Friday, September 11, 2015

981 Cayman/Boxster GT4 Side Scoop Installation Guide!

Did you buy our GT4 side scoop kit to give your 981 Cayman or Boxer a little more oomph in the visual department, as well as increasing the air going into your engine?

The installation process might seem daunting, but Planet-9 member Voyager6 did a fantastic writeup on how he installed them on his own 981 Cayman S (seriously, if you get a chance, check out his thread on his beast of a car).

He was gracious enough to allow us to repost it on our blog for the benefit of other 981 Cayman/Boxster owners, so here's Voyager6's 981 GT4 side scoop installation guide:

Porsche 981 Rocker Panel Removal and GT4 Side Vent Cover (Scoop) Installation Procedure

By Voyager6, Copyright © 2015, All Rights Reserved.

Hosting permission is granted to and May not be reposted to any other website without this author’s express permission.

This procedure will give step by step the process to remove the rocker panels of a 981 Cayman or Boxster and will also include the installation procedures to add the GT4 side vent covers, aka Ram Air Scoops (or scoops) or hidders. The procedure is documented, but any attempt at following the instructions are at your own risk. Steps listed may suffer minor omissions or errors.

The actual removal and replacement of the rocker panels is about a 3 on the 1 to 10 scale of difficulty. The car does not have to be on a lift and could be done with wheels installed on the ground, if you have a couple special Torx bits that can fit between the wheels and fender, but it is much easier to do with the wheels off.

Parts needed:

Scoops with outer vent insert with pre-drilled holes and alignment studs. The latter will significantly reduce the chances of drilling holes at the incorrect location. It is highly recommended.

As spare, optionally, a couple plastic retainers in case something breaks:

  • (2) 98150449700 Rocker repair kit ($13-15 each, fastener and base, fastener not available separately)
  • (2) 99959141340 Fixing Clip (top rocker panel retainer) $1
  • (2) 99950799940 Sill retainer clip (blue) $1


  • Plastic interior trim tools (one with a V gap and angled to give pry force is best)
  • 3/32” drill bit
  • 3/16” drill bit
  • Battery-powered drill
  • T-25 and T-35 screwdriver or bits with a ¼ inch ratchet.
  • Large Channel locks/ adjustable pliers
  • Magnetic parts tray to hold removed screws
  • Roll of painter’s tape, about 1 inch wide.
  • Wide roll of painters tape
  • Pen to mark tape
  • Touch up paint to match your car’s exterior color.

To Remove Rocker Panel:

Jack up car at front lift point. At front wheel well area, remove T-35 screw from underside of rocker panel. It holds the wheel well liner (not shown as I removed the front liner).
If you jack up the front enough, you can get at a similar T-35 screw at the rear wheel well area of the underside of the rocker panel which holds the rear wheel liner to the rocker panel.

Inside the rear wheel well, remove two screws in the liner that go into rocker panel. There is a nut in the general area that does not need to be removed. These screws are difficult to get to with a screwdriver, and can be removed with a proper-sized ratchet and bit. Otherwise, remove the rear wheel and the screws can be removed easily with a Torx screwdriver.
Directly at top of the rear wheel, there is an upward facing T-35 screw that connects the rocker panel to the rear fender. This can be reached with a normal T-35 screwdriver.
If you removed the rear wheel, put it back on and tighten the lug nuts enough to hold the weight of the car.

While car is on a jack, carefully remove eight fasteners from underside of rocker panel , between front and rear wheels.
These are large and can be gripped by your fingers and release when twisted 90 degrees. If stuck due to road grime, rotate the other way until the fastener releases. These retainers have a long slot across them. On my car, the locked position was when the slot is parallel to the rocker and unlocked position when turned perpendicular to the rocker panel. This may not be true for all cars, so inspect the fastener cap before removing them to see if this applies to your car.

Lower the car off the jack.

Now, open the door and remove the outer door sill. The sill pulls outward toward the door, held by four fasteners that fit into grooves in the underside of the sill cover.

Do not pry it up. It may need loosening a bit and putting a trim tool at the ends or under the rubber seal may help give you leverage. I did pop out one of the blue fasteners at the rear of the sill without damage to the fastener and just pushed it back in after pulling the sill away from the passenger compartment.
With the sill off the car, you will see 4 black fasteners that need to be pried out. Use an angled trim tool with a V channel to work under the fastener and press down and the fastener will eventually pop out.

At the door frame, the rocker panel should now feel loose and wiggle freely if you pull on it. This should happen for both the upper door sill area and lower Underbody parts of the rocker panel. If not, recheck for missing screws and retainers.

At this time, there should be nothing left other than clips that hold the rocker panel to the body. It is held by three plastic squeeze clips. You may need to pull the fender liners away from the rocker panel to fully release the rocker panel.
Now, start at the rear fender area and pull the rocker panel outward at the fender/rocker interface. It takes surprising little force to get it to pull off. Next, there is a vertical clip in front of the air vent at the edge of the door frame. That should release next, easily. Finally, from the front wheel well, pull the rocker panel completely off the car. Be sure to have a blanket or something to prevent it from hitting the ground if you are doing this alone. If the front doesn’t release, the panel is flexible enough to mount the scoops without removing the front of the panel.

Reinstallation is the reverse of removal. Start at front and work backward. The only note is to try to make sure the lower 8 fasteners are fully locked (note the locked position of the slots in the head of the fasteners) and to make sure the fender liners are tucked in correctly. The fender liners have a speed nut that must go above the flange of the rocker panel (as screw will press against the rocker into the speed nut. The liner may click when put into place.

Remember to torque the lug nuts to final torque. I use 120 ft-lbs.

