Thread: Series Radius arms

Originally Posted by normbourne

Hi guys,

I've been doing a bit of reading, regarding the benefits or otherwise of filling the chassis with high density polyurethane foam.

My idea was more along the lines of preventing the build up of dust, dirt and water, (having cleaned and painted my chassis interior) thus reducing the oxygen available for corrosion.

But it turns out there are other benefits, namely, sound & vibration proofing, and, importantly, stiffening of the chassis.

Apparently there are two suitable foams available, one is applied by pouring, the other by injection, the mixing taking place via a mixing nozzle at the end of the hose.

One drawback is that if there are any cables etc. within the chassis is that they will become embedded.

But seems to me that that shouldn't be such a problem, in That it would immobilise the cabling and minimise the chafe that occurs when cables are in constant movement.

One would need to be aware of the exothermic effect when the foam cures.

All in all, it seems to be a win,win project.....!!

Anyway lads has anyone ever done this..? I would appreciate a few opinions before embarking on such a project.

Norm.

Did you read this?
Foam Filling Chassis Rails - Experiment gone crazy - The Australian 300zx Owners Association

If you think it will stiffen a landie chassis then I think you are dreaming...
It may help with noise and vibration.
The biggest concern I would have is that moisture is trapped between the steel and the foam, leading to accelerated rusting - then causing all sorts of OHS concerns if you start cutting and welding a foam filled chassis.

Hi Is...rover,

Well that's disappointing, regarding the stiffening, howevever, I think my primary objectives are still valid.

As regards entrapment of moisture, I've been restoring my 2A series, over 20years, all this time it has been in my workshop so it is bone dry.

That is one reason for excluding the dirt dust and oxygen, which of course, once it becomes wet will promote corrosion.

Also once filled, condensation within the chassis becomes a non-event.

Coatings and application methods, are still to be explored..!



Norm.

Originally Posted by isuzurover

Did you read this?
Foam Filling Chassis Rails - Experiment gone crazy - The Australian 300zx Owners Association

If you think it will stiffen a landie chassis then I think you are dreaming...
It may help with noise and vibration.
The biggest concern I would have is that moisture is trapped between the steel and the foam, leading to accelerated rusting - then causing all sorts of OHS concerns if you start cutting and welding a foam filled chassis.

Not surprising. To increase the stiffness of a steel box chassis you need to add something as stiff or stiffer than steel to the walls.
There are no foams or urethanes anywhere near stiff enough and its all in the wrong place to help.

! 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.

I am a big fan of galvanising. Once done you know you won't have to worry about rust for 30-50 years.

The polyurethane foam needs water to cure - so you will need to wet the inside of the chassis before applying to get the foam to expand to fill the whole cavity. I am not convinced there will not be water trapped in there - or water won't get in in some places after creek crossings, etc...
I could very well be wrong... However from what I can see the long term rust issues of foam in 4x4 chassis remain untested...

there is no way you can garrantee 100% filling of the entire chassis space. There will be a day mositure gets in there and it will be trapped longer and lead to what isuzurover has said. I would bet my left nut on it.

HDG is a much better approach IMO.

Edit: It can not be waterproof AND be the same stuff surboards are made from....

We used to do this back in the 60's/70's on rally cars in sills etc. It wll still collect moisture (it's an open cell structure) and it will rust in there. and you will never fill it entirely.

As Isuzurover and Uninformed have said, galvanizing is the answer. It's the only way to guarantee steel a long life in harsh conditions.

Hot dip galvanising is the best but has a risk of warping thin steel. Chassis should be fine.
Zinc electroplating isn't quite as good but will still get in all the nooks and crannies.
Spray galvanising is as good as electroplating but can only be done externally.
Cold galvanising (zinc rich paint) is the easiest and cheapest but least reliable.

Just look at boat trailers and see how they last.