How to Make Minor Corvette Sheet-Molded Composite Repairs - Skin Deep

Demystifying minor SMC Repairs

Jay Heath Dec 20, 2013 0 Comment(s)
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Far be it from us to counsel restraint when it comes to piloting one's Corvette, particularly if it's a late-model edition kitted up with all the mod cons that make everyday driving such a pleasure. That said, there comes a point at which even the most dedicated Vette votary has to wonder if perhaps it's time to relegate his (or her) pride and joy to weekend duty.

Consider the case of Mark Dickey's "Orange Krush" '01 Z06, a dazzling, LSX454-powered daily driver that graced the cover of our Aug. '05 issue. In the years since its magazine debut, the car has been a veritable lodestone for automotive misfortune, suffering a fascia-defacing runinwith an armadillo in the Arizona desert, a high-speed rear-ending by a furniture truck in Tampa traffic, and, most recently, a vicious side-swiping in the parking lot of a local shopping mall. If Corvettes were stuntmen, Dickey's would be Super Dave Osborne.

Fortunately our Mr. Dickey is a stalwart fellow with an excellent insurance policy, and in the first two of the aforementioned instances, he was able to have the car repaired to full pre-wreck salubrity. The side-swipe fix, meanwhile, is currently underway, which brings us (in admittedly roundabout fashion) to the topic of this how-to article.

While much of the mall-crash damage will be rectified by simply replacing the affected panels, some of these items have been discontinued by GM and will therefore need to be mended with an SMC (sheet-molded composite) repair agent. Dickey entrusted this work to the Corvette pros at AntiVenom in Seffner, Florida—the same folks who handled the mechanical portion of Orange Krush's initial build way back in 2007.

Knowing that minor SMC repairs tend to be well within the capabilities of the average DIYer, we tagged along, camera and notepad in hand, to document the process. Let's take a closer look at how the job unfolded.

Note: The repair method detailed here is only applicable to '82-up Corvettes. Earlier models, which were built using glass-reinforced plastic, or GRP, require a different procedure.

Sheet Molded Composite Repair 3M SMC Repair Kit 02 2/20

1. For this job, we'll be using a 3M SMC-repair kit obtained from Summit Racing (Summit PN tRM-8243). the kit includes the two-part adhesive itself, along with a pair of application nozzles.

Sheet Molded Composite Repair Grinding 03 3/20

2. AntiVenom's Greg Lovell starts the job by grinding the damaged areas down to a depth of approximately a quarter of an inch using a 3M Roloc disc. (Note: If you're following along at home, be sure to use wear an approved protective mask during any portion of the job that requires sanding.)

Sheet Molded Composite Repair Ground Panel 04 4/20

3. The resulting panel should look something like this.

Sheet Molded Composite Repair Panel Grinding 05 5/20

4. With the top surface completed, Lovell repeats the process on the back side of each crack. Here, he's using 80-grit sandpaper to treat a particularly hard-to-reach area.

Sheet Molded Composite Repair Panel Grinding 06 6/20

5. As above, so below.

Sheet Molded Composite Repair Dust Blowing 07 7/20

6. With the initial sanding work done, Lovell blows away any residual dust with compressed air...

Sheet Molded Composite Repair Surface Cleaning 08 8/20

7. ...then thoroughly cleans the surrounding painted area using greaseand-wax remover. If you're doing this work yourself, be sure to avoid getting any of the removing agent on the exposed fiberglass.

Sheet Molded Composite Repair Panel Evening 09 9/20

8. The next step involves evening up and securing the fractured surfaces to ensure a nice, flat repair. any method will do, as this creative pen-and-Vise-Grip configuration amply illustrates.

Sheet Molded Composite Repair Compound Application 10 10/20

9. After installing one of the two included nozzles on the tube of two-part adhesive, Lovell uses a purposespecific 3M gun (Summit PN tRM-8571) to apply a moderate amount of compound to the first damaged area.

Sheet Molded Composite Repair Brace 11 11/20

10. In this photo, you can see how our makeshift brace forces the upper and lower portions of the panel firmly together at the crack.

Sheet Molded Composite Repair Smoothening And Flattening 12 12/20

11. Immediately following the initial application, Lovell uses a rubber squeegee to smooth and flatten the adhesive over the affected area. you'll need to work fast here, as this material achieves a rock-hard consistency in just 50 seconds.

Sheet Molded Composite Repair Smoothening And Flattening 13 13/20

12. As with the sanding, Lovell repeats the job on the rear side of the panel.

Sheet Molded Composite Repair Adhesive Application 14 14/20

13. The result is shown here. when you're done applying the adhesive, allow it to cure for at least an hour before moving on to the next step.

Sheet Molded Composite Repair Surface Prep 15 15/20

14. With the adhesive fully cured, Lovell uses a 180-grit sanding disc to begin preparing the treated surfaces for body filler.

Sheet Molded Composite Repair Sanding 16 16/20

15. After smoothing out the area with the sanding disc, he finishes the filler-prep process by hand, using 80-grit sandpaper. the goal here is to leave a slight V-shaped concavity along the length of each crack (front and back); this will provide a good point of purchase for the filler.

Sheet Molded Composite Repair Repaired Panel 17 17/20

16. Here's the finished product, receiving a fresh blast of dust-dispersing compressed air.

Sheet Molded Composite Repair 3M Platinum Plus Body Filler 18 18/20

17. Lovell applies 3M Platinum Plus body Filler (3M PN 35863) to a squeegee using the company's Dynamic Mixing System. the latter item, which bears no small resemblance to an oversize Star trek phaser gun, obviates the need for hand mixing, a tedious process ripe with opportunity for user error.

Sheet Molded Composite Repair Body Filler Application 19 19/20

18. Using the squeegee, he then trowels on the filler, smoothing as he goes. as in the previous steps, he'll repeat the job on the backside of the panel.

Sheet Molded Composite Repair Reapired Panel 20 20/20

19. At long last, our once-rumpled panel is ready for final sanding, primer, and paint. Not bad for a few hours' work.

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