C4 power windows have gone through a few engineering changes from the agonizingly slow '84-'86 ribbon-lift windows to the later scissor-lift windows. The design stayed roughly the same except for the actual lifting device until 1994, when a front window guide was added to lessen window rattle and slop when the window was in any position. Previously, unless the window was fully open or closed at the limit stops, rattles occurred when you closed the door or were riding down the road. Nothing is foolproof, and the window-guide design proved to have a weakness-eventually the guide breaks, and the window has no upper limit stop at the front. The guide also doubles as the upper window limit travel stop. When the plastic-guide/upper-limit stop breaks, the window can become extremely out of position and, in some cases, glass breakage occurs. Corvette coupes get a double whammy as the glass can break, and the paint at the rear pillar gets scraped.
Nobody looks at the window for positioning before they close their door, unless they've noticed the window doesn't look quite right. If all of a sudden the window is too high at the front, most likely the stop is broken.
The task of fixing these issues is not too difficult, You can plan on spending a couple of hours removing the door panel and fighting the thread locking adhesive retaining the upper window stop to the glass. On the up side, the door panel can get a thorough cleaning while everything is apart. Our particular guide/upper-limit stop replacement Corvette had this issue for a while, but we recognized the problem and kept the window down a bit to compensate for the annoying problem. But enough enough's as they say, and it was time to rectify the situation.
Things You'll Need
- 3M black strip caulk
- KD trim pad removing tool
(PN 2822) - Window guide/stop LH
(PN 49549): $17.99 - Window guide/stop RH
(PN 49550): $17.99 - Whisper quiet door insulator LH
(PN 35469): $19.99 - Whisper quiet door insulator RH
(PN 35470): $19.99
 Broken C4 window guides can...  Broken C4 window guides can cause lots of problems. Let's fix 'em! |  1: Door-panel removal and...  1: Door-panel removal and replacement is similar whether you have an '84 or '96 C4. The manual door-lock knob must be removed by pulling the knob off the actuator rod. We use a hooked pick to pull it off carefully. The '90-'96 Corvettes have a screw hidden under the lock knob, while the '84-89 cars do not. Once the lock knob is removed, the screw can be accessed. |  2: The '90-'96 Corvette courtesy...  2: The '90-'96 Corvette courtesy light also conceals another door-panel retaining screw. We're pushing the light back in here to remove the light assembly. We use a thin flat-bladed screwdriver to ease it out from the top. Pry gently at each upper corner with care as it's easy to break the flexible retaining tabs off. |
 3: The door-lock harness...  3: The door-lock harness connector fits tightly on the switch. pry it off carefully by slowly working it back and forth until it releases. Excessive force here can break the door panel plate. Also beware of using a metallic object, such as a screwdriver, to pry the connector off the switch. The terminals can be shorted together causing a blown courtesy fuse. There are two courtesy fuses located in the dash fuse panel; they are tagged right- and left-hand courtesy fuse if you happen to blow one during repairs. |  4: Now we can remove the...  4: Now we can remove the lower door-panel plastic pushpins using our K-D Tools trim-remover tool. Push the tool all the way against the pushpins for support before working the pins side to side to release them from the door. Avoid putting the removal tool between the door panel and the pushpin since the panel can be scratched easily. |  5: We need to remove the...  5: We need to remove the aluminum reinforcement panel next, so the rear upper-limit glass stop requires removal. The rear upper-limit stop has two 10mm screws holding it to the plate and is adjustable. You can mark around the large washer with a magic marker or use the witness marks on the plate to restore it to the correct location. |