Bonding in a 401/403 Rear Screen.

[Geoff Kingston]

I am not that far off needing to refit the rear screen in one of my 401, I phoned my local car painters and as luck would have it a local mobile windscreen specialist was due in and he popped round later to look at the job.
Firstly he did not think the glue they use would grab the glass, it would have to be supported by the frame and secondly he had concerns about the glass itself as it does not have the modern etched strip around its edge which helps the glue stick better to the glass. His major concern however was the lack of the black enamel strip around the edges of the glass which protect the glue from the effects of the suns ultraviolet rays which would melt the glue if it was not there.
Thinking about this afterwards however I did wonder if this might not actually be an issue as the glass is fitted from the inside and the lip of the body is going to shield the glass along the perimeter where it has been glued in place. The screen fitter thought the bonding material may fail after about a year and the screen start to leak.
He suggested as an alternative that it simply be sealed in place on a bead of high quality black silicone.
I have read in the past comments about bonding the these screens in place using modern adhesive sealer's but have seen no follow up of how effective these were after a few years use and what adhesives were used.
Any advise would be much appreciated.
Geoff.

[peterg]

When I fitted my rear window I sealed it with the same black mastic I used to seal the front window rubber seal. I also put a small amount around the bottom of the body to stop water pooling and seeping down between the body and glass into the wooden frame.

I'm not sure glueing the glass to the body would work or be a good idea.

The main problem was the bottom of the frame had rotted and needed replacing.

[Bellerophon]

The Bristol Aeroplane Company used 50% DumDum mixed with 50%of Bostic C
which worked very well. However, I am not certain if these products are still available now, but there are several modern means to fix the window into place
but they need to be flexible to cope with the expansion of the aluminium against the glass.
An extra piece of information which you will not find any where else is the part number of the wooden filet which holds the glass in position, it is N 705712A, there may be a drawing in the archives with sizes. This was supplied oversize and had ro be fitted first to the aperture and then to take the aluminium surround plus the roof lining which is trapped between the two.
I hope this is of help, so the best of luck.
Bellerophon

[Geoff Kingston]

I think perhaps using a bonding type material rather than a sealer may not be a good idea especially as the original mix was flexible.
I was very lucky to have an original wooden frame made by Bristol and bought many years ago and even luckier that Dave Ralls who has done some trimming work on my cars was able to make up a jig to reproduce them. Made in the same was as the original the only departure is that after realising that most of the adjustment, as they were made oversize originally,is on the inside of the frame is that Dave makes them in two pieces with a small number of the inside laminations separate to reduce the amount off work if the inner alloy frame is larger than average, I have four of those alloy trims here and none of them are the same size or shape though reassuringly all the frames are a snug fit in the surround in the body. If anyone needs his contact details please let me know.
Going back to the sealants there are a lot of choices on the market and perhaps asking one of my friends who used to have an ocean going trimaran might be an idea as there would have been sun movement and salt water thrown into the mix.

[Geoff Kingston]

An update, used a flexible sealer not a bonding adhesive. Glass was a tight fit,car came with three rear screens and I assumed correctly as it turned out that the one in the middle which had been cleaned was the correct one for the car though it did not fit first time, which was a pity as we ended up with as much sealer on us as the glass and surround. Tried the other two screens no go and checked the screen to frame size on the first one and it seemed very good.
Did a trial fit again but this time instead of locating the base of the glass first we got the top into place and were then able to push and pull the bottom into place.
With the glass supported the sealer was reapplied and we then got the frame in behind the glass to support it and securely screwed in place.
A messy awkward job but will let the sealer set for a few days before cleaning up the excess.
Also took the opportunity to seal round the new front screen rubber which did not sit as well as I would have liked and is slightly shorter that the seal BODA does for these cars. Not worth changing now as will have to come out if the car is ever painted. It wont leak but until cleaned up round the edges looks a bit messy. Not as bad as the carpets though which first saw service in OAE954 when it was sent to Craven and Hedrick in New York in 1951.
This car cosmetically is not going to win any shows but it is developing a character of salvage, make do and mend, I think a lot of fun like a pair of favourite slippers.

[mikebro]

Geoff, you mention using a flexible sealer - which one?

Thanks

Mike

[Geoff Kingston]

Mike,
On the recommendation of my local car body repair garage I used 3M 08509 Windscreen Sealer, this is a mastic sealer that remains flexible, seems to stick to anything and makes an awful mess!, easily cleaned off with white spirit.
It seems to have done a good job and will allow future removal of the glass if need be, exposed to the air the outer surface skinned over but still feels a bit tacky.
We also put it under the new front screen rubber which seemed a bit too soft, not quite as deep as the one boda supply and did not sit as flush as I would have liked on one corner. The sealer filled the gap but any pressure in the corner would force a bit out so I over sealed that area with Granvilles Black Silicone Sealer which drys to a non tacky finish.
If I change the front screen rubber at a later date for the BODA supplied one I will use the 3M sealer under that as well.
Geoff.