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dusky007

S13\180sx Vented Bonnet DIY

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Todays custom cars have outrageous designs and even more outrageous prices. Some custom Bonnets can be as high as $1,500. Customizing your own bonnet not only means that no one else has your exact bonnet, but is a cheap alternative to buying a custom fabricated bonnet. To get the ball rolling on the custom bonnet project you need a few things.

The first thing that you must have is the bonnet that you are going to customize. Preferably this is a bonnet that you don't need off of your car.

 

 

The second thing you need is supplies. The following supplies will be needed to make a custom bonnet. Fiberglass Repair Kit, Bondo Body Filler, Sandpaper 60, 150, 250, 500, 1200 wet sanding paper, Jigsaw, Fine tooth metal cutting blades for the jigsaw, Dremel Tool or cutting tool, Lots of cutting wheels, Electric sander and a clean open work area.

 

The third thing you need maybe the most important thing. You need patience to do bodywork. It takes a while for anything involving the body so you are warned. Take your time and don't rush it. The more time you put into your bonnet the better it will look.

 

That's about it for stuff you need. You ready to begin?

 

The first thing you need to think about when making a custom bonnet is where the hood vents / scoops reside. This is the most important part of desiging your bonnet. Make a few sketches of what you want your bonnet to look like. Get opinions and think it out.

 

Next you need to decide if the idea you have is a feasable one. Check all the dimensions 3 times and take off the the spash gaurd on the bottom of your engine and shine a light up there and make sure you have room when the bonnet is closed. My hood vent ends up right between the valve cover and the fan shroud. Make sure you are exactly sure where the vent is going to be will fit and then mark where the cut will be with a marker. Take into consideration the bonnet supports you will have to cut.

 

After you have the marks on the bonnet cut a small slit in the bonnet with the dremel tool and a cut wheel. This is so you don't have to drill a big hole to fit the blade of the jig saw in. (Don't forget to take the hood liner off first!) After you have cut a small slit in the bonnet place the jig saw on the hood and start chopping away. Go slowly so you are very accurate and don't have any jagged edges. Go slowly and stopping often to check your work. The Picture below shows the bonnet after marking and cutting.

 

hood1_1_.jpg

 

 

After you have finished all the cutting sand the area down to the metal around the cut on the top of the bonnet. After you have done this mark where the under bonnet framing needs to be cut in order to make the bend.

 

hood2_1_.jpg

 

After you have marked the bonnet to cut the framing begin cutting with the cutting tool or dremel tool. Be careful not to go through the top of the bonnet. After you are done cutting remove the framing carefully. The piece might be a little tough to pull off, it has adhesive between the framing and the sheetmetal. Dont be afraid to rip the stuff.

 

hood3_1_.jpg

 

After most of the frame work is removed there is one more peice of frame work to be removed. This peice that needs to be removed is about 1/2 inch away from all the previous cuts to allow the sheetmetal to fold down. See the black marker of the picture above? This is where the framework had to be trimmed to allow the sheet metal to fold down. After this is done make sure the flap can move without any obstructions.

 

Now the fun part. Take your current bonnet off and pop the new one on to ensure that it fits. (This is the moment of truth.) When you decided that it fits push the flap down as far as you want it or until it hits something. I could get an 1 3/4 inch opening for the vent in my bonnet. That's pretty big for a vent. After you envisioning what it's going to looklike when it's done take the bonnet off and mark how big the vent can be. The picture below is the fitment process.

 

hood4_1_.jpg

 

After you are done deciding how big the vent can be cut some wood blocks the size of the proposed vent and insert them into the vent. This will hold the size while you work on the hood. The picture below shows the wood blocks in place.

 

hood5_1_.jpg

 

Now is the time to open the windows in your work area. Get out that fiberglass kit you got at the store. Follow the instructions on your fiberglass kit and mix the resin and hardener. Apply the soaked fiberglass sheet as pictured below on the side of the vent and a support in the middle. Try to make the fiberglass like a wall at 90 degrees on the side.

 

hood6_1_.jpg

 

Try not to get too high on the fumes and go have a cold glass of iced tea or something. The Fiberglass will probably take about an hour to dry depending on how much harderner you used. After the Fiberglass has dried you're ready to break out the bondo. Fill in the sides of the vent and the support. Several applications will be nessary to get the right look of the wall. Sanding and re-applying the bondo will be nessary. After the front looks good do the same to the back of the bonnet. Take your time and make it look professional. This part takes the longest.

 

hood7_1_.jpg

hood8_1_.jpg

hood9_1_.jpg

 

Notice in this picture I put some glue on the old bonnet framing to prevent rattles.

 

hood10_1_.jpg

 

 

Make sure there are no bubbles in the glue and everything is smooth. It's almost ready to goto the body shop at this point. Take your old hood off right before you are ready to get the new one painted and put the customized bonnet on. Make sure it fits how you like it and don't forget to tell the body shop to paint the underside of the hood too. Sometimes if you don't tell them they won't paint it. Get a few estimates before you get the work done and consider quality and if they will blend the paint. My bonnet cost $200 to get painted. No blending was nessary because the fenders were just painted. The picture below is the night before it went to the body shop.

 

hood11_1_.jpg

 

Well here is the finished product.. Whatcha think? Not bad for some low buck mod, and it's very functional as well!

 

hood12_1_.jpg

hood13_1_.jpg

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Nice write up mate, gives me a few Ideas for my S13 lid!

Much less than a fiberglass number and gives me an excuse to put a black bonnet on! F**KING pander it

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Nice, Gave Me A Few Ideas for the ols s13, have to post some pics when i get round to it

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Ive also seen bonnets that have a whole triangle section cut out between the structure lines and then covered with mesh. also comes up great.

good work!

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what did you use to get the middle support in the vent? is it metal or built up fiberglass??

 

cheers

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Id say the cops would have a field day with you for street use. They could say youve weakened the structural integrity of the bonnet

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