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Window Replacement for 1972 Corvette Scarlett Project Car

Through a Glass Darkly: Replacing the windows in Scarlett, our 1972 Corvette Project

Jeremy D. Clough Feb 17, 2017 0 Comment(s)
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Since we’ve completed most of the serious mechanical work on Scarlett, our 1972 Corvette coupe project car, it’s time to turn to the body and interior as we get ready to put the body back on our mostly assembled Street Shop, Inc. chassis. This means prioritizing things that have to be done in a specific order or cannot be done at all, such as replacing the back glass. Although we will be able to unlatch the rear window (thanks to our shortened guide wedges), once the body is back on, the rollbar will trap the window inside the rear storage compartment. Since the rear window will no longer come out of the car’s interior, any window work is now or never.

Although there was nothing drastically wrong with the back glass, both the window (all the windows, really) and the soft aluminum frame did have the scratches expected of a car that’s over 40 years old. While perfectly acceptable on a car that’ll be driven, as deep as we’ve gotten into Scarlett, we’re well past the point of reinstalling things we know aren’t flawless. Not to mention we wanted all the windows tinted. We were unsuccessful at convincing glass supply house Auto City Classic to produce a set of windows in their grey “smoked” tint available on other models so we ordered all the glass in the only available color, which is the original green tint.

Windshield installation was left to the pros. The door glass, however, we already had out when we installed the Corvette Central electric window conversion (“Get Down,” Mar. ’16). This time, after having the new windows tinted we went ahead and installed all new components on the glass as well as degreasing and refurbishing the tracks in which the various rollers move. Since the windows never sealed well, in addition to rattling whenever the door was closed or even opened briskly, we replaced the door seals and cushions while we were at it. As the photos show, both are relatively straightforward. The sole exception is the rear mounting screw on the window seal, which may require the removal of a piece of weatherstripping to access.

The rear glass is where it gets fun. There are two parts to it: removing/replacing the glass and refurbishing the window frame itself. Both proved to be far more involved than we expected.

The top and bottom halves of the frame are connected at the bottom corners of the frame by a screw and a roll pin on either corner. In addition to these two screws, four more hold the guide wedges, which locate the bottom of the window for installation. All six must be removed to refurbish the frame. While roll pins are often troublesome, they came out easily this time, leaving the screws as the problem children. Even after soaking in penetrating oil, four of the six were frozen in place. We had to first drill the heads out to disassemble the frame then drill out the remaining screw shank and threads.

Since we were drilling a hard (steel) screw in a soft (aluminum) frame, we carefully clamped the frame in the mill to minimize movement and the attendant risk of the bit wandering around the screw rather than cutting into it. With that done, we bead-blasted the frame and Tray Walden TIG welded the holes back up. Although we had scribed a line on either side of the guide wedges so we could locate the holes again after welding, those marks did not survive welding and we instead had to locate and re-drill the holes using the remnants of the original holes still visible inside the window channel.

After welding, we dressed the aluminum frame back down to the factory contours, first using a hand grinder and then using a fine pillar file sourced from gunsmith supply house Brownells, backing the file with sandpaper for finish work. While sandpaper is usually an excellent way to round off edges that are supposed to be sharp, backing it with a file (akin to blocking a car) gives it a flat abrasive surface. With that prep work done, the frame will go off to be stripped of its anodizing and get polished and replated before final assembly.

Installing the glass back into the refurbished frame requires the use of window setting tape, which is unfortunately usually only available by the roll. We now have 50 feet of 1/32-inch tape and expect to have plenty left over. Although final glass installation will have to wait until the frame is replated, we partially test-fit the glass in the lower frame and it is a tight, tight fit. Take your sweet time: the rear window glass is frighteningly thin and if it breaks while you’re pushing on it you have an excellent chance of getting a bad cut.

1972 Chevrolet Corvette Lift Channel 2/21

01. Once you get the glass out, this is what you have to look forward to: lots of sludge and old grease. We replaced all of the moving parts, including the roller/slider assembly in the channel, and refurbished the tracks, which will need to be heavily regreased prior to reassembly.

1972 Corvette Window Replacement Project Scarlett 3/21

02. If you’re reusing the old glass, these are what have to come off: (L-R) the lift channel bushing and nut, roller bearing and bushing. Most of these parts are included in the rebuild kit supplied by Corvette Central with the exception of new rubber washers and the round nuts, which can either be reused or ordered separately.

