Whats best to cure/prevent Surface Rust on underside?

TWO

TWO

Zorg Guru (I)
Joined
Dec 5, 2011
Points
94
Location
Chelmsford
Model of Z
Z Sport Roadster 2.2
Damned road gri!!!! :-q ......I've just noticed a high level of surface rust on the underside of the Zed :( which I am now attempting to remove with a wire brush.

I realise the car is now 10 years old so something had to be expected :((

Once I've removed the rust; does anyone have any recomendations for the best product to cure/prevent the rust re-occurring...........I'm torn between either a light spray over with WD40/Waxoil (obviously avoiding the discs [-x ;) ) or go for some thick underseal.

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I will take some 'after' pics when complete.

I look forward to your comments.
 
This should develop intop an interesting thread :-bd
I have no specific advice to offer except that salt+car+water=rust
If there was a cure I'm sure that the motor car manufacturers would either charge a fortune for it, or deny its existence!

Waxoyl seems to work on brake lines but I'm not sure of it's longevity on exposed suspension members.
The same argument would apply to hammerites, powder coatings etc.

The only effective solution is not to drive it :(
 
Blimey that looks bad
Has it spent its life at the seaside
I guess it just superficial
 
Thats looks a clever idea HT :)
A must in sea water
 
Have a look at Boankes thread on .net :-o and see what he has done and with what. ;)

It looks like the engine room of the titanic. [-x
 
hammerite underbody sealant seems to work well, Like a black paint with waxoyl in it that stays tacky. My grandad swears by the stuff. Its a pain to apply though as it gets everywhere.
 
I used to used Supertrol 001 for cavities and ADUP bronze superseal for wheel arches and floor pans.That's going back 40years and they used to work.Anything that stops VW type 3s,Hillman Hunters and Cortinas rusting has got to be good. 8-|

Supertrol 001 is still available but not the ADUP.

The way to go now seems to be Dinitrol 3125 for cavities and Dinitrol 4941 for the rest.It's not cheap but classic car clubs recommend them. :-bd
 
If I was you I would treat all rusty areas with I wire brush then hammerite grey rust killing primer and then smooth black hammerite top coat..
Or you could replace the lot with new and keep it clean...
 
z3cade said:
Or you could replace the lot with new and keep it clean...
Click to expand...

Just to comment that since I've owned the Zed from the middle of last year; that the car has never seen rain, or been out in the recently gritted roads and is stored in a 100% dry garage...............thats why its such a surprise to see the amount of surface rust on the underside................... :ymsigh:

I cannot vouch for its previous life; but given the immaculate condition of the paint work and interior; it appears that it has been well cared for.

It looks from now on; that I will be spending just as many hours cleanining the underside of the car, as the paintwork & interior.

Many thanks for all of the recommendations........the Dinitrol option looks very interesting. :-bd

I will keep you posted.
 
Phosphating is a waste of time it has a maximum of 24 hours NSS salt spray resistance (NSS = Neutral Salt Spray Test = standard for corrosion resistance)

100 hours NSS is equivalent to 1 year in real life, so you would be changing phosphate parts every 3 months. The Marine, Oil & Gas and rail industry either utilise Stainless or Exotic corrosion resistant metals or they are coated in heavy Zinc (Sheradizing) finishes or heavy organic / inorganinc finishes including Aluminium Flake

Most chassis items (Under Car or exposed areas) have to meet at least 800 hrs NSS with some new finishes claiming to achieve 1500 or 2500 hours NSS

Phosphating is generally used for internal engine components or for internal trim parts that are not cosmetic. In engines it is used to control torque tension on cylinder head bolts

The trouble with the higher NSS specification finishes is the majority are non sacrificial i.e once they are scratched to the bear metal the corrosion resistance is removed / impaired This is why the photos look so bad, it is the abuse the parts have got (stones, grit etc) that has disrupted the protective layer, the road salt just helps to accelerate this once the damage has occured. On the other hand Zinc Chromate finishes are sacrificial and this relies on the Zinc Corroding before the steel substrate, therefore when a zinc chromate part is scratched the zinc corrodes and the corrosion by products fill the scratch thus extending the corrosion resistance these types of finish will achieve at most 500 hours NSS.

