Installing new weatherstripping doesn’t just stop leaks, it can be a welcome improvement in daily driving, thanks to reduced wind noise. However, it’s easy to get overwhelmed with all the technical terms surrounding these rubber seals. Here’s what you need to know to buy the correct weatherstripping and fit it to your vehicle.
Where is Weatherstripping Used on My Vehicle?
Automotive weatherstripping is used to seal spaces around windows, as well as spaces around any moving pieces of the body. This includes doors, windows, the trunk, the hood, and even around fenders.
What Does Weatherstripping Do?
Seals keep rain water and splashes from puddles from seeping into the vehicle, which can cause rust and mold growth. The rubber’s flexibility is used for vibration control, absorbing shocks and preventing direct contact between metal components. Seals also help with noise control by blocking air from entering through spaces around car doors and windows while driving.
Why Do Automotive Rubber Seals Fail?
Wear and tear is a problem, but the environment is also a major cause of seal failure. Like paint, rubber is susceptible to damage from UV light. Over time, this light can break down seals that are exposed to sunlight. Older rubber degrades when exposed to ozone. While there isn’t much ozone in the open air, heaters can generate this gas. Park your classic car in a garage next to the heater, and your seals can rot away in a matter of months.
What Should I Look for When I Buy Weatherstripping?
This is one area where it’s worth buying Original Equipment Manufacturer (OEM) parts. While it’s not hard to find an aftermarket spark plug or oil filter that works like a factory part, slight differences in manufacturing can make the difference between a high-quality fit and a rattling or leaky seal. The labor saved by these perfect-fitting pieces make them the best value, even if the part cost is higher.
If you can’t get OEM parts, buy seals from a top tier manufacturer. There are several suppliers that specialize in reproduction seals for classic cars that no longer have factory support. These are the closest you can get to buying a new automotive OEM quality weatherstrip, but even the best parts may need some modifications. Quality management wasn’t as good in the past, so spaces between parts of the doors or the trunk of a car model can vary a lot from vehicle to vehicle.
Most seals are designed to fit a specific part on a specific vehicle. However, some standard designs, like classic windshield weatherstrips, are sold in bulk. When you buy universal windshield moldings or belt line weatherstrips, it’s up to you to determine the size and length you need for your project.
What are the Different Types of Seals?
The Types of Seal Construction
While older seals were usually made from butyl or natural rubber, most current OEM and aftermarket seals are made out of polyurethane-based EPDM rubber. EPDM is popular due to its high tensile strength, low temperature resistance and excellent all-around weather resistance. It’s the same material used to make most high pressure air hoses. Neoprene is sometimes used on hood seals, due to its high oil and chemical resistance, while nitrile rubber is used to make rigid seals. These materials are used alone or as the main material in a multi-part seal. Seals can be divided into construction types called “rubber profiles.” Knowing the difference between these edge protection profiles will help you match seals, as well as buy bulk weather-stripping in the right sizes and lengths.
Dense extrusion: These seals are made of solid rubber. They can bend, but they barely compress. Their main automotive application is holding the windshield of a vehicle in place.
Sponge extrusion: EPDM sponge rubber is a type of closed cell foam that compresses easily without losing its shape. This type of seal is used on door weatherstripping and trunk lid weatherstripping, because it’s easy to make flexible profiles of various shapes that conform to the body of the vehicle.
Clinch seal: This type of seal is made of closed cell foam lined with rubber fingers, wrapped around a metal channel or steel wire. The channel slides over pinch welds, and the fingers keep the seal in place. These are mostly found on door and trunk seals.
Flocking: This is a velvet-like pile coating that can slide against glass without squeaking or leaving scratches. Flocked seals are used around sliding windows.
Bulb trim seals: This type of seal has a round or teardrop shape with a hollow center. This helps them flex when compressed, which makes them ideal for sealing trunks, doors and hoods.
The Names of Seals By Location
When you’re ordering a body seal, you need to know what the piece is called. Some pieces are made specifically for your vehicle, while other pieces may use a generic strip that is cut to fit. The difference between these types depends on the vehicle and where the seal is installed.
Primary door seal: This is the main seal that goes around the door opening, creating a flush fit with the door sill, roof and pillars. Its main function is keeping water out of the cabin.
Secondary door seal: This is a trim seal that goes around the outer edge of the door. It helps direct air flow away from the door, decreasing wind noise.
Beltline moldings: Beltline weatherstripping goes by several names, including window felts, cat whiskers, car window sweeps, division bar channels and anti-rattle seals. Each door has a pair or seals that go on the exterior and interior beltline of a door, sandwiching the glass. This grips the bottom of the window, creating a watertight seal while keeping the window from rattling.
Roof rail: This weatherstripping goes between the roof line and the top of the door or the top edge of the side windows. Convertibles often have a series of these seals that grab onto the window edge when the top is up.
Header bow: This seal runs along the windshield frame of convertibles. It creates a tight seal between the windshield and the top.
Run channel: This U-shaped weatherstrip seals the window in the door. Flexible run channel wraps around the diagonal edge and top of the window frame, sealing the space around the window when it’s up. Rigid run channel runs along the vertical side of the window frame, guiding the window as it moves up and down.
