Stiffen your chassis up to 40% and add less than 20 lbs in weight?
12-29-2002, 09:25 AM
#1
Le Mans Master
Thread Starter
Stiffen your chassis up to 40% and add less than 20 lbs in weight?
Check out this article related to Foamseal Catalyzed Urethane Foam:
Foam-Filling the Chassis
In any high-performance car, it is impossible to make the chassis too stiff. The stiffer the chassis, the higher its natural frequency, making the energy imparted to it by bumps less likely to excite the body's structure. A stiffer chassis enables the use of stiffer springs and shocks without hurting the ride. This is because a stiff, non-flexing chassis transfers more force into the suspension where it can be dissipated by the springs and shocks instead of transferring the force to the occupants. A stiff chassis is also more responsive to roll rate tuning for balancing understeer and oversteer. This is one of the reasons why automotive engineers are continually investigating ways to stiffen chassis without adding weight.
In a final bit of reengineering to stiffen the body, we injected the chassis with catalyzed rigid structural polyurethane foam. 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.
To get the correct foam for our project, we contacted Art Goldman, Foamseal's automotive product manager and author of an SAE (Society of Automotive Engineers) paper on the use of structural foam for the stiffening of automotive unibody structures. We used Foamseal's two-component foam kit, p/n 11-22 to fill the main members of the chassis. Like we mentioned earlier, Foamseal is the supplier that I-CAR, a national certification group for quality auto repair, recommends for the repair of damaged, foam-filled chassis. The Foamseal kit uses a two-part catalyzed polyurethane foam, which quickly cures into rigid, waterproof, closed-cell foam. To prep the car, we carefully masked off all painted areas anywhere where the foam could drip. As this sort of foam is a thermosetting catalyzed plastic, we realized it could be icky if it spilled on paint or any part of the car's interior. This foam is nasty stuff. It is impervious to all known solvents and cleaners.
Rubber gloves must be worn. Get some of it on your hands and it will stay there for more than 3 weeks--don't ask how we know. Do not get this stuff on your paint. Wear old clothes; we ruined ours while learning how to handle the product. We injected the foam into the rocker panels and frame rails of Project Z through existing bolt and drain holes. When injected, the foam reacts like shaving cream and quickly expands to fill the empty space. You can judge how much foam to add by watching its expansion progress through some of the holes. Once injected, the foam expands and begins to cure in about a minute so you need to work fast and plan how you inject the foam before you start.
The life of the foam kit is limited to a few hours once the seal is broken. We filled all of the Z's unibody frame members using five foam kits. When foaming a chassis, you must remember the wires and other lines that pass through the chassis must be relocated or they will be entombed forever.
We were amazed at how this simple procedure improved the performance of the car. The chassis now almost feels like it has a roll cage. A sloped driveway can be driven up sideways with nary a creak. Even though the Z already has a pretty tight chassis, it feels more solid. The ride has improved and road noise has been reduced noticeably. We bet that the car will be even more responsive to chassis tuning measures in the future. If you are a slalom racer, a road racer, have a lowered car or even just want a smoother ride; foaming is a worthy, easy-to-do modification. Foamseal has foams in densities as high as 10 lbs per square foot if you desire to make things even stiffer.
Do not--I repeat--do not attempt to use cheap, hardware-store canned foam. This is not the same thing, and if injected into your chassis, will form a gummy mass that won't dry. Foamseal foam is a professional grade foam, which although it is a little unforgiving to cleanup mistakes, has superior mechanical properties and catalytic curing so it will dry even in an enclosed space.
The Foamseal Two Component Foam Kit consists of two easy-to-use aerosol containers of material with a nozzle and a mixing chamber.
As the foam cures, it expands with the excess coming out of the holes where it was injected. Note how it is important to mask carefully. If you accidentally use too much foam, you could have much more coming out of the holes than we did. If it gets in the carpet, it will never come out.
Here's the product website: http://www.itwfoamseal.com/auto_after_ordering.htm
I'm seriously considering trying this stuff. I sounds like a good way to strengthen and dampen the frame in an inconspicuous manner without adding alot of weight. Since the material is closed cell, it would probably also prevent the frame from rusting from the inside out. However, once you put this stuff inside the frame, there's no way to remove it - it's permenant....
