Does anyone know the purpose of the foam inside the (base of the) A-Pillar (other than to cause A-Pillar rot!)? I cut the rot/rust out of the base of my A-pillars and in the process also dug out all the foam on both sides in prep for welding in the patches. I am now contemplating leaving the foam out after finishing.

I assume the foam was put in there for one of the following reasons:

1) Wind noise reduction
2) Stop water migration from the cowl up the a-pillars (and inside the car)
3) Stop drafts from the cowl up the a-pillars
4) Safety, fire protection
5) To make sure the A-pillars rot out....

My car will not be driven in winter and I am not to concerned about noise so I am not concerned about 1, and 3. I am concerned about 2 and 4, if that is the intended purpose....

So does anyone know why it was put in there from the factory? Is anyone running without it? If you have dug it out what did you replace it with (if you replaced it)?

The car is an 82 Z28 T-Top BTW.

 

Just a guess but GM and others usually use the foam only for sound deadening. It will absorb moisture and will burn so it's not good for fire or moisture. Possibly number 5. With the peeling paint and that foam they wanted to make sure you had to buy another one. JMO

 

i didnt even know there was foam in the a-pillar.

 

I don't believe there was any in my car.

 

Is the foam pliable, or is it more solid? If it's solid, maybe it's there as an attempt to stiffen the the pillars, kinda like that expanding urethane foam people use to stiffen their chassis. Just a guess...

 

It is pretty soft (almost sponge like, but not sponge...) and just at the base of the pillars beside the windshield (in the exact spot they rot in Northern Climates). It is adhered to the metal (my guess it was injected in not placed in), a real pain to remove.

I had no idea it was there either until I cut the a-pillars open (to remove the rusted sheet metal).

 

Found the same sort of thing in my 1966 El Camino when replacing some rusted metal. Couple of spongy blocks near the bottom of the a-pillar. On one bit of metal I cut out, the back side had hardly any rust on it and was still bare metal looking. Here's a pic of one of the blocks.

 

sound deadning and prevent vibration...

 

I've got the same thing in my Monte SS. Anddddd the base of the A pillar's have rot in them. I agree it was only put there to rot out the A pillars!

 

It's factory and it's mushy open cell stuff applied much like butyl rope. IT's in the rear fenders too and it's where water collects and causes them to rust out along with the crappy seam sealer they used that goes brittle. The only way to maybe prevent it is to soak the living hell out of it with penetrating rust preventative wax.

 

5 for sure