Foam Filling of Vehicle Chassis's

I wouldn't do it...for several reasons.

1) Many of those foams will hold water if submerged.

2) Over time, any bending and flexing of the chassis can crack the hardened foam; if it cracks, any embedded wiring will break as well.

3) If you or anyone else ever has to take it apart, it's going to be a royal pain.

I've had good luck with these types of products. They help deaden vibration, and seal all metal surfaces.

https://www.rustoleum.com/CBGProduct.asp?pid=364

Not to forget the out-gassing of toxic fumes over time.

I would think if it was really a good idea auto manufactures would be doing it, too.

Don't forget the expansion pressure as well, blew the sills of a car once with foam

For some reason I was thinking that he wanted to fill spaces in the body, like inside fenders; however, I'll stick with my original assessment.

A quick search shows that Land Rover chassis' come with drain holes in them, which would be blocked by the foam. I could easily see water finding it's way into the chassis, with no way to escape. It wouldn't take much to get it starting to rust from the inside out.

The designers probably had a good reason for wanting it to breath.

Agreed.

I wouldn't think a Land Rover's chassis would not need to be stiffer than the original strength. It IS a Land Rover, after all.

I can understand not wanting to get mud and salt water buildup in the chassis, which seems to be a common problem.

If it was mine, the only modification that I might think about making, would be to add a port(s) to the chassis, that you could attach a water hose to. That way you could flush the entire thing out after a day of romping in the muck.

Back in the late '70s when I had a macho 4 WD I played in the mud every time it rained.

That was about 10 times a year here in AZ.

All I ever did was spray what I could get to at the (then) quarter car wash. It was still going strong after 20 years when I sold it.

I think there's a good chance that Norm's car could see some beach/saltwater action.

https://maps.google.com/maps?hl=en&source=hp&q=townsville+australia&oq=&ie=UTF-8

How true!

All the more reason to NOT foam it, but rinse it as you suggest.

I have done this to reduce vibration and provide sound deadening.

Most vehicles do not run any type of wiring through the chassis or frame members. In fact, I cannot think of any vehicle I have owned that did, which isn't to say they there aren't vehicles out there which have that.

I am about to undertake something similar with my '07 Wrangler, which collects an unseemly amount of mud throughout nooks and crannies which only contributes to vehicle weight and balance issues. This is especially noted between running gear rock shields and the items they are designed to protect.

Specifically, I did this on my '90 Cherokee and never regretted it.

Did you foam INSIDE the chassis/frame tubes, or body panels?

Just curious.

Both...but I made sure that where I filled did *not* have wiring that would be trapped.

The situations which were/may have been created couldn't have been any worse than those created by Jeep/AMC/Chrysler engineers.

Have you seen the rear quarters on most of those vehicles in areas of the country where detrimental debris (salt/sand) is allowed to collect in the many nooks and crannies? I solved that issue on at least one account.

Around here the auto body guys hate everyone who foams any part of their vehicles.

No matter how ell rated the foam may be to repel moisture once it's put in a vehicle it seems to do just the opposite and promotes rust like crazy.

Plus should any further body or metal repair need be done foam is very very flammable.

What should be a simple bit of patch work can easily turn into a raging vehicle fire. Same with one wire ever getting a hot enough to pass the flash point of the foam as well.

If you love your vehicle enough to restore it then do things right and talk to a knowledgeable and experienced auto body professional and see what they recommend. The odds are what they recommend to use won't come from a local home building center in a $5 can