Back to phosphating, this is just bear plated zinc or manganese without a chromate conversion layer, as such it is very porous and corrosion starts on the base layer straight away, but a slower rate due to the Zinc or manganese corroding.

So for if i was cleaning the bits under my car i would:

Remove the heavy castings (Brackets, Wish bones etc), have them pickled or shot blast to remove the rust and then either have them galvanised or powder coated.

Fasteners or fixings I would buy in either a delta, dacromet or dorreltech finish, these are all 1000 hour NSS finishes and will be OEM specced finishes, so i would buy the replacements from the Dealer not Screw Fix or B&Q. later BMW finishes are Zinc / Nickel which is also between 800 - 1000 hours NSS and this has the sacrificial coating of zinc covered by an inert coating of Nickel, can get a really good black finish to these.

For your large panel items I would just clean away the rust and treat with proprietary paints like hammerite and wax oil over the top to repel moisture. The under body panels were painted the same as the car (7 layers) plus an underbody seal.
 
Simples!

All you ever wanted to know about corosion protection in one reply.

(Don't yell Maurice about the bear metal though..,.,)


Z3nt from m'iPhone on Tapatalk
 
Actually, noticed the error, you will not see big furry wild creatures when scratching the surface, i did mean bare!! ;)
 
Mine only had very light surface rust when I bought it in 2008 but I took it HERE and it had the full treatment using Waxoyl and nearly 4 years on it still looks fine. They did all the underside, wishbones, drop link arms, etc and took the wheel arch liners out, etc. When BMW repaired my boot welds they commented on how well the re-injection and underseal had been done.
 
Zed Carer said:
Mine only had very light surface rust when I bought it in 2008 but I took it HERE and it had the full treatment using Waxoyl and nearly 4 years on it still looks fine. They did all the underside, wishbones, drop link arms, etc and took the wheel arch liners out, etc. When BMW repaired my boot welds they commented on how well the re-injection and underseal had been done.
Click to expand...

how much was it to have done ?
 
Re: phosphated nuts

hard top said:
zedonist said:
Phosphating is a waste of time
Click to expand...

http://www.hoffmanswinnerscircle.com/69 ... Photos.htm
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They won't look that good after 6 months if the guy takes his car outside. It will show signs of rust in 12 months if he keeps it indoors due to humidity.

I Worked for Bodycote for. Many years as a Metallurgist, Before working as an Applications Engineer at Jag Land Rover, So I can speak here with some authority on corrosion.

At the end of the day it is all about a Galvanic reaction causing the steel / Iron to revert back to its natural state of Iron Oxide, you can't stop it, but you can slow it down by covering in either a metal higher up the Galvanic series or by covering in an Inert material.

Galvanic materials slow the process due to those materials corroding before the base metal, but when they are exhausted, the base material corrodes.

Inert Materials such as paint, plastic coating etc will protect indefinitely until they become damaged, and the base metal is attacked.

Stainless steel is corrosion resistant because of the large amount of Chromium in the metal, which corrodes and forms a passivated layer on the surface that then acts similar to a plated finish, however if this layer is prevented from forming (acidic or alkaline environment) then even Stainless Steel rusts.

I will post separately later all finish types and their capabilities,
 
Easy

Just get a big empty jug and 1/2 fill with grease top up with your used engine oil

Mix it all up and with a paint brush paint it on

:-?? just the same as waxoil
 
swamper said:
Zed Carer said:
Mine only had very light surface rust when I bought it in 2008 but I took it HERE and it had the full treatment using Waxoyl and nearly 4 years on it still looks fine. They did all the underside, wishbones, drop link arms, etc and took the wheel arch liners out, etc. When BMW repaired my boot welds they commented on how well the re-injection and underseal had been done.
Click to expand...

how much was it to have done ?
Click to expand...
£245 for the full treatment, free inspection after the first year then £20 for the next annual inspections - includes any touching up that needs doing. He's been getting recommendations on Pistonheads (Yorkshire Area) as well. Have you looked in the gallery? He did a DB7 for someone who bought it as a long term keeper.
 
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