Door waterproof membrane?

[molten]

Hello
Did Triumph glue the plastic sheet membrane on the rear of the door just to keep moisture off the back of the hardboard door cards (failed miserably)?

My new plywood door cards are painted in exterior gloss so  should not need the membrane going back if the above is correct.

Thanks

[rotoflex]

I believe I've seen the plastic sheet behind the door panels on the GT6 referred to as the "moisture barrier".

As to whether it will not be needed if you've now got painted plywood door panels:  There is a similar moisture barrier sheet (although made of a more rubbery material) in the same location between the door & door panels on my 1999 Neon, & those panels are plastic!  There must be something not immediately obvious to us going on at that interface.

[JSBulmer]

The painted plywood will provide a bit better protection against moisture than the original hardboard did.  However, it will not be waterproof nor will it fully resist moisture penetration.  Paint by itself does provide some resistance, but it does not provide ultimate protection - plastic and rubber membranes would provide much better protection.

That being said, you will likely get a lot of years of life from the plywood.  Your car is 35 years old now and likely when new the owner was not concerned about the weather in which it was being driven, and possibly driven a lot.  With our older restored cars we tend to be a bit more careful about when we drive and how many miles we go (unless you plan on it being a daily driver in all circumstances).

At some point the painted plywood will fail - similar to what the hardboard did.  If you want longer term protection than regular plywood, consider using either a marine grade or pressure treated or alternatively seal the non visible side and all edges with a proper moisture resistance / retarder product.

jb

[molten]

Good points.

I will be long gone though before the plywood door cards would need to be replaced - I hope :o

Thanks for your comments
Scott

[Howard81]

The lower part of the plastic door liners actually tuck in the door bottom. This was to further protect the door cards getting wet and rotting. Any water let in past the window scrapers would run down the plastic and into the door bottom, then (theoretically) out of the door drain holes.

Very important to make sure that the drain holes are unblocked and that the bottom of the Dior is very throughly waterproofed!!