so I got a new CF hood for free....awesome. long story how I got it for another time. (but I'm proud to say it didn't include any sexual favors)


anyway, I don't want it to get all cloudy in 12-18 months...I'm doing some painting this weekend, and I have a nice new paint gun and some really good clear coat.

Will it be worth it to drop a layer of clear coat on this brand new carbon fiber hood to help extend its life?

Or will it happen anyway and I'm just creating another layer I'll have to sand off in 18 months?


TIA

---

Jon Burke - KI6LSW
Blog: http://psgrallywrx.blogspot.com/

You could just paint it, lol, cf doesnt look THAT cool.

---

Welcome to the cult of JVL drink the koolaid or be banned.

When I was looking at replacing a hood on my daily driver wrx I found that all of the CF hoods were heavier than the stock aluminum.

---

First Rally: 2001
Driver (7), Co-Driver (44)
Drivers (16)
Clerk (10), Official (7), Volunteer (4)
Cars Built (1), Engines Built (0) Cages Built (0)
Last Updated, January 4, 2015

Quote
john vanlandingham
Blame is for idiots. losers.

Last year I sanded and cleared the rear wing on ACPs Evo. The top coat was all cloudy and kind of blistering. It cleaned up nicely with 30 minutes of work or so. I hear that is a big problem with those.

I would guess that a clear coat with some sort of UV inhibitor would be a good idea.

It has always surprised me how heavy some fiberglas parts are compared to stock fenders and hoods, at least Japanese fenders and hoods.

The reason that most of those rice boy CF parts are heavier than the stock item is because only the outer layer is CF (for "the look" and all the reinforcing layers are fiberglass and often thicker than is necessary.
Proper CF bodywork on real race cars is very, very expensive and weighs next to nothing. For instance, the front bumper on the Ferrari GT2 ALMS car cost about $5000 (and would get damaged or destroyed every race.) For the Lexus Speed World Challenge car our bodywork bill was in the neighborhood of $250,000. That was for 2 cars worth of bodywork (every removable panel on the car, including the roof skin), the molds and the design work. Everything was custom made by an outside contractor.

Doivi Clarkinen Wrote:
-------------------------------------------------------
> The reason that most of those rice boy CF parts
> are heavier than the stock item is because only
> the outer layer is CF (for "the look" and all the
> reinforcing layers are fiberglass and often
> thicker than is necessary.
> Proper CF bodywork on real race cars is very,
> very expensive and weighs next to nothing. For
> instance, the front bumper on the Ferrari GT2 ALMS
> car cost about $5000 (and would get damaged or
> destroyed every race.) For the Lexus Speed World
> Challenge car our bodywork bill was in the
> neighborhood of $250,000. That was for 2 cars
> worth of bodywork (every removable panel on the
> car, including the roof skin), the molds and the
> design work. Everything was custom made by an
> outside contractor.


thanks, I was going to post that, but I couldnt remember if it was aluminum core, or fiberglass core. It's all for looks unless it's real, like Dave said.

---

Welcome to the cult of JVL drink the koolaid or be banned.

Sell it and buy some real go-fast stuff with the money!

heymagic Wrote:
-------------------------------------------------------
> Last year I sanded and cleared the rear wing on
> ACPs Evo. The top coat was all cloudy and kind of
> blistering. It cleaned up nicely with 30 minutes
> of work or so. I hear that is a big problem with
> those.
>
> I would guess that a clear coat with some sort of
> UV inhibitor would be a good idea.
>
> It has always surprised me how heavy some
> fiberglas parts are compared to stock fenders and
> hoods, at least Japanese fenders and hoods.


Gene, when you were working on ACP's wing....did the 'cloudy' part go away when you were sanding? or did you just smooth it out and then the clear coat 'cleaned' away the oxidation?

thx

---

Jon Burke - KI6LSW
Blog: http://psgrallywrx.blogspot.com/

eyesoreracing Wrote:
-------------------------------------------------------
> Sell it and buy some real go-fast stuff with the
> money!

Stop Making Sense.

