Joined: Aug 2017 Posts: 1,230 Threads: 33
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Location: Salop
Car type: '28 GE Cup. '28 AD Chummy '30 RL Saloon. '34 RP Saloon. Too Many toys!
14-04-2021, 09:23 AM
(This post was last modified: 14-04-2021, 09:30 AM by Hedd_Jones.)
My advice, go to the antique centre near Nantwich, last time I went (after lockdown #1), there were still 2No top halfs of vintage car windscreens in one of the stands, they've been there at least 2 years, just a bit pricey in my view.
Buy one or the other, should provide you with suitable, if not 100% accurate sides to make something 95% of people would consider perfect.
The other alternative is find a chummy screen, or a screen off a later 2 or 4 seater and doctor that. I have a 2/4 seater screen here (ex a forum member), was going to doctor it for my GE Cup, but I've swapped it (and some other stuff) for a 'Stadium' Screen. Coming next week.
The 2/4 seater screen is going on a trials chummy.
Joined: Apr 2018 Posts: 172 Threads: 65
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Firstly thanks to everyone for their advice and help.
I have some 7/8 nominal OD tubing which I could use for the bottom tube and, conveniently, some steel conduit which slides inside the brass tube very nicely.
Somewhere I think I have a short piece of brass channel which may be enough for the uprights leaving just the bottom “H” section brass, some “D” section steel for the side brackets, the glass and a small piece of brass sheet for the corner pieces and hood fixings to buy. (I say only but even that looks like it could easily come to £120 plus plating).
The only think I really don’t understand is that I’ve now seen photos of the internal (fixed) steel tube where this is just slotted around 45 degrees of the circumference to accept the threaded portion of the butterfly bolts. These appear to screw through some pieces of tapped steel rod inserted into the tube but I can’t see how this works.
If you tighten to butterfly bolts I presume the threaded end just bears on the opposite side of the steel tube thereby forcing the tapped bar back against the inside of the steel tube. This would certainly prevent the tapped steel inserts rotating but the only reason the brass tube and windscreen couldn’t rotate would be because the butterfly bolts pass through it which seems unlikely so I feel I’m not grasping this.
I’ve also seen reference to people cutting a slit down the steel tube so that when the butterfly bolt is tightened the tube can expand and thereby grip the inside of the brass tube. This seems a more likely solution but the photos I’ve found don’t seem to show this.
I’m sorry if I’m being a bit thick but can anyone explain how this actually works?
John.
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Charles,
Yes I did get your e-mail but have only just responded to your PM.
My lack of understanding related to Item 10 on your sketch and the slitting I mentioned was from several sources including the reply from Dave Wortley on here.
It looks to me as though the originals didn't have any slit so the tube didn't expand when the butterfly screw was tightened but more recently some have modified this presumably to hold the screen more rigidly.
John.
Joined: Aug 2017 Posts: 532 Threads: 46
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Location: Oakley, Hants, UK
Car type: 1929 AD Tourer, 1930 Rosengart LR2, Rosengart LR4 Van 1938 APE Tourer (Opal)
I bought two for £145 on eBay which I thought was quite reasonable
I am always interested in any information about Rosengart details or current owners.
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15-04-2021, 05:18 PM
(This post was last modified: 15-04-2021, 05:18 PM by Charles P.)
When the butterfly (part 12) screws far enough in to part 11 to touch the back of the tube (part 10) it pulls part 11 forward. The larger diameter section of part 11 then binds on the inside of the main cross tube (part 3), holding the screen in position. Making the larger diameter section of part 11 longer adds greater friction area. Well, that's what I did and its worked well for many years. It would be advantageous in my mind to make part 11 out of stainless. When left after a good soaking parts 10 and 11 do rust togther a bit.
C
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Location: North Yorkshire
I've a home made top opening screen on my Trial Chummy. It's very similar to that Charles shows for his Ulster although, obviously, it pivots at the top, not the bottom. The butterflys work in the same way. When attempting a trials section we've always opened the top of the screen and tightened it with the butterflys and it's never fallen down in 13 years of bouncing up and down trials hills. The use of stainless is a good suggestion as is a wipe of Copper Slip on the threads of the butterflys for the same reason.
Steve
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That's very helpful Charles as it makes the clearance of Item 11 inside the tube (Item 11) important since presumably it needs to be loose enough to allow it to move radially when tightened. Also the head diameter needs to be a close fit inside the brass tube Item 2 so that it will bind up when tightened.
Due to my lack of machinery I was thinking of grinding the head of a large diameter bolt down and using this to create Item 11 thinking the head was just so it didn't disappear down inside Item 10 but obviously I will need to get this somewhat more accurate.
Not sure when I will be able to get it done but at least I now understand how it's intended to work.
Out of interest I had seen reference to someone making Item 11 from Delrin so it would be low friction and corrosion free but this looks like at probably wouldn't work as there would also be little friction between it and the brass tube.
John.
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Location: Deepest darkest Kent
Charles' drawing is from the instructions for the late Alan Raeburn windscreen kit.
I have one of these kits and the inner tube is split.
