Don H. Posted January 10, 2023 Report Share Posted January 10, 2023 The Lucas 7" headlamp trim rims with screw-clamp fixing have always appealed to me. Partly because the attachment is secure and visible and partly because they're uncommon. They were never fitted as standard to sidescreen TRs as far as I know, although I've seen them on some cars (including one former works car, @iain). I got a set a few years ago from one of our correspondents here -- thanks @foster461-- and I had them rechromed a while ago as I was having some other stuff done. I'm considering fixing them to my TR3B this season. But one of the original and odd screws is missing. It's a weirdo, thank you very much Mr. Lucas, that seems to be neither UNF 8-32 or metric M5, although close to both, with a slotted head that isn't quite like any cheese head I've seen. Probably BSF, dontcha think? I'd be OK with replacing both screws with something that fits. Any ideas of where one might find something like that? The screw is Lucas part number 552816, a 15/16" rim fixing screw. The trim ring is Lucas part number 552822, I believe. I should have taken this one when I had the chance 10+ years ago! I have a good friend who's a superb machinist, and he could probably single point one, but he's so unreliable in other ways it would likely be the rest of my life before I saw it... Quote Link to post Share on other sites
Hamish Posted January 10, 2023 Report Share Posted January 10, 2023 Has the chroming affected -reduced the thread size ? Quote Link to post Share on other sites
iain Posted January 10, 2023 Report Share Posted January 10, 2023 Don I’ll try and check mine over the next few days I have some Wierd taps and dies so will investigate. Quote Link to post Share on other sites
Don H. Posted January 10, 2023 Author Report Share Posted January 10, 2023 5 minutes ago, Hamish said: Has the chroming affected -reduced the thread size ? No, it was protected from rechroming as far as I can tell. The original screw fits perfectly. Quote Link to post Share on other sites
Don H. Posted January 10, 2023 Author Report Share Posted January 10, 2023 4 minutes ago, iain said: Don I’ll try and check mine over the next few days I have some Wierd taps and dies so will investigate. Thx! Quote Link to post Share on other sites
Dale Moore Posted January 10, 2023 Report Share Posted January 10, 2023 2 BA?? Hard to gauge against the rule but looks like it could be around 31 tpi Dale Quote Link to post Share on other sites
Don H. Posted January 10, 2023 Author Report Share Posted January 10, 2023 (edited) 8 minutes ago, Dale Moore said: 2 BA?? Hard to gauge against the rule but looks like it could be around 31 tpi Dale Could be. The original screw fits a bit loose into a M5 x 0.8 mm thread checker, but an M5 x 0.8 screw won't go into the trim ring. Something like this could possibly work: https://britishfasteners.com/2ba-stainless-steel-cheesehead-x-1-6588.html Edited January 10, 2023 by Don H. Quote Link to post Share on other sites
Ian Vincent Posted January 10, 2023 Report Share Posted January 10, 2023 Don, if you can’t find a genuine replacement then you could just run an M5 tap through the hole. Bit of a one way trip but it would probably provide a solution. Rgds Ian Quote Link to post Share on other sites
Dale Moore Posted January 10, 2023 Report Share Posted January 10, 2023 Might be worth a shot Don. With the screw being stainless just make sure it doesn't pick up when screwing it in. May be a good idea to run a 2 BA tap down if you have / can get one Quote Link to post Share on other sites
Don H. Posted January 10, 2023 Author Report Share Posted January 10, 2023 One can apparently buy chrome 2BA socket-head screws by each. I might have to bring a few home as a souvenir from the Goodwood Members Meeting this year.https://hh-ms.com/product/2ba-unf-allen-screws/ That site notes 2BA is interchangeable with 3/16 BSF. Is that right? Quote Link to post Share on other sites
RobH Posted January 10, 2023 Report Share Posted January 10, 2023 (edited) 19 minutes ago, Don H. said: That site notes 2BA is interchangeable with 3/16 BSF. Is that right? No. BA is actually metric - 2BA is 0.81mm pitch which is 31.35 tpi and 4.7mm OD. 3/16 BSF is 32 tpi and 4.76mm OD also the thread angle is different - 47.5 degrees rather than 55 degrees. It is close but not interchangeable. Edited January 10, 2023 by RobH Quote Link to post Share on other sites
