280Z double floor removal?

[Reinier]

Hi guys,

One thing that has been bugging from the moment I bought my 1977 280Z, is the double floor design of the trunk. I absolutely hate it.

So I am going to remove it by cutting away to extra lip behind the seats making it as high as in the 240Z and drilling out the spot welds on all the brackets. All the stuff encircled in green on the picture.

Cutting the lip will also give me space to use an hamer and dolly to fix the secrets compartments which were butchered for a speaker install grrrrrrr.

The 280Z also has two raised rails or beam like thingies. Does anyone know what's underneath and if they are structural or just for supporting the wooden floor and spreading the weight? I have encircled them in orange.

I can either remove them as well or maybe use some high density foam to fill up some of the space around them and end up with a carpet that has 2 bumps which is no big deal I think.

What do you guys think? Am I making a mistake by modifying the trunk floor?

Best,

Reinier

 

 

[grannyknot]

Most of the green stuff you can remove without consequence but I would be careful with the lip at the front of that area.  You can cut it down in height but you should replace the horizontal lip as that is part of the structure.

The orange areas you can not cut off without compromising the structure of the car, those are part of the subframe of the uni-body.   If you like you could pick up a pair of drug bin lids and bolt them right on, the holes are already there.

[rturbo 930]

As I recall, the beams in orange were added in the later cars to deal with the added weight of the larger fuel tank, and probably the general increase in weight the cars had by then. Earlier cars didn't have them, and it's possible you could remove them without consequence. I wouldn't necessarily recommend it, but I'm not convinced the structure would be any worse off than a 70-76 car.

[Captain Obvious]

I did pretty much exactly what you are planning. But first... some background.

The 70-76 cars had a full sized spare and a full depth spare recess in the back deck. But in 77, they changed all that. They went to the space saver collapsible spare and reduced the depth of the spare tire well such that the spare now sits proud of the rear deck surface. And they also changed all the sheet metal and uni-body pretty much everywhere, including the rear decking. Those metal supports used to be located underneath the deck lid on earlier years, but moved to above the decking for 77.  I wasn't there when they did all the modifications, but the rumor on the street is they did all that in order to allow a larger fuel tank for 77. In short... They traded less storage space in the rear for a larger gas tank.

So with all that said...

I drilled out the spot welds in the original piece spanning the two rear wheels. And no, I'm not worried at all about it changing the rigidity of the vehicle. 1) It never went all the way to the sides (there's about a 25mm gap at each end), and 2) The piece that it was spot welded to is identical to the previous years. They just spot welded an extension to the vertical piece they used from 70 to 76.

Here's the piece in question. You can see about half the spot welds drilled out on the near side:

And here's what it looks like once you get all the welds drilled and the piece loose from the car:

Unfortunately, taking that piece out leaves a rough edge that does not look "finished":

So to finish the now rough edge that exposed... I used the same piece they used in the previous years and screwed into place (just like the previous years):

And as for the rest of it... I used foam to build up around those rear metal frame members to give me a flatter surface to build a new deck. I don't have any good pics of that process, but I'll see if I can get some of the finished product.

Edited December 15, 2020 by Captain Obvious
typo

[Reinier]

Thanks for the great info Captain Obvious. Drilling out those spot welds is a great idea.

[Captain Obvious]

Glad to help.

On my car now, the forward section of my rear decking (from the strut towers forward) is carpet right over the metal decking. In other words, it's just like all the previous years. But further back, I went to a narrower spare tire and made new wood decking pieces for the rearmost section. I relocated the new wood floor as low as I could possibly install it while still fitting over the spare and those metal support braces.

So, in the end, I've got a step back there... It's lower right behind the seats and then steps up about 25mm or so with a false floor over the spare.

If you aren't going to install a spare at all, you could probably lower that false floor even lower back there.

[siteunseen]

20 hours ago, grannyknot said:

Most of the green stuff you can remove without consequence but I would be careful with the lip at the front of that area.  You can cut it down in height but you should replace the horizontal lip as that is part of the structure.

The orange areas you can not cut off without compromising the structure of the car, those are part of the subframe of the uni-body.   If you like you could pick up a pair of drug bin lids and bolt them right on, the holes are already there.

Drug bins...yep back in the days before the sniffer dog. 

[Reinier]

5 hours ago, Captain Obvious said:

Glad to help.

On my car now, the forward section of my rear decking (from the strut towers forward) is carpet right over the metal decking. In other words, it's just like all the previous years. But further back, I went to a narrower spare tire and made new wood decking pieces for the rearmost section. I relocated the new wood floor as low as I could possibly install it while still fitting over the spare and those metal support braces.

So, in the end, I've got a step back there... It's lower right behind the seats and then steps up about 25mm or so with a false floor over the spare.

If you aren't going to install a spare at all, you could probably lower that false floor even lower back there.

Yeah I don't want a spare so I think I will just put a plate over the spare space and that will be my floor.

What have you done to tidy up the inside of the tail lights? Does the interior trim panel from earlier cars fit?

[Captain Obvious]

Well if you aren't going to store any spare at all, that recess makes a great storage area. Or you could put a big sub-woofer speaker into the wood over it. 

So I just reused my original 77 taillight panel interior finish panel. Since I was making a new wood floor back there, I just trimmed the edges of the wood so it fit the new lower location on the panel.

[siteunseen]

I remember that! Mr Irwin I believe?

 

Edited December 16, 2020 by siteunseen

[Captain Obvious]

Yeah, perfect. Just like that.

I'm pretty sure you could hit the brown note with that much woofer!!    

[siteunseen]

14 hours ago, Captain Obvious said:

Yeah, perfect. Just like that.

I'm pretty sure you could hit the brown note with that much woofer!!    

I'd rather think about Theresa Lynn sitting on the speaker in Howard Stern's "Private Parts" movie. 

Edited December 17, 2020 by siteunseen