Jim Smart
November 28, 2016
Photos By: Manufacturers

Welcome to the world of cool fiberglass body bolt-ons for your classic Mustang. Fiberglass adds a real dash of class to any restomod. But be prepared, most aftermarket fiberglass has to be massaged because there are so many variables. Each fiberglass body part is still handmade in mass production. Even original Shelby Mustang fiberglass from the ’60s had to be massaged to fit properly, which made those original Shelby Mustangs time-consuming to build.

Through the use of better resins and techniques fiberglass has become more forgiving today. It keeps its shape better, resulting in more precise fitment and longevity. Fiberglass, as its name implies, is a glass fiber mesh mixed with a plastic resin. This is known as glass-reinforced plastic or glass-reinforced resin.

Where fiberglass projects typically goes off the rails is through poor technique—not all the ’glass manufacturers follow proper procedure. By the same token, if you’re repairing fiberglass, proper technique is vital. Fiberglass prep begins as a guide coat process in which you use contrasting colors to locate high and low spots. Lay down a light-colored sandable primer, then a corresponding dark color sandable primer and start block sanding with fine paper. This is a fact-finding mission where you unearth high and low spots, much as you would with steel. Working fiberglass properly to get rid of the waves and dimples is what separates the novices from the professionals.

Something we’ve learned from street-rod builders also applies to Mustang restorers—the mock-up. A mock-up helps check fit and finish before paint and final assembly. Never paint a Mustang body before doing a mock-up in primer coat. It is strongly suggested you wear latex or rubber gloves. Fingerprints come to life on bare steel, causing rust issues, and skin oil causes primer and paint adhesion issues on fiberglass and steel. Wearing protective gloves guards both your skin and the surface.

01. Panel fitment begins at the body with quarter panel end caps, front-fender extensions, fascia, and tail panel. In order to properly fit the deck lid and hood, you need solid reference points.

02. Fiberglass doesn’t come out of the box ready to prime and paint. Once you’re close to fitment, the panels normally have to be trimmed, shaved, and filled to get gaps where they should be. Always fit the end caps first, then the deck lid.

03. Fiberglass fitment is a tedious task, but well worth the time and it gives great return on investment. Terry Simpson of the Restomod Shop in Stockton, California, stresses panel installation on the body before performing any finish work to get the most uniformity.

04. Side scoops can be the trickiest to fit because you’re working with the body’s natural belt line, which is those simulated side scoops in the quarter panels. According to Terry, you have to take the fiberglass scoop and be sure it fits by drawing a pencil line in the quarter panel and measuring before you permanently attach the scoop with adhesive or screws.

05. Ground effects, such as this piece from Mustangs Plus, are among the easiest to fit because they follow the Mustang’s rocker panel. These are attached with either screws or rivets.

06. Terry suggests using aluminum reinforcements on some fiberglass panel flanges to prevent distortion. This front apron is reinforced to allow it to maintain its shape once installed. Because the front apron is under tremendous air loads, reinforcement at mounting surfaces is vital.

07. This classic teardrop scooped hood for 1965-1966 Mustangs from Mustangs Plus is a cool retro piece that brings back thoughts of Ford’s Total Performance years in the ’60s. If you’re building an old-school drag racer or road racer, this is a terrific mod.

08. Take Ford’s 1969-1970 SportsRoof and weave sizzle into the steak using this racing valance from Mustangs Plus. Oh, sure, it will bolt onto the convertible and hardtop with splendid results, too, but we like this approach to the SportsRoof, which gives a 1969-1970 Mustang an SCCA/Trans-Am persona.

09. These bolt-on side scoops from Mustangs Plus for 1965-1968 Mustangs are straightforward to install and require minimum prep work.

10. Here’s a 1967-1968 Mustang convertible at The Restomod Shop with the full compliment of fiberglass from Mustangs Plus. It looks like a big, one-piece molded body. The only downside to molding in fiberglass is the huge challenges that come if you have an accident and must replace any body panels.

11. Fiberglass wheelwell flares like this one give the classic Mustang an IMSA-racer demeanor. Fiberglass and steel have different expansion properties, which can lead to cracking due to poor prep work. Follow manufacturer’s instructions to the letter.

12. Not all classic Mustang fiberglass is Shelby style. This Eleanor-style hood (PN 16612-1H) from National Parts Depot yields a more custom look with a lower hood line for improved visibility.

13. We like this one-piece front fascia for 1967-1968 Mustangs from National Parts Depot. The fascia (PN 8190-8A) is an affordable piece designed to improve a Mustang’s appearance and offers good fit and easy installation.