Sash channel: This metal U-shaped channel attaches to the window regulator and supports the bottom of the window glass. A rubber filler wraps around the sash channel, protecting the edge of the glass.
Lock pillar filler: This weatherstrip seals the gap below the rear quarter window. These rear window seals are usually found on cars without a B-pillar, like convertibles.
Division post: This is a type of vent window seal found on classic cars. It fits over the vertical post, creating a tight seal when the window is closed. Unlike quarter window seals, the division post seal only meets with the inside of the glass pane.
Vent seal: Also called quarter window channels, these seal the edge between the vent window and the main window in the door. While front vent windows are rare on modern vehicles, most rear doors have a small vent window. This shortens the main window, so it can roll down into the door.
Windshield seals and locking strips: Modern windshield are installed using a glue that permanently bonds the glass to the windshield frame. The seal that goes around the glass protects the edges of the windshield and absorbs vibrations between the glass and the windshield frame.
Windows on older cars are held in by a rubber seal instead of glue. The seal’s outer channel slides onto the car, and then the window fits into the seal’s inner channel. Once everything is in place, a locking strip slides into the space between these two channels. This flexible wire core pushes the seals outward, creating a rigid window channel that supports the glass while absorbing shocks and vibration.
Divider bar seal: This seal divides sections of glass in a multi-piece windshield.
Hinge pillar: This A-pillar weatherstrip creates a seal between the pillar and the front of the door.
Decorative edge trim: Despite the name, this is a functional seal that goes around the curved edge of a rear door, next to the wheel well.
Sunroof seal: This single piece seal wraps around the window opening. Sunroofs have channels for draining away water. If these are clogged, water can pool and drip into the cabin. Be sure to check these channels for debris, so you can rule them out before replacing the seal.
Cowl: Also called a hood to cowl seal, it runs between the firewall and the hood. This prevents gases from the engine compartment from being directed over the windshield and into the cabin.
Hood: The hood seal runs around the front and sides of the engine compartment or the hood, depending on the vehicle. Engine compartment seals protect mechanical components from water and help guide air around the engine for better cooling and aerodynamics.
Trunk seal: This seal runs around the edges of the trunk.
Hatch seal: This seal runs along the edges of the hatch door or the hatch opening at the end of the rear storage area of an SUV, wagon or hatchback.
Tailgate seal: This seal runs along the bottom and side edges of the truck bed. When the tailgate is closed, it creates a seal that prevents water and dust from blowing up into the bed. This seal isn’t standard on all trucks. However, it’s can be added to help keep the bed clean when using a camper shell or tonneau cover.
Bumper grommets: These seals fill in the space between the fenders and bumper supports on older cars with chrome bumpers, creating a water tight fit.
Splash apron seal: This rubber sheet attaches to the inside of the fender well, protecting the engine compartment. These are made to be easy to remove for maintenance. Most newer vehicles use bolt-on plastic pieces in place of rubber sheets.
Radiator seal: This seal goes between the radiator and the radiator support. If it’s missing or damaged,incoming air can pass around the radiator, which can lead to overheating.
Can I Repair Weatherstripping?
If the rubber is intact and in good shape, it can sometimes be pushed into place for a better seal. You can do this by using a silicone sealer, or by adding extra adhesive behind the seal to push it outward.
How Do I Install Weatherstripping?
Most seals are simple enough that they can be installed by anyone with decent mechanical skills. However, you may want to hire someone with installation experience to fit seal-supported windows. Tolerances are tight, which makes it easy to chip or break the glass.
When you install weatherstripping, you need more than just the molding rubber. For the best seal, you need a specialized cleaner to create a dirt and adhesive-free surface. You may need a special weatherstripping glue to attach the seals, although some seals come with double-sided tape. Clips and fasteners can be reused, but there’s always a chance that you’ll break or lose one during installation. Likewise, plastic edge trims may be brittle after years of weather exposure, especially PVC edge trim used on older vehicles. Most press-on seals include a replacement flange on each end, requiring no extra hardware.
Before you start, compare the new weatherstripping with what’s already installed on your vehicle. If they don’t look identical, the new rubber won’t fit.
Remove the old weatherstripping. There may be screws holding in the corners, and some strips have studs that fit into holes in the body panel.
Apply weatherstripping remover to take off any remaining glue or baked-on rubber.
Do a test fit of the new rubber. Glued-on pieces will shrink a little as they dry. To compensate for this, leave an extra quarter to half-an-inch of weatherstripping on the end. Once the glue cures, you can trim off any excess.
Give the mating surfaces and the seal a final clean to get the best adhesion.
If your application uses glue, apply a light coating of adhesive to the weatherstripping and to the body panel. On applications that use self-adhesive tape, remove the tape backing. Attach the weatherstripping. You will get the best seal in the area where you begin to attach the weatherstripping. Start at the lowest part of the body panel, since it will see the most water.
Install any screws used to hold the seal in place. Double check the seal, especially at the ends.
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