What Lies Beneath

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by Huw Evans  More from Author

Uncovering hard-to-spot frame problems

Among enthusiast cars as a whole, the second-generation Corvette Sting Rays are a high water mark in terms of performance and desirability. Within that realm, the 1967 models have a special place, even though they almost didn’t make it. Chevrolet had originally planned to introduce it’s controversial ‘wasp-waisted’ body for the 1967 model year, but technical difficulties, including some undesirable aerodynamic numbers, caused Corvette Chief Engineer Zora Arkus-Duntov to demand more time in the wind tunnel, delaying the new car’s entry by a year. As a result, the 1967 Corvette emerged as the last of the Sting Rays and a machine that was refined to the hilt. Within five years of the last one being built, these cars were already being collected (among the first postwar cars to enjoy such status). Today, they are highly prized, as reflected in selling prices and demand. Many collectors will pay premium dollars for either high-quality originals, or cars restored to Top Flight status as defined by the National Corvette Restorers Society. Cars of this stature (especially big-block versions) often trade hands in the $85,000-$120,000 range. That’s why if you are looking to buy one or currently own one, it’s worth setting aside the time and funds to examine and restore it. Even though you might not be able to do the complete car from bumper to bumper at once, you can tackle one area before moving on to another.

In this article, we’ll take a highly desirable 1967 427 roadster and work with renowned restoration shop Legendary Motor Car to do a full chassis examination. So grab a cup of coffee and tag along–I guarantee that it’s going to be interesting.

1. At first glance, our specimen looked very presentable. It’s one of 14,436 convertibles built for 1967 and one of a total of 815 painted Tuxedo Black that year. It is one of 3,832 with the L36 427 V-8, rated at 390 horsepower; one of 11,015 with the Muncie M21 four-speed close ratio gearbox; one of 20,308 1967 Corvettes with a Positraction limited-slip differential; one of 4,766 with power brakes; and one of 720 to feature the bolt-on finned aluminum wheels (a one-year-only feature). So it’s a highly desirable car, with some sought after options. Add the fact that it recently had a quality repaint, and it looks like a very good starting point for our chassis restoration.

2. Since we won’t be touching the body and interior during this project, the chassis is removed and the body and interior wrapped in protective film to keep out dust, debris, and any other contaminants.

3. While the chassis is being carefully dismantled we got a chance to talk with Legendary’s Chris Simon who has performed a number of high quality restorations on mid-year Corvettes. “Even though the bodies on these cars are made from fiberglass, they are still prone to rust, more than a lot of people think. Just because the car hasn’t been driven extensively in salt, doesn’t mean that it’s immune.” To illustrate, he pointed us to a complete 1964 Sting Ray coupe, another highly desirable car, with the 327 with Ramjet fuel injection, which was also at Legendary. Although this was a primo car, it illustrated where potential problems can occur.

4. “The chassis is the backbone of the whole car,” says Chris, “so if you’re buying or restoring one, a solid chassis is absolutely critical. GM didn’t change the chassis a great deal between the start of C2 production and the end of the C3 in 1982, but there are some modifications. Still, even if you have a bent or rusted chassis, it’s a lot easier to replace it on a Corvette than some other cars.”

5. One area that Sting Ray chassis are particularly prone to rusting concerns the frame rail box sections, where they meet with the third crossmember, which separates the front part of the chassis from the rear kick up rails. “What happens is that from driving, debris gets thrown up into the wheel wells and then finds its way into the boxed sections,” says Chris. “Then throw in some moisture, either from driving in the rain, or even humidity, and it will cause rust to form. The biggest problem is that the chassis rusts from the inside out, so you can’t often see it until it’s serious.”

6. “Because of the location of the boxed sections, it’s relatively easy for the rust to spread, which can weaken the chassis, causing it to flex at the third member, something that any Sting Ray owner will want to avoid at all costs.”

7. Getting back to our 1967 project, the suspension parts, brakes, wheels, tires, engine and transmission, rear end, body, engine and driveline mounts, cooling and fuel systems, gas tank, and lines have all been removed. Everything has been carefully cataloged, ready for when re-assembly begins.

8. Of note, our big-block Corvette is a driver and even though our focus is on chassis detailing, the chaps at Legendary will also freshen the engine. “This L36 427 has some incorrect parts, including the cylinder heads, ignition wires, alternator, and oil filler cap,” says Chris. “It’s likely that when this car was originally freshened, the correct parts weren’t available and we can tell that the engine hasn’t been touched in some time. We’ll have to detail the engine and replace these components.”

9. In order to check the actual condition of the frame, it needed to be sent away to be bead blasted. Once it was back, it was time to have a look.

10. At the front, everything appeared reasonable, the frame rails and front cross-member appeared to be solid.

11. Moving on to the outer frame rails aft of the front suspension hard-points, we started to notice quite a bit of pitting in the metal. “This will need to be fixed,” says Chris. “The frame for this car actually shows quite a lot of pitting, indicating that’s its been driven quite a bit and in rough weather over the years. Fixing this is time consuming, but necessary for a top restoration.”

12. But pitting wasn’t the only issue. While the driver’s side frame rail looked okay, the passenger side rail told a different story. “The great thing about bead blasting is that it reveals any flaws or problems in the material,” relates Chris. “Here you can see we’ve got our common rust problem. Moisture and dirt has collected on the inside of the frame rail and has started to rust outward. The holes are small, but they’re serious enough that we’ll need to fix them, which will require cutting out the metal here and replacing it.”

13. Moving further aft revealed more problems. “The way Chevrolet originally manufactured these chassis meant that the end plate in the boxed section had a valley at the top, where the seams were formed. That’s where the dirt and moisture get in and you can see here that it’s caused rust perforation.”

14. On the driver’s side things were even worse. On the inside of the rear frame rail, just before the kick up, were obvious signs of previous patch repairs. “Here you can see where work has been done to try and fix rot in the past,” mentions Chris. “The problem is that 25-30 years ago, the tools and technology were not available to perform quality chassis repairs the same way we do today. Many guys would simply cut out and weld a patch panel over the damage, but moisture from the weld and edges of the metal that were already oxidizing would cause the rust to spread. On this car, the patch repair and rust has weakened this part of the chassis considerably, right at the jacking point.”

15. Having had a good look at the chassis on our seemingly solid Sting Ray, it was crunch time. “We’ve seen cars far worse than this,” says Chris, but because this frame does need a lot of work we’ll notify the owner so he can decide if he wants us to restore this one, or use a frame from another car. If we do decide to use another frame, provided it’s in better condition, we’ll also need to align it with the body on this car, since it won’t mate correctly otherwise.”

16. After having talked to the owner, he decided to purchase another frame. “From what we understand, he’s purchased a rolling chassis from another 1967 big-block car. It’s being shipped up from Florida, but until we actually lay eyes on it we won’t be able to say if it is in better condition than the car’s original frame.” Stay tuned; this story is about to get interesting.

Legendary Motor Car Company Ltd
8228 Fifth Line
Halton Hills
Ontario L7G 4S6


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