mark-d · Nov 17, 2012

I just had an idea

Bare with me

Rust needs moisture and oxygen right?

So if I purge my chassis with nitrogen until it's dry and free of oxygen and then seal it with waxoyl do you think it will last a bit longer?

I have the means to do it and measure the oxygen and dryness so do you think it's worth trying?

Bump · Nov 18, 2012

no harm in trying, are there enough entrance points into the chassis to get the waxoyl?

pressbrake · Nov 18, 2012

Its the double skinned parts that kill the chassis because they never dry out and capillary the water everywhere

Nigel-S · Nov 18, 2012

Nitrogen will remove any moisture within the chassis but any treatment you do afterwards will have to be done pretty much straight away. I did my double glazing with nitrogen a couple of years ago and so far, so good. I'm looking into filling my chassis with high density expanding foam and would probably go down the nitrogen route before doing this.

Pikey · Nov 18, 2012

Nigel-S said:
Nitrogen will remove any moisture within the chassis but any treatment you do afterwards will have to be done pretty much straight away. I did my double glazing with nitrogen a couple of years ago and so far, so good. I'm looking into filling my chassis with high density expanding foam and would probably go down the nitrogen route before doing this.

Don't unless you want the chassis to rot out from the inside. condensation will gather in the voids (and there will be voids) water will find it's way in if you go wading and whilst driving in the rain. it will then be trapped in the chassis and rot thru

Turboman · Nov 18, 2012

And you will have a nasty toxic fire when you try and weld it after the foam has rotted it!

owl · Nov 18, 2012

Back in the 80's I used to work at a Land rover specialist, we did many series chassis swops after which we would do a rebuild on the old removed chassis and fit it to the next series that needed a chassis and would give a 5 year garantee with the chassis, all we did was blast the outside and paint it then spray the inside with a mix of waxoil and diesel.
I think it is worth note-ing that we mainly did S3's older chassis didn't seem so bad. Could it be if the factory had treated the inside with something they would of lasted longer.

mark-d · Nov 18, 2012

I might give it a go as I have everything to do it with, although im not sure i will know if its worked or not as im not sure how bad it is inside

mark-d · Nov 18, 2012

pressbrake said:
Its the double skinned parts that kill the chassis because they never dry out and capillary the water everywhere

Where are the double skinned parts?

I guess there is not much you can do about this

Costlyy · Nov 18, 2012

Would it not be better to seal the chassis as air tight as possible then create a partial vacuum and then fill with nitrogen using one of those air-conditioning servicing systems?

Sure it'd be complex but re-filling would be a doddle after you'd installed the valves the first time.

mark-d · Nov 18, 2012

Costlyy said:
Would it not be better to seal the chassis as air tight as possible then create a partial vacuum and then fill with nitrogen using one of those air-conditioning servicing systems?

Sure it'd be complex but re-filling would be a doddle after you'd installed the valves the first time.

If you could make a chassis completely air tight you could keep it under a small amount of pressure with nitrogen but getting the whole thing air tight will be almost impossible.

Some machines are preserved over winter in this way to stop them rusting inside

owl · Nov 18, 2012

mark-d said:
If you could make a chassis completely air tight you could keep it under a small amount of pressure with nitrogen but getting the whole thing air tight will be almost impossible.

Some machines are preserved over winter in this way to stop them rusting inside

Porsche 917's had a Magnesium tube space frame which was prone too crack, so the engineers filled them with nitrogen under pressure and fitted a gauge which they checked at pit stops, only thing was they didn't tell the driver of the cracking problems.

pressbrake · Nov 18, 2012

mark-d said:
Where are the double skinned parts?

I guess there is not much you can do about this

About 18" either side of the spring seats, which means it goes down into the lower parts of the chassis where water collects and sucks it up via capillary action and kills the chassis and there is a nasty trap at the top of the a frame x member

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