mike ellis Posted January 11, 2023 Report Share Posted January 11, 2023 Don, as I read the parts book those split rims were fitted as standard on TR3As up to TS32585 which is why Iain's car has them as does mine. They were also fitted to a few versions of some other cars such as Morris Minors but no suppliers ever seem to have any. I think I may have a couple of old rims knocking around so will have a look and let you know. Mike Quote Link to post Share on other sites
stuart Posted January 11, 2023 Report Share Posted January 11, 2023 I would have said definitely BA as that was used in most Lucas applications. Stuart. Quote Link to post Share on other sites
Don H. Posted January 11, 2023 Author Report Share Posted January 11, 2023 5 hours ago, mike ellis said: Don, as I read the parts book those split rims were fitted as standard on TR3As up to TS32585 which is why Iain's car has them as does mine. They were also fitted to a few versions of some other cars such as Morris Minors but no suppliers ever seem to have any. I think I may have a couple of old rims knocking around so will have a look and let you know. Mike Thanks, Mike. I can't say I've ever seen a full handful over here. Were they fitted to US TR3As, too? A bunch of them must have gotten separated from their cars, I guess. Quote Link to post Share on other sites
Don H. Posted January 11, 2023 Author Report Share Posted January 11, 2023 2 hours ago, stuart said: I would have said definitely BA as that was used in most Lucas applications. Stuart. Yes, that makes sense, Stuart. A thread type used for many small, "precision" applications well beyond Lucas, yes? Quote Link to post Share on other sites
stuart Posted January 11, 2023 Report Share Posted January 11, 2023 23 minutes ago, Don H. said: Yes, that makes sense, Stuart. A thread type used for many small, "precision" applications well beyond Lucas, yes? As used in Italian made washing machines too until not that long ago Stuart. Quote Link to post Share on other sites
RAHTR4 Posted January 11, 2023 Report Share Posted January 11, 2023 Don, I acquired a pair of these particular rims some years ago and coincidently they are currently at the Plater’s awaiting their turn in the queue. I was told at time of purchase that they were fitted to early TR’s so after I got home I checked the period Lucas Catalogues to see what they were actually fitted to and the following are the notes I made at the time. Fitted to all Standard car exported to Persia up to 1956. Fitted to TR3 exported to Switzerland in 1958. These rims then disappeared from all subsequent years of the Lucas Catalogues. My take from this was that they were a rare part. I have no idea what the actual thread is, however as I still have the original two screws – I did not pass these to the Plater, I was concerned they might be lost.! – so I have just checked through all the spare Lucas screws and found the Headlight adjuster screw, part number 554288, has the same thread and are slightly longer. These will obviously work differently, because both location brackets are internally threaded the screw will pull the joint together. The original screw having a plain wasted area below its head means the threaded portion will pass completely through the first location bracket into the second bracket and tighten the joint by compression only. Obviously this is based on an original Lucas part, so I do not know if the modern reproduction screws carry the same thread. I have too many other Lucas screws to be able check them all, so I stopped at the first suitable one I found. As the screw is located under the Headlight I think it would be very hard to spot when installed. Regards, Richard Quote Link to post Share on other sites
TR4Tony VC Posted January 11, 2023 Report Share Posted January 11, 2023 Hi all i looked into this some time ago and it’s a BA / cycle type thread as with most Lucas lamp applications so I’d suggest trying that. If it’s a repro lamp ring they are sometimes ‘odd’ in that they are completely wierd, so I recut them as 2BA / UNF as its close. I have a tap and die somewhere so I’ll find the numbers if you are stuck for the UNF variant. regards Tony Quote Link to post Share on other sites
