Water spots on Carbon

[Al N.]

I figured this was semi-technical so I put it in this section.

 

Has anyone had an issue with water spots on their carbon fenders? Especially the front ones?

 

I finally got around to washing my car after 7-7-7 (it was a mess down there after the Friday AM drive in the wet) and noticed that I have a few water spots that are pretty hard to get out...think a clay bar would work? Would that be safe for the finish of the carbon?

[slngsht]

Al, are these white spots that are smooth on the outside?

On the way back from the dragon, at one of the gas station, we noticed them on Scott's car.

One theory was that the spot was caused by rocks hitting the fender from underneath, and causing a little seperation in the laminate, hence the white.

 

I have no idea if that's the case though.

[Al N.]

Al, are these white spots that are smooth on the outside?

 

:hurray:

 

Ding, ding, ding...Mr. Ebrahimi you have won a prize. It is exactly that...no amount of non-abrasive cleaning seems to get them out. I did notice some crazy wear on the EVO mag long term r400 fenders, but thought it was because of amount of mileage/wear they put on those cars.

 

I guess there's nothing I can do about it and will just have to tell the concours judges "Oh, they all do that...":jester:

[kar120c]

Working in the areospace field and having carbon fiber exp. I can only offer these observations.

 

1.carbon fiber has become the "NEW" must have, go fast body part in alot of street tuning mags. ie: it's the answer to super light weight and strong.

 

1a. the C/F used in the aerospace and F1 industry IS NOT the same as you and i buy. (sorry but true)

 

1b. the cost of pre-preg C/F that must be stored in freezer at a controlled temp, and when taken out has a working time of about 3 hours then must be baged and sealed and then put into a autoclave for a pre determended time and temp cost big $'s. perfect moulds, clean rooms, state of the art autoclaves etc.

 

2. just like quality cotton, C/F has a thread count and weave. It's all about count and weave BABY

 

3. Having seen "so called C/F part's on street cars is i'm sorry "A JOKE" it is nothing but cheap pre-peg,that is paper thin' low count, loose weave, and then they put a thick coat of clear on the ext. the make it look cool, you would be better off using a good quality fiberglass or alloy fender, weight gain is a non issue.

 

4. since you have them on your car you are stuck whith then, here's what you do...... modifiy your fender mounts so you can lower the fender closer to the tire. they all move as one so the gap can be real close. that's for the fronts only, for the rears i would spray some rubberized rock sheild on the inner fender to stop the rocks/stones from hitting the bottom of the fender.

 

sorry about the bitching on street C/F but it is what it is. you can buy a 4x8 sheet of alluminum let's say from the 1100 series for about $50 to $70 or you can buy a 4x8 sheet of 7075 T6 for about $400. THEY BOTH LOOK THE SAME, except one is as hard as a beer can and one is NOT......can you tell the difference?

 

:cry: :nonod:

[gjslutz]

Kar120c thanks for educating us not in the know. It saved me $$ from purchasing some parts for my Birkin as well as my A/C. It is great to have this info prior to the money leaving my pocket, thanks.

[Alaskossie]

Al, this problem was the subject of a thread in Blatchat about two weeks ago. The consensus is that some water (perhaps in combination with heat from the sun) white-spots carbon fiber wings pretty badly. I saw a R400 Caterham at LOG 27 in Snowmass, CO this year that had been driven from Texas, and the wings and nosecone were spotted pretty badly, and the spots would hardly come off.

 

I am building a Caterham Seven at present, with c/f nosecone and wings. The nosecone has been painted body color, but I have had the wings coated on the underside with pickup-truck bedliner, and clear-coated on the outside to give a protective finish. The c/f really absorbs the clearcoat -- it took 6 quarts (at $52 per quart) to do the fenders.

 

We'll see if all of this prep does the trick.

 

Tom Meacham

[Al N.]

The consensus is that some water (perhaps in combination with heat from the sun) white-spots carbon fiber wings pretty badly.

