Talk Morgan Forums Morgan Sports Cars Morgan Aero 8, 2012< Plus 8, SuperSports, Coupe & Aeromax Aero Corrosion Protection

The Aero is essentially all aluminium.

Whilst at the factory I was told that the tub is made from a "passivated" alloy that is approved for marine use, so won't corrode when used in the winter, even if there is salt on the road.

All the people I know that have aluminium boats have little magnesium sacrificial anodes screwed to the hull, the idea is these corrode before the aluminium. But boats sit in salt water. Our cars don't. Even so I was wondering if there is any need to do more than wash down the Aero when used in the winter, or if such annodic protection might be worth fitting.

Does anyone know for sure? As the Aeros have been about for 12 years or so it should now be obvious if they corrode, or not.

The chassis may not corrode Peter, but the body panels on Aero-bodied Aeros (sounds odd, but you know what I mean) can show corrosion. An odd, but common, place for this is around the circular rear lights where pin-pricks of electrolytic corrosion cause tiny paint bubbles from the inside where moisture can collect. Don't know whether trad-bodied Aeros will have the same issue.

Ps - a sacrificial anode needs to be in an ionic medium to work. So unless you intend to keep your car in a tank when you are not using it, then I don't think this is the answer.

Stuart,

thanks for this reassuring information.

I know that sacrificial anodes need to be in an ionic solution, normally seawater. I was thinking along the lines that when wet with salty water from road salt the anodes might corrode in preference to the chassis. But of course most of the time they would do nothing and if, as you say, the chassis doesn't corrode anyway they serve no purpose.

Body work corrosion is another matter. Along with many aircraft operators I'm a great believer in using ACF50. It was designed to protect the inside surfaces of aluminium aircraft, for example inside the wing. So spraying it inside the aluminium body of an Aero might help inhibit the corrosion you mention.

As to the Aero Plus 8 the body is essentially a slightly wider and longer Roadster body: we know they don't corrode other than where they are in contact with steel. The Aero has no structural steel so that bodes well. Even so I think oiling the beading between wing and body with ACF50, as per normal on a Trad, can do no harm. But I'll think about getting the inside of the body at the rear and under the wings sprayed as well.

The corrosion points on the aeros around the light are where the steel light fixings are fixed to the aluminium body. The sponge that hold the light restains the moisture and maybe road salt and this the results in some for electrolysis and paint erosion.

All the aeros I've seen with paint corrosion have had it occur in the same places.

Yes, and bottom of wings can corrode, and around side exhausts, and also rear wheel-arches a bit, and where wings meet front bumper unit, and I believe round front side-lights on some cars. It's all caused by electrolytic reaction and poor consideration of metal to metal interfaces in my view. None of it is serious and is easily repaired. After nearly 8 years since manufacture my Aero looks as good and drives as well as it ever did although I have spent about £1500 - £2000 over the last 4 years on minor repairs due to this corrosion to keep the car looking as near perfect as possible.

Chassis looks absolutely brand new from underneath and looks set to outlive me.

I know that Aston Martins, Ferraris, Lamborghinis and no doubt many other cars using aluminium have similar issues. ACF50 may be a solution but I don't see it stopping electrolytic corrosion.

I did an experiment once by fitting zinc sacrificial anodes in the rear wheel arches of a brand new disco between the ali body and the steel. They were positioned where the spray from the wheels would hopefully keep them moist but they never did work very well.

Good luck with your battle against entropy

All,

Delighted to hear the chassis tub seems to last...but as far as the bodywork is concerned the rear lights on the Plus 8 are as per the Trads, seperated from the alloy by plastic "tubes". So perhaps that helps, I've not seen a Trad made since the 90s with signs of corrosion on the rear pannel round the lights.

As to the rest, if only MMC would discover 316 stainless fastenings...but where possible mild steel or zinc plated steel fasteners should be exchanged for stainless.

ACF 50 comes with bold claims:

ACF 50

But for about £25,00 a year why not spray it every where there is a known issue?
I sprayed between wings and body, along the bonnet hinge, inside all the indicators and lights and all over the area inside the rer valence: easy on a Roadster with the rear wheel removed. Not so sure on the Plus 8 as it isn't clear if the pannel where the spare would go is designed to be removed. I'll find out in due course.

I also sprayed all the engine, just to keep the alloy looking nice....!

Peter, I've heard that stainless against aluminium is the worst possible combination.....?
A year or so ago I did a test which entailed coating 6 inch pieces of piano wire mounted into a wood block, with different things.
Acf, WD40, waxoyl, ordinary wax, engine oil and some others I can't remember. I then left this block out in the garden over winter.
Rather unbelievably, the best protection offered by a long way was WD40!
I hesitated to report it on the site here as there was plenty of anti WD40 stuff being said at the time about it being hygroscopic etc. However, my test prompted me to contact a client who is a real expert in the area who said that WD, whilst not as effective as it used to be because they had to remove some of the poisonous stuff, was actually just as brilliant as they claim. I hasten to add though, that my samples were subjected to no friction, which could change everything in a car situation.
Re salt on aluminium my expert recommended something motorcyclists spray on the front forks; you'll know what it is.
Lastly I remember using sacrificial anodes in my Triumph Herald in the 60's......they were called the doors!
Nick

Thanks for a most useful thread. My Aero has exactly the corrosion around the rear light. I am debating about a respray which will make 4 panels to date!

""I've heard that stainless against aluminium is the worst possible combination.....?""

http://www.zygology.com/productcart/pc/Galvanic-Corrosion-Chart.html

The further a metal is apart on the cathodic table the greater the measures needed to prevent electrolysis.

Stainless and aluminium are not good friends but as you will have noted on Morgans there is a physical barrier in place where bulkhead and inner wings (s/s) meet the aluminium for this very reason.