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Discussion Starter · #1 ·
Custom Front Bumper:
Merging Two Bumpers Together:

First off, I should apologize for such a long post.
To make a short story long….I purchased our 2000 Spyder earlier this year. It needed a little work but not anything I didn’t think I couldn’t handle. One of the conditions my Better Half put on the purchase of the Spyder was the need to repaint the front bumper cover. The bumper was in pretty rough shape. Along with some major stone chips, paint had peeled off of in areas as large as my hand. I would have happily agreed to just about anything to be “allowed” the Spyder. Yeah, I know. Who wears the pants and all. The Spyder was still considered a major investment for us both and it’s not exactly the most practical car in the world. I wouldn’t dream of just buying one on my own and expect to live to tell the tale.

After several smaller repairs and details had been successfully taken care of on the car it became time to repaint the bumper. I figured I would have to remove the bumper from the car, strip it, sand it all smooth, then prime, base, clear coat, polish, and wax. I knew it would already be a PITA so why not end up with a bumper closer to what I really wanted? If I was going to put all this time, energy, and money into a bumper, I wanted one a little more classic looking than the standard fare. I wanted a front bumper that was just a few inches longer, rounder, and sleeker. “Please insert your phallic jokes here. “ I wanted a bumper with some classic sports car lines and better aerodynamics. Now don’t get me wrong. I really like the old, original, stock Spyder bumpers. I wanted something close to that but not exactly that. To each his own I guess. After searching all my bumper options online, I decided to modify my own. It would be less expensive (not including my time) than one of the prefabbed bumpers and it would be one of a kind!

I guess this is a good time to disclose that I have no real auto body experience other than a few bondo and rattle can repairs on a couple of junk cars over the years. However, I am a creative problem solver, an over thinker, and a classically trained artist/sculptor. I have sculpted, repaired, and refinished many unique things out of a wide variety of odd stuff over the years. I figured these skills and the internet would be all I would need. A plastic bumper is a plastic bumper. A little glue, a little fiberglass, a little body filler, a little paint. Maybe a long week worth of work and I’d be golden.

I didn’t know everything I didn’t know.

So if this is something you have ever thought about trying, it is definitely a doable project. Follow this post if you care as it may give you some ideas on what to expect and how to proceed. Please keep in mind that there is more than one way to skin a cat. The way I solved a problem may not be the best, easiest, or most professional way for it to be done. There is not much else out there on the subject but check out some of these other sites for different ideas.

I did not choose the “make a master positive and cast a mold” method as it would have been cost prohibitive and a lot more work. Instead I chose to merge two different bumpers into one unique bumper. I used my original 2000 Spyder bumper as the first bumper. I figured if I could remove it by myself, I could put it back on by myself without having to get an expensive body shop involved for fitment. My original bumper was in pretty rough shape anyway.
I needed a second bumper to work with. I began my search for another bumper cover. I looked at used bumpers from Lambos to Ferraris. Porsches to Cobras. Miatas to Maseratis. I scoured eBay and Craigslist to analyze all my options. At first I was thinking I’d make something really exotic similar to the Lexus LFA. Finally realizing I have no real idea what I’m doing. I better just keep it simple stupid. This car is a daily driver so I couldn’t have something too close to the ground as it would be doomed. It had to look decent and be a little bit practical. So I narrowed down my search to cars that had a wheelbase width and standard ground clearance close to the standard Spyders. Thank you Wikipedia. I finally found what I thought was a perfect fit! My second bumper comes from a car that is universally considered to be a beautiful sports car. A car relatively rare in the U.S as it had only been available for sale stateside for a couple of years in its last incarnation. A car that beat out the Dodge Viper as the best new sports car of the year in 93. And finally, a bumper I could afford. Be prepared to spend anywhere between $130.00 to $500.00 or more on another bumper. You can pick up a used Boxter bumper for a couple a hundred. It could probably be made to work. Can anyone guess what the other bumper is? Here is a clue.

After making a road trip to Orlando and back to pick up the second bumper, I was ready to begin.
Let me start by saying that if this is a project you really want to do but have little experience doing, be prepared for all of your family, friends, coworkers, and neighbors to look at you as if you had gone stark raving mad. No one will understand why you would want to take a perfectly good car bumper and chop it all to hell. Be prepared for some odd looks. Another tip. However long you think it will take, triple it. This project took me almost 2 months. Granted, I had no idea what I was doing. A lot of time was wasted waiting for stuff to be delivered after I realized my original ideas weren’t going to work. Unless you have a spare bumper lying around, be prepared to be without your Spyder for several weeks.
After working on it for a week or so, you may begin to question your own sanity. Why did I take a perfectly good bumper and chop it all to hell? Fear not. If you made it this far, there is no turning back. Your only other option would be to buy a third bumper and install it. Let’s not think about that. Failure is not an option.

