Eaton Supercharger

[Evna]

Hi all,
My Supercharger has started shedding it's paint in small flakes giving the appearance of a bad case of Acne, thus this appears to be one of my over-winter jobs so I decided to try and track down some new paint.

First to the Jaguar Dealership - I wont mention that it was a Stratstone...ooops, as usual they looked at me very blank and then someone else there told me they were american components and to try and contact the manufacturer via the net!! I did send an email to Eaton, but as yet have not received a response (3 months) so assume it's not going to happen.
I went to one of my local bodyshops who suggested I try a specialist paint dealer as it would need to be a high temperature paint and they may be able to match the colour, they pointed me in the direction of a local midlands company Jawel Paints thus I went along to see them, on explaining they said.. we only do high temperature paints in certain colours Red, Yellow, Blue, Green, Black and White!! and not at all interested... Not wanting to paint the supercharger a bright primary colour I decided to leave it at that.

The paint has mainly flaked off one side of the supercharger and just on the top surface where the word Suprcharger is cast into the metal and on closer inspection seemed quite delecate I was able to flake off most of it from just that top surface leaving the base silver of the metal. There seems to be no primer used under the gunmetal colour at all.

I hope to repair this without disturbing the Supercharger as the car is running perfectly well and I don't want to disturb anything. I had also considered buying a spare off a scrapper to have reconditioned and replace but if it isn't broke, why try and fix it?

So... Does anyone have any ideas on what the actual colour is, what paint is used and where I can purchase the paint..

Thanks in advance all info welcome.

[joejag308]

Sooner than be stuck in a messy groove....i would try rubbing the affected paint down and then applying a good primer then try matching the Silver with Hammerrite...silver (they do a spray) it wont be too far away either.

[J44EAG]

Aladyne chemical etch primer is the only material that will adhere to aluminium.

You may be able to beg a small quantity from your local flying club maintenance unit. It is difficult commercially to obtain in small quantities from high street locations. It is an adhesion promotion product and not designed as a filler primer. You will need to source that separately from a specialist supplier in view that it must be of a heat resistant variety only. The Frost range of products may provide a suitable paint type.

If you have difficulty sourcing aladyne etch, try your local yacht chandler. They may stock a two pack water based etch produced by International Paints. Cost around £17 for the kit. This product must not be allowed to get wet after application and must immediately be covered up by an epoxy type primer at first opportunity.

The same goes for the top finish coats which would probably be of the exhaust high temperature paint class. This type of paint may easily be found at motor stores across the land.

It is worth noting that aluminium, magnesium, bronze, brass, titanium, cupro-nickle, stainless steel, copper and other metals, whether alloyed or not, can present specific problems where paint finishes are concerned. The correct choice of product for such applications is all important. Half measures are rarely successful especially where such metals are subjected to regular heat cycling and high temperatures. Paint technology in these situations is a specialist subject and advice should be sought from paint technical help desks who will know the best products to use for a particular job. Guess work is not an option.

Regret to say that Finnigans, Hammerite etc are ferous rust prevention paints only and will not adhere to aluminium. Domestic alkyd or poly type paints will also be unsuitable as they will burn off a hot running super charger.

Mike

[stuarthardy]

Properly clean the aluminium part and have it chromate conversion coated. This is a simple process that can be achieved by brushing or dipping. It gives a yellowish finish to which paints will adhere.

I'd need some time to find suitable paint types but these finishes are extremely durable, commonly being used in defence equipment.

Regards

[Evna]

Thanks for the responses guys.... looks like I'm either gonna need a BSc in paint technology or find a decent specialist paint shop or such... any recommendations?

[Evna]

Because the flaking was so bad on one side of the supercharger I have now taken the paint from the top surface and have left it at that for now... I hope the picture will give some idea... the flaking is evident on tge other side but is nowhere near as severe, however, the right side was only a little worse than that when I obtained the car in Feb this year it had got much worse over the summer months.

[J44EAG]

As a trained aircraft engineer having dealt with aluminium components on a regular basis, I offer further thoughts.

Treatment of aluminium sheet components not subject to heat stress temperature reversals are relatively easy to refinish. They are not subject to thermal shock on a repeating cycle or does a paint single or two pack finish have to be able to tolerate that heat or be required to continue to adhere to the aluminium substrate under such arduous working conditions.

A supercharge is a different animal from the above. It is subject to heat stress reversal, expansion and contraction and high working temperatures. As such, having spent a couple of hours last night looking at refinishing materials commonly available, I`m obliged to draw simple initial conclusions. This however may change somewhat as I research the subject further.

Firstly, having Googled, the following problem came to light. Typing "heat resistant paint for aluminium" into the browser lead fundamentally to common ordinary aluminium paint in its own right. Not quite what I wanted or what is likely to reliably adhere to an aluminium supercharger under high heat soak conditions. Remember that any finish applied is only as good as the base adhesion process.

Going further, I then hit several high tech scientific sites. Evna is certainly correct about a BSc being required but I think an MSc might be more appropriate. Moving on, I hit heavy industry processes to MOD type specs which included vitreous finishes and electrostatic conversion, powder coatings and sacrificial anodisation. In deep now!

