Dismantling Windscreen

[Kevin49]

Hi all,

I need to replace my windscreen due to a large crack at the top but my stanchions do not have screws in securing the screen frame but appear to have been riveted directly into the frame grove, also there's no tennon plate.

 

One stanchion I've managed to un-rivet with a bit of brute force but I nearly bent the stanchion doing it, which is chromed brass I think. I've removed the rubber body seal that has revealed a couple of small screws in each lower corner of the frame. I can't undo the screws at the moment but when I do I assume the frame will come apart and I'll be able to drill off the rivet. Am I likely to have to drill off these screws too!

 

Any advice appreciated.

Regards

Kevin

[Rodbr]

Hi Kevin,

The bottom of the screen frame is a single piece and the rest being sides and top one whole piece.

At the bottom corners, there are almost right angled pieces screwed the tie the frame together.

As you have, I think got one, stantion off carefully drill side screws and the ones on the underside. plus bottom ones on the rivited stantion side. This will allow you to remove the bottom rail. sideways.

Then slide the screen out from the Top frame (STOUT GLOVES NEED TO BE WORN)

 

Once the screen is out you can drill the rivits out to free the stantion. Then you can drill out the last corner piece.

 

This is the only way to get the bottom rail out since you cannot drill the other corner piece on the side where the stantion is still rivited.

The Moss catelogue does not show the exploded view but there is a bubble picture of the corner pieces.

 

When you have the frame and stantion with glass removed you need to be extremely carful not to allow it to bend or you will distort the frame and may be unlikely to get the glass an drubber to fit. You need to phone a friend or make a brace of some sort. Bre warned as bendy as a bendy thing.

 

Clean the threads and check fit with the proper screws, (there are two different sizes) check screw lengths carefully as you will crack the new screen if you get it wrong.

Either try to buy or contact me as I have a spare set of tenon plates.

 

Hope this helps.

Rgds

Rod

 

[Kevin49]

Many thanks for that Rod.

k

[billg]

Once you have removed all the visible screws and rivets and dismantled the whole screen if you look inside the brass channels you will see some square section steel blocks which are tapped with a BA thread. Often the threads on these are either stripped or the screw shanks are rusted in . In most cases you need to run a drill or a tap down these and find matching screws

 

Moss has all the little brackets etc which add up

 

Regards

 

Bill G

[Ashley James]

Page 96

 

http://www.coh-baines.co.uk/pdfs/catalogue_compressed.pdf

[stuart]

I did write up a small piece on putting a screen frame together once you have dismantled it.

Pasted in as follows.

Stuart.

 

 

I assume you have all managed to take the frame to bits to start and now have the stanchions/tenon plates/top and bottom sections of frame and the two small plates for the lower rubber to scuttle and a new pair of corner brackets all laid out on the bench in front of you and all trace of the old screen rubber and the upper and lower sealing rubbers removed.

First of all check that the tenax studs across the top of the frame do not protrude inside at all as it only takes a fraction of protrusion to crack the glass.

Make sure that the two steel blocks on either side of the upper section of the frame are present and that the threads are good (10 UNFx32 )

Check the lower frame section has at least three small rubber blocks located in the channel to keep the glass up and centred in the frame.

Try the frame around the glass with out any rubber fitted to determine if the curves match as its not unknown for the frames to be bent and repro glasses to have a different curve to the originals.

Fit the two angle brackets to the ends of the lower section of frame with two screws with the leg that has three screw holes in facing upwards. You may find that the repro counter sunk screws that come with the brackets have larger heads than the original ones so you may have to carefully drill slightly larger the circular cut outs in the outer channel of the frame (Not the inner holes) to allow the screws to go in. Always apply some copperslip or similar to the screws to facilitate removal at a later date and apply a little waxoyl or similar to the brackets as they do tend to go rusty.

Lay the new screen on some sponge or a clean towel curved ends upwards. Clean any stickers off with some spirit wipe and check around the edge of the glass for any of the laminate sandwich sticking out and if necessary trim off with a sharp knife.

Lay the new screen rubber around the edge of the screen and secure roughly with some tape (It will move around all over the place until you have the frame finally clamped up but just make sure that you keep an eye on it and keep it roughly centralised on the edge of the glass) Have the ends of the rubber together in the centre at the bottom of the glass and trim off to allow about an inch and a half of overlap.

