I am starting the process of building a cf/kevlar roof cap.
The car does not use the roof skin for structural integrity.
How many layers of 6oz cf should I use? I also have available to me 6K and 12K carbon fiber up to 18oz.
also what adhesive do you recomend for bonding the roof cap to a steel unibody? I will be using infusion epoxy with VARTM.
if you mean that you are doing a cosmetic skin onto the existing steel roof, why dont you just vac a couple of layers on with epoxy? ive done it a few times, comes out great, just a ???load of sanding clears.
Not sure if you understood or not. Perhaps you did.
This is a roof replacement panel. The customer drills out the spot welds on their oem car roof, remove it and replace it with a composite roof.
I was thinking 2 layers of carbon fiber 6oz 3K, and three layers of 6oz fiberglass cloth in the middle, epoxy infusion resin.
http://www.racingcomposite.net/unt?id=305
try the link above it has some good info on it hope that helps.
Do you intend to use any core material or attach stiffening ribs? Or will the roof skin only be supported at the edges?
These questions about lay up schedule are always difficult to answer with such little info provided. Without see the part in question, it’s impossible to determine load paths. A good general starting point would be 8 plies of 6oz carbon, with plies 2,3,6 and 7 layed up at ±45*. Guaranteed to warp otherwise.
There are quite a few adhesives out there that work well for bonding composites to metals. Choose a paste that won’t sag, and install rivets at 12" spacing for a mechanical backup joint and to hold it while the adhesive cures.
So this is a roof with NO substructure ? I know when I did the BMW Z4 Coupe roofs (substructured),they were held in place with 1 bolt in each corner (hidden),and placed back on with the same Urethane sealer as OEM had used. Very strong.
…as TET has eluded…SOME bulker like core, should be considered even if the steel OEM skin lacked any.
I also used some small cut thickness stops ,made of rubber…so as to avoid over sinking the depth of the lid when clamped down. It made the skin surface perfect in surface level.
I need to get an oem roof for this car.
7 layers of 6oz = about what .060 inch? I’ll have to use mostly fiberglass cloth b/c these guys won’t pay for all cf construction.
More advice is appreciated 
My concern is, will there be room for a core material if core is used? Most inner roofs have a few vertical supports running across the width.
That is what i do. I am building roofs for the cars and they are really expensive if they are made out from 6-7 layers of CF
^^ I agree, all cf in 6 to 8 layers is a lot of money, around $300 in cf alone.
Geez, how cheap do people expect the parts to be? An entire roof-size piece is a lot of labor and materials. Buyers should know that.
The majority of car enthusiasts are frugal. They would rather spend $10,000 on their engine than on body parts.
of course. after all, even changing the whole exterior of the carto carbon won’t save you more than lets say, 5% of the total weight…
I think most of the buyers just like the look of a cf roof.
hey Aga, what twill weave configuration/weight are you using?
The title of this thread is confusing as we are (I think) talking about a replacement roof panel not a roof cap.
We make infused CF roofs occasionally, material costs aren’t so bad as we use:
2 x 2by2 twill
2mm infusion coremat
woven roving (FG)
Black Diolen.
The black Diolen (like Kevlar) is used to hold the thing together in the event of an accident, protect the occupants and also to stop any corrosion which may be caused by putting CF against steel.
We make them because OE roofs aren’t available any more, are known for rusting and also many are sunroof equipped which make them very heavy - ours aren’t of course being both a lot lighter and stronger. People get rid of OE roofs due to rust and because you can’t get a cage in a sunroof equipped car.
I made the mould for myself really (for a project I’m slowly building), and just use it to knockout the odd roof to help pay for it, it is a three part mould.
They fetch good money, but only occasionally sell.
Very good finish. Can you please explain what did you use to make that gel coat? Did you mix with your gel coat a Duratech High Glass additive? How thick is your gel coat?
245 gr/m 2x2 twill
that sounds like our US 9oz twill weave. Thanks.