creekman

First a little back ground… I’ve installed a LS3/480 HP V8 in my 2003 C4S. As part of the conversion I installed a custom 3rd radiator where Porsche had installed an oil radiator for the Tiptronic cars. I wanted to utilize the grill venting on the GT2 bumpers for better airflow for the 3rd radiator. On my last trip to California in Dec., 2014 I purchased an aftermarket 996 GT2 FiberGlass front bumper. I met with the owner of the company, I showed him my car and subsequently ordered a 996 GT2 bumper. The very limited instructions say you should take the bumper to a professional to make the install since there is some fitting to be done. I received the bumper in good order and started the fit and install. I might add that I worked my way through school in a body shop, plus I have more tools and equipment than a lot of shops. Anyway, I struggled with the fit, mostly the bumper lacked clearance under the radiators. I talked to the owner and he emphasized that there would be some fitting. So with that information I did some cutting on the bumper tray for clearance of radiator supports. Long story short after several other back and forths with the shop they finally agreed that they sold me the wrong bumper. The bumper that I got was for a narrow body car. They refunded some of the money for the bumper and since I had made cuts on the bumper he said just keep it. Anyone need a 996 GT2 bumper? My next stop was a search on the internet. I found a company that had modified a 997 GT2 bumper to fit the 996 head lights, what a great idea... This bumper was nearly twice as expensive, part of that extra cost was the factory grills and LED lights that I purchased with the bumper. I liked the fact the 997 GT2 bumper had LED lights and was a little more aggressive looking than the 996 GT2 bumper. After coming up short on the first bumper I had a long discussion with the owner of the company on the 997 bumper. I ordered it with the caveat that he would personally check the bumper out before shipping. You’ll see later that didn’t happen, welcome to the world of after-market Fiber Glass components. INSTALLATION: Before you can do a trial fit of the bumper to the car I would do the following: 1. Take a hand file and be sure that the trailing edge of the bumper returns at the wheel wells are to your satisfaction. I made sure there was an even flow to the edge as well as put a small radius on the inboard edge. Paint will stick to a radius edge better than a sharp one. 2. Next measure the opening between the plastic channel (this part is on the car directly in front/below the hood) where the top lip of the bumper will be inserted. The channel opening is fixed so you have to sand/grind down the bumper lip so it can be inserted into the channel. I took drills and tried several until the drill slipped into the channel, then used my Veneer Calipers to measure the drill diameter for the channel opening. Mine measured .190” plus. 3. Next I took a D8 sander and reduced the fiberglas lip to the .190" measurement. Don’t over do it since there won’t be a lot of fiberglas left, just sand the lip down enough so the lip will seat all the way into the channel. Be careful of the two mounting tabs, they are slightly protruding/sticking up so as you sand across the bumper lip to reduce the thickness you can take too much material off of the two tabs. All the sanding was done on the inside of the bumper. These tabs are where your first two mounting screws (flat head philips) will attach and will center your new bumper. You can adjust the hood clearance/gap by raising or lowering the plastic channel, the channel is held in place with 10mm nuts. 4. Next I sanded and leveled the two returns at the marker lights. Again, all the sanding was done on the inside of the bumper. These returns will slip into the groove created by the plastic bracket and the lower return of the fender sheet metal. Along those lines I would cover the fender from the head light back to the wheel well opening with blue/green masking tape. That will protect the paint during the install. These plastic brackets are adjustable, so take a 10mm socket and loosen the brackets so they’re as low as they will go for the first time. You can measure the thickness of the fiberglas returns to be sure they’re going to slip into the retaining channel. I would try and make the thickness of the fiberglass returns as consistent as possible. If you need to drop the plastic bracket further down you can elongate the mounting holes. I had to do that on the left side. Remember that the fiber glass layup is not always consistent so you want to sand/grind the back sides of these areas so your finished gap/lines between the fender and bumper are even. 5. This item might not be in order, but I would remove the forward fender liners before installing the bumper for the first time so you only have to worry about the fit of the bumper and not have any obstructions. Also you’ll see that the liners will need some work, this is due to the fact that the bottom of the bumper is too wide. 6. You’ll need to provide spacers at the forward recess of the marker light location. I turned two aluminum donuts, .441"O.D. X .190"I.D. X .126" tall. The reason for the spacers is to allow the front tabs of the marker light to slip over the fiberglass. You can use washers or tubing to do the same thing. The back of the marker light snaps into place. I might add that after riveting the lower plates (see later info on this) I ended up with taller spacers. See Pix No. 1. 