MGB Windscreen Rebuild
October 9, 2004 - Plainfield, Illinois
There's a big gap here at both ends, so bring out the tourniquet.
Click for BIGGER pictures, average 26K
Remove interior kick panels, remove two large bolts at each side, two smaller bolts in the center, and the windscreen lifts off. Remove small screws from the frame, the first three on top and two on bottom at each end, and the frame end rails can be pulled off with the corner brackets still attached to the end frames. Remove one cap nut to free the center strut and pull off top and bottom frame rails. The old rubber seal may be disposed of along with the old glass. If you're saving the glass, dispose of the seal anyway.
Install new foam rubber seal on edge of the new glass being careful to align it symmetrically. Do not stretch the seal, or you will end up with excess length. For assembly we started with bottom rail first, maybe because the top edge of the glass is shorter and straighter and easier to set on the table. Mix dish washing soap and water in a strong slippery solution. Soak the rubber strip and the slot in the rail with an ample coating of the slippery stuff, and press the rail over the rubber edge. Be sure to get the full width of the rubber edge into the slot, and align the rail symmetrically at the ends.
With the bottom rail in place, invert the assembly and install the top rail in similar manner. Use lots of the slippery solution, center the rail, press firmly in place. We learn the hard way that the ends like to pop up, so someone needs to hold the ends down until the cap nut can be installed to the center strut to hold it all together. The last two pictures above show final position of the bottom and top rails prior to installation of the ends.
Using more slippery solution, assemble the end rails in similar manner. Notice photo at top of page. When there was trouble closing all the gaps we used a rope tourniquet end to end to pull the frame together to allow installation of the screws. It was convenient to rope the bottom frame legs and install the bottom screws first, then the same procedure for the top. Having it all assembled once, we then removed one end frame to allow installation of the bottom rubber seal. Sorry no pictures of that procedure, as all hands were busy at once. But you can review the April '04 tech session for those pictures. The fat rubber bottom seal has to slide in the whole length of the frame starting at one end. In case this procedure takes a while, the dish soap solution may dry too fast leaving you with a sticky non-slider. So here we used Goop hand cleaner to lubricate the "T" slot in the frame and the rubber seal. One person was restraining the bracketed end of the assembly to keep it from sliding off the table while a few people were pushing the new rubber seal along the bottom track. It also helps for another person to align and feed the loose and as it enters the track. Having had considerable trouble with one of these just six months earlier, we were pleasingly surprised to find the rubber piece slid right in this time with no problem. Apparently practice makes perfect. More likely it was a matter of better preparation in greasing up the slider.
With the bottom seal in place, the ends of the rubber bit are trimmed to match the angle of the frame, and the end frame is installed again for keeps. Two holes were punched through the bottom rubber seal at the finishing end to allow installation of the screws for fastening of the bottom corner bracket.
Addendum 08Feb08 - A follow up note from Roger Killin:
While assembling my 1970 MGB windshield I discovered that it was not necessary to punch holes in the bottom rubber seal to access the screw holes that secure to end post. The old seal didn't have any holes. With the top rail, bottom rail, 1 post, glass, and glass seal in position, I pushed the seal into position against the installed post, then cut it to the proper length. I then kept pushing up and down the whole length of the seal, with about 5 minutes of pushing and pulling I was able to compress the seal enough to expose the screw holes at the other end of the bottom rail, and secure the other side post. Once this last post was secure I pulled the seal back to it's normal "decompressed" length.
Before installing the assembly on the car, we slipped a rope inside of the curl of the bottom rubber seal. Then as the assembly was pressed down into position on the car body, the rope was pulled forward to pull the lip of the rubber seal forward to lay flat on the car body ahead of the windscreen. See also the April '04 tech session for those pictures. The two center bracket screws need to be in place before the assembly is pushed fully down onto the body. Then the assembly needs to be held down tight at both ends while the center screws are drawn up a little and the end bolts are installed from inside the cockpit. On the rubber dash cars this is a bit of a problem, as the ends of the dash and the bracket holding the dash obstruct access for bolt installation. This would be a lot easier if the dash was out of the car, but since R&R of the dash is a rather large chore, one may chose to fight it and skin a few knuckles to leave the dash in place.
As with all jobs on MG's, it's only a matter of patience and persistence to succeed (and we always do). With the assembly in place, the final task will be to trim the top ends of the external side seals to best mate with the rag top attachment. The last picture shows the MG logo on the glass, now the brand name logo of British Motor Industry Heritage Trust, who are now supplying the glass. We are happy to report that this one fits perfectly.
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