[Modified by Monty, 8:27 AM 12/29/2002]
Foam-Filling the Chassis
In any high-performance car, it is impossible to make the chassis too stiff. The stiffer the chassis, the higher its natural frequency, making the energy imparted to it by bumps less likely to excite the body's structure. A stiffer chassis enables the use of stiffer springs and shocks without hurting the ride. This is because a stiff, non-flexing chassis transfers more force into the suspension where it can be dissipated by the springs and shocks instead of transferring the force to the occupants. A stiff chassis is also more responsive to roll rate tuning for balancing understeer and oversteer. This is one of the reasons why automotive engineers are continually investigating ways to stiffen chassis without adding weight.
In a final bit of reengineering to stiffen the body, we injected the chassis with catalyzed rigid structural polyurethane foam. 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.
To get the correct foam for our project, we contacted Art Goldman, Foamseal's automotive product manager and author of an SAE (Society of Automotive Engineers) paper on the use of structural foam for the stiffening of automotive unibody structures. We used Foamseal's two-component foam kit, p/n 11-22 to fill the main members of the chassis. Like we mentioned earlier, Foamseal is the supplier that I-CAR, a national certification group for quality auto repair, recommends for the repair of damaged, foam-filled chassis. The Foamseal kit uses a two-part catalyzed polyurethane foam, which quickly cures into rigid, waterproof, closed-cell foam. To prep the car, we carefully masked off all painted areas anywhere where the foam could drip. As this sort of foam is a thermosetting catalyzed plastic, we realized it could be icky if it spilled on paint or any part of the car's interior. This foam is nasty stuff. It is impervious to all known solvents and cleaners.
Rubber gloves must be worn. Get some of it on your hands and it will stay there for more than 3 weeks--don't ask how we know. Do not get this stuff on your paint. Wear old clothes; we ruined ours while learning how to handle the product. We injected the foam into the rocker panels and frame rails of Project Z through existing bolt and drain holes. When injected, the foam reacts like shaving cream and quickly expands to fill the empty space. You can judge how much foam to add by watching its expansion progress through some of the holes. Once injected, the foam expands and begins to cure in about a minute so you need to work fast and plan how you inject the foam before you start.
The life of the foam kit is limited to a few hours once the seal is broken. We filled all of the Z's unibody frame members using five foam kits. When foaming a chassis, you must remember the wires and other lines that pass through the chassis must be relocated or they will be entombed forever.
We were amazed at how this simple procedure improved the performance of the car. The chassis now almost feels like it has a roll cage. A sloped driveway can be driven up sideways with nary a creak. Even though the Z already has a pretty tight chassis, it feels more solid. The ride has improved and road noise has been reduced noticeably. We bet that the car will be even more responsive to chassis tuning measures in the future. If you are a slalom racer, a road racer, have a lowered car or even just want a smoother ride; foaming is a worthy, easy-to-do modification. Foamseal has foams in densities as high as 10 lbs per square foot if you desire to make things even stiffer.
Do not--I repeat--do not attempt to use cheap, hardware-store canned foam. This is not the same thing, and if injected into your chassis, will form a gummy mass that won't dry. Foamseal foam is a professional grade foam, which although it is a little unforgiving to cleanup mistakes, has superior mechanical properties and catalytic curing so it will dry even in an enclosed space.
The Foamseal Two Component Foam Kit consists of two easy-to-use aerosol containers of material with a nozzle and a mixing chamber.
As the foam cures, it expands with the excess coming out of the holes where it was injected. Note how it is important to mask carefully. If you accidentally use too much foam, you could have much more coming out of the holes than we did. If it gets in the carpet, it will never come out.
Here's the product website: http://www.itwfoamseal.com/auto_after_ordering.htm
I'm seriously considering trying this stuff. I sounds like a good way to strengthen and dampen the frame in an inconspicuous manner without adding alot of weight. Since the material is closed cell, it would probably also prevent the frame from rusting from the inside out. However, once you put this stuff inside the frame, there's no way to remove it - it's permenant....
[Modified by Monty, 8:27 AM 12/29/2002]
12-29-2002, 10:17 AM
#2
Le Mans Master
Re: Stiffen your chassis up to 40% and add less than 20 lbs in weight? (Monty)
Very interesting :yesnod: . Let us know if you try it, I'd be interested in hearing how the installation is :) .
12-29-2002, 11:00 AM
#3
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Re: Stiffen your chassis up to 40% and add less than 20 lbs in weight? (Monty)
Thank's Monty,
You know, there was a thread recently that talked about this. They were saying a lot of import cars were using this stuff. Sounds good to me, and it sure couldn't hurt... I wonder if it would make things a little quieter as well...
