MGB roadsters are popular classic sports cars. MGBs were made in England and have classic, attractive looks combined with simple, durable construction. MGB convertibles use a simple canvas top that is easy to lower and raise when the need arises. The top can degrade over time from constant use and exposure to the elements. Eventually it will need to be replaced for it to function properly. This is a task that can be done by the owner with the right tools.
Install the top on warm day or in a warm garage, preferably when it is at least 60 degrees. Unlatch the top where it fastens to the top of the windshield frame. Lower the top half way. Remove the seal on the header rail on the top. If the seal cannot be pulled out, use a small screwdriver to pry it out.
Drill out the rivets that are exposed once the seal is removed with an electric drill and a drill bit that is the same size as the rivets. If you are reusing the aluminum seal retaining clip, make sure it is not damaged.
Pull the top fabric off of the header rail under the retaining clip that was removed in Step 2. This will be glued on and will take a little effort to remove. Undo the side snaps that hold the top to the bodywork just past the doors.
Grasp the rear flap of the top in your hands and pull it back sharply to allow the steel retaining bar in the back of the top to slide out of the chrome, tear-drop shaped retainers on the body. Undo all of the snaps inside the car that hold the top to the top frame bows.
Lift the top off of the top frame. Slide the steel retaining bar out of its pocket in the top. Check the bolts on the top frame to ensure that they are in place, tight and not stripped. Replace any bolts while the top is off.
Slide the steel retaining bar into the pocket of the new top. Lay the new top over the top frame on the car, which should be about half-way raised. Take care to avoid scratching the new plastic windows on the top. Push the fasteners on the tongue flaps onto the car. These snap on just past the door on either side.
Slide the rear of the top forward so that the retaining bar engages with the tear-drop shaped retainers on the bodywork. Raise the top frame into its fully-up position. Center the front edge of the top on the header rail by making sure that equal amounts of material extend over the door windows on either side of the car. Pull the top tight front front to back so that there are no wrinkles, but do pull it so it is fully taught.
Ensure that the top is centered on the header rail and is pulled to eliminate wrinkles. Mark the underside of the top with chalk or a light-colored marker where it aligns with the header rail. Peel a foot of top material back from the header rail. Brush on a layer of contact cement to the lower front surface of the top and the top of the header rail. Apply the glue only in front of the chalk mark.
Let the cement set up for five minutes. Starting at the middle of the top, carefully press the top down onto the header rail making sure that the chalk mark lines up with the header rail. Ensure that there are no air bubbles where the top is glued to the header rail.
Test fit the top. Fold the exposed front edge of the top under the header rail. Put the top in the full upright position. Fasten the toggle clamps so it is secured to the windshield frame. Make sure the outer edges of the header rail are covered with top material. Adjust the fit of the top if necessary.
Hold the aluminum header rail retaining strip up to the header rail. Poke holes on the material with an awl. Do not poke the hole so far that you also go through the second layer of material.
Rivet the retainer onto the header rail with rivet a gun. Slide a new header rail seal into the retaining strip by pressing it into place with a flat head screwdriver. Trim off any excess seal material on either end with a knife.
Cut off any excess top material that is exposed around the edge of the header tail. Fasten the snaps inside the car that hold the top to the top bows.
