F40 LM Restoration

It is a great thread. I am happy to have caught it at the beginning so that I can follow the project throughout.

 

Whats that shaft running outside of the transmission at the bottom side of it?

 

I just sent you an email but that is exactly what I suggested. Typically in cases like this, a good layer of fiberglass in between the carbon and aluminum is all you need to eliminate the corrosion.

 

Is it HOT in here or is it just those tank?

 

This is what Boeing did on the 777 Aero 07 - Design for Corrosion

"For example, graphite fibers, which are used to reinforce some plastic structure, present a particularly challenging galvanic corrosion combination. The fibers are good electrical conductors and they produce a large galvanic potential with the aluminum alloys used in airplane structure. The only practical, effective method of preventing corrosion is to keep moisture from simultaneously contacting aluminum structure and carbon fibers by finishing, sealing, using durable isolating materials such as fiberglass, and providing drainage."

I don't know if a moisture drain is necessary here, whereas the aircraft application involves radical changes of temperature and pressure which would induce condensation.

 

Moisture is simply a catalyst. Galvanic corrosion occurs in dry environments as well; it simply takes longer for the effects to manifest themselves in failure. For something that fuel tanks, think of the temperature deltas in a humid environment (Northern Europe and England, for example) and the condensation that occurs. Cold gas being poured into hot tanks, early morning drives from cold garages, etc. That's sort of besides the point but there is no way that drainage will have any marked improvement on that.

Years ago, before we started using titanium dropouts and bottom bracket shells exclusively on serious top shelf racing bicycles, we were using lightweight aluminum dropouts and titanium shells. We all knew that galvanic corrosion was an issue because early on in carbon fiber bike construction, manufacturers were using carbon tubes bonded to aluminum lugs and it was only a matter of years before the frames started separating at the junctions (I had two break on me in rides). Anyways, it was obvious that galvanic corrosion was a real issue. So what we did for a couple of years (before we were able to develop laser cut titanium dropouts) was "glass in" the aluminum dropouts where they contacted the carbon. I still have one of those early bikes - it's 12 years old now) and the dropouts have not even come close to delaminating or breaking down at the junction. And this is a high stress part of a bicycle and gets exposed to water a lot. A *good* layer of fiberglass will do the trick and this case, would be a perfect application for that as a boundary layer.

Hope that helps.

 

I think this is probably right. The thing to watch out for though is water condensation that might bridge the fiberglass gap via the pores and bring the C/F and aluminium surfaces into electrical contact again (water is an ionic conductor). Again I suspect this won't happen in the application at hand, so that a drain is not necessary. But it might be good to get experienced input.

 

There will be air space in the pores of the fiberglass which could conceivably be places where condensation could occur. This space will form a continuous path between the two outer surfaces, so that condensing water could span that space and corrosion could occur. This is what Boeing guarded against when they installed a drain in the 777. But their operating range of temps and pressures is enormous, so that cyclic penetration and condensation of humid air is likely. But my intuition (background in materials physics) is that the risk of this occurring in your fuel tank is very small esp. if you have a good seal so that air does not cycle in and out.

 

If the cf layer being proposed is for outer crash protection to the tanks, then a better and stronger solution would be to use woven kevlar instead and the bonus is no galvanic corrosion issues either.

To give a period look you could then add a final layer of carbon kevlar to match the rest of the car

 

Tim,
It looks as if you have also increased your petrol capacity aswell with the new and improved fuel cell's? In the last picture I like the baffle which the original cell seems to be missing. Great stuff man.

 

Don't sweat about that stuff. People keep asking why my major is taking so long (2 months+) but what happens is we work on it a little, order more parts, wait for parts, and while waiting I learn something else through my phone calls and emails with others, make some changes, work on it a little, order more parts, learn something else, make some changes, etc. And I have to say that had I banged this out in 3 weeks, the end product would not be nearly as perfect as it's shaping up to be. A lot of long term proper solutions.

So just know that's a necessary part of the journey, Tim.

 

Do it right the first time.

Tim I am very happy that you realize such an undertaking takes time if done correctly.

 

Yes. The good news is that taking it slow extends the fun and produces a better result. The bad news is it takes longer (duh) and probably costs more.

 

Probably? No doubt that it does. It doesn't help that you miss your car so much that you buy another Ferrari in the meantime. Long services cost way more than you think.

 

Yes no doubt the initial cost is higher. I don't know to what extent these additional early costs are offset by longer term savings due to problems avoided (assuming you keep the car).

 

Well for me, the F40 is the one car that I can say I plan on keeping for my lifetime. Consequently, making sure everything is done properly with the only burden being that parts last longer, work better, and perform more effectively is the only real way to own one of these. You can drive it with complete confidence.