1972 Corvette Window Removal Tool 4/21

03. You’ll also want the removal tool shown here that fits into the two holes located on the round nut. While it is possible to remove the nut without it, the tool will make it much easier and is $15 well spent.

1972 Corvette Window Front Roller 5/21

04. The two-piece bushing in the front of the glass snaps easily into place. Replace the front roller, slip the roller and slider assembly into its channel and the glass is ready to go back in.

1972 Corvette Door Seals 6/21

05. While the glass was out, we also updated the door seals to avoid leaks. The seal is held in place with two easy-to-access screws (three in our case) located under the lip of the seal.

1972 Corvette Window Seal 7/21

06. Once the screws are out, gently pull the seal away from the door. The locking tabs should simply pop out. If a tab or two stays put, like this one, it’s easy enough to lever it out.

1972 Corvette Window Outer Seals 8/21

07. We replaced the window seals with a new set of outer window seals from Corvette Central (left) shown here with the one we removed (right). Note the difference in the shape and texture of the seal: the Corvette Central version is a reproduction of the original with correct material, beading and bends.

1972 Corvette Anti Rattle Cushions Per Door 9/21

08. There are two anti-rattle cushions per door: one front, one rear. To replace the cushions without redoing the entire window, it will save time to mark the original mounting location for the cushions before removing the bolt. You’ll want to hang on tightly during removal; otherwise, you’ll be trying to fish the cushion out from the bottom of the door.

1972 Corvette Back Glass 10/21
1972 Corvette Window Replacement Project Scarlett 11/21

09-10. The back glass is the fun part. The top and bottom frame halves are held together at each corner with a screw and a steel roll pin, which is the rust-red dot you see. If you intend to have the frame stripped and re-anodized you’ll have to remove the screws that hold the guide wedges in place. Note that the guide wedges have been shortened to allow the window to be removed in the tight confines created by the rollbar, even though it won’t be able to come out of the rear storage area.

1972 Corvette Window Replacement 12/21

11. Although one of the corner screws turned out easily, the other was frozen in place. Even after letting it sit with penetrating oil we had no choice but to drill the head out so the frame could be disassembled.

1972 Corvette Window Center Screws 13/21

12. With the two corner screws removed, we used a pin punch to drift out the two roll pins at each corner. There are special punches for roll pins that ensure you don’t spread the pin out, locking it in place, but these two pins moved easily without the need for special tools.

1972 Corvette Clean Window Setting Tape 14/21

13. After carefully removing the glass, use a thin screwdriver or other tool to clean the old window setting tape from the channel in the window frame.

1972 Corvette Window Guide Screws 15/21

14. Like the one stubborn corner screw, three of the four guide wedge mounting screws were frozen in place and snapped off during removal attempts.

1972 Corvette Aluminum Frame 16/21

15. Since the aluminum frame was being sent off to be re-anodized and absolutely no steel parts can be submerged in the anodizing solution, we clamped the frame in the mill to drill out the broken screws and ensure all the steel fragments were removed.

1972 Corvette Tig Welded 17/21

16. Tray Walden carefully TIG welded up the drilled-out holes so they could be redrilled and tapped.

1972 Corvette Window Frame 18/21

17. After welding, Tray ground down the surface of the frame and then did the finish work with a pillar file sourced from gunsmith supply house Brownells, using sandpaper wrapped around the file for the final smoothing.

1972 Corvette Window Frame 19/21

18. The screws that hold the guide wedges in place in the lower frame are 6-32. We couldn’t locate the tap and matching #36 drill bit at three local auto parts stores but found them easily at a hardware store.

1972 Corvette Window Channel 20/21

19. Once the window setting tape is folded over the glass, carefully push the glass into the channel in the window frame. The rear window glass is frighteningly thin so take your sweet time. This shot is a mockup for illustration purposes: for the actual installation, we’ll use a lubricant such as soap to get it in easier.

1972 Corvette Window Replacement Project Scarlett 21/21

20. Once the glass has been completely seated in the channel and the frame is fully reassembled, carefully trim the exposed tape. A razor knife with an adjustable blade is helpful as you can limit the blade depth to just enough to score and peel the tape without scratching the glass.

Sources

Corvette Central
Sawyer, MI 49125
800-345-4122
www.corvettecentral.com
Street Shop, Inc.
Athens, AL 35611
256-233-5809
www.streetshopinc.com
Auto City Classic, Inc.
800-828-2212
www.autocityclassic.com
Brownells
800-741-0015
www.brownells.com

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