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ab90
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Group: Forum Members
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Hi all, Newbie from the UK here. I have been thinking for a while about making some parts for my car, and how to go about it. I have watched some tutorials on Youtube etc and thought it was about time I gave it a go, so I thought I would sign up here to get some advice from the experts. I hope you can help. I have a 1980's Porsche 911 with a targa roof. I don't use the targa roof, so I was trying to think of possible ways to create a sort of hard top shell from carbon fibre or similar to go over the soft part of the roof. I've included a picture of an example of the roof how it is now.  Could anyone recommend a way that I could replicate the shape of this roof to try and make this? Or am I being ridiculous?! My initial thoughts were to maybe lay some sort of plastic sheet over it and fibreglass onto that to give me something to build off to create a pattern and then to make a mould from. My day job is designing injection moulds for turbine blades and other complex things, so I can visualise how I could make a mould for this, and potentially if I can make a good enough pattern I will scan it and get one of the chaps at work to CNC the mould into modelboard, but I am just struggling to figure out how I could make the pattern. Any help would be greatly appreciated, or if I am stupid for even considering this please feel free to tell me that as well! Cheers.
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Classicarbon
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+xHi all, Newbie from the UK here. I have been thinking for a while about making some parts for my car, and how to go about it. I have watched some tutorials on Youtube etc and thought it was about time I gave it a go, so I thought I would sign up here to get some advice from the experts. I hope you can help. I have a 1980's Porsche 911 with a targa roof. I don't use the targa roof, so I was trying to think of possible ways to create a sort of hard top shell from carbon fibre or similar to go over the soft part of the roof. I've included a picture of an example of the roof how it is now. Could anyone recommend a way that I could replicate the shape of this roof to try and make this? Or am I being ridiculous?! My initial thoughts were to maybe lay some sort of plastic sheet over it and fibreglass onto that to give me something to build off to create a pattern and then to make a mould from. My day job is designing injection moulds for turbine blades and other complex things, so I can visualise how I could make a mould for this, and potentially if I can make a good enough pattern I will scan it and get one of the chaps at work to CNC the mould into modelboard, but I am just struggling to figure out how I could make the pattern. Any help would be greatly appreciated, or if I am stupid for even considering this please feel free to tell me that as well! Cheers. Can you take the roof off? If so job will be easier. I'm quite begginer but I think best is to use gelcoat and make fiberglass mould.Then make CF roof out of it.
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Warren (Staff)
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Group: Administrators
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Definitely want the roof off the car.
Are you trying to replace it or just make a protective cover?
You would probably want to make a splash mould from the roof to use to make a pattern which you can smooth out and shape accordingly.
Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant
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ab90
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Group: Forum Members
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Thanks for the replies.
Yes, the roof can come out, and is essentially a metal frame with the fabric attached.
I was just looking to make a cover really, as I think I'd have issues while driving with wind and the seals leaking if I replace the whole thing.
Not entirely sure what you mean by splash mould.. Can you elaborate?
Thanks.
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Warren (Staff)
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A rough mould simply for the purpose of making a pattern. You then shape and finish the pattern to the desired shape and finish then take a mould from that for making the actual part itself.
Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant
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MarkMK
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Your first consideration looks to be finding a reliable method of covering the material of the roof, so that you can create an initial mould. I'm assuming that you don't want to sacrifice the existing roof, so some sort of covering that will be self-releasing would be ideal It would leave some overlap ridges to deal with later on, but gaffa/duct tape is a quick and easy suggestion and gel coat will release from it without any additional prep work. The resultant mould would be quite rough in terms of it's surface, but it should allow you to make a pretty accurate pattern, in terms of dimensions, that you can then put some work into smoothing to an acceptable finish. You'd likely find it easier to put work into a rough pattern than a rough mould, I think It might be worth giving the temporary mould a couple of coats of gel coat, as this should provide a bit of leeway when it comes to sanding. Just a suggestion, but you might have an alternative product in mind for your initial covering of the roof? Something that will release reliably from gel coat would be best (test it beforehand if unsure) and the less work it will leave you to tidy up later the better
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ab90
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Group: Forum Members
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It’s been a while but I’m back! and I’ve started making progress on the roof. So, when I first posted I had just got the car, didn’t know it well and had not had the roof off. It turns out it’s actually sort of half way to where I want it. As it’s a track car, it turns out rather than keep it the metal frame with the fabric covering, the previous owner had kept the two side rails of the frame (Driver side & Passenger side) and cut out the rest, joined them with a sheet of fibre glass and covered with fabric. It’s a bit crude but it’s half way to the hard top that I wanted and gives me something to build off. I’ve spent the last few evenings removing the fabric and all the glue and getting it to a state it’s ready to work on. See here:   So, my plan now was to skin it, with either fibre glass or carbon fibre so I can paint it to match the body. You will see on the second photo of the exterior side there is a bit of a step where the fibre glass sheet is attached to the rails. My plan was to use some fibre glass body filler over this step and over the roof to smooth it off as best as I can, and then skin over the top with carbon fibre or fibre glass and then paint. The one thing I was concerned with is that it’s quite flimsy at the moment, do you think the skinning would be enough to reinforce this and make it stable? I did consider getting some of the cured carbon fibre rod and fibre glassing that to the inside of the roof and the frame to stiffen it up a bit. Also, is it stands, it is bolted to the car, so I wanted to potentially keep the corner bolts in place to help locate the roof when taking on and off, and fibre glassing over them so they are held captive, and fill the other holes in prior to skinning and I have another solution to attach it to make it easier than 5-6 screws to take on and off. Do you think this would be a good way of going about this? Or can you suggest any other ways? Also, a pointer to any good products would be great! Thanks
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MarkMK
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Skinning the whole thing is a possibility and the resin that EC sells is a good product to use However, skinning is quite labour intensive when is comes to the finishing work and achieving a really good finish on larger parts can be difficult, unless you're thinking of only flatting things to a stage where you can have it professionally clear coated. There is also shrinkage of the resin to consider, especially on a part that will be exposed to plenty of sun so, ideally, you'd need to think about giving it an elevated post-cure to speed-up that process and it'll give you a more resilient resin surface to flat and prep. Added to that, you'll be adding a bit of weight and it might be desirable to lose a bit if the car is track-focused? Unless you're minded to proceed with making a mould of the whole thing with a view to creating a carbon fibre copy, then perhaps you could think about replacing the main section with a carbon sheet and just skinning the side sections? Overall, though, the general shape doesn't appear overly complicated and it sounds like you have the design skills to create a supporting structure for the underside, if adding more strength to the roof is needed (have you a roll cage fitted already?). Perhaps some elements of the side sections could also be retained and bonded back in to provide the necessary fixings also? I only suggest this as with the stripping-down that you've already done, it looks like you're half-way to a mould-able original, so it seems that you'd only need a reliable coating on it to think about adding flanges and creating a mould? Just a few considerations, but I appreciate that skinning can sometimes feel a bit of an easier route to achieving the cosmetic look you're after. As an initial project, skinning something of that size can be a bit daunting, though, so it'd be good to experiment on something a little smaller, initially, just to get the feel for it. Things like getting the edges neat without compromising the fit can be difficult, for example.
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ab90
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Thanks for the detailed reply and the tips. You’ve given me lots to think about!
Regarding the surface finish, the plan was to only flat it enough as so it can be clear coated, or even painted or vinyl wrapped black to match the car.
The car has spent most of its life as a track car, but it is road legal. I’ve bought it as a project and I am making it more suited to doing both, so I imagine the weight that the skinning would add would be negligible compared to something like carpet, and it’s not a show car by any stretch, most of the panels are already fibreglass, so the finish doesn’t have to be perfect, and with this being my first attempt at trying this I’m not expecting it to be!
I’m fairly confident I could make a mould, but with it being my first attempt at any type of carbon fibre, I wanted to use some basics to get something that works that I could potentially make a mould from in the future.
It does have a full roll cage, so the supports I wanted to add weren’t to stiffen the roof, more to make the panel itself stiffer as currently it flexes quite a bit if you don’t hold both sides when you pick it up which makes it difficult to put on or take off.
I’ve looked on the shop, and do you think the large skinning kit would be enough for something of this size? Or should I buy separately?
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