With the screen laid on the bench in front of you with the pointed lower corners towards you and the upper section of the frame in front of it slide the upper frame down over the screen guiding each leg down over the edges of the screen and keeping the rubber centralised on the edge of the screen until it starts to go tight (Rubber hammer will help to tap the frame on)

Pull the sealing rubber tight in the middle of the bottom of the glass and tape off.

Then fit the lower rail up to the glass guiding the corner brackets into the upper frame. (Large sash clamps, the type used by carpenters for window frames will help to pull the two sections together or a large professional Black and Decker Workmate will do the job as well.) Keep checking that the rubber is centralised around the glass and hasn’t left a gap in the centre, if there is too much overlap then trim it down as it needs to butt together when finally fitted. Also check the bottom corners haven’t got caught in the join of the two sections of the frame.

You then need to fit the two screws (Copperslipped) in each side of the bottom ends of the top frame section to secure the corner brackets (Top two holes of the three in the bracket.)

You will find that a small pin punch inserted into one of the holes in the side of the frame and then into the bracket will give you the leverage required to line up the holes.

Once you have the frame securely screwed together then trim the rubber off with a craft knife close in to the edge of the frame and go round it with a thin bead of non setting windscreen sealer and finger wipe it tight into the edge and also into the bottom corners as very often the repro glasses can be a bit short and you can end up with a small gap there.

Fit the lower screen to scuttle seal. Originals and some good repros can be slid into the channel. Most repros these days wont and require the use of a blunt screw driver to insert the “T” into the channel manually all the way along. (Be careful to fit it the correct way round. Looking from the end of the rubber it is shaped like a “T” BUT THE TOP FLAT THAT GOES IN THE CHANNEL IS ANGLED SLIGHTLY AND THE LOWER LEG NEEDS TO POINT BACKWARDS TOWARDS THE INSIDE OF THE CAR!

Pull the rubber as tight as possible across the bottom of the frame but don’t trim the excess off yet.

Apply some sealer to the inner and outer faces of the tenon plates and then assemble them with the stanchions to the frame. The attachment screws are two different lengths the upper two being shorter than the lower one. To prevent cracking of the screen carefully check the length of the upper two with a small screwdriver through the holes, as soon as it contacts the rubber then that is the maximum length to be used. (Screws are raised countersunk slotted.)

Pull the edges of the lower screen seal out until it is tight and then fit the two small retaining plates either side of the rear of the stanchions and then trim the ends of the rubber neatly. There should also be two small pieces of sponge rubber that goes in the slots in the stanchions next to the ends of the lower rubber that should seal against the scuttle but these have been unavailable for some years and I usually just make up a “sausage” of DumDum and press that into the channel.

Fit the top sealing rubber by sliding the lower “T” into the channel. (Again the repros wont do that so it will also have to be manually inserted into the channel with a blunt screw driver.) trim the ends so that they slightly cover the top ends of the stanchions to stop any leaks from the corners of the hood.

Refit entire unit to the car. In the case of earlier cars by sliding onto the scuttle brackets and tightening up the Dzus fasteners or in the case of later cars by inserting the screws into the captives in the scuttle.

[Kevin49]

Gentlemen, a hugh thank you for all the advice, job for the weekend!

regards

k

[Kevin49]

Of course that should have read a huge thank-you!

 

So far, following the instructions above I have managed to remove the lower frame and remaining stantion and managed to remove the glass. I've not found the little steel blocks or rubber blocks mentioned by Stuart above, are these required to be made?

 

regards

Kevin

[Rodbr]

Hi kevin,

Preparation to fit the screen.

Depending on the fit of your "new" screen you will need to make new rubber blocks. I suggest you play with the old glass without the rubber seal. You will see that the screen "floats" in the frame. when you install the rubber seal it is effectively still floating without any blacks fitted. Get used to putting some asking tape on the glass as a guide to where the glass should fit evenly be within the frame.

The reason that this is critical is that the stantion screws can and DO hit the edge of the glass and either crack it straight away or very soon after fitted and the car flexes.

