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

[Paulytunes]

At this point I am wondering if I should just bite the bullet and buy the set of 280Z floors and frame rails or if I should do a little more uncovering to see the full extent of the rust? 

[rturbo 930]

I don't see a reason to buy floors, and I don't know what condition your frame rails are in, I haven't really seen a clear shot of them where I know what I'm looking at. Your driver's floor looks like it has rust through only where it joins the frame rail, and some surface rust around the drain holes. Is there something I'm not seeing? I'm just hesitant to suggest that you go ahead and completely cut out your floors since that's a pretty significant job. I also just don't see the point of a whole floor if a patch is all that is needed. Total replacement only makes sense IMO when it's less work than doing a bunch patches. Do your frame rails still have the flanges on them where the floors are rusted? Are they rotted through on the bottom? Are they badly dented?

I just went back and read your initial post again. Sounds like you're not going to be the one doing the work. If so I think the question of what you should buy should be left to the person doing the work. Also sounds like you're having trouble finding someone to do the work, so I'll throw this out there. Tim at https://industrygarage.com/. He's a Z guy and his work can be seen at the Street Bandito youtube channel. They're in the same building as his father's body shop in Baltimore where he used to work, and I know he does some customer work. Not sure if he'd be interested in your project, but worth a shot if you're having trouble finding someone. 

 

[Paulytunes]

19 hours ago, rturbo 930 said:

I don't see a reason to buy floors, and I don't know what condition your frame rails are in, I haven't really seen a clear shot of them where I know what I'm looking at. Your driver's floor looks like it has rust through only where it joins the frame rail, and some surface rust around the drain holes. Is there something I'm not seeing? I'm just hesitant to suggest that you go ahead and completely cut out your floors since that's a pretty significant job. I also just don't see the point of a whole floor if a patch is all that is needed. Total replacement only makes sense IMO when it's less work than doing a bunch patches. Do your frame rails still have the flanges on them where the floors are rusted? Are they rotted through on the bottom? Are they badly dented?

I just went back and read your initial post again. Sounds like you're not going to be the one doing the work. If so I think the question of what you should buy should be left to the person doing the work. Also sounds like you're having trouble finding someone to do the work, so I'll throw this out there. Tim at https://industrygarage.com/. He's a Z guy and his work can be seen at the Street Bandito youtube channel. They're in the same building as his father's body shop in Baltimore where he used to work, and I know he does some customer work. Not sure if he'd be interested in your project, but worth a shot if you're having trouble finding someone. 

 

Thanks!  From what I can see, the rails still look solid.  No dents, and the driver side has the flanges intact.  It's harder to tell on the passenger side - I'll need to go and take a closer look.  From what I can tell from looking under the car without a lift, the rails look to be complete.

I'm sort of on the fence now about the work.  I've shown photos and talked to a few friends who have done their own hobby auto work.  They have encouraged me not to be too afraid of trying to learn how to do some patch welding if that's all that is needed.  I did do some welding many years ago I was on the mini-baja team years ago at UMBC, so I am not a complete welding virgin, ha ha.  Still, I may reach out to Tim - Thanks for the contact info!  

 

[HusseinHolland]

Do you have better quality/clear pics of the floor? The shots you posted are either unfocused or poor quality, so it's really hard to tell what's perforation & rust vs. shadow/tar etc., since we can't zoom in & get any clarification. For the underside, unless you remove the undercoat you mentioned as being added, you are not going to know how extensive the rot is. It's been my experience it's always worse than what is apparent. 

In this pic, it looks like the rust & perforation goes all the way across the from of the floor beneath the pedals. In one of the other pics, it looks like coffee can under the seat rail. 

If you are doing it yourself, and have some prior MIG/TIG experience, it's really just a question of stripping all the undercoat, cutting out all the obvious rust back to clean metal, then evaluate whether you can patch or if you need to replace entire panels. The metal used on these seems to be very thin gauge, I'm surprised how easily the outer panel flex on my 75. 

Edited November 24, 2023 by HusseinHolland

[rturbo 930]

4 hours ago, Paulytunes said:

Thanks!  From what I can see, the rails still look solid.  No dents, and the driver side has the flanges intact.  It's harder to tell on the passenger side - I'll need to go and take a closer look.  From what I can tell from looking under the car without a lift, the rails look to be complete.

I'm sort of on the fence now about the work.  I've shown photos and talked to a few friends who have done their own hobby auto work.  They have encouraged me not to be too afraid of trying to learn how to do some patch welding if that's all that is needed.  I did do some welding many years ago I was on the mini-baja team years ago at UMBC, so I am not a complete welding virgin, ha ha.  Still, I may reach out to Tim - Thanks for the contact info!  

