Wednesday, January 26, 2011

C3 Corvette Driver Frame Off Restoration

The article featured on this page is from the January 2011 issue of Auto Enthusiast Magazine.

C3 Corvette Driver Frame Off Restoration

A hands-on approach to bringing back a C3 chassis.

Story Chris Petris

Images Stephanie Petris

Sure, it is much easier to justify restoring, or partially restoring, a high-value Corvette. What about the 1977 Corvette? It can be a fun driver experience and the purchase price can be reasonable.

We all know that most 1977 Corvettes will never have strong resale value. Many times, we don’t consider the fun factor; and all too often, we think of the monetary value and the investment side of purchases. All the while, you could have a really great time enjoying the Corvette experience in any year Corvette.

When a customer came to Petris Enterprises to talk about his 1977 project car, we knew that the situation was precarious. If the cost was prohibitive, the customer would have to put off the project or possibly sell it. We began our estimate without even looking at the ’77, using our historical facts of what all 1963-1982 Corvettes typically require to restore the chassis/drivetrain.

As our estimate approached $10,000, all of us were thinking this project had a very good chance of never beginning. Our estimate was broken down into front suspension, steering, rear suspension/driveline, and engine bay. The ’77’s owner had previously purchased a remanufactured engine for the project. Now, we had to put all of the items together to make sense of the scope of the project.

When you’ve been involved with plenty of these 1963-1982 Corvettes, you realize sometimes it makes sense to do more work to save money for the customer. As crazy as that may sound, if all the chassis components are rusty or corroded, extra time is spent for every process. Does it make more sense to remove the body and restore the chassis? Working around a corroded chassis with stubborn fasteners can lead to a lot of extra time spent, especially if the body mounts are in rough shape.

One more meeting with the customer was necessary to cover our estimate and get his input on his expectations by making sure we understood what the customer’s expectations were. Other helpful info was how he planned to use the ’77 after we completed the project: everyday driver, short runs to local cruise-ins, or long road trips? Our conversation concerning the estimate ended with a positive note for the time being. We would include a few enhancements on the estimate to enjoy the ’77 on his planned road trips.

The next phase was a scheduled appointment to bring the ’77 in and go over the project in person, comparing our estimate to what we had in hand.

While we waited on the ’77’s arrival, we added our discussed upgrades on our estimate to really enjoy the car on road trips. The original Turbo 400 trans was tough, but an overdrive trans would make driving more enjoyable. Wiring modifications would also make the early electrical system handle the added load from other enhancements. We were ready, and our preliminary estimate at $12,000 was ready for our next meeting.

The ’77 Arrives

At first glance, the Corvette looked like it had fairly good paint on it, albeit the few spots of peeling paint on the hood and rear deck area. The ’77 had not been started in some time, requiring us to push it onto the lift for inspection. The underside was like many Corvettes of this era; some areas of restoration or repairs had been done over the years. Oddly, the front suspension had been previously cleaned and painted during what appeared to be a bushing replacement many years prior. The back half looked like it had seen better days for sure. All the rear suspension components were rusty and all bushings were worn, cracked, or just plain deteriorated. Further inspection showed severely rotted body mounts and some driver-side body damage. The condition of the underside was directing us to body removal and the possibility that our project may never get started. As much as we were reluctant to mention it to the owner, it was imperative that he understands we wanted to remove the body to do the job right.

The owner left us with some more info about what he wanted to do with the project and some of the pieces that he had purchased previously. We went to work firming up the estimate now that we had a tangible piece to look at. Our estimate would cover body removal, chassis disassembly, cleaning, and painting. All wear-sensitive suspension and driveline components would be replaced. The customer-supplied engine would be installed with a reman 700R4 O/D trans to get it through the gears. Our estimate swelled to $13,000 for the chassis restoration before any work might ever start. Two thousand dollars was put into an escrow account on the estimate for incidentals. We were really pushing the body-off job to do the project correctly and make sure the owner would be satisfied. We could certainly do the job piece by piece, but in reality, they would end up spending more money.

As we sat down for our next discussion concerning our estimate about the ’77’s fate, we felt that it was very important that the owner know what would lie ahead if we proceeded. The ’77 did have some promise. Interior-wise, it was in exceptional shape except for the carpet. In real numbers, $25,000 dollars was what we felt would ultimately be spent on the ’77 to make it a good looking, long- distance cruiser.