 

Trial fit the corner blocks as you will probably need to enlarge the holes as the screw heads are typically larger than the originals. Does this before re-chroming!

These effectively pull the frame tight as you do them up and give a good fit at the lower corners.

 

Now you need to look at the inside corners of the stantions and hopefully the screws that hold the chrome plated plates on the inside that clamp the lower screen rubber. These are about 11/4" parrallellogram shape and new ones need to be bent to shape, you can use the originals if you have them but get them palted at the same time as the screen. They are in your face a bit and you might be disappointed if they are scruffy.

[stuart]

The steel blocks that take the stancions screws either side will need to be made if they are missing. They were originally screwed to the sides of the frame with very small countersunk machine screws (some thing like No 6 size). The thread for the main stanchion screws into those blocks is 10/32.UNF The rubber blocks as Rod says are needed to stop the screen floating in the frame.

Stuart.

[Ian Vincent]

I am also dismantling a windscreen frame so all of this is extremely helpful - many thanks to all contributors.

 

I have successfully drilled out the screws holding the corner brackets and removed the glass and am now in the process of removing the stub ends of the stanchion screws that remained embedded in the little steel blocks (even though they were brass screws).

 

I note Stuart's comments about the larger screws being 10/32 UNF but since this is only a gnats c**k different to 2BA, and the latter are far easier to get hold of, I have cleaned the threads out with a 2BA tap and will go with that. Quite why TR would have mixed 10/32 UNF and 6BA in the same fitting is beyond me - surely it would have been easier to stick to BA sizes all round for the small stuff?

 

Anyway, having drilled out the screws on one of the blocks and cleaned out the threads with a tap, I can't actually remove the block itself - I given it quite a bit of persuasion with a mallet and am extremely wary of damaging the frame as I guess that is a piece of 'unobtainium'. Is it OK to leave the blocks in place when I have the frame re-chromed and on the off chance that one comes loose and is lost, it would be pretty straightforward to make another.

 

Suggestions pls?

 

Rgds Ian

[stuart]

The little steel mounting blocks if you examine them carefully are held to the frame by some very small countersunk machine screws and normally are impossible to remove. If they are missing then look carefully at the frame and you should see the threaded holes where they are mounted. You do need them as there is really no other way to screw the stanchions on properly.The strain rearwards with a hood fitted is quite considerable never mind forward airflow.

Stuart.

[Ian Vincent]

Hi Stuart,

 

I have spotted the little 6BA c'sunk screws that hold the blocks in place and having drilled out the head on one (actually, I drilled it right though and re-tapped the hole), I still can't remove the block. I appreciate that I need the blocks so that the stanchions can be securely fixed to the screen frame but my issue is, do I really need to carry on and drill out the rest of the 6BA fixings and then struggle to remove the blocks before I have the frame re-chromed or can I just leave them in place for the re-chroming?

 

Rgds Ian

[stuart]

Leave them in place, I always do and have never had a problem with the chroming process.. Especially as the thread in the frame for the little blocks is very short and being in brass is quite fragile.

Stuart.

[Ian Vincent]

Now you need to look at the inside corners of the stantions and hopefully the screws that hold the chrome plated plates on the inside that clamp the lower screen rubber. These are about 11/4" parrallellogram shape and new ones need to be bent to shape, you can use the originals if you have them but get them palted at the same time as the screen. They are in your face a bit and you might be disappointed if they are scruffy.

 

Does anyone know of a source for the tiny cap head self tapping screws that fix these plates to the bottom of the windscreen frame, or do I have to get my existing slightly rusty ones re-chromed?

 

Rgds Ian

[billg]

Hi there

The flat stainless little corner plates which shape the rubber seal came complete with tiny self tappers from Moss. I re- drilled pilot holes for these screws. Once you have finished he screen and mounted it you feel very self satisfied!!!

 

Bill G @ NB

[McMuttley]

Does anyone have a pic of how these corner plates (finishers? are fixed ?

 

I have new plates and screws, but cannot see how they fit and what they are meant to achieve with the rubber.

 

Thanks

[stuart]

Like this, you need to keep the rubber under tension so it sits nice on the scuttle and the repro plates often need grinding down a bit and bending to suit.

Stuart.

