[MWG968@optimum.net]

I have been searching the web and reading the forums trying to find ways to reduce weight on the 968. Found GT Racing and it seems you could almost build an entire 968 out of fiberglass. That sounds very appealing when I think of the huge wait savings that could be had yet i searched the forum and no one really seems to mention anything about it. What exactly am I missing? Is there some extremely obvious reason that everyone avoids these? I was throwing around the idea of finding a second 968 in a salvage yard with some slight damage and replacing as many pieces as I could with the GT racing body panels and then repainting the whole car. Does anyone have any experience with this? I would really appreciate some info thanks!

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[Cloud9...68]

Are you thinking of doing this for a track car, or a street car? If for a street car, be careful. I've heard that fiberglass aftermaket parts' fit is abysmal. I'm turning mine into a mostly-track car, and bought a used fiberglass hood of unknown origin (I think it's probably a GT Racing hood), and should be ready to test-fit it soon, but from what I've read, I'm expecting to be sorely disappointed. There are a lot of other places to look to for losing weight first, although even the simplest weight loss item always seems to come with some compromise.

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[MWG968@optimum.net]

it would be for a mostly track/autocross car that I would want to keep street legal since I don't have the money to trailer. I had feared that this was the problem. please let me know how the hood ends up fitting.

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[flash]

i've seen the GT Racing hood. it is NOT a great fit. works fine for a track car. looks like poop for a street car if you care at all about things like that.

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[judge]

I don't have much experience with car panels, but I know a bit about fibreglass in boats. IMO there are two main issues;



A. Any fibre reinforced panel will only be as good as the mould it was made in. This assumes a female mould - male moulding or freehanding would be prohibitively expensive because of the time involved to achieve even the most basic fit and finish. That's the "lure" of FRP manufacturing; make a mould and then you can flop out panels quickly and at low cost. Trouble is, unless you CAN sell scores or hundreds of units you'll never get any return on a properly produced, accurate mould. For our cars I doubt very much that anyone has the incentive to invest sufficient in the tooling to make a panel with any but the most basic fit and finnish. Maybe ok for a talented amateur with a track car but not much else.



B. The second issue is the weight/strength issue. Unless you are using very high tech stuff like pre-preg carbon or E or S glass cured in high temperature autoclaves, a simple single skin panel would need to be way too thick to achieve sufficient rigidity and then it would almost certainly weigh more than the original alloy panel. To achieve the necessary stiffness would require either a foam or balsa core, sandwiched between 2 layers of fibres, or a complex [read expensive and time consuming to engineer and produce] web to reinforce the skin and pick up the loadings. This is fine for big budget racers, but, except for small lightly stressed panels, not an option for everyman.



Having said all that it can be done, look at the early Lotus cars, but it is not as simple as unbolting the original panels and picking up a set on ebay.



Please feel free to ignore or flame any of the above. What do I know....I'm a lawyer!! <img src="/forum/images/smilies/968/tongue.png" class="smilie" alt="" />

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[RS Barn]

The fiberglass products I have used don't fit worth a darn. Hoods are always too short (at least on one side) and fenders are horrible.

The hood on my FH car would flex upwards at 120+mph until I put louvers in it to reduce heat and lift. Then it worked great.

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[flash]

yeah- lifting is a problem with fiberglass. i've used a lot of it over the years, and unless reinforcing ridges are put in it on the underside, which all but eliminates the weight reduction, the flex allows too much lifting, especially if care is not taken to prevent extraneous air from entering the engine bay, and not being equally relieved. even something as simple as opening up the driver side oil cooler space creates a LOT of extra air under the hood. that extra air must then have an extra exit. i've spent a LOT of time working on the engine bay aerodynamics, and underbody aerodynamics, and it's not simple by any stretch. a fiberglass hood can be a real problem, and cost you a lot in drag. the stock hood is 39lbs. a decent fiberglass hood, that won't have these problems, will be about 20. is it worth it? maybe. it's a lot easier to work on the car with it removed, and it's easier to repair, and 19 lbs is 19lbs.



tough call.

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[MC968CS]

Anyone know of a good quality and fit light weight hood maker? Even in CF.



I am taking bolt on and it fits and works 'levels of quality'?



I know you get what you pay for too.

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[Langley968]

I do not know if there are any weight savings with 968 fiberglass body panels, but I sell aluminum service bodies for pickup trucks and they are much lighter (and stronger) than a similar size fiberglass service body. To acheive appropriate rigidity the thickness needs to be increased and any weight savings is gone. For those that care about recycling, fiberglass is not very "green", since it is impossible to recycle.

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[craigawoodman]

Mark,



There is a supplier of fibreglass hoods/bonnets in NZ that I was looking at. From memory they make both the drop in and OE replacement types.



Like Flash and Pete have alluded to - these all possibly need to be vented to remove under hood pressure and heat. This should improve under car aero as well (not as much hot air funnelling under the car and raising pressure - hence lift).



Craig

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[flash]

yeah - the fiberglass and carbon fiber over fiberglass stuff i've seen doesn't fit perfectly, and requires quite a bit of work or compromise. you choose.



as for weight savings, it all depends on how close to OEM fit you want. as langley has said, by the time you get the appropriate reinforcements in there, you don't save much weight. the OEM hood only weighs 39lbs to begin with. you might save 30-40lbs across the entire car. every pound counts, but there are a lot more cost effective places in the car to lose weight, especially since the rules may not allow it.

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[Dubai944]

The guards, hood, front end and flares on my car are all GT racing. None of them fit properly and it took a lot of work to make them work. OK for a race car, but it would be hard to get an acceptable look on a road car if you take much pride in your panel gaps!



Here is an example of the fine quality of GT Racing fibreglass panels... These doors were so warped my fibreglass guy couldn't get them to fit properly even after cutting the top frames off and resetting them. To their credit, GT Racing refunded me the cost, but man they were crap.

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[tamathumper]

Wow, that's not even close!

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[Cloud9...68]

Gulp... I haven't test-fitted the fiberglass hood I bought used from unknown origins (but I suspect it's GT Racing). Fearing the worst...

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[Dubai944]

Hoods are a lot easier to adapt than fixed panels so you should be ok.

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[Cloud9...68]

[quote name='Dubai944' timestamp='1357528313' post='137094']

Hoods are a lot easier to adapt than fixed panels so you should be ok.

[/quote]

Thanks; hopefully that will be the case

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[Langley968]

Is there not an added risk with regards to the flammability of fiberglass with regards to a race / track car?

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[flash]

lol - it usually crumbles, disintegrates, or flies off the car before it burns

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[Langley968]

[quote name='flash' timestamp='1357602839' post='137139']

lol - it usually crumbles, disintegrates, or flies off the car before it burns

[/quote]



Ah! Understood... <img src="/forum/images/smilies/968/icon_lol1.gif" class="smilie" alt="" />

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[MC968CS]

Hmmm, thanks. Not worth the effort for me I think. i'll just continue to drive it harder into corners than my competitors in their modern Porsche's, like our 968's are good for!

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