Floor pan drain plug hole sizes

[Av8ferg]

Gents, 

Making progress on my 280z.  I am replacing the carpet now but need to prep the floor.  A few questions for the experts,  I’ve looked over historical threads and see conflicting into.  

1. My floor pan are solid with only mild surface rust just around drain holes.  I’ve read people removing the sound proofing before installing new sound proofing matting and carpet to make sure there is no rust under the old stuff.  Is this necessary?  With not visible rust anywhere seems like a lot of extra work. I haven’t found any rust on the car anywhere so far even in the most likely areas.  

2, I was going to clean the drain holes with some naval jelly to stop the rust and then prime and paint the drain holes.  I’m looking for new drain plugs but I cannot figure out the  exact sizes I need.  On this forum and at stores that sell the plugs (MSA, Z car Dept and Z car Source) all the sizes seem different.  Anywhere from 25mm to 46mm?  So what size to I need?  I need all the holes plugged in the floor area and under the seats.  Does anyone know what the actual sizes are?  If I were at the car I’d go and measure but I’m in another state right now and want to order them the be there when I arrive.  

Any advice on either of the above questions would be awesome.  

[SoCalJim]

1. I had some surface rust under my original sound deadening matting.  So, I think removing at least around the driver/passenger floor areas is advisable.

2. I recently replaced mine.  I used 44mm, 24mm, and 20mm floor pan grommets from Z Car Source of Arizona.

[SoCalJim]

I went a bit further with my sound deadening replacement.

 

[Av8ferg]

Looks like some quality work there.  I appreciate the info.  I read somewhere that the holes were not the same every year.  I guess if they don’t fit I’ll send them back . 

[SoCalJim]

Perhaps you can pick up a cheap digital calipers from a place like Harbor Freight and measure what you have.  That’s how I handled it.