1972 Chevrolet Corvette Project Car - Seat Install, Part 1

Everything In Its Place - Installing Corbeau A4 seats in our ’72 project car

Jeremy D. Clough Jan 30, 2014 0 Comment(s)
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Even in relatively stock form, older Corvettes can be quite capable cars—capable enough that it can be tough to stay in place in the driver seat during hard cornering. While not a major problem on a strictly street car—after all, you probably shouldn’t be pushing hard enough on public roads that it matters—it’s hardly confidence inspiring, and even if you prefer to simply cruise long distances in your Vette, the seats make a world of difference in how pleasant that experience is.

The good news is that seat design has come a long way since the days of the Nixon administration, when our ’72 project coupe, aka “Scarlett,” was built. Since we began this project, we’ve performed a complete suspension rebuild, including a rear coilover conversion from Van Steel, 17-inch wheels from Summit (with 275/40 tires front and rear), and Wilwood brakes. All of this has dramatically increased the car’s road-holding ability, and we still haven’t installed the built LS3 stroker (see “Building the Beast,” Parts 1-3) that will more than double Scarlett’s current 300 horsepower. With this much added performance, it’s even more important to stay firmly planted behind the wheel at all times.

With this in mind, we turned to Corbeau for a set of the company’s highly regarded A4 reclining seats, along with five-point harnesses. In this article we’ll cover the basic seat installation, for those who simply want the extra comfort and support of modern performance buckets. Next month we’ll look at what it takes to add the harnesses.

A4 C5 Sport C3 2/26

01. From right are the A4, a C5 Sport seat, and a factory C3 unit. While the C5 seat has more structure than the C3 bucket, the Corbeau is more supportive still. Even better, a pair costs about the same as a new set of C5 leather seat covers.

Corbeau has been in business for more than 50 years, and the firm prides itself both on the broad array of seats and mounting systems it offers—including everything from street-car buckets to those designed for Baja racing—as well as its customer service. (Reps make a point of responding to every email received during business hours within one hour.)

While Corbeau offers many seating options for racing vehicles, including HANS–compatible models with shells made of Kevlar or carbon fiber, the A4 seats offer the added benefit of reclining, which makes them a good choice for a car that’ll be street driven. The reclining feature is controlled by a lever located near the pivot point of the seatback. The lever is mounted on the left side for the driver seat, and the right side for the passenger seat, something you’ll want to keep in mind during installation. The Corbeaus also let you adjust the angle of the seatback, which the C3’s factory latch mechanism didn’t allow (when it worked at all, which was rare).

To ensure the best fit for your application, begin by selecting your seats, then choose the proper mounting brackets for the car into which you’ll be installing them. Brackets are available in a choice of fixed or sliding configurations, with either one or two latches on the slider. We chose the sliding brackets with two latches, in order to better resist the sort of load we anticipate putting on them on the track. Both of the latches are attached to a bar that runs across the front of the seat.

The A4 comes in a variety of covering materials, including leather, cloth, and microseude, and it can be custom ordered in other materials as well. Other options include an inflatable lumbar support with a manually operated air pump, seat heaters in both the lower and upper cushions (also available separately for installation in other manufacturers’ seats), and a “fifth slot,” which is a plastic-reinforced slot in the lower cushion through which the anti-submarine belt in a five-point harness fits.

With track use in mind, we selected the fifth-slot option, and ordered the seats in microseude. While many people think of leather as the default material for Corvette seats, there’s a reason many high-end sports cars currently use synthetics like Alcantara. Specifically, the rougher surface of the suede-like material helps keep you in place in the seat better than slick, finished leather. In a nod to durability, our microseude Corbeaus came with leather patches to ward off wear on the higher-traffic portions of the seat.

Corbeau A4 Seats Five Point Harness 6/26

While the factory buckets feature a small bulge on either side of the seat cushion, they can’t compare to the amount of support offered by a true performance seat. The sides of the A4’s lower cushions are raised to secure the sides of the upper thighs and buttocks, and the upper portion of the seat wraps closely around the waist—so much so that Corbeau recommends the standard A4 for those with waist sizes of up to 36 inches, and the A4 Wide for those broader in the beam. Note that if you tend to wear bulky items on your waist—a large cellular phone or, for those with CCW permits, a holstered pistol—you may want to find another place to put those things while driving, lest they become pressed uncomfortably into your side.

The top of the backrest wraps around your shoulders—a bit closely for me, I found, though I got used to it—and extends well above where the factory seats stop, which gives added support to the head. Whether or not you order your A4s with the fifth slot, both sides of the headrest portion have a slot to accommodate the shoulder straps of a five-point harness. Weight-wise, the A4, with bracket, came in at a little less than 40 pounds, the same as a factory seat and about 4 pounds lighter than a leather C5 Sport bucket, which is a popular retrofit for older Corvettes.

Corbeau A4 Seats Seat 7/26

06. Since the A4 is available for several different vehicles, you’ll need to order the correct seat brackets for your car. Brackets come standard with a single latch for the slider, but you can upgrade to two, as shown here.

To install the seats, we first assembled the A4s to their brackets by following the recommended practice of sliding the upper part of the welded bracket all the way forward and installing the two front bolts (without fully tightening them), then bringing the bracket all the way backwards and installing the rear bolts. The bracket mounted quickly and easily to the driver-side seat. I found the passenger-side bracket needed a little more encouragement, but it still bolted into place without modification. Be careful not to put too much pressure on the bar that controls the seat latches during assembly, as it can pivot out of its mounting points if you apply too much pressure to one side while the seat track isn’t assembled. Once the brackets were all in place, I tightened down all four bolts, and the seats were ready to be bolted into the car.