[McMuttley]

thanks stu - would i be right in thinking that this has to be done with the screen off - i could see how I could get a screwdriver to the screw at the angle as the scuttle stopped access ?

 

silly question, doesn't it lift the rubber away from the scuttle if it is pushing up from the inside ?

 

The absence of the bottom two stanchion screws keeps my rubber tight to the scuttle !

 

Also my frame only appears to have one single tiny screw hole

Edited April 8, 2014 by McMuttley

[Lebro]

I fitted the end plates during my major re-build of last year.

I am going to take them out the next time the screen comes off, because:

 

1) They are scratching the paintwork of the scuttle (I could grind them down but read on)

2) Yes, they do hold the rubber away from the scuttle, & allow draughts, & rain in.

 

So I can't actually see that they are of any good purpose.

 

Bob.

[stuart]

If you have fitted the rubber the right way round and tensioned it up properly before fitting the plates and bent the plates correctly then the plates dont push the rubber away.

Very often the two little holes are hard to find as the original screws very often break off flush when removing.

Stuart.

[Rodbr]

Here's a piccy of them newly fitted, this is why all the advice is to allow the rubber to relax for a period before working further on it. You must have the holes ready for the tiny screws, i.e cleaned and tapped if necessary, only trim enough that allows the excess to be removed. Note the tag in the picture.

 

You must fit them with tension in the rubber, this needs sixteen fingers and 27 hands with the patience of a saint.

Pull the rubber to get tension, use an bluntish awl (as in sailmakers) Emgineering term in Scotland is a POGER ( pronoinced po jer) try to find the the first hole, without the plate, when you have the first one put a tiny hole through the rubber still with tension.

 

Then comes the next fun job, even funnier without an original to work with, Bend the plate to shape without the rubber sandwiched, trial fit the screws in the holes and make sure you know which one is which after trial fit and that the plate is as tight as possible to the stantion.

 

next

Insert the screw through plate then through the hole you made previously and wiggle it till you get it entered in the hole. adjust the plate till it matches where you did your trial fit and then fish for the other hole. There is no easy way it takes time and extreme patience.

 

Only when you have both side plates fitted do you think about trimming any excess off. Only take off what you must to make it neat. Sometimes you do need a smear of Dum Dum or similar at the ends.

 

Without enough tension in the rubber and the plates fitted the rubber will never seal to the scuttle. This why the rubber is fitted the reverse to what looks natural and why it must have tension!!!!! If the plates hit the scuttle they are fitted wrongly I'm afraid, again the orientation is always obvious and as the repros are just flat plates more so.

 

 

[McMuttley]

.....mmmmmm your chrome is so shiny and your glass so clear

 

 

.....mmmmm ? that plate looks very different in shape to what I have, mine is closer to the flat heart shape in Stu's pic

[Rodbr]

I think you'll find that angle of the picture makes the difference. If you have the originals compare the new shiny ones and bend and shape to them. These are Moss ones and bent to conform to the shape and do the job. Compared to originals they were virtually identical but I'm afraid that each car has it's own little foibles that means it isn't always straight forward.

 

The next bit to get right is the rubber for the top of the screen.right and takes about two weeks to avoid shrinkage.

 

 

 

 

I think to completely restore a screen to look good you need to budget for the guts of £500 - £600 and leave plenty of time. Thats what will give you a screen that doesn't leak, doesn't crack the glass. and seals properly. This is not a job that you want to have done by someone unless you accept that it really is that many hours to do it properly. There is no such thing as a cheap screen refurbishment.

 

COAT EVERY SCREW YOU FIT AND EVERY THREAD WITH COPPASLIP OR SIMILAR to avoid grief when your screen cracks due to the good advice being either ignored or shortcut. No offence meant, but screw length is critical and trial fitting everything before final build is equally important.

Edited April 8, 2014 by Rodbr

[billg]

Rod has really spelt this out very well and he is being very generous with his time writing down what is one of the trickier jobs on the car.

 

Regards

 

Bill G @ NB

 

Ps spent all day motoring with some Huston on a 200 mile trip over hilly roads from North Berwick to Stirling then Liiearn and back again!

 

It was rainy most of the time so I now know the limits to the adhesion of the set of Vredsteins bought last year!

 

I'm now going to try the newer Michelins on the steel wheels