Did you have your frame seam welded? I haven’t but I'm thinking I should do it before the body goes back on. :lol: :crazy
http://forums.corvetteforum.com/zerothread?id=447699
[Modified by Stingraycrazy, 5:02 PM 12/29/2002]
You know, there was a thread recently that talked about this. They were saying a lot of import cars were using this stuff. Sounds good to me, and it sure couldn't hurt... I wonder if it would make things a little quieter as well...
Did you have your frame seam welded? I haven’t but I'm thinking I should do it before the body goes back on. :lol: :crazy
http://forums.corvetteforum.com/zerothread?id=447699
[Modified by Stingraycrazy, 5:02 PM 12/29/2002]
12-29-2002, 11:49 AM
#4
Le Mans Master
Re: Stiffen your chassis up to 40% and add less than 20 lbs in weight? (Monty)
When used by the OEMs in body structure applications, structural foam is a "band-aid". It's pretty dense and costs much more than actually engineering your structure correctly in the first place. If your targets are met by doing your design right the first time, there won't be a need for foam.
Now using it on your C3 to add stiffness to something that was designed around 1961... sound like a good application.
Matt
Body design engineer
One of the Big Three
Now using it on your C3 to add stiffness to something that was designed around 1961... sound like a good application.
Matt
Body design engineer
One of the Big Three
12-29-2002, 11:55 AM
#5
Team Owner
Re: Stiffen your chassis up to 40% and add less than 20 lbs in weight? (Scooter70)
Scooter, I have a 30 year old C3 frame under there, surface rust only,...but that' the thing....surface rust on inside also....and NO way to clean it...not easily anyway....not without doing a frame pulling, and acid dipping....I wonder if even then it would be clean enough inside to put that foam...I suspect it would do nothing but trap water as there is nothing for the foam to strondly adhear to, and the gaps and lack of air circulation would act to trap water forever....rust out in a year or less......
dirt accumulation over the last 30 years is of course also a problem....
any thoughts/comments???
thanks....
GENE
dirt accumulation over the last 30 years is of course also a problem....
any thoughts/comments???
thanks....
GENE
12-29-2002, 11:56 AM
#6
Team Owner
Re: Stiffen your chassis up to 40% and add less than 20 lbs in weight? ()
Very interesting:) Do you have any idea how many kits are needed?
Stingraycrazy if you have the most of the body off I would weld all the seams and consider doing the gusset kit around the rear trailing arms.
Stingraycrazy if you have the most of the body off I would weld all the seams and consider doing the gusset kit around the rear trailing arms.
12-29-2002, 12:17 PM
#7
Racer
Re: Stiffen your chassis up to 40% and add less than 20 lbs in weight? (Monty)
Not that it particularly applies here, but the OEs use structural foam only in the center section of the car, as use in front or rear rail structures would adversly affect the engineered-in collapse properties designed to protect the occupants.
Structural foam is commonly found in Ford rockers, and many japanese pillars.
Structural foam is commonly found in Ford rockers, and many japanese pillars.
12-29-2002, 12:30 PM
#8
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Re: Stiffen your chassis up to 40% and add less than 20 lbs in weight? () (gkull)
Gkull, I've got the offset trailing arms but I'm leaning toward welding the all the seams on the frame. The foam has an 8:1 expansion rate and becomes hard as a rock from what I've read online. I wonder if you used it on a stock non seam welded frame if it would separate the spot welds? Just a thought... :crazy:
12-29-2002, 12:33 PM
#9
Drifting
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Re: Stiffen your chassis up to 40% and add less than 20 lbs in weight? (Monty)
Monty, I had brought this up in the thread mentioned above and threatened to be the guinea pig, but if someone else is willing to try then I'm ALL for that! ;)
Seriously, I don't know if you've done any recent suspension work, but the best test would be to drive it around a bit before the foam and then add the foam and try it then so we are just testing the improvements with the foam by itself.
Anyway, I would LOVE to do this to my car one of these days. <sigh> ::adding another project to the list::
-terry
Seriously, I don't know if you've done any recent suspension work, but the best test would be to drive it around a bit before the foam and then add the foam and try it then so we are just testing the improvements with the foam by itself.
Anyway, I would LOVE to do this to my car one of these days. <sigh> ::adding another project to the list::
-terry
12-29-2002, 12:59 PM
#10
Re: Stiffen your chassis up to 40% and add less than 20 lbs in weight? (terryrudy)
I would only consider this if I had my frame zinc plated (dipped) when there's moist in there it will not rust (even when the zinc coat is cracked because of some stress)
Seems like an otherwise excellent idea though.
Marck
Seems like an otherwise excellent idea though.
