Diy Lightweight Fibreglass Bonnet

[skylinecouple]

You wouldn't be the first person to start a business from a small project like this. I always like to see people having a go. Good on you. Let us know the end weight and photos of vent cutout then all painted up.

[r33cruiser]

hey buddy. im looking to replace my bonnet too. i cant decide between a carbon vented, or a fg vented item.

how stable is the fg item at highway speed?

have u had any problems? easily cracked etc?

[Coxie]

Both items are fine, they are just as good as factory items if made properly. Never seem any problems with them cracking or anything, only problem i've seen is with carbon fibre bonnets when the clearcoat/gelcoat fades and turns a whitey colour and sometimes flakes off, usually caused by old age spending too many hours under the sun or just lack of care and it is purely cosmetic.

[r33cruiser]

thats great thanks. not really a fan of having a non painted c/f bonnet anyways. looks cheap.

[mad082]

if you do add any more glass in, do it from underneath, for 2 reasons. 1: saves you having to smooth it out again, and 2: the more you add to the top, the further it is going to sit out from the lights and be higher than the 1/4 panels

[jeffworld2]

there is no carbon fibre bonnet on the market that is as strong as the original metal.

you will find they are quite flexible and thats why you need bonnet pins to stop them lifting on the edges in the wind. They crack when they bend too much, often around the top of the radiator area. If it is pinned down properly it wont flex and will last forever.

fibreglass and carbon will crack or tear in a crash too, unlike a metal bonnet which will fold and bend.

don't go thinking they are stronger is all im saying lol.

here are some pics of what track speeds do to bonnets

[r33cruiser]

so u DO reccommend bonnet pins for a lighter bonnet??

i have been told conflicting things.

Edited July 15, 2009 by r33cruiser

[mad082]

i think it isn't so much because it is lighter, but because it is more flexible. steel is rigid so it can just have a single latch in the centre, but fibreglass is more flexible and at speed once a corner started to lift it would just keep on lifting, because the higher it lifts the more force it gets lifting it. if you have ever paid attention on the v8 supercars when they lift the bonnet, it flexes all over the place because it has no frame underneath it.

[jeffworld2]

there are photos of mine and other cars with only two bonnet pins going down the straight at oran park at the sau day with the leading edge of the bonnets a good 10cm above the headlights in the middle. we now use more pins lol.

yes it is because they are flexible, not because they are light. take the frame off a metal bonnet and it will do the same thing. fg or cf will always be more flexible for the same amount of material

[mad082]

how do the r34 v-spec2 gtr's go with their carbon bonnets?

another way to help with flexing and lifting at speed would be to make it with piece of aluminium running along the front where you are going to pin it. bit late to put it it now, but if you were doing it again you could make the front thin, put the aluminium in then make it thicker so that the aluminium is closer to the top. if you had it closer to the bottom layers then there is more chance of the glass just tearing around it, but having it in the upper layers means the force is pushing the glass into it, rather than lifting it away from it if it's lower in the layers.

[2gceffy]

another thing that would help is spray bog, its perfect for what your doin because theres no highs or lows that an applicator can leave.. just block block block then prime

how much in glass and matting has it set you back? conpared to buying one ?

[r33cruiser]

so if u have a genuine $$$ carbon fibre bonnet, it shouldnt have this flex issue?

[jeffworld2]

I dont think there are many diy carbon bonnets in oz.

the flexibility comes from it not being as strong as thick or strong as steel. Most glass or carbon bonnets will flex if you let them. put pins in and it cant flex

[Peter89]

damn, that's a deep cut. hope everything works fine after all the surgery.

top job on the bonnet.

[08yannch]

awesome thread. so is this going to be a street or race only bonnet. would like to know costs.

[Peter89]

awesome thread. so is this going to be a street or race only bonnet. would like to know costs.

legally in vic im quite sure you have to have a metal bonnet, don't think fibreglass is allowed however unlikely they would notice.

[Coxie]

Yeah will be for a road car, laws arent too harsh over here. Costs were about $50 for 5L of resin, $5 per square metre of matt, so about $15 - $20 worth, and $30 for body filler so it's been pretty cheap so far.

[mad082]

the guy making the bonnet is in new zealand, so for him it doesn't matter

and nice job on the hand mate. hope it heals soon

[Duncan]

haha post in the injury thread! thats a good effort.

[Giantr32typem]

bump awesome