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We cover all MG & Rover cars, We are the MG Owners Club & Rover Owners club, combined in one, from Rover 75 to MGZT, from Rover 800 to MGB, we are here for all your MG Rover MGR cars

How To's

Fitting a heated windscreen

Unread postby Alanaslan » Sat Jun 30, 2018 9:33 pm

Hi everyone, I am a sad old retired Engineer with degrees in Aero, Electrical and Mechanical engineering, I was in charge of looking after the public buildings for a District Council up here in Scotland for the last two decades of my working life. I also had lumped in my remit Health and safety, staff training, and welfare.
In my spare time I used to restore classic cars everything from a trio of Bond Bugs to a 1958 Le-Mans Aston. I was not in the restoration business to make money but to keep lovely old lady’s on the road where they should be and not rusting away in a barn.
I used to organise car shows and trips for 450 guests to Le-Mans every year along with the Classic every other year. Sadly a little over a decade ago I broke my back and life changed. I still try to keep my hand in though what used to take an hour can now take a day.

Last weekend saw me fitting my new heated front windscreen to my Rover 75 Tourer. I can no longer guarantee that I will be able to scrape the ice from the screen in the winter and my current 75 does not have the preheater that my previous 75s have had. So I purchased a heated Front screen.
I was having a good day and the weather was being kind so off came the windscreen wiper arms with me needing a puller for the offside one, Note to self Donate wiper arm puller to Club tool library.
Then pop off the Chrome trim around the outside of the screen. Then inside the car and pop off both door pillar trim panels, remove the mirror from its bonded clip and disconnect the rain sensor. Back to the outside lift the bonnet and remove the bonnetseal from the back of the engine bay then remove the plastic panel and open up both pleniums. Whilst there check pleniums are dry and the drains are running free also change the cabin air filter for a new one.

Now out with the long sharp knife I use a snap blade model knife for which I have a box of 100 blades well probably only forty left slipping the knife between the car body shell and the glass I cut the mastic as best I can all along the top and down both sides. Then using a windscreen bond cutter I load it with anew blade and drag it along the bottom edge seal. Then with another new blade in my snap blade knife I move into the car and push it between the shell in front of the dash and the glass and drag it along cutting what is left of the seal. Assuming you have got a good cut along the top and sides of the screen, you can get your shoulder against the screen whilst kneeling on the seats and push the screen out whilst performing the final cut along the bottom of the screens seal.
The full removal of the screen takes about thirty to forty mins. Don’t worrie if the screen breaks during removal it is going to the civic dump anaway.
Clean up the apature thatthe screen fits against a blade scraper is great for this job make sure all the old glue has been removesd, vacuum around the area inside the car and engine bay cleaning up any slivers of glass or muck. Then wipe down the whole area that the new adhesive will be going on to. Use a pure solvent so that no trace is left after it has flashed off or dried.
Now measure where the rain sensor is located on the old screen and where the rear view mirror mount goes, I recomend a drawing using the black areas of the screen around these mounts so you know where to put them on your new screen. Your blade scraper will remove the mirror mount remember to mark the top or the bottom as the mount has like a three sided nut on it that the mirror quarter turns on to. The metal surface of the mount that attaches to the screen must be clean with no trace of old glue.
Work out where you are placing the mount from your drawing and attach it to the glass with a quality two part epoxy adhesive, from my trade days I used to use a special two part Locktight product now I just use gorilla two part epoxy. Mis up the glue and apply to the surface of the mount making sure that the mount is facing the correct way for attaching the wire or to “flat down” you will understand that comment if you come to do the job.
Now to mount your rain sensor. I have always found from passed experance that these things only work 40% of the time if removed and reapplied.
Sorry should have said when the mirror mount is aligned in the correct place facing the correct way use a piece of Masking tape to secure it in place until the glue dries.
The rain sensor I always as a matter of course fit a new one. You should find them on fleebay for around the thirty pound mark well worth the investment as is a quality epoxy for the mirror mount. On many cars I would use a UV set adhesive for mirror mounts. However on the Rover the Screen Blackout around the mirror area prevents the UV lamp from penetrating properly and you do not get a secure bond so use a quality two part epoxy.

Think that is me covered getting the hole ready to take the new screen. I now use a fast flash self etch primer that is black in colour which I apply with a small retunglar sponge. I use a slice of hi density foam like your Flash magic sponge. But I bought 1000 from China ten years ago now down to my last couple of hundred. The primer I use I apply to the inside face of the new windscreen about 20mm all round the inside face I also apply the same stuff to the metal surround of the apature the screen seals against. I usually give both surfaces a couple of coats.
The primer solvent has a very low flash point and so dries very quickly.

Now the fun bit using a frame gun and a 45 degree cut on the nosel of the windscreen bond adhesive squeeze out a bead the whole way around the apature the bead should be chisel shaped and about 4mm high it takes me one full canaster of windscreen to fit a front screen to a Rover 75. Now cut two pieces of masking tape 2 inch wide or a quality adhesive tape each about 8 to 10 inches long. Make sure the heated screen wires are coming inside the car and able to run up the front pillars. Then with two glass suction handles lift the screen from the tressles and place it on the adhesive where it should go to cover the apature hole with a even overlap all the way around. Then firmly push the screen into the adhesive bed ensuring that it is a straight push with no slide. Then using your two lengths of adhesive tape secure half to the car roof and the other half to the new windscreen this prevents the screen from slipping down under its own weight.
Please wait 24 hours before attaching the rear view mirror to its mount as it pushes over the mount then is turned through 30 degrees anti clockwise to secure it..
At this point you can start to clip back in the chrome trim around the glass and replace the plastic panels and covers around the rear of the bonnet just below the screen.
The bottom screen trim panel is held in place with oval shaped plastic clips. I have a box of these as I replace them as a mater of course but you can buy a pack of them with enough for the job for under a tenner on fleebay. I need to buy more as there are only about ten left in my box. You tend to use them every time you check your pleniums or change the cabin air filter.
If one has broken in the hole preventing a new one from being fitted, you can clear the hole with a small pozzy or Philips screwdriver.
So this is the first part of fitting your new heated screen. I will add the wiring part inthe next 48 hours. Hope this makes those thinking of changing their windscreen feel more competant
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Unread postby baconbuttyman » Sun Jul 01, 2018 6:37 pm

what a great how to,
Thanks matey, may have a go myself
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