Marck
12-29-2002, 01:23 PM
#11
Drifting
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St. Jude Donor '05
Re: Stiffen your chassis up to 40% and add less than 20 lbs in weight? (terryrudy)
I still think it sounds like a good idea, In the Thread C-3 Chassis Flex we had going a week or so ago I posted that the Foam was water resistant from the Flex Foam website. I would like to think that if your frame was dry at the time of application, it would remain so after applying the new foam.
Scooter70 Matt could you explain the theory behind the foam if you are familiar with it? Is it somewhat like GM impregnating the Balsa floor in the C-5 with epoxy? Or does it reflect the properties of structural cells?
Another good point was Frontal Impact to the frame and the inability to absorb the crash. I see no difference in this and an 8 point cage giving structure to prohibit the same.
I have reviewed the other thread several times and on my street car I see foam in its future also. Maybe I need to buy an extra frame to put up anyway.
I still believe we can add some type of spine and I eagerly await Jason Staley's report on the idea and how much will be required to suppor tour need.
I think that this may be a very good addition to our C-3's
Terry, Have you ordered that Flex Foam yet?
Oh yeah, they give bulk sales discounts also.
Thanks, JIM :smash:
Scooter70 Matt could you explain the theory behind the foam if you are familiar with it? Is it somewhat like GM impregnating the Balsa floor in the C-5 with epoxy? Or does it reflect the properties of structural cells?
Another good point was Frontal Impact to the frame and the inability to absorb the crash. I see no difference in this and an 8 point cage giving structure to prohibit the same.
I have reviewed the other thread several times and on my street car I see foam in its future also. Maybe I need to buy an extra frame to put up anyway.
I still believe we can add some type of spine and I eagerly await Jason Staley's report on the idea and how much will be required to suppor tour need.
I think that this may be a very good addition to our C-3's
Terry, Have you ordered that Flex Foam yet?
Oh yeah, they give bulk sales discounts also.
Thanks, JIM :smash:
12-29-2002, 06:58 PM
#12
Drifting
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Re: Stiffen your chassis up to 40% and add less than 20 lbs in weight? (PROSOUTH)
Jim, no I have not ordered the foam yet. I was hoping there would be a group discount. I am up for it if we can get a group deal going, though I'll be up for it anyway, after I recover from the holidays.
-terry
-terry
12-29-2002, 07:15 PM
#13
Le Mans Master
Thread Starter
Re: Stiffen your chassis up to 40% and add less than 20 lbs in weight? (terryrudy)
I must've missed the other thread where this was mentioned, sorry for the dupe. I just came across it this morning in a magazine and checked out the website. It looked like an interesting idea but I had never heard of it before.
I think I'm going to do it next winter.
I think I'm going to do it next winter.
12-29-2002, 09:49 PM
#14
Le Mans Master
Re: Stiffen your chassis up to 40% and add less than 20 lbs in weight? (Monty)
This sounds good, but I am sceptical for some of the reasons that Gene mentions.
Mainly, can you get the stuff to stick good enough to a 'weathered' frame.
I'm gonna stick to seam welding and maybe some gusset work.
Mainly, can you get the stuff to stick good enough to a 'weathered' frame.
I'm gonna stick to seam welding and maybe some gusset work.
12-30-2002, 12:14 AM
#15
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St. Jude Donor '05
Re: Stiffen your chassis up to 40% and add less than 20 lbs in weight? (Daves_rusty_75)
Dave I don't think there is any stick to it. This is a lot like the packing foam you see in packages being sprayed in to a piece of plastic wrap,It expands and contours to everthing it meets. From what I understand this foam actually puts a low pressure against the inside of the frame trying to swell. This consumes the entire frame cavity creating a structural beam instead of just an empty tube.
The C-5 has a Balsa floorpan. It in its self is not strong at all. But when you impregnate it with an epoxy it becomes extremely rigid. I understand this application of foam in a C-3 tube to be an example of the C-5 Balsa and Epoxy both in one application. The foam enters the cavity and expands completely filling the frame tube and then the foams cellular structure hardens and creates an extremley rigid beam within the frame tube.
I don't think there is any stick to it to it.
The manufactorer says it is not water retentive. However I can't say that the filling of the cavity will or will not promote rust. My frame is good, If it will last twnty more years I won't have to worry about it anyway. If it doesn't, I see a tube frame with C-5 running gear in my future. :yesnod: JIM
Hope this was correct? JIM :lol:
The C-5 has a Balsa floorpan. It in its self is not strong at all. But when you impregnate it with an epoxy it becomes extremely rigid. I understand this application of foam in a C-3 tube to be an example of the C-5 Balsa and Epoxy both in one application. The foam enters the cavity and expands completely filling the frame tube and then the foams cellular structure hardens and creates an extremley rigid beam within the frame tube.
