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Unzipped Composites

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About Unzipped Composites

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    R34 GTT
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  1. Massive pressure surges, coupled with heat. Not an ideal situation for AN style fittings. The issue is, in most situations the hose will be ok, you don't tend to load up a power steering rack too much in every day operation. But on the odd occasion, you might hold the steering on full lock for too long and the hose will let go. Or you might need to make a couple of sharp yanks on the steering wheel and you'll see momentary pressures over 3000psi. Hydraulic hoses will often be made with a crimp fitting that gets crimped on at over 15000psi - significantly better than an AN style compression fitting that bites down on an olive or cuts into the rubber hose at however much pressure you manage to put on it with a shifter... I've had this conversation with so many guys at the track, and they always insist that 'we use this hose all the time and never had any issues' or 'the rep at the hose shop said it would be fine'. And so many times I've seen those cars going home early on a trailer because the power steering hose let go. Take it to a shop, get one made. Hydraulic hoses aren't expensive or hard to make, they just need to be done properly with the right equipment. The guys making those hoses aren't scared of making a power steering hose for a light vehicle, that's a walk in the park.
  2. If NZ is a little closer to home, Franklin Engineering has some dress up stuff for RB's. From memory their bolt kits might only be for the cam covers, but they've got some nice other stuff too.
  3. AN hose and fittings should not be used for hydraulic applications like power steering. Get a proper hydraulic hose made up - it will probably cost less than trying to do it with AN hose and fittings.
  4. When you say suspension, which parts of the suspension have you changed? The R34 GT uses an eyelet type mount on the bottom of the rear strut, same as R33 GTST's. The GTT uses a forklet on the bottom of the rear strut. Gearbox is different as mentioned. Because the gearbox is smaller, the driveshaft is shorter. So if you fit a GTT gearbox, you also need the driveshaft and diff. Off the top of my head, the rest is mechanically the same.
  5. The R34 GT (non turbo) gearbox is essentially an RB20 gearbox, very weak and uses a push type clutch. The R34 GTT gearbox is exactly the same as an RB25DET gearbox, but uses a pull type clutch. If you are planning on changing to an R34 GTT gearbox/driveline at any point, then don't upgrade the clutch for your current gearbox - it won't be a direct swap without converting the GTT gearbox to a push type clutch.
  6. Sure, but if it's a wank factor thing then there's plenty of other stuff there that they could have done - fuse box cover, washer bottle, rad shroud, etc. Strut towers are an odd place to start, especially considering it isn't really a bang up job either, it's a little bit rough compared to how gorgeous the rest of the car is. I'm sure they had a reason, it just isn't obvious to me and I'd love to know what the Nismo designers were thinking with it.
  7. As long as you have the push/pull variant correct.
  8. Would really love to know their reasoning for wrapping the strut towers in carbon. It's doing nothing for strength/rigidity, so I feel it can only be a looks thing... but thats an odd place to start doing stuff in carbon.
  9. Yeh unfortunately you'll never get a great surface finish using PVA release agent. It forms it's own surface, and even sprayed, it will get bits of dust in it and not lay down flat etc. It has it's uses, but I use it very rarely these days. Semi-permanent chemical release agents are the way to go. There's no reason your current mould can't work for carbon. The biggest issue would be whether you have used a polyester or vinyl ester tooling gelcoat, as you would want to use epoxy to make your carbon component and epoxy isn't compatible with polyester, it will stick to it. If you've used polyester, then to use your current mould you would need to spray PVA release agent in order to build up a nice thick film with absolutely no fish eyes or porosity where the epoxy can come into direct contact with the mould surface. For that reason, I wouldn't bother trying to sort out the surface finish on your current mould. I assume you'll be painting the fibreglass bodywork, in which case that will sort out the finish on that, and if you do end up using it for carbon then you'll have to use PVA anyway and then clear coating the carbon will be the best way to get a decent surface finish on that. In all honesty though, I wouldn't bother with trying to wet-lay carbon. You really need vacuum to get good consolidation and get full advantage of the strength to weight, and if you've got the equipment for vacuum then you may as well be infusing to really get a perfect result straight from the mould. To infuse, your current mould may be a bit troublesome. The flanges are quite small, so you will struggle to position your consumables and get a good seal, which is critical. Really need a 5" flange for infusion. Then with infusion as I mentioned above, you can get a perfect surface finish straight from the mould - so then you would want your mould surface to be vinyl ester and have the surface finish you want so that you can use a chemical release agent. Carbon layup could be quite a bit lighter than the fibreglass layup. On the bonnet section I would do a single layer of 200g twill, a 2mm core, and then another layer of the 200g twill. The fenders and front bumper sections don't need the core, they could be a single layer of 200g and a single layer of 450g and that would be plenty strong enough. Extra reinforcement around the mounting points again and you're dusted. With infusion, you should be able to get the total weight of the entire front end down to about 4-5kg. If you get the chance, definitely come over for one of my courses. It's a great 4 days, bunch of fun, you'll learn way more than anyone can handle, and it's worth it just for the lunches 😉 haha seriously though, if you're interested let me know. For my interstate guys I try to do 4 days in a row rather than splitting it over two weekends. You lose a bit of the course content because there isn't enough time to post cure the moulds you make to use them with pre-preg, so I have to supply some moulds for that part of it, but it saves you spending a week over here.
