I have my interior out and am about to get seat reapolstered and am interested in the thought of expansion foam for sound deadning and chassis strength. I have been reading a few old threads but none of them are for FB's I do not want a roll cage and am a huge DIY but am wondering if I could get some pointers? A few that i have thought of is remove all wires and what not that run through these open areas and have the interior completly out. So if you care to chime in on the subject at all I am open to ideas. Thanks Brandon.

 

There is an automotive structural foam. Check your local auto paint supplier. It's pricey.

The auto foam will not absorb moisture like some of the house foams an.

 

ITW Foam Seal

http://www.foamseal.com/auto_aftermarket.htm

Thats in my plans...

 

That is kinda pricey. I wonder how many we would need for our cars? Since I have my interior out i was looking in the back from where bins would be back and the only wires that would need to be removed would be the fuel door, tail light and speaker wires and that is real easy. When I do decide to do this I will do the door fram and a pillars as well. Any onyone else done this on a first gen?

 

Take out the amp and fader controls plus the cruse control module, all of these are under the seat and in the bin.

 

I foamed almost all of the voids in mine with Great Stuff, that was before I knew about the moisture draw. I used 40 cans of it and about 20% of it oozed out as overfill.

It is also an aerobic sealant, it needs air to set. I had 'growth' 6 weeks after I foamed it. Where it didn't get air, there are some very large bubbles in the foam.

The foam at the autobody store is about 15 a can, aerosol.

 

15 a can at any autobody store huh? That is the stuff you can use? I read not to use what you used I guess I know why now. Trochoid were you pleased with the results of the wrong foam? If so I could only imagine what the correct application could do. I would love to do this the right way BUT my wife is starting school and quitting her job although i will be getting a raise we have sort of decided to wait until later. Thanks for post with pics thats great! Anyone else have pics or results Good or bad or stories to tell from doing this?

 

The ITW includes a catalyst that makes the foam set without having to have the air touch it... Sport compact car did a Z with 5 kits... I think we would likely need three but not sure have not yet done it.

Sorry to use you as an example trocoid but this is what you should not to... you reelly should have taped off all the extra frame holes

Toxic_d

 

What exactly is the point? Just use dedicated automotive acoustic deadener mat and foam and your set. Without all the negative just seen.

 

The foam seal acts to stiffen the chassis without much added weight...

 

Id love it if there were b4 and after results on skidpad or slalom it is too bad no magazines ever have a 7 as aproject car especially a FB.

 

Not a problem. I didn't realize it was the wrong stuff when I used it. I did it mostly for sound deadning, the cage stiffens it up pretty well. It kinda like a skate board now.

I left the holes open to get a complete fill of the voids, just didn't know it would take so many cans. If I had taped the holes, it would prpbably never set.

The chassis looked hilarious with foam oozing out of every hole.

 

lol....c/mon!! The shear aspect ratio of that expanding foam has to be ridiculously low! You're dreaming if you think it actually stiffens the monocoque chassis of an RX-7!!

 

Its used in higher-end cars to help stiff the chassis and provide some albeit minimal sound dampening. IE lexus and others...

" Structural foam, in the 2 lb per cubic foot density that we used, can stiffen chassis members up to 40 percent.

Higher densities of foam can increase stiffness by up to 300 percent. Since we cannot retool custom parts to redo the Z's body, we figured that this would be an excellent, low-cost way of greatly increasing chassis stiffness. Injecting foam is not a new technique for chassis stiffening. The Infiniti Q45 uses this sort of foam in some of its chassis members to increase stiffness, as do a few other premium cars. In fact, the foam we chose is the foam recommended to repair damaged Q45s."

 

It's used as a sound deadener in those applications...

 

i worked for infiniti for a year in the parts dept. 90% of our business was parts for cars in body shops. most of the time this foam you speak of was never replaced because it did not affect structural rigidity. it was merely sound dampening. not trying to contradict, i am just stating what i know from behind the infiniti counter.

 

FBII thanks for your input... it seems that the only other benefit would be in the case of an accident where the foam would act to absorb some of the energy of the crash. I'm not finding the documents I wanted to backup the structural side of things.

As a side note though, foam is also used in sandwich style FRP layup to add to the structural integrity of the part being made without a weight penalty. There are other options as well in the FRP layup such as aluminum honeycombs and such, but foams should not be ruled out.

 

I have a picture that looks almost like the foam in your picture.



The spray kind of matches the foam, don't you agree?

 

that pic looks kind of sick.. hahahah