Corbeau A4 Seats Welded Flat Steel 8/26

We then removed the factory seats, which were held in place by a mishmash of bolts, washers, lock washers, and nuts. Once everything was unbolted, I lifted out the seats—a process I found easier with the T-tops removed—and vacuumed and shampooed the carpet underneath it.

Fortunately, I had laid one of the brackets on the floor of the car before installing it on the seat. It became apparent at this point that the factory seatbelt retractor kept the bracket from sitting flush, something that’s easier to see when you’re not wrestling 40 pounds of seat. Out came the factory belts, replaced by the lap-belt portion of the five-point harnesses, which I bolted to the factory mounting points.

Once the seatbelt reel no longer interfered with the seat positioning, I used Grade 8 hardware from the local O’Reilly to bolt the new seats back into place. All in all, the project could be done in a Saturday afternoon.

From behind the wheel, I discovered that even though the A4 has the lowest profile of the Corbeau seats, it’s still fairly high. It raised the seating position noticeably, making it difficult to fold the buckets all the way forward without popping the T-top latches to allow extra headroom. For what they offer though, it’s a trade I’ll gladly make.

Corbeau A4 Seats Remove T 9/26

08. The first step in installing the A4s is to take out the T-tops, which will make it easier both to get the old seats out and get the new, taller ones in.

Corbeau A4 Seats Four 10/26

09. The factory seats are held in by four bolts, one at each corner. Slide the seat forward to unbolt the rears, and rearward to get to the fronts.

Corbeau A4 Seats Old Mounting 11/26

10. The old seat-mounting hardware, which should be ditched and replaced with new Grade 8 bolts. Including seatbelt-mounting bolts, there’s about $40 or $50 in hardware holding the new seats in place.

Corbeau A4 Seats 12/26

11. The floorpans with seats removed. You never know what you’ll find under there, but now’s a good time to vacuum and shampoo the carpet before you cover it back up again.

Corbeau A4 Seats Test Fit 13/26

12. It’s also a good idea to lay down the seat bracket and check to make sure all the holes line up before you attach it to the seat. In our case, we found the seatbelt reel beneath the carpet wouldn’t let the bracket lie flat.

Ken Coopman, a former Corvette road racer (and one of Scarlett’s previous owners) once told me that few things make as big a difference in a car’s handling as the seats. Having taken the car for a quick run through some twisties up in the mountains, I now know why. With the seat keeping you firmly in place, you have a much greater feel for what the car is doing, whether it’s the initial “bite” on turn-in, or the exact moment of weight transfer toward the outside as the suspension loads up. It’s a night-and-day difference compared with the factory seats. I even found the Corbeaus to be much more comfortable than the mushy factory buckets when I took Scarlett on a few-hour drive through a combination of two-lanes and interstate.

Next month, we’ll look at staying even more firmly planted in the A4s by installing five-point harnesses and the crossbar to which they mount.

Corbeau A4 Seats Factory 14/26

13. Since we were replacing the factory belts with Corbeau’s five-point harnesses anyway, we started the removal of the factory reel by unscrewing the door sill.

Corbeau A4 Seats Removing The 15/26

14. Removing the sill and peeling back the carpet revealed the reel cover, which is held in place by four screws. This piece covers the retractor for the outboard seatbelt.

Corbeau A4 Seats 16/26

15. The reel itself is held in place by one large screw in a reinforced mounting point. From there, the belt passes under the seatbelt guide.

Corbeau A4 Seats Removing 17/26

16. With the reel removed, unbolt at least one end of the guide. With that done, lift the guide up enough to take out the old belt and slip the new one under it.

Corbeau A4 Seats Bolt 18/26

17. After cleaning up the accumulated debris, we bolted the tab on the end of the Corbeau lap belt to the factory mounting point and threaded the belt through the guide. Though not shown here, the latter item was then bolted back in place with fresh Grade 8 bolts.

Corbeau A4 Seats Outboard Lap 19/26

18. After attaching the outboard lap belt to its mounting point under the seat, we bolted the new inboard seatbelt to its factory mounting point. While we ordered five-point harnesses, factory-style seatbelts are also available from Corbeau.

Corbeau A4 Seats 20/26

19. With the carpet still pulled back, we thinned the insulation to make it easier line up the bolts, brackets, and holes. This would also provide the flattest, most solid mounting surface possible.

Corbeau A4 Seats Threaded 21/26

20. Fold the carpet back down, remembering to thread the seatbelt through its slot in the carpet, then make sure all of your bolts will line up and fit in their holes.

Corbeau A4 Seats Mounting 22/26

21. To install the seat brackets on the seat, start by unscrewing the four mounting bolts from the bottom of the seat.

Corbeau A4 Seats Forward Mounting 23/26

22. Slide the upper part of the seat brackets all the way forward, then reinstall the two forward mounting bolts. Tighten them down enough to clear the sliders, but not so tight that the bracket can’t be moved around on the seat to align the other two holes.

Corbeau A4 Seats Rear Mounting 24/26

23. Repeat the same procedure with the rear mounting holes. Once you can get them lined up and started, go back and tighten the front bolts. Now it’s time to bolt the seats into the car.

Corbeau A4 Seats Install Rear 25/26

24. After placing the seat in position in the car, install the rear bolts by sliding the seat as far forward as possible, then threading the bolts down into their holes. We used Grade 8 hardware here as well.

Corbeau A4 Seats Mounting 26/26

25. There’s only so far back the seat can slide, which means limited access to the front mounting holes. Now is a really good time to have a ratcheting wrench, provided you can fit it between the seat and bolt head.

Sources

Corbeau Seats
Sandy, UT 84070
801-255-3737
www.corbeau.com
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