---

John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

Jon,

If I remember correctly..the wing was wrapped in vinyl. We had to remove that for some reason and the there was a factory clear coat of some sort over the CF that was going bad. Some of it lifted with the wrap. I sanded that off and then hit it with some rattle can clear and it actually looked great. Andrew said that was a big problem with Evo wings.




Jon Burke Wrote:
-------------------------------------------------------
> heymagic Wrote:
> --------------------------------------------------
> -----
> > Last year I sanded and cleared the rear wing
> on
> > ACPs Evo. The top coat was all cloudy and
> kind of
> > blistering. It cleaned up nicely with 30
> minutes
> > of work or so. I hear that is a big problem
> with
> > those.
> >
> > I would guess that a clear coat with some
> sort of
> > UV inhibitor would be a good idea.
> >
> > It has always surprised me how heavy some
> > fiberglas parts are compared to stock fenders
> and
> > hoods, at least Japanese fenders and hoods.
>
>
> Gene, when you were working on ACP's wing....did
> the 'cloudy' part go away when you were sanding?
> or did you just smooth it out and then the clear
> coat 'cleaned' away the oxidation?
>
> thx
>
>
>
> Jon Burke - KI6LSW
> Blog:
> 'Holy Shit!' @ 4:10

I'll have to admit now that I'm going to be using a carbon hood for the build I'm doing but only because;

I have no stock hood.

I have no "getting rare" JDM hood.

One of our suppliers is making it for me for "favours" (take that however you like )

I HAVE specified vacumed carbon ONLY with minimal/no reinforcment (probably have to use 4 hood pins) Must be floppy as hell and weigh NOTHING.

AND..... I'm painting it so I don't have the embarrasment of a shiny carbon hood.

---

Gone fishing

I'd like to comment a bit here. For my formula SAE car at Michigan Tech I was on the composites team, so we built up all the carbon fiber/fiberglass body work for the car.

The biggest thing that will get you strength to weight ratios good for racing is using pre-preg carbon fiber rolls (as carbon fiber roll is made it is pre-soaked in the proper ratio of epoxy), then vacuum forming into your mold and THEN baking it in a large oven while still under vacuum.

If you were to only do one of the three steps above (pre-preg, vacuum, baking) I would do vacuum forming. The pre-preg (also known as dry layup) stuff we had was required to be baking to get a strong cure (in a way it softened the epoxy and then cured it). You need to keep your pre-preg roll frozen so it won't cure on its own.

The process of making your parts from scratch is more time consuming. For example for our nose cone and side pods... had to make your plug, which is a full sized model of what your piece will look like. If you were making a hood you could use your OEM hood as your plug. If you're making your own, it's using a foam core base and then cutting to a rough shape. Then using bondo and lots of sanding you make it as smooth as possible.

Second you would layup a mold around that with a mix of wet layup fiberglass and cloth sheet to make a stiff mold. Usually we made the molds so they were two parts and then bolted together. Once you have the mold, you fill the seams from the with modeling clay. Give a rough look at the interior for any rough spots and clean it up since the surface of your mold determines the surface of the final product. A good wet sand will make it nice. You then spray the mold with a release, lay up your composite (dry or wet) making sure you press out all your bubbles/air and you have a good 2-3 layers of carbon fiber. With a wet layup the less epoxy you use the better but be sure to check for the epoxy to composite fabric ratio for ultimate strength. Then you wrap that in more of the cloth sheet and then a vacuum seal bag hooked to a vacuum pump.

Once it's all sealed up, we threw it in our oven. Our oven was some large pieces of plywood, with ghetto aluminum lined insulation, and a basic thermostat to control the temperature and electric heater all formed into a long box. If I remember the temp was somewhere in the 250° range. It warmed the room it was in just as much as it did inside but it did the job of regulating temperature well. Bake for several hours. Pull out the mold and you got some wicked looking parts.

I wouldn't say our parts and method could be used for making things like control arms. But we made our seat using this method. It was 2-3 layers of carbon fiber and never had any issues with us sitting in it. Didn't have any heat related issues as the headers were directly behind the seat but we gold foil lined the back of the seat.