The owner had already purchased the engine, radiator, electric radiator cooling fans and other small items that we considered into the $25k equation. The ’77’s exterior would require stripping and some body repair before paint. If all went well, this could be done for $5k if the driven part is put into the final painted product. The final topic was the owner helping with the project. Was this smart for them or us? We made it perfectly clear that cost overruns were possible, and we had not disassembled the first piece yet. We should try to stay within the original plan as it is way too easy to get carried away with upgrades and shiny pieces. It’s important to rein yourself in and keep an eye on the budget to avoid getting out of control.

Sweat Equity

As a shop owner, this can be a good or bad thing. There is no way that having an owner work in the shop makes sense. Insurance liability is one thing, disrupting the shop workflow costs dearly. The owner had mentioned that he would paint the exterior when the time came for that. Would they consider prepping the underside of the body once it was removed? As it turns out, he said if there was a way to do it, he would. This was a win-win for us and the owner. We had planned to put the body on a cart we designed to store it out of the way. If we could secure the body to the cart and bring it to his garage, it would free up shop space. As good as this sounds for us and the owner, we felt it was important that they consider the cost of his labor and materials. Everybody’s time is valuable and should be considered when figuring his project costs. Many owners feel that the experience would not be complete without a hands-on approach, which is understandable. Now that we were all on the same page, we waited for the owner’s decision. As it turns out, his budget was $15k for our portion of the project.


How do you make sense of the cost when you can go out and buy a decent looking, running, driving 1976-1982 Corvette for under $15k? All too often, really good looking aesthetics cover a multitude of issues. This doesn’t mean that all the good looking sharks are like this, but if you revamp the car from the ground up, you know what you have. Who’s to say what year is the best looking? Many Corvette enthusiasts have feelings for particular generations, and many feel that the shark’s styling is the ultimate. On the positive side, the ’77 will be new from front to rear with handling, ride and performance enhancements. We don’t try to sway the owner, because it is his decision to make. We need to present all the options and give them ideas on what products are beneficial. One thing that we try to convey is that if we need to make a repair in a certain area, sometimes it makes sense dollarwise to do more. Why pay twice to disassemble components when we could have replaced a few more and not have to revisit the area again for many years?

Our conversation with the owner revealed they liked the look and feel of the shark. The ’77 had been purchased for $15,000 almost 20 years ago and sat in the garage for most of that time. Now that they were able to work from home, it was time to move ahead with the project. The estimate was approved for the body removal, and a plan of attack formulated.

Work Begins

There were not too many surprises during body removal, except for the previous body damage in the driver door area. There were a few odd things, though, like it appeared the driver side had been hit and repaired very early in the ’77’s life. Some of the wheelhouse panels were coming loose and fit poorly. The floor pan, concealed by the rear crossmember, had broken loose, causing major road noise. The frame was in good condition and straight but with many rusty fasteners. There was no way that we could have hammered out the trailing arm bolts. Cutting would have been the only option with the body on. But, we had the body off in about five hours. Simply cutting the trailing arm bolts can take a couple of hours. Replacing the body mounts without lifting the body completely can take eight hours, and they had to be replaced in this project. Three to four hours of the body mount replacement is just to get the bushings out and the new pieces back in place, never mind the aggravation of getting the body mount bolts loose.

Chassis disassembly went well with very few worn or damaged additional pieces found above our estimate. The only major cost was that the differential pinion gear had issues. We found the inner pinion bearing had never been seated against the shim and pinion. We knew that it would be almost impossible to place a new bearing in the exact same location. The change in pinion depth could very likely cause a whiny rearend. We decided that the smart thing to do was change the ring-and-pinion and, while we were there, upgrade to a 3.73 for acceleration. On an up note, we were able to cross some items off our estimate, bringing us just about even with the cost of parts.

We got the body on our cart ready for the owner to take it away. The chassis is disassembled, waiting on the sandblaster to clean all 62 pieces. Parts are ordered now that we have noted and checked off our estimate parts list.