7. If you want a tighter fit under the headlights, then you'll have to add some fiberglass/filler. I’m assuming the bumper is made with polyester resin so you could use strips of mat which would be easy to taper - or you could use a strong putty. If you have the sources, poly resin with milled fibers will also work. I used a product called U-Pol which is a Bondo type product, but has glass fibers. It worked easy, sanded easy, a great product. If you use some type of filler you should consider drilling small holes in the putty/filler area to help the filler adhesion – I’m sure you would do this without me mentioning it, but sand off the white primer finish on the bumper so you can make a good bond to the bumper… See Pixs No. 2, 3 and 4. I don’t understand if they modified the molds for the 996 why they didn’t come up with a better fit under the headlights… 8. Here’s the big issue with this bumper, the top of the bumper is dead on with it’s mounting holes, some where drilled, others had dimples where the holes would have to be drilled. But the bottom of the bumper is approximately 2” too wide so a closure strip will have to be added to the fender liners. Again, I don’t know why you make a custom bumper and the molds were not made to fit the car that it was made for. Further, I have 19” wheels with a bigger off-set than the factory 18’s. The bumper stuck out farther than my wheels, looked like a choo-choo cattle catcher. So I took a cut off wheel and made 3-5 slices on the bottom tray at the corners, then pulled the bumper together using wire attached at the marker light area mounting holes. I twisted the double wire with a screw driver until the cut joints at the bottom tray came together. I used JB Weld on the inside of the bumper to cement the joints together. I had planned to use aluminum .040” plates that later would be riveted to give the cut area reinforcement. I wouldn’t rely on the JB Weld for long term, in my case I used aluminum doublers, but you might consider laying in some additional Fiber Glass. See pix No. 5. 9. The bottom bumper tray will cover up several mounting points to the radiator supports, several other mounting locations as well as the fender liner. I have an aircraft tool that is used for locating blind holes, see pix No. 6. You can put two hack saw blades together to make your own locating tool. However I might add until you have every other fastening secured I would not drill any mounting holes in the bumper tray until that’s done. Ask me how I know… The bumper tray fits the bottom of the car, but there’s an approximate gap of 7/8" between the tray and the factory mounting points so you’ll need spacers. I machined spacers out of aluminum, I used a large diameter so I would spread the contact area. Also I used large S.S. fender washers under the screw heads. See pix No.7, 8 and 9. Regarding the 7/8” gap, the spacers takes care of the immediate problem of securing the bumper, but the downside is that it reduces the chin spoiler clearance from 6-7/8" on my factory Turbo bumper to 6” on the 997 GT2 bumper. Plus the 997 GT2 reworked bumper for the 996 overhangs further forward so your up and down driveway clearance will be dramatically reduced. In my case I have a 14% grade to my drive apron and the only way I can get the car to the street is to back out and have a spotter to tell me when to swing the front end just missing the curb return. I’ll have to re-do my drive approach to make using the car workable. Don’t get me wrong, I love the look of the bumper, the LED lights, it’s well made, much better than the first bumper, albeit a lot more expensive. I’m just passing on how to’s to prevent any any lost souls like me surprises. 10. Here’s the reinforcing plates that I used for the bumper tray cut areas. However I’ve extended the plates both to the rear and to the outside to cover open areas under the radiators that the factory bumper originally covered. Again the new bumper should have addressed that… See pix No. 10. 11. Here’s your last challenge, closing up the gap between the fender liner and the new bumper side fenders… Your biggest problem will be to heat and form the fender liner so the outside edge moves forward to tuck in behind the fender/bumper return. Right now the new bumper wheel arch is slightly forward of where the factory liner wants to be. I made a wood buck and heated the back side with my heat gun and formed the fender liner forward. All of this will be obvious to you once you get this far. I put the buck in the bench vise, then set the liner down over the buck once it was hot. You’ll have to hold the liner over the buck until it cools down. Here’s the wood buck that I band sawed out, very simple, but it worked like a charm. See pix No. 11 12. Depending on your needs and abilities you can leave the gap, use rubber or plastic to fill the liner gap. I chose to use .040” aluminum and riveted it to the fender liner… See pix No. 12 13. Here’s how I solved the tow eye bumper plug installation… See pix 13 and 14. 14. Regarding the radiator intake boots: Here’s the information that’s worth the price of admission if you’re going to do this bumper…The manufacture of the bumper doesn’t know, I only backed into this information by accident. 2 years ago I bought a new air intake boot since mine had a tear in it. The bumper company said that either you chop up your existing boot or go without and just let the air migrate through your grill and across your radiators willy-nilly. I cut away on my existing boot and it was a mess and fit the bumper poorly… I happen to look at the P/N on the boot and it began with a 997 P/N. I figured if a 997 boot fit the radiator on my C4S then all I had to do was to order the 997 GT2 boot. Sure enough it fit both the radiator and the GT2 bumper. I did have to snip a couple of places, but overall it was a good fit. See pix 15. 15. I connected the LED lights, took the one amber incandescent light in the LED body and turned that into a directional light. Also I completed the RennTech side marker light conversion to a directional light. I used a honey cone aluminum mesh that I fitted and installed behind the grill openings. I removed the grills for painting, then re-installed them, then attached the fitted grills (I had them powder painted) with hot glue. It would have been a lot better installing the grill mesh before installing the grills. I might add that I bought the Porsche factory grills and LED lights. Lastly, I used the factory rubber eye brows under the headlights, I cut off the mounting tabs and use the 1/2” 3M molding attachment tape to bond them to the bumper. Loren has already posted the schematic I used for connecting the LED lights. Most of this work is pretty generic to any after market bumper. Take your time, measure twice, cut once and you’ll be ok… There’s a lot of nuances that I haven’t gone into, if you have any specific question, feel free to PM me. Good luck, Pix No. 1 Pix No. 2 Pix No. 3 Pix No. 4 Pix No. 5 Pix No. 6 Pix No. 7 Pix No. 8 Pix No. 9 Pix No. 10 Pix No. 11 Pix No. 12 Pix No. 13 Pix No. 14 Pix No. 15