Early Window Rubber Channel Replacement 1925-1932

By Stephen Kassis

Early Fisher Body cars, including Chevrolet, Oldsmobile, Pontiac, Oakland, Buick, Cadillac and possibly Durant, all used a rubber window channel with felt covering. This channel is held in place with a metal retainer that is mounted down inside the door where it is not visible. There is one retainer on each side of the window and is held in place with nails, spot welds or screws. The rubber window channel simply slides into the retainer and is held at the top by a nail or screw.

All Fisher closed body cars: Sedan, Coupe, Coach, & Sedan Delivery bodies all use 5/16″ wide vertical side window channel (70-1168). The Cabriolet & Landau Phaetons (convertible models with chrome frames on the glass) use a 9/16″ wide channel (70-1169). The vertical side channel is very different from the horizontal channel used across the top of the glass. Therefore, separate measurements will be needed for the channel for the sides and the channel for the top. Chevrolet, unlike some of the more expensive Fisher Body cars did not have an actual channel across the top of the side windows. Instead, the factory used a thin felt piece which was nailed across the top of each window opening.

Note: Cabriolet & Landau Phaeton models do not use a channel across the top of the window opening. Instead they have different seals mounted on the convertible top. Vertical side window channels in these convertible models only run down inside the door.

Replacing this channel is a simple process but proper measurements are necessary before ordering the channel. To measure the window channel it is important to know where to take the measurements. Vertical side window channel is measured separately from the horizontal top of the window opening.

MEASURING:

Instead of the original horizontal felt, there is a replacement channel which was made for the more expensive GM cars. This channel (70-306) is 1/2″ wide rubber with felt covering and can be installed across the top of each window for an excellent seal against the elements. The measurement for the horizontal channels across the top of the glass is very simple – just measure the width of the glass from side to side. This same measurement can be used for the beltline seal that is at the bottom of the door window opening. Beltline seals will be explained later in this article. Once you determine the total number of inches you will require, add them up and divide by 12. This will give you the total number of feet of channel required.

The next measurement will be the vertical side window channel. This measurement is easiest to do with the door panels removed. However, it can still be done if you are not removing the door panels. If you want to replace the window stop bumpers (70-110), the door panels must be removed.

Begin measuring at the top of the window opening and measure down to the bumper stop down inside the door. If you have removed the door panel, you will see a “U” shaped stop bumper at the bottom of travel of the door glass on each side.

If the door panel will remain in place, remove the window glass from the opening to get this measurement. In order to remove the window, roll the glass all the way down, and remove all the inner window metal moldings surrounding the glass. Remove the nail or screw at the top of the window channel on each side. While cranking the glass up, pull the top of the glass inward. Crank the glass all the way up and out of the window opening. When the metal sash (bottom piece that holds the glass) is high enough you will be able to slide it off of the regulator arm. With the glass removed, crank the regulator arm back down into the opening.

Slide a tape measure down into the opening until it rests on the bumper stop. Extend the tape measure to the top of the window opening to get the proper measurement. Measure both sides to be sure. Total the number of inches required and divide by 12 to get the number of feet necessary. The vertical side window channel measurement must be separate from the horizontal top window channel measurement as the design of each channel is different.

Note: The rear glass on most early Coupes rolls up & down. This glass will use the same window channels – top and sides – as the door windows and measurements are done the same.

At the bottom of each window channel is a rubber bumper stop that prevents the window travel from going too far. Two of these are required per window (70-110). These can only be replaced if the door panels have been removed. Tip: While door panels are off, it is an excellent opportunity to add sound deadening material to the inside of the door. This is a highly recommended improvement to make your ride more quiet.

BELTLINE SEALS:

Beltline rubber window seal is used at the bottom of each window opening to prevent water from entering the opening. There are three different designs used, depending on the year of the car and the plant of manufacture. Determine which was used on your vehicle before ordering. Early cars – 1925-1931 most often used a seal that was held in place by a thin metal strip that is nailed on top of the rubber to hold it in place (70-64). This seal is located just below the window opening on the outer edge.

The second most common beltline seal was crimped into the front edge of the metal sash channel which holds the glass at the bottom of the window. The sash has an extra metal piece at the outer edge and the rubber seal (70-79) gets crimped into this metal piece.