Also, I'm sure dave can comment on this, you'll want to keep some sort of reinforcement on your hood. I remember the Sport Compact Car article on the sentra SE-R and they removed the hood reinforcement for weight savings. On the track the hood was flapping around with all the wind and bowing like crazy. If anything, you could sandwich your layers of over some sort of honeycomb structure to give some beef in areas. But you want to have that hood reinforcement on there.

Just to be clear, that was Jared Holstein's car, not mine! He spent hours cutting ~10 pounds out of his hood instead of fixing his wiring so the car would start. That's a good example of the kind of whacked priorities that get guys like JVL all flameilicious when they hear about carbon fiber and they assume (probably correctly) that the bits are going on a car in desperate need of something else. Which, of course, is why carbon fiber questions on this forum always have to start with excuses and apologies.

But, yea, the point is well made. Reinforcement on the leading edge is a very good idea.

The best CF hoods I've seen just use a honeycomb layer sandwiched between the pretty top and rough engine side of the hood. This gives you a remarkably rigid hood (you can stand on it) that weighs nearly nothing (~6 lbs for a Sentra hood).

-Dave

BillyElliot Wrote:
-------------------------------------------------------
> I'd like to comment a bit here. For my formula
> SAE car at Michigan Tech I was on the composites
> team, so we built up all the carbon
> fiber/fiberglass body work for the car.
>
> The biggest thing that will get you strength to
> weight ratios good for racing is using pre-preg
> carbon fiber rolls (as carbon fiber roll is made
> it is pre-soaked in the proper ratio of epoxy),
> then vacuum forming into your mold and THEN baking
> it in a large oven while still under vacuum.
>
> If you were to only do one of the three steps
> above (pre-preg, vacuum, baking) I would do vacuum
> forming. The pre-preg (also known as dry layup)
> stuff we had was required to be baking to get a
> strong cure (in a way it softened the epoxy and
> then cured it). You need to keep your pre-preg
> roll frozen so it won't cure on its own.
>
> The process of making your parts from scratch is
> more time consuming. For example for our nose
> cone and side pods... had to make your plug, which
> is a full sized model of what your piece will look
> like. If you were making a hood you could use
> your OEM hood as your plug. If you're making your
> own, it's using a foam core base and then cutting
> to a rough shape. Then using bondo and lots of
> sanding you make it as smooth as possible.
>
> Second you would layup a mold around that with a
> mix of wet layup fiberglass and cloth sheet to
> make a stiff mold. Usually we made the molds so
> they were two parts and then bolted together.
> Once you have the mold, you fill the seams from
> the with modeling clay. Give a rough look at the
> interior for any rough spots and clean it up since
> the surface of your mold determines the surface of
> the final product. A good wet sand will make it
> nice. You then spray the mold with a release, lay
> up your composite (dry or wet) making sure you
> press out all your bubbles/air and you have a good
> 2-3 layers of carbon fiber. With a wet layup the
> less epoxy you use the better but be sure to check
> for the epoxy to composite fabric ratio for
> ultimate strength. Then you wrap that in more of
> the cloth sheet and then a vacuum seal bag hooked
> to a vacuum pump.
>
> Once it's all sealed up, we threw it in our oven.
> Our oven was some large pieces of plywood, with
> ghetto aluminum lined insulation, and a basic
> thermostat to control the temperature and electric
> heater all formed into a long box. If I remember
> the temp was somewhere in the 250° range. It
> warmed the room it was in just as much as it did
> inside but it did the job of regulating
> temperature well. Bake for several hours. Pull
> out the mold and you got some wicked looking
> parts.
>
> I wouldn't say our parts and method could be used
> for making things like control arms. But we made
> our seat using this method. It was 2-3 layers of
> carbon fiber and never had any issues with us
> sitting in it. Didn't have any heat related
> issues as the headers were directly behind the
> seat but we gold foil lined the back of the
> seat.
>

When you layed up the prepreg for the car, did you guys use 0-90 and 45 degree lay up techniques with mirror'ed ply layering? The aerospace stuff is layed up that way for the strength, as the weave does have a direction. Did the body work designers care about that? I wouldn't think it would help a HUGE amount, but it might help a bit for where the wind will bow the part.

---

Welcome to the cult of JVL drink the koolaid or be banned.