14. National Parts Depot has a variety of cowl induction style hoods for classic Mustangs. These hoods make room for taller engines and induction systems without hindering visibility.

15. Check out this 1969-1970 Mustang six-lamp G.T. 350/G.T. 500 tail panel from National Parts Depot, which adds a splash of salsa to any Mustang restomod project. Of course, you’re going to want the Shelby-style deck lid and end caps to complement this tail panel along with the corresponding lenses, trim, and pop-open gas cap.

16. We can’t think of Shelby fiberglass without thinking of Tony D. Branda Shelby & Mustang, which offers a complete line of snake-bitten fiberglass for classic Mustangs. No one has been doing this longer than Tony Branda. That means, you can consult with these guys and wind up with the right fiberglass for your project. This is the 1967 Shelby G.T. 350/G.T. 500 hood for 1967-1968 Mustangs.

17. You have the option of a 1965-1966 Shelby hood or this blend-in, bolt-on scoop, which is common to 1965-1966 G.T. 350s, from Tony D. Branda Shelby & Mustang. It’s a nice piece to add to any steel or fiberglass hood.

18. While we’re on the subject of fiberglass parts from Tony D. Branda, keep interior parts in mind. This fiberglass 1966 Shelby G.T. 350 rear package floor can be dropped into any 1965-1966 Mustang fastback to provide luggage space and eliminate unnecessary fold-down rear seat weight.

19. When you install a fiberglass hood, factory hood support springs for a steel hood provide too much tension for a fiberglass hood. Tony D. Branda has the solution with these low-tension springs for ’glass-hooded classic Mustangs.

20. Tony D. Branda Shelby & Mustang makes it possible for you to fit a 1969-1970 Mustang with the G.T. 350/G.T. 500 front end. This is the 1969-1970 Shelby hood, which is compatible only with a complete fiberglass Shelby front end. Because this can get very expensive, not many 1969-1970 Mustangs get this treatment.

21. Stang-Aholics fiberglass body parts for 1965-1970 Mustangs employ exceptional quality because they understand the frustration of fiberglass installation and prep firsthand. As a result, Stang-Aholics has taken what they’ve learned from fiberglass installation and applied it to the fiberglass manufacturing process. Finish work in white makes Stang-Aholics fiberglass user friendly. High-end ISO resin and hand-laid fiberglass makes the difference, plus they keep it in the mold for 24 hours for complete curing without distortion.

22. Jim Reeves of Jim’s Classics & Hot Rods in California’s Central Valley explains that fiberglass, and even die-cast body parts, don’t just bolt right onto fenders and quarter panels. You must modify boltholes for adequate adjustment. Do a fit check first, and then determine how best to mate these parts with a precision fit.

23. We like the way these headlight doors and grille stone guard fit together. The Stang-Aholics fascia is positioned, fit-checked, and installed. Flange nuts and washers achieve the kind of security we want in a fiberglass installation. Never over-tighten fiberglass parts, and always use fender washers beneath the bolt heads and nuts. If you really want to spice up your work, look to stainless flange-head bolts and nuts or factory hardware from National Parts Depot.

24. Jim Reeves wraps up the fitment process by checking fit and securing the fiberglass. He stresses getting fitment right, and then snugging fasteners temporarily until all the body panel fitment is complete. Using nylon washers between the metal fenders and body panel is advised to prevent paint cracking during final assembly, avoiding over-tightening.

25. Get hood-to-fender and fender-to-cowl gaps where you want them, then drill 1/8-inch holes through hinge attachment points to use alignment pins when it’s time to permanently install the hood. The hood and decklid are the toughest adjustment tasks. The hinge to apron adjustment is mostly about hood angle.

26. Begin decklid adjustments with the quarter panel end caps. Adjust the end caps first, then adjust the deck lid.

27. Decklid height adjustments are accomplished with these adjustment bumpers, which screw into the steel tail panel. Adjust the bumpers up or down to control decklid height.

28. Jim bolts on a 1967 fascia, which is a one-piece affair, compared to 1968’s three-piece. This is a huge one-piece fascia, and it is challenging to install and adjust. You’re going to need two people.

29. Stang-Aholics offers you a choice of inboard or outboard high-beam location with its 1967 fascia and grille packages. All hardware to enable you to install this fascia and grille is available from Stang-Aholics.

30. When you’re shopping for fiberglass, look for the details like studs that are deeply anchored in the fiberglass for solid security. It is virtually impossible to pull these guys out. Once tight, these Stang-Aholics pieces don’t move.