The least common and a universal seal is a filler channel (70-75). It is “U” shaped with a lip that sticks out the front. It is installed as a filler to hold the glass into the lower metal sash channel. The lip sticks out toward the outer edge of the window opening to seal the glass to the window opening when the glass is raised.

On all three of these parts, the measurement required will be the same as the measurement for the horizontal top glass seal, which was measured earlier. Only one of these seals is used per vehicle at the factory, however, there may be mismatched pieces in your vehicle. Check everything to be sure.

Note: If you are more comfortable with metric measurements, total the number of millimeters and divide by 25.4. Divide the result by 12 to give you the total number of feet that will be required.

INSTALLATION:

It will be easiest to install the beltline seals first. The glass must be removed to do this step. If using 70-64 seal, this is held with a metal strip, nailed below the outer edge of the window opening. Clean and prepare the metal strip by painting to prevent rust. Let dry overnight. Cut the seal to length, lay the metal strip onto the rubber and nail in place with the angled edge facing inward toward the glass.

If using 70-79 seal, this is crimped into the outer edge of the metal sash channel that holds the window glass. If you are installing new glass, remove the old glass from the metal channel by driving a narrow screwdriver between the glass and the sash. Pry up a little at a time to remove the sash from the glass. Use caution and it is often possible to get the old glass out without damaging it.

With a small screwdriver pry open the front crimp channel and remove the remains of the old rubber seal. Sandblast or wire brush it to clean the channel of any filler and/or rust. Treat with a rust preventive paint such as POR-15 or Hirsch Miracle Paint. Let this dry overnight. Slide the new rubber seal (70-79) into the outer edge and crimp it in place.

Use CV-294A, CV-294B or CV-294C filler to install the sash channel onto the glass. Which is needed will be determined by the thickness required – either 1/32″, 1/16″ or 3/64″ thick. Wrap the filler over the bottom edge of the glass. If the glass is not perfectly rectangular, be sure to orient the sash properly so that the rubber seal is to the outer edge when installed. Use a padded work surface and start one end of the sash over the filler onto the glass and tap down carefully with a rubber mallet. Continue across the sash until it is seated all the way down onto the glass. Trim excess filler with a utility knife.

If you are using the universal beltline seal (70-75) filler, remove the glass from the sash channel as described above. Clean old filler and rust from the sash channel and treat with rust preventative paint such as POR-15 or Hirsch Miracle Paint. Let it dry overnight. Cut the filler to the length of the sash channel. Face the lip outward toward the outer opening of the window. Install with a rubber mallet and padded working surface as described above.

To replace the vertical side window channel, remove the glass as described earlier. If you will be replacing the window stop bumpers (70-110), remove the old pieces and nail new bumpers into place. Pull the old vertical channel out of the retainers on either side of the window opening. Inspect the metal retainers, if damaged or rusted, replacements are available (AF-437 & AF-437A). Cut the new rubber channel to the proper length and slide into the retainers inside the door. Push each channel all the way down into the door and leave the upper part loose on each side.

Crank the window regulator up until the arm is above the lower window opening. Install the glass by inserting the window sash assembly into the vertical window seals that are loosely hanging at each side. Align the sash with the regulator pin and crank the glass down into the channels until it can be aligned vertically in the window opening. Continue cranking the glass all the way to the bottom. Straighten the vertical channels and put a single nail or screw at the top to hold it in place. Check the operation of the window to make sure there is no binding in the up and down movement. If the glass is too tight, it may require that the vertical edges of the glass are sanded down slightly to allow free movement.

The horizontal top channel (70-306) should be installed after the window glass is operating smoothly. Cut the horizontal channel to fit in between the vertical channels on either side. Crank the window up part way and slide the horizontal channel onto the top edge of the glass. Crank the glass all the way up and mark the proper location of the new channel. Lower the window glass. Using short, small head nails, nail the channel in place from one side to the other. Check the alignment with the window glass as you go. When finished, the glass should slide all the way into the top channel and provide an excellent seal for the window. Reinstall inner metal window moldings and the job is complete.