenger side frame rail, which appears to be some sort of rubber strip and long pieces of metal, held together with Bondo or something else.  Looks like whichever PO did this repair decided that no welding was the way to go.  Searching on YouTube for non-welding floor pan repair also yielded lots of other interesting results, although I have yet to see someone recommending coffee cans or a similar circumstance to my repair.  

I am also struggling a bit with looking at images of the floor pans in Grannyknot's link and other ones on Amazon, eBay, Z Car Depot, and Motorsport Auto and comparing them to my floors.  It looks like the drain pan holes are in the wrong places.

That large hole on the D/S isn't stock, a PO has cut that out.

  I assume that the end that bends up is the front, and would replace where the second coffee can bottom is on the passenger side photo at the top of the image.  Is that correct?  

Yes, you're correct

I guess the other question that I have is what can I do from prevent this from happening again once the rusty metal is replaced with all new sheet metal?  Is the root cause of the rust years of rainwater getting into a body seam, weep holes getting clogged with debris, water pooling and eventually causing rust formation?  Is the best and only preventative measure to avoid any precipitation and keep the Z in the garage, or is there something else I should be doing to eliminate the source of water infiltration?  

The best way is to replace the windshield gasket if there are any signs of it leaking, then when you have done the repairs to the floor pan and your new metal in place, clean the metal, sand the metal, clean it again and spray with 2 part epoxy primer on both sides,  paint then seam seal any joins, spray the bottom with one of the new rocker guards. 

This the piece that curves up in the foot well and attaches to the floor pan, now you don't have to replace that entire piece, you can just cut the bottom 4" off and just replace the piece that connects to the floor pan, or you can just use some sheet metal and make up your own patch and save some money.

https://kfvintagejdm.com/shop/datsun/firewall-repairsection-behind-battery-tray-datsun240z/

 

 

[grannyknot]

Hey, they make just the toe board so you may not need that entire piece that I linked to above,https://kfvintagejdm.com/shop/datsun/toe-board-left-side-datsun-240z/

With the new floor pans you order you will also need the bottom rails as they look like they are shot too, https://kfvintagejdm.com/shop/datsun/utv-sprocket/