 

If the rails have no damage, then I see no point in replacing them. I think you can probably get away with just replacing the strip of metal where the rail meets the floor, which should be an easy enough patch to make and shape with basic tools. Areas of surface rust or minor pitting can be treated with naval jelly or similar. It's a much smaller job than total replacement of floors and rails, would save you a good bit of money, and would also serve as a good learning experience. Also, it's a good place to learn being the floor since it's not visible. But, as Hussein says below, you need to know exactly how much rust damage there is before you can begin. Detailed, well lit photos would be helpful, and we don't know yet if the damage goes beyond just the front floor section. 

[Yarb]

Do yourself a big favor and get the Nidage Borescope from Amazon for less than $30 and look up inside the frame rails through the drain ports. You might be surprised by what you find. Also take a screw driver and tap along the bottom frame rail and see if you find soft spots. It’s a blue tooth setup that’s pretty cool. At least you can see what you have to work with.

[CanTechZ]

3 hours ago, Yarb said:

Do yourself a big favor and get the Nidage Borescope from Amazon for less than $30 and look up inside the frame rails through the drain ports. You might be surprised by what you find. Also take a screw driver and tap along the bottom frame rail and see if you find soft spots. It’s a blue tooth setup that’s pretty cool. At least you can see what you have to work with.

Here's what I found on my 1970 doing as you suggested on my front rails.

 

Edited November 25, 2023 by CanTechZ

[Paulytunes]

5 hours ago, Yarb said:

Do yourself a big favor and get the Nidage Borescope from Amazon for less than $30 and look up inside the frame rails through the drain ports. You might be surprised by what you find. Also take a screw driver and tap along the bottom frame rail and see if you find soft spots. It’s a blue tooth setup that’s pretty cool. At least you can see what you have to work with.

Done and thanks!  It was $23 today as a black Friday deal.  It'll be here in a week.  I concur with all that I still have a lot of work to do.  I want to angle grind away the areas in front of the pedals and clear out what looks like surface rust.  Sorry about the quality of the photos - I guess my phone isn't the best for taking photos in the garage.    

[Paulytunes]

2 hours ago, CanTechZ said:

Here's what I found on my 1970 doing as you suggested on my front rails.

 

Yikes!  I've tapped around quite a bit on my floor boards.  After watching your video, I'm scared to do the same to my rails.  But, I do need to know the full extent of the rust so I can get rid of it.

[Yarb]

The camera will give you a better idea for many parts of the car including the radiator support and front rails as well. Once you find an area that looks satisfactory Eastwood makes a product to coat those areas with an extension nozzle to reach deep inside.

[Paulytunes]

I've been working at grinding down the inside of the floor over the past few weeks when I have had some free time. 

Driver Side:  The rail looks to be original but bent in a few places.  It no longer meets the floor in the rear.  In the front, the floor looks like it was cut away in the front and a new piece of metal was riveted to the original floor that remains.  The bad areas of the floor are in the front, and along the frame rail, there are perforations near the seat rails too.  The floor aft of the seam seal is all solid - no visible rust or corrosion.  The bottom of the rail appears to be corrosion free (hard to tell in the photos), but the inner front side looks deteriorated, I'm concerned that if I grind it or poke at it, it may just flake away.   

Passenger Side:  The frame rail was replaced by a previous owner.  You can see areas where it has been bolted in.  As far as I know, this was not stock (feel free to correct me if I am wrong).  It looks beefier too, like some of the replacement rails (maybe from Dragon Z?) I saw online.  Most of the rust damage here was along the run of the frame rail, and this is where one of the previous owners performed the coffee can, rubber, bondo non-welded repairs.  It is the worst at the front, continues along the rail until it stops before the seat rail.  There is also a pretty substantial hole that was filled in with Bondo.  Note to self - next time try to poke it out instead of grinding to minimize the dust.

So I'm pondering the best course of action.  I want to repair it correctly, which means some amount of welding.  I don't know that the driver side frame rail can be easily reattached to the floor, so maybe I should just invest in a new driver side frame rail?   Is there a rule of thumb as far when the whole floor should be replaced versus if cutting out the damaged areas and patching in new sheet metal will suffice?   

[grannyknot]

You need new pans and rails, from the extensive rust your photos are showing now I don't think it is even worth removing any more of the tar and paint.  It's a big job for sure, but so is trying to weld patches to punky old metal like the last guy did.