Jerk_Racer

Who here has used foam to stiffen up their frames? Any words of wisdom for those looking to go down this path would be most welcome. Thanks.

jerk_racer@hotmail.com

No7Yet

Not many people. The FC frame, while perhaps not up to S2000 standards, is pretty good. When most people want to stiffen it up, they just get a roll cage That's my rec.

Brandon

FPrep2ndGenRX7

I researched that pretty hard last year and decided it wasn't worth it. If you could figure out exactly where to put the stuff in the chassis it might be worth it, otherwise you would just be sticking it in a hole and hoping for the best. I'll put my money toward known good upgrades till then.

Icemark

Yeah I have done it in the running board frames on all my RX-7s.

Night and day difference, worth every penny of the $50 to do it.

Hell you could even do it for cheaper than that by buying the stuff in the can at Home depot. Those cans are only $4 a piece and you would only need 3 or so per side rail.

FPrep2ndGenRX7

Icemark - There is a big difference in the Home Depot foam for insulation and the industrial grade structural foam. If you felt a difference then there might be even more to gain from using the industrial structural foam if thats not what you used. I had a link for it at one time. I'll try to find it again.

Icemark

My first two RX-7s I used the same structural stuff used in the 90's T-birds. Cost around $50 to shoot in (when I did the dissassembly to the running boards).

Two part hard set polyurathane expanding foam, mixed in gun, injected into the car's cavities.

From what I felt, there was little to no difference. You could barely push a finger into either when it is set correctly. Maybe I need to go find the brand name of the home depot stuff, as they carry several diferent types.

RETed

You're probably referring to the article that was printed in Sport Compact Car by Mike Kojima.&nbsp I know the guy...

It was an interesting article nonetheless.&nbsp It was backed up with SAE information (I've gone through that those too) which made a lot of sense.&nbsp The article proposes that the possible gain in stiffness was great considering the cost of the product.

Now, what a lot of people do as mistakes...&nbsp You cannot use the consumer stuff that is available at the local hardware store.&nbsp You need to find INDUSTRIAL-grade 2-part catalytic urethane foam - this stuff is not easy to find.&nbsp The FC has a number of potential area which can be foamed - just look at the side sail (B-pillars) and crossmembers right behind the rear seats.&nbsp I would assume this procedure would give the FC some serious stiffening, considering we're talking under $100 worth of materials...



-Ted

Samps

How much does the stuff weigh?

RETed

It's typical of the consumer grade stuff that you can get at the hardware store.&nbsp I believe one of the brands is called "StuffIt" in the red and yellow can (don't use this!).&nbsp The industrial grade stuff comes in different densities and a lot more stable than the spray can stuff.&nbsp It's expanding foam, so it's very light!&nbsp Any one who has unpacked packages with this this stuff (especially spcialty computer equipment) knows how light it is...



-Ted

FPrep2ndGenRX7

I'll find the link and post it samps.

Ted, I researched the foam starting with the article you are talking about. Forgot the brand name. I should probably try it in my FP car. $100 isin't alot in great scheme of things.

KNONFS

iTrader: (14)

Hey Ted,

I think you can get that product from :
www.selectproducts.com
But its not meant to be used on a air gun (I think). I used to use this product for car audio things!

Jerk_Racer

This is more of what I was asking about.
http://www.farwestmaterials.com/polyfoams.htm
I've heard it can be messy, and it's completely permament. I don't see a problem with pulling the wiring from these cavities to keep them from being entombed and therefore unable to be serviced if need be in the future. I would like to get a cage in my car, but right now that is not feasible. My head will be touching it if it were in place. I'm 5'10" but sit very upright. With a helmet on I have to slide my seat back and tilt it some more just so my head has a bit of space around it. This should be remedied whenever I get around to installing a bucket seat as low as I can go while still allowing for fore/aft movement. I understand (and very much desire) the merits of a cage. Better insurance than any company can provide in case of accident. However, I also want a very stiff car in the meantime.
I just assumed that some other FC owners have done this and would be willing to give their ideas upon this.

jerk_racer@hotmail.com

RETed

I did a quick search on Yahoo with "expanding foam sport compact car" and got one decent hit off a Miata GB on the materials.&nbsp That might be a good place to start?