This lead my own thoughts towards the original finishing processes utilising supplying contractors experience in producing a supercharger with a coating suitable and required for such a rigorous application. The Eaton supercharger is, I believe, an American product and I`m now keen to find out what process Eaton originally applied to their product. One thing is for sure. It wasn`t applied with a hairy great brush on the end of a stick using typical High Street obtainable products!

What I think we can be certain of is that the Eaton process will have required some considerable investment by way of production plant and a coating process that will be beyond our being able to successfully reproduce ourselves in our own garages. So that is where I am with this research at present and will continue my efforts to see how superchargers can be successfully refinished. I`ve tried not to form a hard and fast opinion at present but I have it in mind that we may have to look beyond our own facilities and abilities to find a long life answer to refinishing of such heavily thermally stressed difficult to finish components.

The alternative might be to clean buff and polish the externals of such units in rather the style of XK type rocker covers that we see so often. That process should not be carried out using carborundum based wet and dry production papers that would trace carbon into aluminium and cause rampant future corrosion by way of galvanic action. That is another subject. Suffice to say that flower paper would not cause such electrolytic corrosion damage and there are many polishing kits available that would do no harm to units manufactured from aluminium alloy.

That`s it for the time being. All further comments encouraged.

Mike K

[Evna]

Well, thanks for that Mike...

I'm still trying to locate somewhere/someone who can assist me in my search.. I also spotted this on Ebay
http://www.ebay.co.uk/itm/JAGUAR-XJR-XK ... 1c2120b768
and have messaged the seller to see if I can find out where he had the work done... it seems to have stood up to the first 20,000mls which at current usage will take me 7 years to complete so may be an option providing he comes back with some good info.

Ian
(Evna)

[stuarthardy]

Hi Ian

At the risk of being shouted down again I will try to make a contribution.

It is clear that the paint finish on the Eaton parts is not up to much, as evidenced by the fact that its flaking off in chunks. I would venture that they are probably powder coated parts only expected to last the warranty period. Most people don't realise that powder paint does not actually adhere to the part but forms a crust around it. This is why it is possible to get coverage on a sharp edge, which is impossible with wet paint. Powder paint is great until it gets damaged, then it will flake off in chunks, just like you are experiencing.

You could spend a lot of time researching the finishes available and then spend a lot of money getting the parts painted or you could simply have them powder coated and be prepared to have them redone periodically.

Personally, I would have them chromate conversion coated and then painted using a water based epoxy paint. As I said previously, the chromate process provides a key for the paint to adhere to, without it the paint won't stick. You could try somewhere such as Hard Anodising in Kidderminster for the chromate treatment - they know their stuff although it is a simple process using a brush or a swab if the parts can't be immersed.

I don't think the temperatures seen by the outer surfaces of the castings will be terribly high - the biggest problem is the climatic conditions which the epoxy paint process should endure without hardship.

As an alternative, you could consider having the parts anodised instead of painting them but be careful to select a process that will not lead to growth of the parts as the coatings can be very thick.

Hope this helps in some small way.

Regards

[Evna]

Thanks for that Stuart, I believe the original finish is a powder coating and as you say it is very thin... I have seen another couple of XJR's both approx the same age as mine, give or take a year and their Superchargers have no evidence of such chipping so I have no idea what happened to the one on mine but evidently something must have.

I have been in touch with the poster of the auction on ebay which I posted above and he can arrange to get my components powder coated for a reasonable cost, unfortunately I'd have to get them removed and send them to him and as he is in Aberdeenshire and I live in Staffordshire it a bit drawn out but I am considering this as a possbility.

I will also look into your suggestions, I had talked to someone re anodising and he had mentioned the need to be careful of thickness of coatings.

Finally as regards the heat on the outer surfaces of the supercharger components I have no idea of actual temperatures but can confirm they are quite substantial even without pushing the performance in any way.

Thanks for your assistance

[J44EAG]

I think Starts appraisal is excellent.

Powder coating would be the most obvious finish I suppose from new. Like many finishes subject to heat, breakdown of the structure is inevitable given sufficient time. Chipping is in fact quite common where the finish doesn`t expand and contract at quite the same rate as the base material.

I`d be hesitant of anodising, I think. That type of finish is likely to be anodic to the supercharge aluminium and to be regarded ultimately as sacrificial. Typically I`ve seen it used on aluminium boat window frames and on high performance flexible brake pipe kits. The seal nuts on the end of such pipes are commonly to be found together with the option of various coloured decorative finishes. I am uncertain however as to how well anodising of a super charger would last or retain its initial good looks. The guys you spoke to would be more able to advise than I can in this respect. My knowledge runs out at this point.

Perhaps when you`ve had the job done you could post some images. I`m sure we would all like to see the finished result.

An intriguing subject indeed.

Mike

[stuarthardy]

Hi Ian

There are dozens of places to get powder coating done, I know a couple in Staffordshire and several in the West Midlands. You are in the heartland of such things and there is absolutely no need to send them to Aberdeen to get them done, especially when the person you spoke to would probably add a premium for his trouble.

If you want them powder coating then I can give you details of some people fairly near you. Depends on what colour you want to some extent.

I would still recommend you have them chromate coated and then epoxy (wet) painted though.

Mike, anodizing is added as a protective coating, it is not sacrificial.

Regards