Chassis stiffening foam result - Part 1, qualitative result*

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H8tred
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Chassis stiffening foam result - Part 1, qualitative result*

Postby H8tred » Wed Aug 08, 2007 11:56 am

This is my qualitative result, and I will share my quantitative (experimental research) later once I collected those data.

I was first inspired by Mike Kojima project Z32, and really motivated by Epstein(Chris) and the SAE paper 1999-01-1785.

Previously, we had serious and detail discussion over the pro and con of chassis foam; there were plenty of successful cases out there, like Kojima's project Z32, Mines, Apexi, and MCR demo R34; and maybe more. And what really get me going is the test results and strong evident from the SAE paper by Daimler Chrysler Corporation, which performed a test on a SUV. So I want to try this first hand.

Before I start describe the qualitative result, i want to share some result that was performed by Daimler Chrysler Corp first, and due to copyright, I can not post the entire article here.

First of all, Vibration 101: Natural Frequency of a body is square root of stiffness of the body over mass of the body.Fn = (K/m)^(1/2)K is the stiffness coefficient of the body, m is the mass, Fn is natural frequency. So the stiffer the body, the higher the natural frequency.

Credit goes to Daimler Chrysler

here is a study of which joint is most sensitive to foam filling



Here is the original Abstract of that SAE paper 1999-01-1785

Quote »Stability and structural integrity are extremely important in the design of a vehicle. Structural foams, when used to fill body cavities and joints, can greatly improve the stiffness of the vehicle, and provide additional acoustical and structural benefits.This study involves modal testing and finite element analysis on a Sport utility vehicle to understand the effect of structural foam on modal behavior. The modal analysis studies are performed on this vehicle to investigate the dynamic characteristics, joint stiffness and overall body behavior. A design of experiments (DOE) study was performed to understand how the foam's density and placement in the body influences vehicle stiffness. Prior to the design of experiments, a design sensitivity analysis (DSA) was done to identify the sensitive joints in the body structure and to minimize the number of design variables in the DOE Study.[/quote]And the Conclusion:

Quote »The most sensitive area of the body were found to be the A-pillar, the D-pillar and their joints. With structural foam injected into this sensitive areas, the vehicle body was significantly stiffened, as shown by the increase in modal frequencies. The 1st torsional mode was most effected with an increase of 29.1% in modal frequency.The design sensitivity analysis and design of experiments described here, can be used to identify the sensitive ares of the body structure. This results are useful in the determining the best application locations for structural foam.[/quote]--------------------------------------Well, enough talking, let's get down to business. First of all I want to thanks God gave us a safe working environment; my boys Ryan and Jason whose came all the way to my house to help me; and my fiancée, Julie who put up with our boys for the entire weekend.

At first we tried to do some physical measurement of the chassis flex, like how much the door gap distort and close up while it was jacked up,

But it was no luck, we ended up having 3 wheels off the ground, and the door still shut perfectly, i was impressed and yet upset.

We should have measured the distance between the frame rail holes as described in the FSM. But we were ready to Git-R-done.

First step is remove both seats, interior trims, and carpet. So the A,B,C pillar and rocker panels are fully exposed.

A pillar (noticed the drain hose)

B pillar

C pillar (again, another drain hose)

the longest process is the tape everything carefully, since that junk will harden and sticks on the paint if you are not careful. Here is the rocker taped up.... "me love you long time"

Duct tape works wonderful to cover up some big holes.

Handifoam II-22 kit

Have the interior well cover is very important, get duct tape ready to cover the holes after injection

Foam filled rocker panel

as you can see, it was a good, uniform, completed fill...

We found a trick, it is filled the cavities more than enough, and before it expands out of the holes, cover it with duct tape to force the foam to have a tighter fill, result as a slightly higher density.

completed Rocker

completed A pillar

completed floor pan cross rail

completed B pillar

B pillar middle

completed C pillar

everything back together

like nothing happened at all


Modified by H8tred at 6:51 AM 8/9/2007


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Re: Chassis stiffening foam result - Part 1, qualitative ... (H8tred)

Postby H8tred » Wed Aug 08, 2007 11:57 am

Impression:

This stuff works!!!

