body and interior Black Layer On 1975 Bmw '02 Floor Pans

[cjeria]

Hi All, I'm an 02' newb. I just bought my first 02' and I'm in the process of fixing it up. There's a little rust here and there, and I've read that the floor pans are target for rust. After inspecting the interior, I noticed a layer of black tar-like stuff that seems to be pretty stuck to the floor pans. On the passenger side, there's a sheet of metal (also glued to the floors with foam over). My first thought is the last owner put this in as reinforcement due to a possible bad rust problem? Has anybody seen anything like this before?

 

Any idea on what this is and whether it should be removed to tackle any rust would be greatly appreciated.

 

Thanks!

[cjeria]

Ok so after a little research, I realized that the black stuff is sound deadening, but what about the sheet of metal on the passenger side? Is that normal?

 

Thanks again.

[esty]

what does it look like from the bottom side...

[eurotrash]

you just separated the foam on the aluminum backing on the passenger side.. Keep digging.

[Paul7002]

There shouldn't be an extra layer of sheet metal.  Think you may be right that PO put it down for reinforcement.  Probably not a good sign.  Crawl under and poke at the floor and see what happens.

[nbcbird]

IIRC, BMW never used the foam padding or aluminum cladding shown in your first photo.  The aluminum (looks also like some modern sound deadening material) could have been a heat shield since the exhaust runs under that area--it would have been very flimsy reinforcement.  Both should pull up fairly easily.  The black sound deadening usually hides rust underneath, so most folks remove it--the preferred FAQ method seems to be dry ice (or a heat gun a distant second).  I would try to remove a bit of the black sheeting and see what the condition your floor pans are in.  If there is absolutely no rust, you would probably be safe in leaving the deadening as is (I was lucky and didn't have any rust and left mine in place).  Good luck.

Edited October 30, 2013 by nbcbird

[Rocan]

my 76 has the same metal sheet and deadening on the passenger side. Good to know it's not just my car... at this point that metal sheet is all thats holding my floorpan together! haha

[cjeria]

Thanks everyone. There definitely is rust below the front and back passenger side of the car. It's really bad and could be very easily penetrated with a screwdriver. 

 

Here are the pics http://www.flickr.com/photos/11286801@N07/10676472696/in/photostream/

 

Was considering using a rust converter, but, I'm skeptical since I've read mixed reviews online. POR15 seems to be the popular option for many, however, I think i'd rather remove the rust completely and weld back in a panel from Walloth & Nesch.

 

Time to get dirty!

[AustrianVespaGuy]

Hi CJ!  Since it seems like you've already started, here's what you do for this project:

 

Step 1, rip out all of the old carpet and throw it away.

Step 2, to get rid of that old sound deadening, spread dry ice all over it to freeze, then whack it with a hammer to break it into pieces, which you can then just pick up and get rid of.

Step 3, patch/repair any rusty spots that you have now uncovered

Step 4, paint the entire now-bare floor with good 'ol POR-15 rust preventative paint.

Step 5, stick down some new FatMat (or similar) modern (and light weight) sound deadener.

Step 6, install fresh brand new carpet, easily obtained from Etsy here on the FAQ site!

 

A few pics attached, hope this helps!

[cjeria]

Thanks AutrianVespaGuy! How long did this project take you? Did you weld and patch up the floors yourself? I've never welded before but i'm considering taking a welding course at TechShop (http://www.techshop.ws/) and doing it myself so save money.

 

Thanks for the pics, very helpful!

[cjeria]

Step 2, to get rid of that old sound deadening, spread dry ice all over it to freeze, then whack it with a hammer to break it into pieces, which you can then just pick up and get rid of.

 

 

@@AustrianVespaGuy,

 

How many pounds of dry ice did you use? 

 

Thanks!  

[AustrianVespaGuy]

Pretty much took me one full weekend, but there wasn't a whole lot that I needed to do on the floors, just a few little fiberglass patches (quarter size or so mostly) here and there, but I didn't need to do any welding on mine.  I think that was about 15 lbs. of dry ice total, or approx. one large bucket's worth!

 

-Carl

[cjeria]

I successfully removed the sound deadening material with dry ice. Tried the hair dryer alternative and I've got to say, that was way harder than the dry ice option. It took me about 15 minutes to remove a few inches with the blow dryer, and an hour to remove all of the sound deadening within an hour.

 

I also found plenty of rust on the floor pans on the front and back passenger pans (see pics).

 

I'm taking a course on how to MIG weld at http://techshop.ws/ and hopefully gain a better understanding of how much work removing this rust really is. Luckily, it's in an area that will be covered up, so maybe it's a good place to put my new skills to practice? I got plenty of work ahead of me.

 

 

[jgerock]

You are this far along - remove the rear seat and see what lies beneath.

['76mintgrün'02]

remove the rear seat and see what lies beneath.

I agree.

I also removed the sear support piece to get at the rust under the flange. Mine was butchered for speakers and quite rusty. That panel is no longer available, so if you do decide to remove it, treat it nicely so you can put it back.

(In the upper left of the last photo you can see the corner of a foam pad I found under my carpet. It has layers of foam/rubber/foam and was not glued down. I put it back after repairing the floor. Seems like effective sound dampener, assuming water is no longer an issue.)