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Cymber
United Kingdom
966 Posts |
 Posted - 03/03/2011 : 20:36:27
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What size should the P Type horn button mounting bolts be? The holes take 4BA but the bolt heads are too big, was it a special headed bolt?
Maurice Blakey. |
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LewPalmer
USA
3243 Posts |
Posted - 03/03/2011 : 23:12:23
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Maurice,
4BA sound about right, but you're correct. The heads are quite small - enough to clear the bakelite button. I'd advise turning the head diameter down so as to clear.
Lew Palmer
Registrar, NAMMMR |
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bahnisch
Australia
674 Posts |
Posted - 04/03/2011 : 09:33:37
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| I have what I think are the original metal thread screws. They are very small in diameter (4BA? Is that about 2mm or less?). They have very small raised countersunk heads and engage in small nuts (or tapped into a plate behind the dashboard?).I doubt whether such m.t. screws are available anywhere, turning down larger screws (and enlarging the holes, etc) may have to be the answer. |
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DickMorbey
United Kingdom
3677 Posts |
Posted - 04/03/2011 : 10:41:13
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The horn switch and fixings on my PA were original to the car and the setscrews are more like flat cheesehead screws rather than raised head countersunk ones. See the pic (sorry about the dust!)
Best wishes
Dick |
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Bruce Sutherland
United Kingdom
1564 Posts |
Posted - 04/03/2011 : 10:55:46
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I had to repair my old brown horn/dip switch and the long through fixing bolts were 5BA; couldn't find any so made some by threading some 1/8" dia (c.8mm) brass bar at both ends and at one end silver soldering a 5BA brass nut and machining this back to form a head - see below: 
Bruce. (PB0564) |
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Alan Bertram
United Kingdom
199 Posts |
Posted - 04/03/2011 : 20:21:26
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Maurice,
My P type horn button is mounted using cheese head screws with 5mm diameter heads about 2mm deep, but these may possibly be 6BA. As Bruce has identified the correct size as 5BA, I hope this is of help.
The following link should show a source for nickle plated 5BA cheese head screws X 1 1/4" long which should do the job. www.fiennes.co.uk/Parts/Catalogue/Q/QB
Across the pond this company also supplies 5BA cheese head screws up to 2" long. www.britishfasteners.com/index.php/categories/ba-cheesehead-screws/page-2/
Regards,Alan
PA 0397 |
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Nick Feakes
USA
3372 Posts |
Posted - 04/03/2011 : 22:30:31
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Hi Alan
I believe the screws should be raised countersunk and I made mine as I was unable to source them. I soldered stainless steel ends (which when polished look as though they have been chrome plated) onto 1/8" brass rods threaded 5BA.
Nick |
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bahnisch
Australia
674 Posts |
Posted - 05/03/2011 : 09:17:06
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| At the risk of sounding like a "smart alec" I do not think that the cheese head screws are original, my TC has the raised/countersunk ones exactly the same as my F-type. Nor does the switch in the photo appear to be the original type, more like 1950's commercial vehicles (Austin trucks?). I have seen the later type on "restored" TC's etc. The later ones have a smaller diameter horn button and a raised centre of the metal bezel (again as in the photo), but they are a similar pattern and work just the same. To prove that I am a true bore, I might also say that my F-type has "DIPPED" and "NORMAL" stamped on the metal bezel instead of "D" and "H" as on my TC. The use of the term "dipped" is interesting, probably because the left hand F-type headlamp had a solenoid which canted the reflector down and the right hand one went out(?). |
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Alan Bertram
United Kingdom
199 Posts |
Posted - 05/03/2011 : 22:33:37
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Hi Nick,
Thank you for your information. I have found a couple of 5BA cheese head screws in my "bits box" the heads are 5.5mm diameter and should turn down to a raised countersink OK when I get some time. In the meantime my 6BA cheese heads screws will be happy to stay on the horn, where they have been at least since the early 1960's.
Alan |
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Cymber
United Kingdom
966 Posts |
Posted - 06/03/2011 : 11:13:59
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Thanks guys. I now know what should be there and it seems probable that the large holes to take 4BA screws were my doing many years ago. I am going to use M3.5 raised head countersunk screws as used on mains switches and sockets with modified heads reduced to 5BA size, these are readily available in brass or nickel plated. Stainless would be nice but I have not yet founda source.
Maurice. |
Edited by - Cymber on 06/03/2011 11:15:06 |
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