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

[Patcon]

Well let's start with the car is 50 years old. If you treated it as a cheap car and drove it in all sorts of weather, your repair aught to last another 50. If you properly prime your repairs and avoid salted roads I expect your repairs will last 100 or so years. I suspect at that point there will be other challenges to operating your 150+ year old ICE car on public roads. Provided you're still here. 😉

[Paulytunes]

13 hours ago, grannyknot said:

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/

Thanks, it's nice to know that all these parts are available.  I guess what I will need depends on the extent of the rust, so I guess I really do need to keep removing the previous repairs and find out where the rust ends and the good metal begins.  Hopefully, I don't end up with an undrivable Flintstones cruiser.  It's odd that one of the POs would drill an extra drain hole, I don't understand why they would do that.  I did notice some of the parts you referenced were for the 240Z - I assume they were the same for the all the S30 models?  Mechanically, I have run into differences between model year 280Zs on certain parts.   

[Paulytunes]

12 hours ago, Patcon said:

Well let's start with the car is 50 years old. If you treated it as a cheap car and drove it in all sorts of weather, your repair aught to last another 50. If you properly prime your repairs and avoid salted roads I expect your repairs will last 100 or so years. I suspect at that point there will be other challenges to operating your 150+ year old ICE car on public roads. Provided you're still here. 😉

Point taken.  I guess I tend to forget just how old these cars have become and how old I am getting.  My intent is to drive the car and enjoy it but treat it as a classic.  I always keep it in the garage, avoid bad weather whenever possible, and not to drive when there is a threat of snow and MDOT pretreats the roads with copious amounts of road salt and other chemicals. 

[rturbo 930]

9 minutes ago, Paulytunes said:

 I did notice some of the parts you referenced were for the 240Z - I assume they were the same for the all the S30 models?  Mechanically, I have run into differences between model year 280Zs on certain parts.   

They are not the same. The rails won't fit. The toe board might fit on the driver's side with some work, not sure about the passenger side, the floor steps down on one side of the rail. Your car being a 2+2 will only complicate matters, although if you're only doing the front footwell area it may not be a problem. You will need to find the appropriate 280Z equivalent parts, or learn how to shape metal. I would also consider patching instead of replacing, from the photos the full extent of the damage doesn't seem to be revealed, it may or may not warrant full replacement. Get all the tar off the floor before making that call. 

[Paulytunes]

10 minutes ago, rturbo 930 said:

They are not the same. The rails won't fit. The toe board might fit on the driver's side with some work, not sure about the passenger side, the floor steps down on one side of the rail. Your car being a 2+2 will only complicate matters, although if you're only doing the front footwell area it may not be a problem. You will need to find the appropriate 280Z equivalent parts, or learn how to shape metal. I would also consider patching instead of replacing, from the photos the full extent of the damage doesn't seem to be revealed, it may or may not warrant full replacement. Get all the tar off the floor before making that call. 

I sort of suspected that there may be a difference.  Nissan seemed to like to change parts in some cases almost yearly.  I found that out the hard way with my 1983 810/Maxima. 

I'll keep at removing the tar and the repairs to get a full assessment of the damage.  I did pull out the rear seats, and everything to the rear of the first front seat rail appears to be solid and in good shape.  I guess I won't fully know until I pull up all the tar though.    

[grannyknot]

8 hours ago, Paulytunes said:

Thanks, it's nice to know that all these parts are available.  I guess what I will need depends on the extent of the rust, so I guess I really do need to keep removing the previous repairs and find out where the rust ends and the good metal begins.  Hopefully, I don't end up with an undrivable Flintstones cruiser.  It's odd that one of the POs would drill an extra drain hole, I don't understand why they would do that.  I did notice some of the parts you referenced were for the 240Z - I assume they were the same for the all the S30 models?  Mechanically, I have run into differences between model year 280Zs on certain parts.   

My bad, all I had to do was look at the title of the thread. My comments were for a 240Z, sorry for the confusion.

[HusseinHolland]

From my experience with rusted floors on 70's era cars, it's ALWAYS worse than it appears. Looking at your pics, until all the tar is removed, you're not going to know just how extensive it is. Since they added undercoat to cover up shoddy repairs, you will likely also need to remove material from the underside to properly evaluate the repairs needed to the frame rails, since the work will always involve repairs to both sides of any panel junction (floor to sill, floor to frame rail, floor to firewall, etc...)

[Paulytunes]

So I had some time this morning today to try the dry ice method to remove the tar mat from the floors and get a better idea of the extent of the rust and other non-welded repair work.  It was definitely easier than just scraping, but was more work than some of the YouTube videos would lead you to believe, unless I did it wrong.  Still, I was also able to turn it into a science lesson for my kids (who were off today for Thanksgiving break) to demonstrate the difference in thermal properties of differing materials.  My son seemed to think it was cool, but my daughter lost interest pretty quickly.    

It looks like the driver side is the worst, especially at the front.  The passenger side appears to be localized along the rail, and it looks like there was a bolted repair performed on the rail.  They had put in more Maxwell House coffee cans along the passenger rail with some sort of rubberized coating, tar mat, and what looked like some Bondo.  Despite the holes, the floor feels solid in most places.   I guess I have some grinding to do now to get rid of the rust and see where I need new sheet metal.  

[grannyknot]

   Nice, much better. How is the floor pans under the seats?  Your dash and door cards are in beautiful shape.

[HusseinHolland]

Much better viewing inside. Got any pics of the underside where those rails & floor meet the bulkhead? The type of issue that can arise is where there are multiple overlapping panels. This was on my X1/9

Once I removed that perforated forward section: multiple layers to address. That would be my concern with your level of visible floor rot

When you patch panels you have to consider how the new & old are joined - butt, lap, etc., you want to make sure you don't create water traps. 

In the end, I cut pretty much all of it out, so I could fit the panel inside at the leading and inner edge and under/outside along the rocker & seat frame area, to match the original flow of the panel welds. You do want to investigate what path makes the most sense. Your DS looks like most of it should go, depending on what it looks like under the seat frame rail....

Edited November 23, 2023 by HusseinHolland

[Paulytunes]

3 hours ago, grannyknot said:

   Nice, much better. How is the floor pans under the seats?  Your dash and door cards are in beautiful shape.

Thanks!  Driver side has some rust and a few perforations.  Passenger side appears to be in decent shape.  

[Paulytunes]

12 minutes ago, HusseinHolland said:

Much better viewing inside. Got any pics of the underside where those rails & floor meet the bulkhead? The type of issue that can arise is where there are multiple overlapping panels. This was on my X1/9

Once I removed that perforated forward section: multiple layers to address. That would be my concern with your level of visible floor rot

When you patch panels you have to consider how the new & old are joined - butt, lap, etc., you want to make sure you don't create water traps. 

In the end, I cut pretty much all of it out, so I could fit the panel inside at the leading and inner edge and under/outside along the rocker & seat frame area, to match the original flow of the panel welds. You do want to investigate what path makes the most sense. Your DS looks like most of it should go, depending on what it looks like under the seat frame rail....

Yeah, I need to get under and take a more detailed look.  My initial glances are that it appears to be solid, and the mechanic that looked at it for me when I bought it didn't see anything when he had it on the lift.  I am looking into getting one of those portable lifts (maybe tomorrow if there are any good sales) so I can get under and take a look.  If not, I have four decent jackstands and just need to verify the jacking points are in good enough shape to support the car.  Of course, this will be after all of the requisite holiday festivities, decorating, and other activities.  

Happy Thanksgiving to all of you, BTW!  I am happy to be part of such a great Z community and keeping our cars and hobby alive!