It's been a while since I’ve posted an update - and that time has been full of work! Just compare the last photo in the post above to what my 911 looks like now:
That's right, she's getting ready for paint so everything must go! But before all the panels can go, I had to fit the ’72 RS TRE bodykit. This is a popular option, so I thought I’d talk through how to put all the various pieces on. This post is all about the nitty gritty of the build, but for less in-depth coverage, you can follow the story here:
Porsche Backdate Pt 6: Bustin' Ass on Fiberglass | FactoryTwoFour
The TRE kit I bought included:
Ducktail
Rear bumper
Front bumper
Hood
Fender extensions for longhood
Panel mating rubber
Extra Parts You’ll Need:
U-clips
Hood tie downs
3+ inch Bolts
Body screws
Fiberglass and resin
Body sealer
Tools You’ll Need:
Ratchet and sockets
Philips screwdrivers
Welder (or body shop)
Mechanics Wire
Angle grinder and cutting wheel
To kick it off, remove your bumpers front and rear. Also remove the impact bumper posts if you’ve got them (mine is an ’88) – I used a combination of extentions to access the shy bolts on the passenger rear, and moved the washer fluid tank out of the way for the driver’s front.
Then remove your whaletail or decklid. Now that your car is looking suitably punkrock, install your sweet new ducktail! Make sure to do this without the grill. You’ll need to access the inside of the compartment while it is closed. To lock the tail close, you can either use the factory latch, racing tie downs, or both. I went with just tie downs. This fiberglass part, like all fiberglass, will require some love via sandpaper and body filler on both the fiberglass and your metal chassis. Keep massaging the lines until your panel gaps are as small as possible. I continued working on mine after this picture was taken to get that forward gap as small as possible.
All in all, the tail is pretty simple. You’ll spend your time on the sanding and checking over and over till it’s perfect. When it is time to install the grill, I had to grind out square indentations to fit the bolt holders in the grill I got from TRE.
Next you can install the rear bumper. Cut away (or drill out the rivets) of the center light box between taillights. You can choose to leave top section/roof of this box to act as a bracket to screw the fiberglass tail to. I found just welding in 3 small tabs across this area easier, but to each their own!
Grind back all cut metal till smooth. Fit bumper with just your hands and check for alignment and any twisting in the fiberglass part. With an assistant, hold the bumper up and make either the right or left fender edge flush while making sure the center section is as high as possible. Once it is flush on the leading edge and looks good, mark the holes already in the body that used to hold the old heavy bumper. Now that you have marked where the holes go, drill out the fiberglass on those marks on this one side. Mate the pieces together again and pass mechanic’s wire or even a bolt through to hold that corner up temporarily. Move to the other side of the car – once again flush and once again pushed up at the center – and mark the holes. Remove the whole fender again and drill this side.
Once again offer up the fender to the body and connect with temporary measures. You’ll notice that the fiberglass lip width far exceeds of the body’s steel. While that is mostly harmless it will interfere with the reinforcing U-clips you’ll need to protect the fiberglass and the body. Whatever clips you’ve purchased will inform what kind of notch you’ll need to cut out of the fiberglass. Simply mark your required cut around the existing holes all around and remove the bumper again.
Cut out all the tabs, mate it up again, install your U-clips - mine required cutting and customizing my own out of sheet metal to deal with the thickness of the two body pieces -
You can now thread in the screws all around.
At every step ensure your corners are still flush. I let mine sit installed for a week to “bend” everything into shape. If you left the center section of metal or created your own metal tabs to connect the center, drill this out now and connect with body panel screws.
After a week I removed the bumper again and started on the fiberglass patch of the exhaust hole. I did this after the initial fitting process and after “bending” it so as not to stress the patch I created. Create a rough area around the exhaust hole for the fiberglass to adhere to with 80 grit sandpaper on both sides. From the finished and smooth side, lay down one sheet of fiberglass and liberally coat it with resin. Let this single layer dry overnight. You now have a solid backing to layer on. Now from the rough side, layer half circle cuts and build up to flush and even with the existing bumper. Once again, be liberal with the resin. Let this cure and begin sanding. Fill in any gaps or pits with body filler and sand more. Repeat this process until you have a smooth finish that looks invisible.
Moving to the front of the car now, install the fiberglass hood and check for fitment. All gaps should be even from front to back, and the leading edge should be perfectly straight and level. I found my hood to be somewhat bowed upward. To fix this, park the car and hood in the sun for an hour and let it warm up. Next put some weight (35-50 lbs) distributed evenly across where it is bowed. This should flatten it down to even with the fender.
Once you are happy with the hood’s placement, you can move on the front bumper. Suspend the bumper at the level it will be installed by placing wood or cushions underneath it. Some cars will have pre-existing holes that line up with the 4 embedded bolts in the TRE fender. If not, place a nail in both of the top holes and press firmly (or lightly hammer) until you’ve made an impression in the rubberized coating of the front firewall. You can somewhat see the nail in this photo:
Drill out this spot and install a bolt through each into the bumper leaving plenty of wiggle room. Now place a nail in the lower two holes and repeat the process. Level the bumper all around and adjust any holes as necessary. You can now move on to installing the lightbox extensions on the fender.
The lightboxes are now sold by TRE as a very convenient part that can be welded onto your existing short-hood fenders, saving you the thousands it can be to buy replacement fenders. These parts are a great addition to the backdating toolchest, but they are not for beginners (like myself) to install. Despite how simple they look to weld up to the fender, this is generally a job best left to body shops. I attempted it myself and wound up with a massive mismatch between lengths:
Your actual fender must be cut somewhat to accommodate the extensions at the perfect angle and pitch. TRE took care of this job for me, and they’ve been great to work with on all phases of this build. I cannot recommend them enough.
Once they had cut and welded in the extensions, I rechecked the hood and front bumper for fitment and confirmed all was copacetic. And that’s it, the full ’72 RS TRE bodykit was fitted. Before bodyfilling and perfecting, it is on to paint stripping in a major way.
But that’s a story for next time…
