Does anyone know if there was anything between the fuel tank and the bottom of the chassis?  Was there any material isolating the tank metal from the chassis?

Thanks in advance for your help.

I am not sure about the 280z, as I live in the UK where they were not officially imported, but If your query relates to a 240Z, or 260Z, there were hard rubber pads on the upper face of the tank that acted as a cushion to the body. I found some pictures of a later model tank, but the fundaments are the same with the early tanks. On my RHD fiche, for whatever reason, it does indicate a part number for the two pads at the top part (image DSC02889, below) of the early tank (up to August 1974), which is 17231-E4100, but not the lower two (image DSC02891, below), although they may be the same part number. I can scan and upload the fiche if that helps. The attached images probably best illustrate the pads, and their locations on the tank.

On my "72" - 240Z    all 4 pads were the same

Along with the pads there's rubber strips between the tank and the metal straps that secure the tank. I think these strips and the pads effectively isolates the tank electrically from the body. I  think that's why there's 2 wires (240Z) or 3 wires (280Z) for the fuel level sending unit.

The rubber pads are 3x1.75” and 1/4 thick. There are matching indents in the tanks to show you exactly where they go.

I do have some pads in the stash that are much thicker at 3/4” but I’m no help at telling you which model they are from. I do have a couple of 4-pad groups taped together that are all the 1/4” thick ones so that is the likely correct set for the 240 and early 280 tanks (75-76) that are the same form factor. 

Edited October 16, 20222 yr by zKars

The last time I needed padding for a "Z" tank, I visited a Hobby Lobby store and found the material that I needed.  Not sure in what department or what the original intended purpose was for the material, but it was rubber like in came in larger pieces that needed to be trimmed to size. 

 

Edited October 16, 20222 yr by mayolives

Sorry I was away from the site for a few days.  Thanks to all for the responses.  The images from U.K. JerZ were very helpful.  I also found some other information indicating that there were two different thickness'.  Those on the higher portion were 1/2" - 9/16" thick while the lower section got 1/4"-5/16" thick.  The images above show these different thickness'.
BTW - sorry for not making it clear - I have a '73 240z.  When I pulled the tank I saw the indents.  My tank has 3 indents for isolators on the lower section and two indents for isolators on the upper section.  I found some neoprene and/or DOBTIM Neoprene that is the right thickness'.
Once again, thanks for the help.

regards,

ron