  10. Go with what Soric specify in their data sheet. I actually meant 550g per m2 per mm thickness, so that's about right. But I couldn't remember exact numbers, it's been awhile since I used Coremat. 1kg per m2 for 2mm thick Coremat seems right. Resin ratio for wet layup of woven, unidirectional or stitched (double bias is a stitched material) is 1:1. So for a 400g DB, you will need 400g of resin per square metre per layer. Your layup schedule sounds good. Make sure you add an extra couple layers of the double bias in the areas where the bodywork is going to be mounted to spread those loads. Also if you are going to use bonnet pins, leave the core out of those areas and do extra double bias. Cores don't like compressive loads, so better to make those areas solid fibreglass. Happy to help man, that's what forums are for! Looking forward to seeing you nail this layup, then later I'll talk you into redoing it in carbon 😉
  11. I had 182/3 across all 6 when I comp tested a few years ago. Done some k's since then, should get the comp tester out again and see how she's feeling these days!
  12. Excellent. Keep in mind with the pigment, you don't want to add too much. White gelcoat is already pigmented, and you ideally don't want to go over 10% total pigment or you may have cure issues. You can add a bit of the blue to get a very light blue tinge, but I wouldn't add more than 5% by weight in case they had a lot of the white pigment in there to begin with. No issue replacing the twill with the CSM, it wont have much of an effect on weight. In that case, I would do the layup similar to the method you used to make your mould, a layer of the 100g CSM as a single skin making sure to get all the air voids out, and let that cure for a couple of hours before doing the biaxial. That will reduce your print through, and reinforce the gelcoat. Then you can use the biaxial to give the laminate it's strength, and it won't matter as much if you get a bit of bridging as the gelcoat will still have some reinforcement behind it. Alternatively, you don't necessarily need twill fibreglass, you could get a plain weave instead. Will just need more relief cuts to go around corners. Foam brushes are fine, they can be a bit easier to use with woven materials than bristle brushes. Not going to notice much difference working with CSM or biaxial. To be honest, on a job this size I would probably use a 5" short-napp roller (same as the fabric rollers you would use to paint a house) for the bulk work, and a 2" bristle brush for the tighter areas where the roller is too much work. That will let you get resin on the job and wet out the fibres quickly. Then use a disc roller to consolidate each layer and get the air bubbles out.
  13. Yeh most of the cars I work with are PDM, they're very good. I just can't quite stretch the budget there yet, this is already turning into one of those 'oh shit I got a bit excited' parts of the cars life 😅 And hopefully I'll have a bit more composites chat coming soon! As much as I enjoy talking turbos and 'Milspec' wiring - composites are my field and what will set this build apart!
  14. Yeh they are continuous fibres, so they won't break down like CSM. Harder to work with, but what you want to do is get all your fibreglass ready before you mix any resin or even apply the PVA. Lay the glass into the mould, and try to push it into all the corners as tight as you can. Take note of where it tries to 'bridge' the corners as you push it into place. If the fibres won't move to let you get them into place, then cut the fibres where they bridge to give it some relief and let it sit in place. Then use strips of glass with about an inch overlap either side to reinforce the cut sections. Make sure you do all of your glass and have it all ready before starting the layup, you don't want to be messing around with any of that while your resin is going off. Kind of like what I was doing here, you want to get all of the protrusions and features covered in glass with no bridging, and then lay up the bigger sections with the protusions cut out of it, if you know what I mean? For fibreglass with a gelcoat, it's not a huge issue to cut strips of material to reinforce tight areas, and put relief cuts where you need them. Then just add a bit of extra material to make up for the loss of strength where the cuts are.
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