I'm very happy. Not only the turn in is quicker, the poping noise I used to had when I load/unload the rear suspension on a hill/curb is gone.I think filling up the joint between the A-pillar and the firewall helps the most, since the front end is much stiffer, and I started to experience more initial entrance understeering that I didn't have before.

The over all dynamics of the car is solid, and I can feel my suspension is working, also I might need some tires with stiffer sidewall b/c I finally able to feel the flex in the tires. Also I can feel all those slop from the worn out bushings. I can't sense none of those feedbacks before.

Another dramatical result I experienced is, I never able to lock up my rear brakes, I have Q45 brakes front, and stock rear, that's a very bad front bias setup (About 78.5% front from calculation). But since the rocker panels are filled, I guess the rear does not "droop" anymore under extreme weight transfer, and the rear tires are lift up more since the middle is way siffer, and now I'm able to lock up the rear tires under some very heavy stop. Then again, the gutted trunk doesn't help here.

In some slow-mid speed corner, I can induce throttle oversteer quicker and has more linear feedback. I want to describe it as its easy to do weight transfer and it helps rotate the car around some tight stuff. Kinda similar my first impression when i had VLSD and thicker rear swaybar

Another impression is driving across the railroad tracks and bridges gaps, it feels much smoother and less bumpy, quieter too.

So overall it feels like a new car. The car behave differently since I have more entrance under steering, and I have to re-learn how to modulate my brakes.

just for reference information, here is what I have on the car.

Front & Rear strut tower barsProject Silvia Tension bar (similar to Nismo powerbrace)Powertrix spherial solid T/C rod (with upgraded rod ends)Tein S tech springsAGX adj. shocks.Stock front anti roll barS13 HICAS 21mm rear anti barPolyuretane endlinks bushings.SPL subframe spacers

I think those are the only items that are relevant to the handling feedback. So I'll leave the rest

That's all I have so far, if I missed something, I will add them later on.

thanks for you time.

ps. I drove my fiancee's S14 and my car back to back, and also compare it to Ryan's S14, My S14 is definitely the stiffest I want to say it is as stiff as the S2000, closest feeling is probably the 350z that i drove, Ryan said its stiffer, idk

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Re: Chassis stiffening foam result - Part 1, qualitative ... (H8tred)

Postby H8tred » Wed Aug 08, 2007 11:57 am

a few tips:

Dress properly, gloves, old cloths, shoes, pants, and hat are recommended.Few of these foam got skeet skeet on Ryan, and it took him a very long time to scrub all of them off his hands.

Don't inject these foam if it is under 50F, it was recommend to do it around 75F. otherwise the expansion rate won't be consistence.

Shake well before use, and plan ahead, since the mixed foam will harden within minutes, if you are not careful, you will waste a nozzle (each kit supply an extra nozzle).

Use duct tape, spray a bit more than enough (manufacture recommend 1/3 of the volume), let it expands and cover it with duct tape and force them back into the cavities to ensure 100% uniform fill.

Fill those cavities when the car was on ground level, pay attention to JOINTS, that's where most of the gain come from.

Have fun doing it, and tell your friends how much you appreciated their help, since this is not a one man job.

FYI: a few useful information

MSDS component Ahttp://www.fomo.com/pdfs/A1617...5.pdf

MSDS component Bhttp://www.fomo.com/pdfs/A1617...5.pdf

TDShttp://www.fomo.com/pdfs/A1612...2.pdf

foam free rise density 1.75pcffoam in place density 2.00 pcf

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Re: Chassis stiffening foam result - Part 1, qualitative ... (H8tred)

Postby H8tred » Wed Aug 08, 2007 12:01 pm



Again, this write up is thanks to Phillip AKA "gunluvS14" from Fresh Alloy. Many thanks to him. The only part I had in this was asking his permission, rehosting the images, and more cutting and pasting than I ever hope to do again.

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Postby downshift180 » Wed Aug 08, 2007 12:35 pm

not bad at all.

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Re: Chassis stiffening foam result - Part 1, qualitative ... (H8tred)

Postby 91RMKS13 » Wed Aug 08, 2007 12:39 pm

Sticky.

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Re: Chassis stiffening foam result - Part 1, qualitative ... (H8tred)

Postby Death By Thrash Metal » Wed Aug 08, 2007 2:44 pm

Hell Yes H8tred! i really do hope i inspired you to do it even though i didnt Great Job nonethe less!!!!

