just recently got my 10 piece carpet set from 914Rubber it is beautiful

However, there's no backing to the carpet and the original had a sort of clear plastic perhaps the same material that is inside the door panels

Would anyone have any recommendations as to what would be a good backing for the carpet?

I don't recall any plastic on the back of my old stock carpets, but It's been awhile and they are long gone.

The plastic sheeting behind the door cards is a vapor barrier, which wouldn't be needed on the carpets. You should be able to lay them down 'as is', using the grommets to hold the main floor pieces in place. It may take some time for the all of the pieces to lay down fully and conform to the shape of what they are covering.
I didn't need to, but some recommend using a light adhesive spray to hold things in place, especially for the pieces that go over the longs.

To put it succinctly, none.

the original was molded so the backing may look shiny, but is actually part of the casting.

Yes, there was a backing, at least on the 73-74 pieces. Sort of a spray vinyl or something. Most were clear/milky, some were light black.

the original factory carpets had a variety of backings depending on the position in the car.

the pieces that were heat formed to shape had what you might describe as a kind of clear plastic layer. from memory this is the tunnel piece and the left hand sill with the hand brake recess shape. i think also one of the pieces that was shaped t fit over wiring and relays behind one of the seats.

the drivers side floor piece had a kind of bituminous like black kind of backing. possibly a synthetic butyl material.
the passenger side floor piece had some sort of backing but was not as thick.
think passenger side sill piece was similar.

i still have all the original left hand drive carpet pieces from my 74.

i used a kind of closed cell foam sheet cut to shape and glued to the back of the carpet pieces i made for the floor to achieve a factory like fit for my right hand drive carpet set.
means the floor stampings do not show through the carpet. i had to glue down the sill pieces - no capability to heat form. and i sparingly glued down the tunnel piece in strategic spots to get it to hold its shape over the tunnel but i wanted to make sure i could get it up easily to access the tunnel for any maintenance issues. the tunnel piece is not glued down in the original factory carpets. and from memory the drivers side sill piece was not glued down or if it was it was very sparing and only in certain locations.

image of factory lhd carpets. you can see the various backing materials and types depending on position.

@StarBear has a 74 like mine and his factory carpets were identical in terms of varying material backing.

Click to view attachment

FWIW, mine are stock & all shiny in back like George wrote. "73 1.7.

then they changed in 74.
which wouldn't surprise me.
there are a lot of changes that go down with the 74 cars from about nov 73 to may 74.
lots of changes.


@StarBear brought this up a couple of years ago with his car and asked to compare to mine. he was somewhat bemused at the difference in all the pieces. the configuration and differences in the backing between our cars were identical.

the thickest backing on my carpet sets are the heat formed pieces.
these are also branded with pressed in letters TSB. all three of those.
StarBears were the same. had the same brand.

the thinnest pieces have a clear plastic backing but not thick like the formed pieces.
have no impressed letter brand in them.
that plastic backing matches a roll of factory carpet i got hold of from porsche australia back in the 90s. (its that beautiful brown loop that is now unobtainium).
i would call those pieces then raw stock on the basis of the roll i got from porsche.
but the drivers side floor piece is unusual and the piece that goes behind the drivers seat.
both pieces have a kind of black backing that is half way between the standard thin clear backing and the thick heat formed stuff.

another one of those fantastic mysteries of the 914.
penny pinching rationalisation. who bloody knows.
all the little changes through the years and even during the years at random dates and times that constitute narthing but technological trivia.

if we all got together as concourse judges at one of those lah de dah porsche events we could really have fun messing with peoples minds.
good thing i can't be bothered with that sort of stuff.
(lift up the carpet, sorry maaaaaate. i'm blardy well gunna have to take 1,000 points off ya score for those rugs ya call a carpet. ) _

Indeed!

Should I just glue down the pieces that need it with some spray on carpet glue then? The pieces with grommets probably don't need anything at all and would probably be dumb to glue them down

anyone know of a link in this forum or video on the carpet install seems pretty straightforward but I always say that .... then wth?

When I replaced my carpets (years ago, pre-914world), I used carpet tape instead of glue. Only used it where needed, and much easier to remove than glue. YMMV

Good idea. I also have some velcro tape