A window regulator is the mechanical assembly behind a door panel that’s responsible for moving a glass window up or down along a guided track. Basic window regulators which have been around since enclosed automobiles were first introduced 100 years ago are operated by a hand crank, and power window regulators use an electric motor to do the work of moving the glass along its path. In this article, we'll discuss the basic designs of window regulators and how they work.
Accessing window regulators typically requires a bit of labor. First, inner door panels must be removed along with any weather barrier layers behind them. Then, the window regulator can be accessed through cutouts on the interior door frame. Sometimes, rivets must even be drilled out to remove an old window regulator assembly. You may find our article Replacing Your Vehicle's Interior Door Panels helpful because it details the how-to steps of removing a variety of inner door panels.
Two Main Designs Of Window Regulators
Scissor type window regulators are an older design that you'll find mostly on classic vehicles. Built with virtually all metal components, a main arm is connected to the window carriage/tray on one end and to a large plate with gear teeth on the other. If a scissor type assembly is power operated, an electric motor turns a worm gear that meshes with those teeth to move the arms. In the absence of a power motor, a manual crank handle serves the same function.
The main arm is crossed by a smaller secondary arm at a hinged center point, and both arms slide on small wheels along a groove in the bottom of the window tray as they push the window up or pull it down. Scissor type regulators may fail when wheels at the ends of the arms wear out and break off - causing the glass to tilt at an angle inside the door. When the center hinge wears between the two bars as they scissor up and down, the whole mechanism makes noise and the glass will rattle in a sloppy, unpredictable fashion.
Cable-driven window regulators have become popular with automakers in recent decades because their compact size provides more room inside the door for safety beams and airbags, their lighter weight contributes to overall fuel economy, and the integrated assembly reduces manufacturing costs. However, they actually have more parts and are more complex than scissor type regulators.
Cable-driven regulators all feature a metal track (or tracks) mounted vertically inside the door panel that serve as a guide piece or pieces when the window tray slides up and down. Depending on design, some setups have one main regulator track in the center of the door, and other setups will have a track on each side of the glass. Window regulators with one center track typically feature two smaller guide rails along window edges to prevent window wobble during travel.
In cable type setups, an electric motor or manual crank moves wire cables which travel across a series of pulley wheels before connecting to a window tray or clamps. As the cables are pulled fore and aft, the window opens or closes. Cables suspend the full weight of your window, and if they (or the pulley wheels or even plastic window trays) break then the glass will fall unimpeded all the way down into your door panel and be stuck there.
Another weak spot of cable type regulator assemblies are pulley wheels that can become shredded if cables run over them at angles that are askew instead of perfectly straight - a condition that develops if guide rails become warped for any reason.
Manual Window Regulators
Both scissor and cable type regulators can be set up for manual operation with a handle sticking through the door panel to control up and down motion of the glass window. Humans are the "power" behind these types of manual window regulators because the window crank needs to be physically rotated to raise and lower the door glass. As the hand crank is turned, a plate supporting the glass lowers or raises the window into the desired position.
Even though most vehicles today are equipped with power windows, the expression “roll down your window” is still used because it has become so engrained in our language, dating back to when cranking window levers by hand was the only option.
For a good selection of American and import vehicles equipped with manual windows from 1967 through today, check out AC Delco Window Regulators (which were used as original equipment on most GM models) and Cardone Window Regulators.
Genuine Window Regulators cover BMW and Mercedes back to 1968 along with other European and Asian imports from the 1980s on. Additionally, URO Parts specializes in manual (and power) Window Regulators for Mercedes back to 1977.
We’ve got Replace Window Regulators for select Asian models from 1978 through the early 1990s and Goodmark Window Regulators for 1964-73 Ford & GM performance cars. If you’ve got a 1960s GM model, take a look through OPGI Manual Window Regulators. OPGI even offers manual Vent Window Regulators for select GM vehicles so equipped through 1968. And if you’ve got a Chevy C/K pickup from the 1970s through 1991, Sherman Window Regulators have you covered.
Power Window Regulators
In a power window setup, a compact electric motor transfers its motion through a worm gear and a number of spur gears. The end result is significant gear reduction which allows a small motor to generate enough torque to do the work of moving a heavy window assembly over and over. It's interesting to note that most worm gears provide a self-locking function thanks to gear ratios and angles of contact - that's why it's not possible to force a power window open.
Since the beginning of this century, U.S. government regulations have required power window regulators be equipped with sensors that detect if an object is blocking its path when closing (such as a hand or child's arm), then reverse the window so that it opens instead.
Components in modern window regulator assemblies are designed to fit snugly together, with tight clearances. If windows are not cleaned periodically to remove tree sap, dirt, and other airborne pollutants that create a sticky film on the glass surface, significant drag is created and the window is harder to move up or down. Over time and numerous up-down cycles, this extra stress can cause warpage and misalignment of metal regulator tracks as well as premature electric motor burnout. Hastening window regulator failure are cables and pulley wheels - both of which can become chafed and shredded when operating at improper angles.
In some vehicles, an inoperable window motor can be detached and replaced separately from the window regulator assembly. Repairs of this type are much lower in labor and parts costs because the time and effort involved with accessing and replacing an entire regulator assembly are eliminated.
In general, individual power motors that can be replaced separately are a design feature of scissor type window regulator designs, not cable type regulators. If your vehicle has this design, you will see regulators both with and without motors presented. Be sure to order the correct part!
There are recent vehicles for which power windows were an extra-cost option. For this vehicle, you will see both manual and power window regulators offered. Again, be certain that you order the component which is correct for your vehicle.
When it comes to power window regulator assemblies for a large number of makes and models, we recommend the TYC Window Regulators. Dorman Power Window Regulators offer wide coverage for the 1970s through today (also manual regulators back to the 1950s), and Cardone Remanufactured Power Window Motor & Regulator Assemblies cover a range of 1990s vehicles. Beck Arnley Window Regulators are designed for American and import vehicles from the early 1990s through today, and OPGI Power Window Regulators specialize in GM mid-size cars from 1968-72.
To help guide you through the selection of window regulators and related components, we have set up the Replacement Window Components section of our website to provide you all the choices that will fit your specific make, model, and year. Once you car's information is provided, you'll automatically see all applicable choices.
Once you get your new regulator assembly installed, you’ll be pleasantly surprised at how much smoother and easier your window glides up and down. And once you’ve completed the repair on one window and gotten the steps down, don’t be surprised if you’re tempted to go ahead and replace all the others!