Step One:

Secure your second bumper and most of the supplies you will need to start. I made a big mistake right from the word go. My bumper pieces were not sticking to each other. It turns out that bumper plastic is not just bumper plastic. Different manufacturers use different plastics. Not all plastics adhere the same. Do not assume epoxy resin will do the trick. Do not assume fiberglass sticks to anything. Do not assume any over the counter glue will work. Today’s manufactures deliberately impregnate wax and other release agents into the plastic to ease removal from the mold. This also makes modern bumpers difficult to repair. It is usually more cost effective to just purchase a new bumper than to have a body shop repair a broken one.
Find out what kinds of plastics you are working with and how to best adhere them to each other. Will you need a plastic welder? Is there an adhesive that works for all the materials involved? I had to do some research. This site has some excellent information on different plastics and how to bond them together.
Turns out the Toyota bumper is made from TPO or TEO (Thermo Plastic Olefin) and my RX7 bumper was made from PP (Polypropylene) plastic. Normally, they don’t like each other. After much fretting and research I decided to try a product that promised to adhere them both. I purchased three boxes of Dominion Sure Seal’s Plastic Surgery Semi Rigid (XPSAP/4019) plastic adhesive.

This is good stuff. It is a two part adhesive similar to body putty but more flexible. This might be important because different materials expand and contract at different rates. To help avoid expansion cracks in the long term, it is probably a good idea to use materials with similar expansion rates. Another product others seem to like is Lord Fusor-100EZ available here.
I have not worked with the Lord Fusor stuff so I cannot personally vouch for it. If you are going the adhesive route, you will also need to purchase at least a quart of Acetone along with Wax and Tar Remover, and most importantly Adhesion Promoter. I used Dominion Sure Seal’s brand. This may be a good time to start thinking about families of products that will ensure that they all work together. From what I gather, this is especially important in the paint department.

Step Two:
Measure Twice-

Wash off your bumpers with a good dish soap/detergent. Next find the exact center of both bumpers and create a line that runs all the way from top to bottom, end to end on both bumpers. These center lines must match up perfectly later. I then built a wooden frame to support the bumper to keep all the installation holes in their original place. This also keeps the bumper from twisting and warping at some crucial point in the bonding process. If the bumper does not remain perfectly true it will not install correctly. It also makes the bumper much easier to handle. I took my measurements directly from the car and transferred them to my frame. Next draw out the lines along the path that you want to use to cut out the area of the Spyder bumper that will be filled mostly by your new bumper. Try to keep all or as many of the original mounting points as possible for your design. Keep things symmetrical! Whatever you do to one side, you must do the mirror image to the opposite side.

Step Three:
Design and Cut-

When you make it this far, there is no turning back after this next step. You will be committed. Up to this point everything is reversible. If you decide to continue…
Drill a hole in your Spyder bumper large enough to accommodate your jigsaw blade and begin cutting along the lines you measured out earlier. Take your time and make nice, clean, cuts.

Next, insert your second bumper into the opening you just created and find out the areas that will need to be cut out of the second bumper for it to fit snuggly into the first. Mark out areas with a wax pencil or marker and cut out little pieces at a time. Try to keep as much of the second bumper intact as you can. Keep some overlap in as many places as possible as this is where the two will be glued into one. We need some overlap and surface area for the adhesive to work. Keep it symmetrical. Whatever you take off one side, take the mirror image off the other side. Remove all the parts you think will not add to the aesthetics of your new bumper. Any large openings between the two will be filled with fiberglass and fiberglass body filler then sculpted to shape. Sand away all paint from the edges of your cuts.

