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Modifying Nova GSi front bumper

DISCLAIMER: The information in these documents are a collection from experience (friends or myself), magazine articles, mailing lists and internet web sites etc. So don't take these as 100% correct gospel, hence I don't take any responsibility for any of these guides.

Difficulty Rating: 4/5 - A bit fiddly - but worth it.

Download printable Adobe Acrobat file (540K) Download zipped HTML version (3.2MB)	Created: 16 Dec 2000 Revision 1

Click on any of the pics for a larger view.

Before...

...and after.

This is a step-by-step guide on modifying a Nova GSi front bumper so that the middle slat is cut away and replaced with a mesh grille. This particular guide shows how the air duct is 'boxed in' so that it gives depth, other mods simply place a big piece of mesh flush with the surface with the bumper. Because of the boxing in nature, this modification is difficult to do, very fiddly in places and may take several weeks to complete (it took me a month to do, as it was the first time I've ever done this sort of thing). But by following this guide, you should be aware of any problems and be able to do the job much quicker.

You can buy this modification already done, fiberglass copy front bumper from Kingdom Developments (as seen in many car magazines). The difference is that the mesh is flush with the rest of the bumper.

You will need patience, lots of pug (filler), fiberglass and lots of sanding down and filling back up tasks. I chose to do it this way because I've never seen it done before and it is unique, even though I have seen similar, if not identical looking bumpers at recent car shows (Doh!). This modification also retains the use of the towing eye flap, so that it can be removed without damaging the fiberglass/filler, and your work :)

PARTS
Nova GSi bumper	Hack saw	Pad saw	Pug (filler)
Fiberglass Kit	Stanley knife	Permanent Marker	Masking Tape
Mesh	Metal cutters	Spray primmer paint	Sanding paper
Glue/Bonding	Sanding block	File	Strong tape

COST
New Vauxhall Nova GSi front bumper	£100	The part number for a new GSi bumper is 90443248. That is the plastic bumper only (no carriage bar of fixings etc.). Try and get galvanized steel mesh as this is protected from corrosion.
Mesh (stretched diamond shape) 1x1.5m B&Q	£18
Gray plastic primer spray paint (2 cans)	£5 ea

Just before you start, make sure you note the following:

If you've got the Haynes manual for your car, have this is front of you. You'll need it on how to remove the front bumper if you have to (either that or buy one).
Buy various grits of sand paper, 100 is rough, 1000 is smooth, you may use water to make the job easier. Use 200 grit for first time sanding down, then once it starts to get smooth, use 400 grit. Once all the bad holes and cracks have been filed in, start the very smooth stage of sanding down with 600-800 grit.
To bond on plastic, I used Adhesive, which are two compounds mixed together. Or use Silk-o-flex or Tiger Seal that body shops use. Either way, wait 24 hours to dry before continuing.
Try and purchase galvanized steel mesh for the air duct, as this has good prevention properties against corrosion. Use Enamel paint on the metal mesh when spraying.
If painting a new GSi bumper (like what is shown in this guide), spray several layers of plastic primer on. This will show any imperfections missed in the sanding process.
When the bumper is placed back on the car, it may be beneficial to paint the front valence behind the air duct a darker colour (i.e. black). Depending on how dense the mesh is, it may not seem think enough and you will see the valence behind it.

OK, got all the above? Then follow the steps below (remember to click on the pics for a bigger view):

Step 1	Step 2	Step 3

This is what a brand new front Nova GSi bumper looks like, NOTE: it won't be staying like this for long. The idea is to cut out the middle slat making a larger air duct.	Looking from the back, mark where you want to cut. Use a permanent marker and masking tape. In this picture I'm keeping the side wall and lower ledge, so I'll cut right on the edge of it.	OK you've got all the tools and parts, now to make the first cut. Work from inside the bumper and chop off all the thin plastic legs off the top lip and middle slat.

Step 4	Step 5	Step 6

Use the pad saw to cut the first side wall. Remember to keep to the right of this as you can always file off the plastic you don't want. As this was a new bumper the plastic was easy to cut. Cut all the way down till it meets the second lip.	Do the same on the towing eye cover. This piece of plastic is held into place by the two loops snapping into the bumper. By cutting along the side wall, one of the loops will be chopped off. Fortunately one loop is still able to hold the cover in place.	Now with the plastic legs and side wall cut, there is one final cut along the length to separate it from the lower lip spoiler. You'll need to use the pad saw to make a start on the cut, after that use the hack saw.

Step 7	Step 8	Step 9

Use the hacksaw all away along the dip between the top and lower lip spoiler. Once the cut is complete, remove the strip of plastic, but don't throw it away! It will come in handy later on.	Now step back and see what you've done. There's no turning back now. You're 50% away from finishing the cutting sequence. All there is to do now is to chop part of the lower lip spoiler off.	Turn the bumper over again to get at the back. Use a Stanley knife and cut along the line you made with the pen. It's very difficult to make a cut, not enough room yet to use the pad saw. This is to retain the depth of the recess.

