Rivets for threaded plate for plastic tank hold down

[billm]

The rivets used to hold the threaded plate for the plastic tank hold down are no longer available from Porsche (999.190.102.02). I know from the parts book they are 4mm in diameter. I have confirmed this by measuring the holes in the plate and the chassis. I am estimating the grip length at 8mm-9.5mm. I should be able to find a suitable substitute but I don't know what the original material was. Were they made of aluminium or steel? And/or does anyone know of a source?
BillM

[billm]

In the absence of any info on what material the rivets are made of, I am going ahead with aluminum. They were the easiest to find...Home Depot 5/32" (4mm) diam with 1/4" grip.
BillM

[edmayo]

I have an ROW car with factory installed tank, as best I can tell the rivets are non-magnetic, but there is paint on them so could be false signal. I'm sure what you're using will be fine. I just recently did that tank install in another car I have and just used generic alum pop rivets, which is what the factory ones appear to be.

[billm]

Thanks Ed.
As of today I have all of the parts together to install my plastic tank in my 73S. I am not clear on how the front retaining clip is to be attached. Do you bolt it in first and slide the nose of the tank under it? Or do you put the tank in place and slide the retainer in place under the nose of the tank and then thread the bolt up from underneath?
Also do you stick the large tank seal to the tank or to the chassis or dosen't it affect the instalation process?

BillM

[edmayo]

Hi Bill, have you drilled the 8 mm hole for the front mount yet? If not, here's how I do it. With the tank in place slip the front mount in position, making sure the mount is flat to the trunk floor. I use tape to outline the sides and front of the mount, then remove it and the tank and reposition the mount in accordance with your tape marks, I use a transfer punch to perfectly center punch the 8 mm hole, then drill it. Test fit your bolt into the mount, be sure to use a bolt length that only barely goes through the captive nut, you don't want to screw a long bolt into the tank! I install the Porsche supplied foam seal to the tank. Reinstall the tank and front mount, holding the mount with one hand reach under the car and start the bolt with the other hand, moving the mount slightly as necessary to line up the captive nut. You will notice the plastic tank has a slight 'swell' to the bottom making it closer to the ground than the steel one. On my ROW car at stock ride height its not a problem, on my other that I just did it is lower and I didn't like the thought of scraping that plastic tank. Two fixes, one, I bought a skid plate from Robert Gross (on this board) and secondly I took the tank back out and glued water pipe foam insulation to the sides and rear of the tank seat ledge in the trunk floor. That raised the tank about an inch. For the top mounts, because the tank now sits proud of the trunk floor you just need to put one inch spacers under the bolts so that the mounts still sit level holding down the top of the tank.

[billm]

Thanks Ed. That is extremely helpful.
I am starting on step one today: getting the car on jack stands and gettiing the fuel out of the existing tank.
BillM

[sithot]

You can buy all the rivets you could ever want from McMaster-Carr. http://www.mcmaster.com/#standard-rivets/=hoacbw