! I bought the vehicle in 1971, research has shown that the vehicle was built in 1967 which made the car approx 4 years old. One wouldn't have thought it, it was in a terrible state. The previous owner, I suspect, had taken it on numerous beach expeditions. Having said that, I, with my wife and daughter, Undertook a trip from Perth to Townsville, in an as bought condition. There is no doubt that we had a few probs, eg. two broken front springs, etc.but the point is the vehicle kept going....! No matter what. But over the next 20 years, I was forever cutting out rust in the chassis. Eventually I decide to change the chassis for a secondhand military chassis. This chassis was in great condition, apart from dirt and mud in the interior, which I sooned rectified. This was the beginning of a lengthy restoration which had to take second place to my establishing an electrical business and the addition of two more children to the family, hence the resto continues to this day. My experience of rusted out chassis leads me to being quite keen to preventing it happening again. The point has been made that because of where I am located it is likely that exposure to salt will occur, how true, also of course, areas of interest to me involve the salt lakes of Australia's interior. The foam I'm proposing is that supplied by "UScomposites" and is a far cry from the $5-00 can from the local hardware store. It is waterproof, creates tremendous bond to the sub-strate and comes in various strengths. The two compounds that one mixes, are not in themselves flammable. It is the stuff from which surf boards are made which are subject to flexing. But as I say, my main reason for my proposal is to exclude mud and crud from entering the chassis in the first place, sound and vibration proofing are a bonus. If it stiffens the chassis all well & good but that's not the primary purpose.. It is not my intention to use it behind panels etc. there are numerous spray on sound deadening compounds for that purpose. I apologise for the rather lengthy comments. Regards Norm.

If you are doing a restoration there are companies that actually chemically strip the body by dipping it in a special bath.

The dipping not only removes all paint, but removes all rust completely and then applies a rust inhibiting coating on the bare metal.

After the dip you can prime and paint.

The problem with applying foam is that you will no doubt be locking in existing rust and oxidation, which will continue to oxidize the metal underneath the foam. "Rust never sleeps"

The only way to stop the "cancer" is to remove it completely either by cutting it out, sanding or sandblasting the rust out, or chemically stripping.

Sandblasting is a poor choice as it deforms the metal and leaves the metal rippled. Glass or plastic bead blasting is better. However, the chemical strip and rust removal is the best route.

It is bit late for stripping, the resto has progressed to the point where all the bodywork has been re-installed together with the running gear. Having said that, when I cleaned the chassis out, it received a coating of rust converter followed up with a few coats of "Kilrust" paint, with a bit of luck that should negate any internal rust problem. In any case, for rusting to continue, it will require oxygen, which of course would be in fairly limited supply once the chassis has been filled. Norm.

This sounds like you are going to do "it".

It will probably outlast us all.

I say, go for it!!!!!!!!!!!!!

It will probably outlast us all.

Yeah, especially if it never leaves the garage.

It will probably keep the saltwater out. The only additional thing I would do, is after the foam treatment, I would identify all of the holes and fill them with some type of structural urethane caulking.

That is what I followed up with in some cases...the original 3M stuff.

Hi Norm

Reliant chassis members were box section with tubular cross members. I used to fill the box with old engine oil and stuff the cross members with oil soaked rags. It certainly made a difference to the amount of corrosion over time. Later Reliant closed off the box section with the plate on the top rather than the bottom. This was even better since less oil was able to escape through gaps in the welds. A good oily chassis will last forever.

Hi guys, Thank you one and all for the interest, advice etc. tremendous response....! It seems to me, that the main thrust is towards pockets that are not filled and becoming repositories of water, and the eventual breakdown of the foam. Unfortunately there is no way to check. The ideas regarding flooding the interior with fish oil, paint etc. is certainly valid. The problem here is still the ingress of mud & crud etc.which is the prob I was trying to solve. But having said that if the interior is well coated it really won't matter. Mention is made of the sacrificial nature of the Zinc in the galvanising, as protection, I don't know how valid that is, but how about Zinc sacrificial anodes....?? Similar to the type used on marine craft..? Anyway it would certainly be worth a try. Thanks again, Norm.

Sacrificial anodes won't work. Once out of the water, the salt will corrode anything it's touching.

I think you'll be fine with no foam and rinsing, or going with foam and sealing the holes. Finish that thing up and go have some fun with it before you're dead; then it can be someone else's problem.