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MG MGB Technical - Windshield Glass

I picked up a Triplex modified windshield glass to replace the cracked windshield on my 1966 B. The barcode
Sticker on the windshield has part number: FW00415-CLN. I did a Google search on that part number and the search results indicate the windshield fits 77 - 80 MGB. Is there really a difference between early windshield glass and 77-80 glass and will this windshield fit in my '66 B windshield frame?
bhall1

I take it this is a roadster.

The Parts Catalogues only give one glass (AHH8227) and glazing seal (AHH7172) throughout production, but Clausager indicates the glass and glazing seal may have changed in 1977 for thinner glass. Moss Europe (and some others) indicate that the glass changed for the 1972 year, and specifically states that 'early' glass (AHH8227) will not fit 'later' frames, which need HZA5415. Brown & Gammons (and others) does not make that distinction and only refers to OE, Repro, tinted and clear. But all are variations of HZA5415 so the implication from both Moss and B&G is that later glass will fit earlier frames. The only reference to 1972 that Clausager makes is that tinted glass became available on non-North American GTs. Moss and B&G only list one glazing seal for all years.

Current-stock glass to fit later screens like my 1973 does seem to be different shape in the lower corners from the original glass, said to accommodate differences in the frame uprights. There are four different uprights for RHD cars (three for other markets) listed prior to 1977. For 1977 and later uprights are not separately listed, only complete frames and top and bottom rails. There are three different complete frames listed for RHD cars prior to 1977 (two for other markets) and only one frame for all markets for 1977 and later. The effect of the later glass with the cut-outs in the lower corners is that the edge of the glass can be seen from outside, as shown in these pictures of my roadster - firstly just by looking through the glass, and secondly by pulling the seal back, the edge of the glass is arrowed in both cases. I was concerned that with so little overlap between rubber seal and glass it might leak, but hasn't in over 10 years.


paulh4

If it's a Triplex glass there's some coding information on the net to give it's year and month of production that might tell you its age.
Nigel Atkins

Triplex had two coding systems, this compiled by Neil Cairns:

http://www.mgb-stuff.org.uk/misctext.htm#glass
paulh4

Sorry Paul I'd forgot it was on your excellent site, probably where I first saw it.
Nigel Atkins

Paul, thank you for your helpful reply. Of course it is a roadster. I will compare the thickness of my old glass to that of the new glass. Maybe that's the major difference. It is a modified glass with the notches in the corners as indicated in your photo. I'm a little worried that the rubber seal will follow the curve of the glass in the corners instead staying in the frame channel.


As far as the Triplex coding system - it appears to indicate only the manufacturing month and year within a decade but not the decade.
bhall1

That page describes how the coding system changed from the 60s to the 70s so OEM glass can be dated to those decades. I can't see any logo on the replacement screens in my V8 and roadster, but the original glass in my 2004 ZS 180 does. The rear windows are 'Splintex' with no immediately identifiable coding system, the front glass is Pilkington which has dots.

I've since found loads of other pages covering glass dates found by Googling 'windscreen glass date codes', several covering more modern dating systems.
paulh4

The difference is in the bottom corners, early pillars were a bit recessed, later pillars were not. See photo. So the glass is a little wider at the bottom.
Paul Walbran

Photo?

The recess in the lower corners of the glass has already been mentioned, but it seems to be the later glass that has them, implying the later pillars perhaps had a bulge (not a recess) in that position. Both the recessed and the non-recessed glass has fitted my 73 frame.

It's pictures of a guaranteed late upright I'd like to see - ideally the channel as well as external.
paulh4

On windscreens
Here probably 15 tears ago I bought two Triplex screens from the UK for our elan, one for the car and a spare---Wrapped the spare up in an old bedsheet and stored it up in the top of the cupboard out of the way
Then two years ago it was time to fit it up so out it came, unwrapped it and couldn't believe what had happened, it had completely delaminated into two seperate glasses-
Couldn't get another here so had to get one from UK which was an interesting process trying to get a decent freight deal from this end but all credit to the guy I got it from he organised a ripper deal for me
Moral is ,don't bother keeping a spare
William Revit

Not definitive by any means but I've seen a couple of examples on late model cars where the uprights are definitely a different shape to my 73, as in the attached.

On mine (left) the yellow arrow indicates that the upright drops down then turns in to meet the bottom rail, whereas on the other one it just goes straight down past the bottom rail. And to me on the right-hand one there seems to be a definite kink inwards at the blue arrow, which would explain the shape of the later glass if the channel also kinks inwards.


paulh4

Mmmm, don't know what happenned to the photo, I'll try again

Paul Walbran

This thread was discussed between 24/07/2019 and 26/07/2019

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