Some background on Kojima - he's an engineer, and he's a straight up kinda guy.&nbsp I don't mean to attack your comments, but everything that Kojima has said has always been useful for me.&nbsp He used to be one of the head guys at TRD, before they killed the program a few years ago (don't talk to him about Toyotas!), adn now he's with Nissan (probably with the new Nismo program in the U.S.).&nbsp You might want to talk to him directly yourself, as he's a contributing editor for SCC magazine - there should be an e-mail address for him in the mags?


-Ted

SoloIIdrift

this is very interesting, never head of this before, which issue of SCC was this in, and how stiff would it make the car, would anyone do this on a semi-street driven car?

RETed

This was like 1 or 2 year ago - pretty far back.&nbsp the results were subjective (I don't think we all have a multi-million dollar 3-, 4-, 5-, 6-, 7-axis vibration table to fit a car on!), and there was a "noticable" decrease in chassis flex.&nbsp The SAE papers claim it's possible to increase chassis stiffness up to 40%!&nbsp 10%-20% was typical.



-Ted

SoloIIdrift

I see, so you think 20% would make it a bone jarring ride on the street? Doesn't seem like it.

FPrep2ndGenRX7

Stiffening the chassis will not cause a bone jarring ride. Bone jarring ride is from coils and struts. By cutting down on chassis flex you've decreased one variable you have to deal with when tuning your suspension. If the attachment points for your suspension don't move as much your alignment stays closer to what you want when driving. Atleast that's the benefits I see.

Jerk_Racer

I remember the SCC article with the 300ZX having it done. What most recently brought to my attention was an article in the December issue of Option2 where they did this to a FD. The foam was just poured into the frame via holes drilled into the door sill. They also had these braces for the FC that ran along side the frame rails (bolted through the floor pan) and these other braces that attached to the door hinges that came together at the top of the wheel well. These braces were under the fender skin of course. It was the foam that seemed pretty universal in nature. If it works as it should then it should help most applications. People will spend all sorts of money in other areas to get even less results so I figured why this isn't more common.

jerk_racer@hotmail.com

FPrep2ndGenRX7

Not well known plus you have to know were to apply it to a car to make it worth while.

RarestRX

Yo,


My buddy Jon did it to his GTUs:

http://www.geocities.com/dorifto/urethane.html


And you might want to check out his main site:

http://www.geocities.com/dorifto/

He's a total gearhead and one of the founding members of Team GTUs!!

KS
1989 GTUs "Doriftoooo time!"

RETed

WHOA!&nbsp One thing I got against that link RarestRX dropped is that DO NOT DO THIS WITH THE CAR JACKED UP.

It's the same principle about installing a roll cage with the car in the air.&nbsp You do not want to do that, because you're changing the chassis dimesions just a little bit.

Please, if you're going to try this, do it on a level surface with all four wheels on the ground.&nbsp This is where the chassis is at rest.&nbsp Putting the car up on jackstands is going to tweak the chassis a bit.&nbsp Using the expanding foam is going to load the frame up, but once you drop it down you'll have a chassis that's under weird stress, because it was stiffened while up in the air.




-Ted

RarestRX

Yo,


I think Jon used the jack while the foam was still liquid, so it would "slosh" forward to get complete coverage, then he used the jack to slosh it back towards the back...

That's what I think....

Or...looking at the pictures...I think he jacked it up by the differential so the chassis isn't loaded, or it's loaded by the suspension, not jackstands....


KS
1989 GTUs "Yep."

Silkworm

Rarest,

Ask Jon if he likes that picture on his main page.. I took it

I agree with Ted however, even with it jacked by the rear diff there's going to be some stress on the chassis. Tempted to try this on the Trans Am

PaulC

ps. tell him not to stress about the pic, it's cool

RarestRX

Yo,


Hey, he gave ya props on the pic!

Head on Photo! Woo hoo!

You used to be NASA's main photographer, or was that after?

Someone took a SWEET *** pick of my Scirocco going through 8A at Sears Point.

I'll tell him I didn't rat him out to Da Man.

*grin*

KS
1989 GTUs "Good job!"

Silkworm

No, we're still NASA's photographers... We stopped putting our copyright on the pics since people complained.. S'alright, we do ok without it.
Come by and visit http://www.headonphotos.net
PaulC