There’s an old saying journeymen car painters pass on to the new kids entering the trade, and that’s, if nothing else, make sure the driver door and the top of the hood look good. That’s a bit of advice I’d like to share with anyone that owns a 1984-’96 C4 Corvette. Whether you’re going to sell the car or you intend to cherish it forever, make sure the outer window seals are near mint or your C4 will be perceived to be in crummy overall condition.
A case in point is the triple-black 1990 Z51 Corvette featured in this article. I bought the car a year ago when I decided I needed a dependable economy car to take the monetary sting out of daily-driving my ’05 GMC Sierra. I found the 69,000-mile Z51 listed on Santa Barbara’s Craigslist 125 miles from my home; and the price was right. I had the seller email me a photo of the SPID (service parts identification sticker located inside console lid) and discovered the original owner checked all the right boxes when he ordered the car new from the dealer. I learned every performance option found on a 1990 RPO ZR1 or RPO B2K Callaway was on this car.
Anxious and armed with an envelope full of cash, I fled Orange County before sunrise. I’ll never forget my first impression of the black Z51 as I pulled into the driveway, it had a strong presence, as all Corvettes do, but its gap-toothed cracked outer window seals made it look bad. I took this as a summation of the car’s overall condition and I was beginning to lose interest fast. I wasn’t all that excited to test drive the Z51, but the owner insisted. I headed north from his beachfront home up the coast through the lush foliage of Hope Ranch and that was all it took to decide I was going to buy this car.
I’m not real adept when it comes time to chisel an owner down on the price of a used car, so it came in real handy that the two of us were standing next to the shabby window seals while we were discussing price. There’s no question in my mind the bad outer window seals undermined the seller’s perceived value of his car, and that’s the reason I got a good deal on a really great car.
Beyond cosmetic considerations, there’s numerous operational benefits to be gained by renewing a C4 Corvette’s outer window seals. The gaps left by missing chunks of rotted outer window seals allow dirt and water to enter inside the door’s workings, creating wind noise and potentially causing power window and electrical switch failures. Rusted window mechanisms can jam and prevent proper function.
For the person that likes to keep their Corvette nicely detailed plus add a few upgrades while they’re doing repair work, replacing the outer window seals presents a good opportunity to super detail the door panels, plus install sound and heat proofing.
01. Here’s what the factory original outer window seals looked like before replacement. Broken outer window seals allow water and dirt to enter inside the door and cause expensive electrical and/or mechanical damage.
02. The first step is to lower both side door windows and then disconnect the negative post of the battery.
03. The door panels must come off in order to replace the outer window seals. All Phillips screws that are visible in the door panels must be removed.
04. Notice how water entering and collecting inside the door caused the door panel screws to rust.
05. Tagging where the screws came from and storing them in a sealed bag is a good practice to ensure original hardware is not misplaced.
06. The power mirror control switch connector plug is released by unhooking (pull tab outward) at the switch.
07. To disconnect the power window switch, a special tool was homemade from a cotter key to release the two locking tabs simultaneously.
08. Twisting the special homemade tool upward opened the two locking tabs enough to separate the plug from the switch.
09. To remove the courtesy light from the door panel, there are two tabs on top of the light that need to be pressed down. Then the top of the light comes out first.
10. Behind the courtesy light is a Phillips screw that must be removed.
11. To access the Phillips screw behind the door lock knob, a hook tool is used to pull the lock knob forward.
12. The door lock knob pulls outward to release it from the lock rod.
13. The hook tool was used to pull the lock rod down and forward to allow access to remove the hidden Phillips screw.
14. The inside door handle is pulled outward (same as opening the door) to release the lock panel from the door panel.
15. The door lock panel pulls outward to remove, but does not need to be removed completely from the wiring.
16. The rear hatch switch (adjacent the inside door lock mechanism at rear) must be disconnected. Unplug by opening the locking tab.
17. To replace the outer window seals, this clear plastic liner does not need to be removed, but I chose to upgrade to the later year model C4 door panel insulators from Corvette Central (PN 284084).
18. The two clips holding the liner only need to come forward enough to unwrap the clear plastic liner from the clips.
19. While the clear plastic liner was removed, I used the access to blow out and vacuum dirt and broken chunks of the original outer seal left inside the door.
20. There are three pop rivets that must be drilled out to remove the old outer window seal. To gain access to the rivets, the door weatherstripping must be moved out of the way.
21. After removing the two 7mm-headed bolts and carefully peeling the weatherstrip back, blue tape was used to hold the weatherstrip clear of the drill.
22. Notice how nicely the new Corvette Central door panel insulator conforms to the door with heavier material.
23. To keep the Z51 factory correct, the original screws were wire-wheeled and painted with Eastwood semi-gloss Extreme Chassis Black satin spray paint.
24. For additional help keeping the triple-black ’90 Z51 cool and quiet, Dynamat was adhered inside the door panels and doors. Measure the area to be covered and cut it out with a razor blade or mat knife.
25. Use the minimum sized drill bit needed to drill out the rivets. Do not drill any deeper than necessary or a hole might be drilled clean through the door.
26. The window guides must move as far back as they can in order to move the window glass back towards the interior. Mark (scratch) the adjustment position of the two window guides before loosening (do not remove guides).
27. With the three rivets drilled out, the old outer window seal can be removed. Sometimes they fall right off and other times you’ll have to fight to remove. If it is difficult to spread the clip jaws, open to release the outer seal from the door. These fought. Careful not to bend the new outer window seal, start at the rear of the door angling the clips into their corresponding holes and push with a slight twist the new outer window seal into place.
28. Then it worked best to install the three rivets into the installed outer window seal.
29. The next step was to slip the pop rivet gun over the rivet and complete riveting.
30. Do not glue in place. Duct tape is reversible and worked well to hold the door panel insulator in position.
31. Reverse disassembly to install door panels. The door panel was placed over inside the door and pressed from the top down into its place. The electrical connectors (plugs) were attached and the Phillips screws were reinstalled. Mothers’ products were used to clean and detail during and after assembly.