Window Regulator Repair

By Stephen Kassis

Window regulators are the gear driven mechanism that raise and lower door and quarter windows. Early regulators were all manually operated but electrically operated regulators (or power windows) became available as optional equipment on Chevy passenger cars in 1953 and later models. This discussion will focus on mechanical window regulators for both cars & trucks.

Early window regulators in the 1920’s & 1930’S had a single support arm that raised and lowered the glass. These regulators had a fixed stud with a large, round head at the end of the arm. The stud had two round leather washers pushed over the head which acted as a guide for the lower sash channel. The lower sash channel is the horizontal metal strip that attaches to the bottom edge of the window glass. The sash channel will most often have a slotted or grooved area that the stud locks into that holds the window sash stable as it is raised and lowered.

Another early design window regulator, used in Cabriolet and Landau Phaetons, had two single arms driven by a centralized gear and handle. This new design was necessitated by the larger and heavier windows used in these models.

Starting in the mid 1930’s, window regulators came with rolling metal or nylon wheels on a rivet stud at the end of the arm. These wheels took the place of the leather guide washers to keep the sash channel steady and allowed for smoother operation. Later as designs changed, a second arm was added to the regulator which gave it a “scissors” appearance. This second arm would further stabilize the glass and allow for larger window openings and heavier glass assemblies. This arm would have a single wheel at the end which also slides in the lower sash channel.
The final design that will be discussed is a variation of the scissors style. In this design the second (or scissors) arm would have a wheel at both ends. The wheel at the bottom of the second arm would fit into a vertical guide in the door to further stabilize the sash channel.

Rebuilding of any of these regulators will follow similar steps. Start by removing the regulator from the vehicle. The specific steps involved will sometimes be shown in the shop manual for your vehicle. If not, the general procedure would be: 1) Remove the window and door handles and lock knob; 2) Remove the door panel. 3) Remove the glass and sash channel. Do this by removing the window trim, loosening the window channel, cranking the mechanism all the way up while pulling the glass into vehicle. Remove the glass and sash from the window regulator by aligning the studs with the opening in the sash channel. 4) On later vehicles with vent windows, the vent assembly must be removed before removing the door glass.

Move to the workbench and inspect the regulator assembly. A common failure area for early regulators is the metal cup that holds the window crank stud and gear assembly. If this cup is not holding the crank stud steady, it may allow the small gear to disengage from the large regulator gear. There will be 3 or 4 rivets holding this cup in place. Remove the rivets and the cup. Pull the gear out of the regulator and inspect the teeth on the small and large gears. If the gears are in good condition, replacing the cup may be the only necessary repair.

Window regulator repair kits are available for many models of cars & trucks. You may be lucky enough to find NORS (New Old Replacement Stock) repair kits online or at a swap meet. Be sure to check the application before buying as small variations can make it impossible to use a kit that is not designed for your vehicle. Conversely, another kit may have just one piece that is needed to fix your regulator.

There are many reproduction regulator repair kits available. Check to see if one is made for your car. If not, some pieces of a similar kit may be close enough to use to make your regulator work. An example would be the metal retainer cup. You may be able to use a metal cup from a different year by merely drilling different retaining holes in the cup. If the ID and OD are close and the overall height of the cup is the same, it is worth a try. If either of the gears is damaged, it is more important to locate a repair kit or suitable used replacement parts.

Another common problem with the window regulator is worn or broken sash guides. As mentioned earlier, the early version regulators used leather washers and reproduction felt washers make a good replacement for them (AF-214). There are repair kits for the later design with guide wheels. These kits come with a new rivet and nylon wheel. There are two different sizes of rivets: 1/4″ (FS-383) & 5/16″ (FS-383A). Also, there are two different wheels: one with a “V” groove and one that is a solid wheel. Inspect the original regulator to determine what you will need in replacement parts.

On later style regulators, it may be necessary to remove a wheel stud to determine the size of the replacement rivet (stud) that will be needed. Use a drill that is slightly larger than the riveted stud in the regulator arm. Center punch, then drill down to just barely remove the shoulder of the rivet. Be cautious to not damage the metal in the arm itself. Use a small punch to knock the old stud out. Measure the hole size and order the rivet & wheel needed. The most common size rivet used in 1940’s & 1950’s models was the 5/16″ rivet with the “V” shaped wheel (FS-383A).

One final thing to check is the center pivoting rivet on the “scissor” type regulators. If this rivet is loose, it can cause binding in the mechanism. This must be repaired. Sometimes a good sharp strike with a brass hammer will spread the rivet enough to tighten it. However, be careful that it does not make the mechanism bind up. If necessary, a rivet may have to be fabricated to replace the original. If fabrication is chosen, consider drilling the pivot hole slightly larger to get a nice round opening. Fabricate the rivet to the size of the new hole.

With the rivets and wheels replaced, lubricate the regulator gears and pivot points with bearing grease. Temporarily install a handle and work the gears back and forth to spread the grease. The mechanism should be running smoothly. The guide wheels are nylon and require no lubrication. Felt washers for early cars can be lubricated with a few drops of oil.

Inspect all window channels for wear before installing glass back into the door. If the channels are worn, this is an excellent time to replace them.

Reinstall the sash and glass into the door. Before installing the regulator, manually check for smooth operation of the glass in the channel by sliding the glass up and down by hand. The glass should slide in the channel without binding. It is imperative that the glass be kept horizontal when doing this test. If there are problems, the cause must be determined before installation of the regulator. On early wood body cars & trucks, swelling or warping of wood can cause binding. Check for shim material behind the window channel. Remove as necessary to allow for proper operation. It may require sanding the edges of the glass to allow more clearance for the glass. If new wood has been installed into a wood bodied car, this fitting process is particularly important. The wood may have to be sanded down to allow proper fitting of the glass in the door. This is also an excellent time to install sound deadening material into the door shell.Pull out the sash & glass assembly and reinstall the window regulator assembly. Reinstall the sash & glass assembly and connect to the regulator arm. Check the operation of the window with the regulator in place. If all is smooth, finish installing the window channel, window trim, door panel and handles.