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Re: Chassis stiffening foam r ... (Death By Thrash Metal)

Postby H8tred » Wed Aug 08, 2007 5:55 pm

Death By Thrash Metal wrote:Hell Yes H8tred! i really do hope i inspired you to do it even though i didnt Great Job nonethe less!!!!
You inspired me to post this lol, I have rust on my rockers so this isn't something that I want to try right this moment. This is the article from Fresh Alloy reposted here with the permission of the author. I read the long before I got a 240, and had talked about doing it to my 4th gen civic... I would suggest getting coilovers first, and riding on them for a year or so; you can feel where the flex is, and what needs to be reinforced.

I'll post a thread about the goings on of my car soon. A nice little diy JB Weld rust repair...

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Re: Chassis stiffening foam r ... (H8tred)

Postby Death By Thrash Metal » Wed Aug 08, 2007 6:01 pm

sounds great!im dissapointed this year is gonna suck... school starts in a few weeks... i probably wont get a 240 till im 15 1/2 which is in january... meh... maybe if i push my parents i can get it a little earlier, and tinker with everything...i cant wait, i have sooo many ideas that i want to try out, and if they turn out good ill make some tuts... FI HERE I COME!!!!

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Postby Florida240sx » Thu Aug 09, 2007 1:56 am

Where'd you get it from and how much did it use and cost?I can get great stuff from my old work which is household expandable foam. Use it for window/dorr installation blue can and then red can for gaps and cracks, if it's used on a door you'll never get he door open because it swells the door jam shut into the door.

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Re: (Florida240sx)

Postby H8tred » Thu Aug 09, 2007 4:09 am

Florida240sx wrote:Where'd you get it from and how much did it use and cost?I can get great stuff from my old work which is household expandable foam. Use it for window/dorr installation blue can and then red can for gaps and cracks, if it's used on a door you'll never get he door open because it swells the door jam shut into the door.
He said in a later post that he bought 2 of the II-22 kits with plenty left over.

As far as "Great Stuff", my personal experience with it is that it isn't nearly as dense as this stuff. Not that I personally have used any.

The Great Stuff web page doesn't outline any technical data on their page, but I did see that the normal can, and the Great Stuff Pro are made from polystyrene and polyisocyanurate.

So yeah, I don't see Great Stuff working at all in a structural application.

From the original thread started by Death By Trash Metal:
krazydriver wrote:
the problem with the home depot foam (great stuff) is that it expands and hardens when exposed to moisture/humidity. Put it in your frame rails and it will never cure properly... it'll just end up a soft sticky mess.you need the 2-part foams so they chemically cure even though it's in a tight enclosed space.

I was actually planning on doing this to my hatch a few months back... then i realized it would really mess with my ability to repair rust/fix damage/weld anything. So i skipped it and started stitch welding.
you can purchase it from herehttp://www.foampower.com/store....html

or at Grainger (this one is the II-12 kit, smaller capacity vs. the II-22 kit, credit goes to Epstein, he found this at Grainger)http://www.grainger.com/Graing...74493

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Re: (H8tred)