Step Four:

Find common areas between both bumpers that overlap. Strip away the paint and roughen up these areas with a steel brush on a drill or number 40 to 80 grit sandpaper. Measure out registration lines on each bumper to ensure even, level, balanced joining. Pre drill holes equally spaced to mark where you will insert the #8 X ¾” bolts that will be used to create a tight bond between the two bumpers. Others have drilled holes and used plastic ties to hold the pieces together. This may be easier than the bolt method. However, the bolt method was very effective. You may wish to incorporate some steel plates with predrilled holes for bolts in strategic areas for added strength.
Some plastics are so waxy that they just smear. We need clean, rough surface areas to hold our adhesive and bumper parts together. Before joining, wash both bumpers again with detergent and rinse well. Wipe surface areas that are to be bonded together clean with Acetone. Remove any waxy residue with Wax and Tar Remover. Just as you are ready to mix the glue, use the Adhesion Promoter as directed. This stuff is time sensitive.
Make sure your registration lines and center lines all line up! I started in the top center and worked my way out from each side of center. The adhesive is similar to any two part body putty. There is only a working time frame of a couple of minutes after the two parts are mixed together. Only mix as much as you can use in a short time span. For me it was about two equal parts the size of ¾ of a golf ball. Mix thoroughly and work fast.
Spread your glue to both surfaces, line up the registration lines, and slip your bolt with washer into the pre drilled holes. Tighten a washer and nut to the back. Work your way across each side until you are done. Don’t worry if it is not clean and pretty. That part comes later. Worry about symmetry and balance.

Step Five:

Congratulations! If you have been successful up to this point, the hardest part is over. From this point on it is all about making her look good. But before you waste a lot of time doing that, you should probably remove the bumper from the wooden brace and dry fit it to the car to see if it fits. If it doesn’t fit, now is the time to chop it up to make it work. If you followed all the directions above, it should fit like a glove.
Now we need to fill in any open spaces and begin shaping. There seems to be three different ideas as how to go about this. The first is to stretch an old bed sheet or fabric across the entire bumper and secure it taunt. Then, from the inside, you just lay the resin and fiberglass over the fabric and it will already be close to shape. Another method used to fill in empty spaces is to use Styrofoam or spray foam cut, trimmed, and sculpted to shape. Once you get it in place and shaped how you want, you will need to cover it with plastic wrap or paint over it with Elmer’s white glue otherwise the fiberglass resin will eat away at your foam. Then simply lay your fiberglass over the Styrofoam to shape. The third method I did before I discovered the other two. I custom made pieces out of fiberglass off to the side then glued them into place the same way I glued the bumper pieces together using the Dominion Sure Seal adhesive and bolts. They were only two layers thick so were still quite flexible and contoured nicely to the openings. One tip I found is to only use enough resin to barely soak the fiberglass mat. The resin is the weakest link. The strength is in the glass. I also used epoxy resin to fill in the areas between all the different segments for additional strength. Maybe keep a strategically placed bolt or two counter sunk for additional strength between pieces. If you choose to do this, perhaps epoxy resin the bolts into place and use lock washers.

After that, it is simply a matter of laying thin layers of Fiberglass body filler to smooth and shape. Clean and prep with Acetone and Adhesion Promoter for each layer. For the finishing layer, I used a skim coat of Bondo Gold sanded to shape and feathered into all the surrounding areas. Fix any imperfections now as they will only become magnified once primed, painted, and clear coated.

Step Six:
Prime and Paint-

There is already plenty of material on Spyderchat and online on how to prime and paint a bumper. I did find this cheap gazebo styled tent on eBay to use as a well-ventilated paint booth since my garage is full of junk and overspray would get on everything. Other than that, I used the primer, base, and clear coat that I ordered online from Just tell them the make and model and paint code number found on the door. This was my first attempt at spraying with a full sized gun. I ordered the single stage base for ease of use. I think it matched really well and though the paint job is not perfect, it is completely acceptable. Don’t be afraid to save some money and paint it yourself.

Step Seven:
Fit and Finish-

If your car needs it, this is a good time to polish the headlights for clarity. Then replace the bumper. Everything you did to get the bumper off just reverse the process to put the bumper back on : ) I hope you didn’t end up with too many extra bolts. Wait a week for the new clear coat to cure then polish and wax to a high gloss finish. Don’t drive yourself nuts if everything is not completely perfect. If your car is a daily driver like mine, it will soon have stone chips and scratches galore. I didn’t even have it on a week before I had some small stone chips from a few trips to the airport and back. I'm hoping to get at least a couple of years out of the new bumper. I'll keep you posted as to how well it holds up over time. Paint chips or not, what is the point of having a car like the Spyder if you don’t ever take it out for a drive. Good Luck and Enjoy.


731 Posts
Amazing work, very creative and great write-up. It looks fantastic. Thanks for sharing!

7,282 Posts
The good: Well done! You are undeniably a master at your craft; the bumper looks flawless. This write-up was thorough and I appreciate the amount of work you put into sharing this with us.
The bad: I don't think those smooth contours match the sharper lines of the Spyder. However, as far as I am concerned your tastes are beyond criticism ^_^
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