7" retrofit (GDAA WRX)

[satrya]

Another effort to make the shape of the plastic piece closer to the shape of the fins in the OE bumper cover. This time, I'm using the squared edge of an acrylic "template" to push the plastic trim from the inside so it inherits a more squared edge. The plastic piece is first heated, and then placed upside down on the vise grip, and then the acrylic is pushed down onto it:


After a few repeats, the inner side of the plastic piece starts to take on the squarish edge of the acrylic template. The surface is originally bumpy. The picture below shows how some of the bumps at the tip of the piece has flattened out:


This makes the outer surface have a cross section that is more like a squared U channel than a half-circle channel:

[satrya]

Prototyping vent extensions

The previous generation Impreza (GC/GF/GM platform) had vent-opening-like shapes wrapped around the bumper cover's corners (22b version as shown below with one of the openings filled with amber corner parking lights, courtesy of https://nl.wikipedia.org/wiki/Bestan...za_22B_STi.jpg). The GD/GG version carries a bit of that feature in the form of 3 opening shapes, which doesn't extend all the way to the front side. It seems like the GD could use something almost as long as that of the GC/GF/GM version.


Time to prototype the vent extensions (i.e. extending the vent shapes from the OE bumper cover to the fog trim piece). I eyeballed where the upper and lower limits of the vent should extend to. Since the surface is curved, the lines don't look too straight from this angle:


To get a better idea of the shape of the U-cross-sectioned plastic piece to transplant into the fog trim piece, I made a prototype using blue tape folded into itself (to make it stiffer and not have any adhesive side), like so:


The prototype sits like so:


Repeat the process for the lower extension, and remove the rest of the alignment tapes:


Another angle:


It becomes very apparent that any small error in pitch and roll angle will make the extension look misaligned. In this case, having such a small space between the fog trim and the extension space means that the extension doesn't need to be very long. The longer it has to be, the harder it will be to ensure that they all line up nicely. We'll see. This may or may not work. But I'll never know unless I give it a try.

[satrya]

First attempt. The idea is to cut a notch on the fog trim, insert the extension piece, and join it together by heat.

Marking the notch; lift one of the prototypes up and trace where the extension will meet the trim:


Cut. Carefully. (cut resistant gloves just in case)


Heat-joined. This will need some more finishing work to make it nice and smooth, but the joint seems strong enough.


Looks like this when the fog trim is mounted on the bumper cover. It'll need some more work to align the extension shape to the existing OE vents. This takes a lot more time than I'd anticipated. (most DIYs do)

[satrya]

Tweaked the first extension on the passenger side to better match the pitch angle of the OE vent, and mounted the 2nd extension. This time, instead of cutting a notch, I decided to just join the extension to the trim directly by heat. The advantage is that the fog trim's structural integrity isn't compromised by having notches.


Test fit:

[satrya]

Cross section of extension piece

Here's a picture of the cross section of the extension piece; showing how the flattening of the top has squared off the initially U-shaped channel:

[satrya]

Testing an idea on extending the extension to the other side...

I have a generic adhesive backed decoration that has a slightly sharper cross sectional shape. Here it is marked for cutting.


If the OE vent is extended beyond the two extension pieces already added on the fog trim, it would probably show up on the other end like so:


Here's how it might look from a pedestrian several feet away.


A lower vantage point:



The idea is that as the OE vent shape is extended further, the flat surface becomes smaller, and by the time it shows up on the other side of the fog trim, the flat surface has dissapeared, resulting in this sharper shape.

Maybe keeping the cross section the same is better.

[satrya]

Driver's side vent extensions

Working on the driver's side now.

Setting up alignment lines with blue tape:


Cut, and add tape to mark where the extension lands on the fog trim:


Tape a prototype on the fog trim, to help mark where and how the extension should be attached:


Attached:


Both sides with extension; the driver's side extensions are not visible from this angle, but they're there.

[csjoh]

Looks good!

I liked the idea of extending it "through" the fog light cover and have it come out pointier on the inside, but at the same time it doesn't look quite right... maybe try extending it to the edge of the "mouth" in the bumper?

[satrya]

Looks good!

I liked the idea of extending it "through" the fog light cover and have it come out pointier on the inside, but at the same time it doesn't look quite right... maybe try extending it to the edge of the "mouth" in the bumper?

Thx

Doesn't your suggestion mean that the extension won't connect with the fog trim at all? Or did you mean out of the fog trim like I had in post #891, but make that extension long enough to go all the way to enter the lower opening for the radiator? That would be very long. I'd be worried about getting the shape appear crooked.

[satrya]

Aligning further extension

I wanted to see where the extra extension should "point" to. This is because on the OE lower bumper cover opening (for the radiator), there is a black piece that has a bottom, which creates a horizontal line across the opening. After tweaking the possible lines, I ended up with this. The tape delineates the approximate upper and lower edges of the extension.

[satrya]

Extension part

I decided against using this piece I previously planned to use as the extension.


On one hand, the argument for using that piece is that the OE vent at the corner of the bumper cover gets thinner and thinner, to emerge on the other side of the fog trim as a pointed edge. That seems to make sense in a way. However, none of the OE features on the body panels convey something that sharp.

So, I opted to use the same method for the other vent extensions on the opposite side of the fog trim pieces. There are two changes. The first, is to make the piece a little bit thinner (not much, just by a few milimeters) by heating the piece and clamping it to cool. The second, is to add a sharper curvature in order to follow the curved edge of the fog trim pieces.

Adding a sharper curvature by heat forming the material:


And then, cut an appropriate piece to size. It looks like a fingernail of sorts..

[satrya]

The new extension sits more or less like so, but blended further into the surface of the fog trim.




There's quite a bit of excess material from the "fingernail" that needs to be removed once it is affixed to the fog trim piece.


Do the same thing for the other side.

[satrya]

One side done






Now the OE vent (on the bumper cover) appears to go on and lines up with the horizontal shape in the OE bumper cover opening.

[satrya]

On to the not-so-fun part; sanding the extension and the heat-weld joints around it smooth. The area around the extension on the right side of this picture shows the roughness of the joint from the heat welding. The sanding of the area around the left extension is almost done.

[satrya]

First coat of primer.


Next will be successive repeats of wetsand & primer until it is nice enough, especially around the joint of the extension vent pieces.