Our next phase will be getting parts back from the blaster, with our new parts ready for installation after painting. Our local NAPA store has an economy paint line to save a few bucks while preserving the pieces. We chose a urethane primer and synthetic enamel to refinish the frame and all components. We hope you follow along as we move ahead with this fun, drivable ’77 project.

1 We start here, removing the lower valance panels and applying rust penetrating oil to help loosen the crusty screws. All of the screw holes were stripped or had broken screws that required repair.

2 This is the kind of stuff that is easy to forget during body removal. Our antenna ground wire must be removed, or it will be stretched to the breaking point as the body comes off.

3 The front and rear urethane bumpers must come off. We found that running a die over the bumper stud threads saves extra work later. The nuts are rusty, and cleaning the stud makes it easy to remove them with just a few turns of the wrench.

4 When we removed the bumper cover and crash bar, we found a rotted radiator A/C condenser core support. Keeping a note pad nearby can save a lot of time to list the parts that will be required during the reassembly process.

5 We decided to remove the rotted core support, radiator, and A/C condenser before the body lift to lighten the load. Removing the core support side mounting bolts allows the support to move around enough to ease shroud and radiator removal.

6 It’s easy to forget small things like this accelerator cable and the wire harness that connects the engine to the body. Check the engine compartment carefully for any connecting wires or cables.

7 Long ago, the negative battery cable should have been removed. The alternator wiring is part of the forward lamp harness that must be removed. While you’re removing forward lamp harness connectors, don’t forget to disconnect the brake warning light connector from the brake proportioning valve on the frame.

8 The steering coupler must be disconnected and the upper part of the coupler must be pushed off the connecting studs.

9 The A/C system must be evacuated of refrigerant, and the main A/C hose must be removed from the compressor.

10 On the underside, we cut the puny rear exhaust pipes out of the way. Our emergency brake cable pulley must be removed to allow the cable to be free from the frame during the lift.

11 Now the real tough work starts. This is one of the better body mount cushions. How well do you think the doors fit and work when the cushions are rotted? These number one cushions are the easiest to remove because you can access the body bolt nut.

12 This was interesting. The right-side number three body mount bolt was never tightened from the assembly line. We found the cushion and bolt in the mount area without any wrench marks or any evidence of cushion compression.

13 Ninety percent of the time, the number four body mount (behind the rear wheels) will not come loose. A captured nut is used on the top side that uses a steel cage secured to the fiberglass body panel. As soon as pressure is applied, the captured nut spins. So, we cut the bolt with the Sawzall to avoid body damage.

14 The body comes off after carefully looking for any attaching wires, cables, tubes, etc. During the lift, we noticed resistance. After we checked over the engine compartment, we realized the master cylinder brake lines had not been disconnected. This proves we are human and mistakes can happen.

15 Not much left of the original buildsheet was glued to the fuel tank shield. Either the body or the fuel tank and shield has to be removed to access this buildsheet.

16 Everywhere we look, worn parts are evident. This brake rotor is worn well below safe limits. GM says to discard the rotor when worn below 1.215. All of the rotors were below specs and will be replaced.

17 The engine and trans were left in place so we could remove the front springs a little easier. Respect the power of the springs; any contact with them can be dangerous.

18 Out comes the engine and trans for replacement. We will finish removing the front end components once the engine is out of the way. It is best to plan out each phase carefully to make the work as painless as possible.

19 The owner had driven the car infrequently in the past twenty years because of poor performance. Do you think it may be due to the pinched fuel supply hoses under the fuel tank straps?

20 More evidence that everything needs attention on this Corvette. The pitman shaft pushed out of the steering box. The steering box lube is mostly wax and all the lube has been depleted.

21 There would be no way to remove the stubborn trailing arm pivot bolts with the body in place. Our heavy-duty air hammer rattles the trailing arm bolt, knocking the rust holding the bolt in place.

22 Nice huh? Our strut rod could not be removed from the trailing arm spindle mount. Even with the spindle bearing assembly in the press, we could not remove the shock mount in order to remove the strut rod. As pressure was applied, the shock stud was collapsing. Even if it came loose, it would not go through the spindle assembly. We really wanted to save as many pieces as possible to keep costs in check. We used our air hammer with a pinpoint chisel to break the strut rod sleeve loose from the shock mount stud. This worked; the shock mount was junk, but we saved the strut rod and spindle assembly.


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