Step 10	Step 11	Step 12

Once you've done enough cutting with the Stanley knife, use the pad saw to cut along the length of the lower lip spoiler and then use the hack saw to finish.	Using the hack saw, cut along the edge until you meet the same spot on the other end. Again you'll need to use the pad saw and Stanley knife to finish off the job. Once is cut, remove the low lip spoiler.	Take another step back and see what is left. Both the spoiler lips are gone now. All the major cutting of the bumper is over. Use a file or sand paper to remove swarf on the surfaces that have been cut.

Step 13	Step 14	Step 15

All that is left is the side wall and the bottom half of the lower spoiler lip. The next job is to do a lot of filling to get a 'boxed in' shape. This is to give the air duct depth and so the mesh grille won't be right at the front but further in.	Before doing any filling, remove all the plastic swarf off the bumper. The easiest method I found was to run the Stanley knife along the edge. With older bumpers (i.e. second hand items) the plastic might be a bit stiffer.	With the middle slat cut out, cut along the line as shown. You need this in a few seconds, as you need this part as flat as possible.

Step 16	Step 17	Step 18

Place the middle slat along the top of the cut out air duct. You'll needed to wedge it in place (I used some bamboo sticks). Note: it is not long enough to cover all of the top, so place it away from the towing eye cover (i.e. there will be a gap).	With the middle slat along the top, put lots of glue between the mating faces, and again wedge the middle slat in along the top (as shown). Leave for 24 hours to dry.	The middle slat should be firmly glued in. You may have to trim it down to size (i.e. it may be too deep). The gaps in the corner and what is left of the side wall need to be filled in (to give it the 'boxed in' shape).

Step 19	Step 20	Step 21

On the side wall, trim it down enough so that the 'boxed' in shape is level all the way round. Otherwise when the mesh is fitted, it appears to slope (do the same to the towing eye flap as well).	There still will be some plastic left over, cut a small bit off to plug up the gap in the side wall (as shown in the next step). Bend the plastic near the edge to that it follows the curvature of the wall.	Place the small bit of plastic against the gap in the side wall, and adjust as necessary. When complete, put some glue on the mating surfaces.

Step 22	Step 23	Step 24

You will again need to leave this for 24hrs for it to set, put something on them that will hold the piece together, i.e. a G clamp etc.	The towing eye flap is where it starts to get difficult. I want to keep the towing eye, so that I can remove it in the future. Hence I can't fill in the side wall gap as before. So a frame work is required so that the side is split.	From the small bits of plastic left, cut a thin strip and bend it at right angles. Glue this onto the back of the towing eye flap as shown. Place masking tape to hold the plastic in place and also to stop it gluing to the wrong surface. Again wait 24 hours for it to dry.

Step 25	Step 26	Step 27

Yet again using the left over bits of plastic, cut a small piece so that it bridges the gap on the towing eye flap (as shown). Again glue this into place and allow to dry.	With the gap bridged in and the glue fully dry, you should be able to remove the towing eye with no problems.	Use fiberglass on the back to fill in the hole, or rather give it some backing.

Step 28	Step 29	Step 30

Use fiberglass on the other side wall to make the wall complete. Again allow to dry before working on it.	While the fiberglass is out, start filling in the small gaps around the rest of the air duct that you have made with pug.	Carry on with the filler all along the top part of the wall, as this can be sanded down at a latter date to make it smooth.

Step 31	Step 32	Step 33

And again with the filler, pug up the gaps in the towing eye flap so that the side wall becomes solid.	With the towing eye back on the bumper, use enough filler on the side wall so that they don't become stuck together.	Place a thin bit of plastic in between the gap so that you can carry on with the filler without fear of bonding them together (I used the lid of an ice cream tub, which is very thin).

Step 34	Step 35	Step 36

With the plastic separator in place, pug up the wall as much as possible. Once the pug has dried, carefully remove the plastic separator. This should be possible without the pug cracking.	Once removed, you can start sanding down the pug so that the wall becomes uniform (use you artistic flair here and make it curvy as you want) Use 200 grit to remove most unwanted bumps and lumps (using water helps).	Do the same on the other facing wall, as this is much easier to do. Again use 200 grit paper to remove any large lumps and bumps. Add more pug as required to get the correct shape.

Step 37	Step 38	Step 39

With basic filling done, the air duct should look like this. NOTE: this is a long process of filling, sanding, filling, sanding again, finding more air holes and bubbles etc, then do some more filling....the list goes on.	Once all the filling and sanding is complete, clean the surface from dirt and dust with white sprit. Allow to dry (evaporate away). Spray the plastic primmer with thin coats, using a even spray right across the surface. Allow 5 min between each coat to dry.	With some mesh (try and get galvanized), construct a 'tray' shape out of mesh. Make the wings on each side about 3cm deep, and fold these round the side walls.

Step 40	Step 41

Once the mesh is cut out and ready to go on, spray it the colour you want, in my case I sprayed it with Black Enamel paint. Which also helps it stop rusting as it coats it.	Bond on the mesh and squash on the mesh wings so it holds it on. You may have to put some strong tape in place. Allow at least 24hrs to dry. Wipe away any excess with white sprit. Put the front bumper back on the car...and job done :).

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