Body Flex
 

Well i know that having a strut braces for the front and rear has actually reduced some body flex in the car. And im sure have a roll bar would also. Is there anything else that we could do, even if it were custom, to make our cars more rigid? Becasue when im going on driveways, speed bumps, or driving my car kinda hard its quite obvious there is a quite a bit of body flex.

man, I can't remember where I was reading this, but somebody designed new support bars for the a & b pillars. The a pillar hooks from the a pillar between door hinges & the inner fender well. There's also one that hooks the b pillars together right behind the driver's head:

http://www.sromagazine.com/shop/imag...lar-bar-da.jpg

I hear that most of the sheet metal is spot welded in place at the factory, and that seam welding anything you can get your hands on helps out. Then there is another option I have (heard) about and that is chassis foam. New cars like
Infinity use this at the factory and it is reportadly good stuff. Do NOT use any other kind of injection foam from the hardware store... they just dont work.
Read the article that Sport Compact Car Magazine did on this process here
http://www.sportcompactcarweb.com/pr...0zx/index.html
And it is on a 300ZX too!
As soon as I can get my hands on some, with the time... I want to do this to a couple of my cars.
- Dennis

I second the seam welding thing. Thats supposed to help quite a bit. As far as the foam goes I've heard good things about that too. Thats SUPPOSED to really stiffen the chassis though I've never talked to anybody who's actually done it. Only read about it.

Triangulate the front and rear strut bars.

I put this link concerning chassis braces available for Silvias in another thread
http://www.nissansilvia.com/forums/i...owtopic=146066
A well designed half cage will help, agree about the use of foam, some new cars are done with it at the factory.

Ive heard good things about the chassis goo, but the product I heard of was more like concrete. I would put a bar from the rocker to the top of the dash, tie the strut towers, and rails into it, then bars to the back of the rockers from the dash bars really stiffening the back is tough without a cage, If I had unlimited resources, id just cut the roof off do a cage, box tube in the rockers and rails, and chop the roof about 2 inches, cuz hey why not?

Ok heres the quote from the SCC article that I liked
Higher densities of foam can increase stiffness by up to 300 percent.
The stuff is a 2 part foaming epoxy so I guess it can get to be like concrete... just lighter :-) and no bars to crawl in over.

The Bob Sharp Racing Team And The Electromotive Race Teams Seam Welded There 280zx's With Super Success, They Had Just About Zero Flex. Of Course They Welded Every Seam On The Car And Had A Rollcage And Strut Tower Bracing That Was Engineered.

The stuff I heard about was 1 part i think, supposedly thats what the oems use, but I doubt it.

If you're not supposed to use the hardware store foam, then just where do we get the automotive stiffening foam and how much will it run?

I'm sure any foam that will expand and harend in the absence of air can be used. It's just a matter of getting the stuff that will be the most effective. Just find out what the stuff you're "supposed" to use has in it and then hit up the hardware store to find the cheap stuff that has the same ingrediants.

Looks like they spent under $200 on foaming the 300zx in SCC
Here is where they got the foam, as far as buying the cheap stuff, I wont be using anything from the hardware store.
The link to buy the stuff
http://www.foamseal.com/auto_after_ordering.htm
I havent found alternatives but am open to suggestion, except for the insulation foam found in hardware stores.

Maybe look for an epoxy foam rather than a polyester one? Thinking that the latter may absorb moisture. Marine, construction industries?

I dont think you will be able to find a comparable product for less $ I want to know if it really makes the chassis stiffer and how they tested it.

So anyone have any idea exactly where in the 280ZX the foam should be applied? Most hollow areas have wires running through them, or are areas that may need to be unbolted/removed at some point.

Personally, I'm wishing I could apply it to the inside of the door between the window and the outer skin, but it'd be too hard getting in there and I'm sure it wouldn't help much in a side impact collision. I mean, is it just me or does it look like there's nothing in the door to protect me from a side collision, especially since the car's so narrow I'm right up against the door?! A roll cage wouldn't be practical, though maybe a roll bar might help a bit if it's close enough to the seating area that it helps protect the passenger seating (ie getting side-impacted right behind the door area)

Rocker panels is where I've seen it used most. That and inside frame rails. If you pull up the door sills you'll see holes where the foam can be injected. And you can drill holes in the fram rails for injection too. And this isn't something you can just paint on a surface. You pour or pump this stuff into a channel and it FILLS it. It expands until the chemical reaction is done. So make sure where ever you put it has some way for the foam to work it's way out. And dont try to fill a large or long area all at once. Do it in increments. Foam is foam and when it starts expanding it doesn't stop just cause it hits a dead end. It'll pop seems or whatever it takes to keep expanding.

In the process of stripping out the interior, there is plenty of metal but some of the spot welds are a long way apart. Looks like there is plenty of seam welding to be done, should improve the body stiffness significantly.

I sugguest the upper structure, especially if equipped with T-tops. Any extra stiffness in the upper portion will help out. If you think about it the doors dont help too much with flex, so open the doors and all that is left connecting the rear to the front is the weak roof and the previously mentioned frame rails. Kind of box in the frame with foam instead of steel tube roll cage. Man I am going to save up and do this. As far as testing for the rigidity and other physical properties of the foam, just email the company I am shure the engineers have plenty of free info to bable on about. The biggest thing I like about this stuff is it is never seen and performs multiple functions. It stiffens, quietens, and seals all at the same time. It is a closed cell foam that does not allow water to penetrate it and thhus prevents rust. One drawback of major stiffining is you louse any crunch zones and impact forces are transmitted more readily to the occupants, so its a catch 22. Ok thats my last rant about this stuff. IM me if you wwant to talk more about this stuff... I like it and I am going to do it when $ shows up.