Ram Air Scoop Installation

This is dangerous as you have to drill six holes in each rocker panel to mount the scoops. As a result, I rate this as a 7 on a difficulty scale of 1 to 10. It is all too easy to drill holes incorrectly and leave an ugly visible hole in your rocker panel, requiring repair or replacement.

Look at the scoop edge and see the six mounting holes. They are in a raised square.
Hopefully, you purchased the factory GT4 outer air vent ring that comes pre-drilled with two holes and studs to ensure consistent alignment of the scoop on the rocker panel. This is critical to getting the holes in the right place! Do not wimp out and try to reuse your original vents.
If you did purchase the GT4 vent ring, remove the old vent ring from the rocker panel and install the new GT4 outer vent ring. It has three catches that must be pressed while pushing the frame out of the rocker panel. Channel locks work well for this. Once the three catches are loose, the other side will quickly pop out.
Insert the new vent rings into the rocker panel. Start with non-latched side first and then press in the three catches. When in, press in all the way around the ring as it will go just a bit more and you will hear popping sounds as the ring fully seats.

Trial fit the scoop to the rocker panel. Make sure it fits cleanly in the intended recess.

If you have Zunsport side vent grills, now is the best time to install them. They can fit under the scoop. It is recommended to bend the three mounting hooks inward to not scratch the plastic vent ring and then, when in place from behind, use pliers to bend the hooks over the ring’s back edge so the grills will stay in place.
Now comes the dangerous part: marking where to drill the six holes. If you have purchased the full kit with the GT4 vent ring and double backed tape, then good. If not…. worry. A new rocker panel is $200 (plus paint) or filling a miss-drilled hole will cost you more than the ring ever would.

Without the pre-drilled vent, the only hope you have is to take a large sheet of paper and wrap it around the mounting edge of the scoop, draw an outline/pattern and then cut it, leaving tabs to tape to the scoop and the rocker panel. Tape the pattern to the scoop. Then mark/punch the template/pattern where the holes should be. Place the scoop with the taped pattern on the rocker panel. I recommend using wide painter’s tape to hold the scoop firmly to the rocker panel while transferring the pattern, so the scoop won’t move on you. Recheck the scoop alignment and hole position as best you can for fitment. If you tape the pattern off center, you will put the holes in the wrong place and the scoop will not mount correctly and will leave ugly gaps at the scoop-rocker panel interface.

Now, if you did the smart thing and purchased the GT4 vent rings, things are better. Two of the holes are pre-located for you and the alignment studs will ensure repeatability and reliability of the scoop’s hole locations. You can choose to create a pattern as described in the paragraph above or use a quick and dirty way to locate the screw holes:

Take four six inch lengths of painter’s tape, 1 inch wide, and put a horizontal mark to the edge of the tape on both sides at the same location. Roll the ends up a turn or two. Affix a piece of tape to the scoop, from inside to outside, non-glue smooth side against the scoop. The rolled up edges of the tape will hold the tape to the scoop. Align the edge of the tape with the center of one of the holes. Make sure the horizontal mark you made is also at the center of the hole. This sets the approximate hole center. Repeat for all holes.
Place the scoop on the fender, and make sure it is aligned on the mounting studs. Carefully unroll the tape, inside and out, one piece at a time and press the sticky side to the rocker panel, transferring the location to the rocker panel. Once done, remove the scoop and recheck the scoop and visually estimate if the hole centers are proper and correct. Remove any tape and retry if not sure. With this technique, the tape can move on you while transferring it to the rocker panels if you aren’t careful.
Once the hole positions are located on the rocker panel, take a drill with the 3/32 inch bit and make a pilot hole at the intersection of the line and tape edge. Note the angle of the scoop mating surface and adjust the drill angle to match, so you are drilling in the same angle/direction as the screw will take.

Put a pilot hole in each of the two holes in the vent, trying to stay centered. Take an unfolded paperclip or other stiff, but fine wire and stick it into the hole from the back side of the rocker panel and judge where the wire hits the scoop and note how far it is off. You can lift the scoop a little bit to see where the wire hits the scoop. Note the direction that the hole in the rocker panel needs to go to get the wire into the scoop’s screw hole. Adjust the final drill location appropriately. Re-drill using the 3/16 inch bit, taking care to bias the hole in the direction noted by the wire test. This is tedious, but works. Patience is a virtue. Repeat for remaining holes. I recommend the wire test regardless of the method you choose to transfer the hole locations to the rocker panel.

Test fit the scoop and start all six screws. Note if any are off. If so, using the 3/16” bit, auger the hole in the needed direction. Remove the screws. Hopefully you will not be so far off that the hole becomes visible at the edge of the scoop. If a hole becomes visible, your options are pretty much to continue and fill and paint the rocker after re-installation.

Install the tar-like double backed tape on the scoop, carefully aligning it. It does not take well to removal. Peel the white backing off and apply to the scoop, leaving the red backing film on the tape. Each scoop has two tape pieces. Make sure the red tabs meet in the middle. Lightly install the scoops using only an upper and a lower screw, leaving a gap between the scoop and the rocker to pull the red backing off. Note that some of the red backing film will have to be broken as the screws will wind up in the middle of the red backing film. Once off, press the scoop firmly to the rocker panel with one even motion (upper and lower at the same time) and the scoop will be more or less bonded to the panel.

Install remaining screws and tighten and the assembly is done. Reinstall rocker panel and repeat for other side.
Look at the scoop and rocker panel for stone chips, nicks and abrasions that can be fixed with touch up paint. Then reinstall the rocker panels. Repeat for the other side.
Finished Product:


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  2. Fantastic. Thank you for posting this.