I don't think there is any stick to it to it.
The manufactorer says it is not water retentive. However I can't say that the filling of the cavity will or will not promote rust. My frame is good, If it will last twnty more years I won't have to worry about it anyway. If it doesn't, I see a tube frame with C-5 running gear in my future. :yesnod: JIM
Hope this was correct? JIM :lol:
12-30-2002, 07:40 AM
#17
Team Owner
Re: Stiffen your chassis up to 40% and add less than 20 lbs in weight? (mrvette)
Scooter, I have a 30 year old C3 frame under there, surface rust only,...but that' the thing....surface rust on inside also....and NO way to clean it...not easily anyway....not without doing a frame pulling, and acid dipping....I wonder if even then it would be clean enough inside to put that foam...I suspect it would do nothing but trap water as there is nothing for the foam to strondly adhear to, and the gaps and lack of air circulation would act to trap water forever....rust out in a year or less......
dirt accumulation over the last 30 years is of course also a problem....
:iagree:
My thoughts exactly. The only time I think that I would try this is during a body off job. Then I could get the frame dipped and coated, then I would foam it. It sounds like a neat concept and if my body ever comes off I would consider it strongly.
John
dirt accumulation over the last 30 years is of course also a problem....
:iagree:
My thoughts exactly. The only time I think that I would try this is during a body off job. Then I could get the frame dipped and coated, then I would foam it. It sounds like a neat concept and if my body ever comes off I would consider it strongly.
John
12-30-2002, 08:08 AM
#18
Team Owner
Re: Stiffen your chassis up to 40% and add less than 20 lbs in weight? (theandies)
I can see this working pretty well on new steel, but I can NOT see it working well on our cars...just too much crud allowing gaps in the fill....
if there are gaps...say flakes of rust/dirt....well the water will win that battle....
as a contractor, doing kitchens and bathrooms....the old saw....'water wins'..seems to apply here too.....
GENE
if there are gaps...say flakes of rust/dirt....well the water will win that battle....
as a contractor, doing kitchens and bathrooms....the old saw....'water wins'..seems to apply here too.....
GENE
12-30-2002, 12:10 PM
#19
Drifting
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St. Jude Donor '05
Re: Stiffen your chassis up to 40% and add less than 20 lbs in weight? (mrvette)
I had remembered a Company called Ziebart when this came up the other day. They have been shooting foam into cars for years. I tried to find some information on their process on the net but couldn't find any details on it. It did say that they had a process to stop rust in late model cars and cease any further corrosion. Anyone remember them from past experiance? they do have a temperary system that is called drippless oil that is applied annually. If it ws applied and then the foam shot in looks like that might work even better.
The next option is to spray POR-15 into the frame and stop or seal the rust from further growth. The third is some new electrical process for rust protection, and finially to just let the dang thing rust as it is going and see which would be the quickest.
POR-15 works on the theory of sealing out O2 which fuels the corrosion. Would this foam do the same? Would the POR-15 and the foam do even better?
The next option is to spray POR-15 into the frame and stop or seal the rust from further growth. The third is some new electrical process for rust protection, and finially to just let the dang thing rust as it is going and see which would be the quickest.
POR-15 works on the theory of sealing out O2 which fuels the corrosion. Would this foam do the same? Would the POR-15 and the foam do even better?
12-30-2002, 01:14 PM
#20
Re: Stiffen your chassis up to 40% and add less than 20 lbs in weight? (PROSOUTH)
I'll bet a contraption could be made to address some if not all of the corrosion issues inside the frame. Think of a long rubber hose (or clear flexible plastic) plugged at the end. Put a bunch of pin holes around the circumference. feed that end into a opening in the frame. Attach the other end to a paint gun and run that sucker all through the frame. If you started with a naval jelly type (muriatic acid) of mixture, it would neutralize all the rust. then apply POR15 or eastwoods paint. Then fill it with foam. This foam is VERY VERY VERY sticky and will take weeks to wear off if you get it on your skin, so maybe if you treated the surface rust first and then sprayed the foam in, it would seal up every path for water to get into the frame.
I think the surface rust and sealing in moisture is a legitimate concern. Maybe this idea would address it. What do you think? This is definitely a summer time project.
Chris
I think the surface rust and sealing in moisture is a legitimate concern. Maybe this idea would address it. What do you think? This is definitely a summer time project.
Chris