RSR Brake Duct Install!

Old 07-04-2011, 11:10 AM
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Join Date: Jun 2011
Location: Sydney Australia
Posts: 981
Default RSR Brake Duct Install!

My Sunday project was to fit these, a set of RSR brake ducts from

You probably can't tell from the pic, but they need a bit of finishing before they are ready for paint. It looks like they were cleaned up on a belt sander after they came out of the moulds, and so there are some rough grind marks on them. The fibreglass is nice and thick though, they feel quite substantial in your hands.

I started out with 600 grit paper, which got the surface nice and smooth, but didn't get out the last of the fine scratches. This isn't going to be a problem though, as we'll see later.

Measure (using the stock pieces as a template...mine's an aussie model so I don't have the bumperette) and drill out the mounting screw hole.

The ducts don't come with a depression or anything for the screw, so I decided to countersink the holes.

Using a countersink drillbit...which looks like this (you use it after you've drilled a pilot hole)

Then you wipe all the sanding residue off with a tack-cloth, which is kinda like a cloth that has been dipped in this sticky, honey-like substance.

Then wipe off the sticky residue with some pre paint solvent.

What I'm using first, is a primer-filler, which goes on quite thick and gloopy.

The idea is that it'll fill in some of the finer surface imperfections, and so after a few coats, you get this thick, orange-peel finish.

But that's okay, the idea is that you then wet-sand the surface smooth again with some 800 grit paper.

Unsanded on the left, sanded on the right. You can see that the wet sanding actually has rubbed through the primer in some spots, but that isn't the end of the world.

Clean it up with the tack cloth and prepaint solvent again, and then I start with the body colour, which was a can mixed up by my local parts shop, to Porsche colour code 908 (Grand Prix White).

I like to lay quite thin coats at first, so after the first coat you still see plenty of the yellow primer. I aim to get full coverage only after the third coat.

When you mist on thinner coats, you only have to wait about 5-10mins between coats. After 10 coats it'll look like this:

Nice and smooth, with no runs

Then off comes the foglight, and I'm measuring the slot I need to cut in the bumper, using that crease line in the bumper as a reference point. (I want the lip of the duct to sit about 2mm proud of that crease line).

...for some reason I don't have pics of the foglight, but it's easy to remove. Once you remove the trim pieces around it, it's held into this greay plastic bucket by 2 screws ...the 3rd screw you see is for adjusting the angle of the foglight, so if you're turning a screw and nothing is coming loose, that's probably the one you got

Drill 2 holes to mark the end of the slot, and then cut the slot with a dremel.

Finished slot...I should mention that there was somewhat of a variation between the two ducts, so the slot for the other side is actually in a different spot by 5mm. Cut once, measure 5 times The good news is that all of this is well behind the crease line on the bumper, and you'll notice that the foglight stands proud of that crease. So, in the event that you screw it up, throw the ducts to the back of the garage, and quietly refit the foglights, nobody will be the wiser

Also it seems that there is some sort of bracket that's close where the slot is, so that long tab on the duct has to be shortened somewhat.

But once all that is done, it slots in and bolts up like a champ

To finish off the ducts my local hardware store sells this aluminium mesh for flyscreen doors.

Cut slits in it, in readiness for shaping

Fold it to follow the duct as closely as possible, then tape in place.

Then we use my favourite...Qbond, which is this black powder which you sprinkle onto the surface you want to glue. You then add one or two drops of this fluid, and pppsssscchhht...within a second or two it sets rock hard. The great thing about this stuff is that it can "bridge" a gap, you simply lay the powder on more thickly. Super great stuff, I've used it on cracked spoilers and even interior doorhandles. Super strong, and within a few seconds it's set, and so is much more convenient than glue that you have to wait to dry...and there's no messy glue that gets all over your fingers (and then all over the piece you're working on!). Also the powder+fluid system means that the chances of you glueing your hand to your forehead is somewhat reduced

Glue down all the tabs of mesh.

Compared to some other brands, the Design911 ducts sure have a bit of a gap around them, but I don't think it's objectionable and the sculpting of the duct is quite nice.

The eagle-eyed among you will have noted that these ducts do nothing at all, since it's quite clear that they lead to nowhere I've got to replace the a/c fan ballast resistor soon, and when the bumper comes off for that, I'll cut the plastic behind the duct to let the air through. I won't be ducting them to the brakes though, these will be oil cooler ducts
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Old 07-10-2011, 01:09 PM
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Join Date: Jun 2011
Location: Sydney Australia
Posts: 981

Well the bumper came off tonight to do the a/c fan resistor, which seems to be this crappy DIY rite of passage for all 964 owners :lol:

So while the bumper is off, out comes the dremel...

So cut the plastic behind the duct. I resisted the temptation to cut the duct wider, since that would mean losing the mounting point (and bolts) for the stock foglight. This way, the foglight can always be refitted later and the hole covered up.

As I said before, the oil cooler (and a/c condensor) are in the way of these ducts acting as true brake ducts.

But I figure that since the car spends more time in traffic than on the racetrack, that having these RS ducts act as additional sources of cooling air for the oil cooler and a/c condensor can't be a bad thing.

And the RS ducts do look much better than they did in Fake-Duct(TM) mode

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