 

Oh, the fenders have seen quite a bit of water in their 4000 miles...

 

Most notably, here and here.

[JBH]

Having recently replaced a "carbon fiber" rear wing, I have a few comments and thoughts to add:

1. The CF wing used to build my car in 2002 was very thin with a thin laminate. It shattered when I hit a rubber cone at 50- 60 mph. Hardly the properties one would expect for a CF part, but that just reinforces the points made by Kar120c

 

2. The new replacement wing is a different design and weave. While it is still a laminate, it is a thick weave with much more CF. I am quite sure it will still shatter if I hit something, so at $650 each, I think there is a good argument for using fiberglass. Only problem is CF looks really good, so I think the best thing I can do is be careful not to hit anymore cones.

 

3. I spent two days on the South Course at VIR and if you have been there, you know there are lots of larger rocks all around the paddock. I have no white spots on my fenders, so I don't think rocks are the source.

 

4. Using a protective 3M clear film is the way to go. I have also used Grafix, a cling vinyl sheet. It works well too except you have to replace it occasionally.

 

5. I use a polish to take out water spots - it leaves the finish clean and very reflective

[MoPho]

Found this thread on a search about the problem. Unfortunately it recently became much much worse on the car (see attached photo). The new spots suddenly appeared after we had a big rainstorm and the car was in the garage with the cover on it, so it must have been from the humidity. It appears that the spots are actual air/condensation under the clear coat. Somehow the fenders are not completely sealed.

A friend with a body shop who has some experience doing CF repairs on Lotus thinks he may be able to sand off the clear coat and refinish it, though how good it turns out would be dependent on whether there is damage to the weave or not. So hopefully it will work as he can do all four fenders for the cost just one replacement.

 

 

 

Not sure if Kar120c is on here anymore but to address some his points:

 

3. Having seen "so called C/F part's on street cars is i'm sorry "A JOKE" it is nothing but cheap pre-peg,that is paper thin' low count, loose weave, and then they put a thick coat of clear on the ext. the make it look cool, you would be better off using a good quality fiberglass or alloy fender, weight gain is a non issue.

 

While the weight may or may not be a real issue in terms of ultimate performance, there is a significant difference between the weight of the CF and Fiberglass parts on the Seven, especially the nose cone.

Also, as the parts are really just cosmetic and not structural, I don't think the strength of the CF is an issue. If you hit something with Fiberglass it is going to break too, albeit it will be cheaper to repair

 

4. since you have them on your car you are stuck whith then, here's what you do...... modifiy your fender mounts so you can lower the fender closer to the tire. they all move as one so the gap can be real close. that's for the fronts only, for the rears i would spray some rubberized rock sheild on the inner fender to stop the rocks/stones from hitting the bottom of the fender.

 

You never say how this is going to help. Since Al's car is now mine, it should be noted that the front fenders are already as close to the tire as possible, as a matter of fact, they were rubbing the tires and I had to bend the stanchion to clear it

Edited January 6, 2010 by MoPho

[escondidoron]

Morgan said:

Somehow the fenders are not completely sealed.

 

If the fenders were made with pre-preg cloth then it is very likely that they are not sealed. The pre-preg resin does not flow out like you would expect with a wet layup process. If you look at the underside of the fenders and they look porous, then they are likely pre-preg.

 

If you determine that they are not sealed on the underside it would be a good idea to seal them as a part of your attempt at refinishing. This would be pretty easy to do with some epoxy resin (not polyester). Just clean the fenders thoroughly, give the back side a light scuff with a reasonable grit sandpaper, say 220 (you don't want to dig very far into the carbon as you could damage the fibre's integrity if you go to far), and then mix up the resin and brush a couple of coats on the back side. Or you could just paint the back side to seal it up too. Same preparation requirements / issues apply for paint.

 

Contact me off-list if you have any questions.

[MoPho]

Yeah, the plan is to seal the underside

 

 

Thanks

 

 

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