Postby Death By Thrash Metal » Fri Aug 10, 2007 1:13 am

~~~~~Edit: i forgot to mention that the below info is about the home depot stuff IT IS NOT WHAT YOU WANT TO USE IN YOUR CAR (for this project at least) its an HOMEDEPOT FOAM=INSULATOR~~~~~~~~~~~~Like i posted in the starter thread it isnt actually hardening material. It is an insulative. I know because we have used it when remodled my shower, and also my dad (electrical engineer) has his students rund conductivity tests as a lab. They make a little box of the stuff where they put somthing inside (not sure what specifficaly, I think my dad changes what it is yearly) and check how much signal is lost, and whether or not it conducts electricity. they also use a cardboard box ect... to see the diferent signal qualitys as results of different insulators. Im pretty tired so thats probably why it was a bit repetative.But i strongly suggest NOT using that stuff, as it will hardly do ****, and then just fill up your joints with non efficent ****. Take my word for it, that stuff is only a few times stronger than styraphone. And this is one of those things that is cheap, so its best to do it right the first (and only possible) time.

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Postby jdm_master_X » Fri Aug 10, 2007 2:49 am

finally somebody who went ahead and did what most people felt was a waste of time. you definitely did your research and now this is a must do on my list.

excellent work. i vote sticky status!

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Postby pr240sx » Sun Aug 12, 2007 1:54 pm

Well, I did this on my S13 and was a complete disaster.Not only the filling was hard, the actual cleanup of the mess is a headache.

I bought my kits at Grainger, dunno if these kits have an expiration date of some sort but the only thing I could marginally fill was my A pillars.I did this on 4th of July weekend and still cleaning the uncured liquid foam. Not to mention the awfull smell.

If you are going to perform this on your car, be warned and prepared, and wear throwaway clothes!! this thing is sticky as hell!

Well, let see what another chassis reinforcement I can find

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Re: (pr240sx)

Postby H8tred » Mon Aug 13, 2007 5:34 am

Can't really say what went wrong on you application. Did you shake it up?

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Postby pr240sx » Mon Aug 13, 2007 12:47 pm

I shake both cans for like 5 mins or so, temp was 85 to 95 F 80% humidity or soNormal sunny tropical day.At first, the spray worked great, at the second pour, no less than 5 secs after first pour. After this, the process went from bad to worse

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Re: Chassis stiffening foam result - Part 1, qualitative ... (H8tred)

Postby Kaferwerks » Tue Aug 14, 2007 5:40 am

id be weary of the long term effects of such a thing.vw started using foam in the rear area of beetle bodies in the early 70's (around 71-72 i believe) the vast majority of these late model cars have mild to severe rust issues in those areas due to the foam trapping moisture.

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Re: Chassis stiffening foam result - Part 1, qualitative ... (Kaferwerks)

Postby srpowered240sx » Tue Aug 14, 2007 6:14 am

sweet *** improvements, inspired me to do it too. one quick question, if you fill up all the holes to mount the a-pillar trim, rocker panel trim, b-pillar trim, and any ther stuff, how to you re-mount the trim?

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Postby AZhitman » Tue Aug 14, 2007 6:36 am

^ Good question.

I'd also be curious about the effect of using this process in the "frame rails" such as they are.

Well done, H8tred.

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Re: (AZhitman)

Postby H8tred » Tue Aug 14, 2007 9:48 am

Someone asked him the same question on the FA forums. Asked if he had to drill the foam to get the panels back on. He said there were no problems getting the clips back in their holes.

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Postby pr240sx » Tue Aug 14, 2007 9:54 am

Well, you are not pouring concrete!

You can easily push the trim clips back or even poke the foam with a nail or a screwdriver just in case.

this particular foam does not collect moisture, or at least any quantity that could create any problemYou should be more concerned about rattling or the foam becoming loose inside the part.

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Re: Chassis stiffening foam result - Part 1, qualitative ... (H8tred)

Postby mirochuki13 » Fri Sep 14, 2007 3:31 pm

Nice thread.

This looks like a great way to stiffen the car. I think I'll try it on my S13 and do a writeup.

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Postby fullmetal » Mon Jan 12, 2009 1:20 pm

I know it has been a while but does any one know what the density is of this stuff? I know that the marine level is 8lbs and 16lbs I was thinking about using that stuff for the frame rails and what not on the lower section then this stuff up top but I would like to know what the difference should be in density and rigidity.

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Re: (fullmetal)

Postby fullmetal » Mon Jan 12, 2009 1:54 pm

sorry I found it this stuff is 1.75 lbs they also have some that is 3 lbs

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Re: (fullmetal)

Postby H8tred » Tue Jan 13, 2009 1:20 pm

Right on man. I forgot all about this thread haha.

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Re: Chassis stiffening foam result - Part 1, qualitative res

Postby chingaling » Sun Jul 11, 2010 3:37 am

anyone knows if these items ship to australia ?

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Re: Chassis stiffening foam result - Part 1, qualitative res

Postby Chaotic_Warlord » Fri Jun 15, 2012 5:06 pm

Zombie thread revival... Interested to see what kind of long term results this has. Any cracking or change in stiffness after a few years? I'm thinking of doing this as I am trying to reduce body roll and stiffen the frame for better handling in my S14.


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