Don H. Posted January 11, 2023 Author Report Share Posted January 11, 2023 28 minutes ago, RAHTR4 said: Don, I acquired a pair of these particular rims some years ago and coincidently they are currently at the Plater’s awaiting their turn in the queue. I was told at time of purchase that they were fitted to early TR’s so after I got home I checked the period Lucas Catalogues to see what they were actually fitted to and the following are the notes I made at the time. Fitted to all Standard car exported to Persia up to 1956. Fitted to TR3 exported to Switzerland in 1958. These rims then disappeared from all subsequent years of the Lucas Catalogues. My take from this was that they were a rare part. I have no idea what the actual thread is, however as I still have the original two screws – I did not pass these to the Plater, I was concerned they might be lost.! – so I have just checked through all the spare Lucas screws and found the Headlight adjuster screw, part number 554288, has the same thread and are slightly longer. These will obviously work differently, because both location brackets are internally threaded the screw will pull the joint together. The original screw having a plain wasted area below its head means the threaded portion will pass completely through the first location bracket into the second bracket and tighten the joint by compression only. Obviously this is based on an original Lucas part, so I do not know if the modern reproduction screws carry the same thread. I have too many other Lucas screws to be able check them all, so I stopped at the first suitable one I found. As the screw is located under the Headlight I think it would be very hard to spot when installed. Regards, Richard I've seen that part, and wondered about exactly the questions you answered, Richard. Our originals were (are) chrome plated. The headlamp adjusting screw is zinc plated, yes? Quote Link to post Share on other sites
Lebro Posted January 11, 2023 Report Share Posted January 11, 2023 The headlamp adjusting screw could easily be machined to become the other sort. Bob Quote Link to post Share on other sites
BlueTR3A-5EKT Posted January 11, 2023 Report Share Posted January 11, 2023 (edited) Just done some digging..... Would this do? https://www.holden.co.uk/p/cheesehead_screw_for_headlamp_rims Edited January 11, 2023 by BlueTR3A-5EKT Quote Link to post Share on other sites
Don H. Posted January 11, 2023 Author Report Share Posted January 11, 2023 29 minutes ago, BlueTR3A-5EKT said: Just done some digging..... Would this do? https://www.holden.co.uk/p/cheesehead_screw_for_headlamp_rims I don't think it would, Peter. Holden was my first port of call as I started hunting, and I saw that one. It's stated to be 1/4" BSF, and is used with headlight rims in this orientation: Quote Link to post Share on other sites
2long Posted January 11, 2023 Report Share Posted January 11, 2023 This place has some interesting stuff: https://jollyrogersmotors.com/store/p/742-Lucas-552913-Headlamp-Rim-Triumph-TR3-NOS.html Quote Link to post Share on other sites
mike ellis Posted January 11, 2023 Report Share Posted January 11, 2023 From the research I did a few years ago I believe the Lucas part number for that rim is actually 552913. The Triumph number is 119165 and it was fitted to all TR3As from TS22014-TS32585 i.e. Sept '57 to June '58. Also fitted to certain variants of Sunbeam 90 51-53 Morris Minor 50-52 Hillman Minx 51-53 Austin Atlantic 49-52 Austin A30 52 The fixing screw is a great fit in the centre instrument panel wingnut so is presumably the same size. Quote Link to post Share on other sites
Don H. Posted January 11, 2023 Author Report Share Posted January 11, 2023 44 minutes ago, 2long said: This place has some interesting stuff: https://jollyrogersmotors.com/store/p/742-Lucas-552913-Headlamp-Rim-Triumph-TR3-NOS.html I've done business with those guys, Dan. And yes, they do have interesting stuff. The Lucas SFT/SLR 576 driving light stoneguards on my car are from them. They didn't have any split rims on their website the other week, but I haven't spoken to them directly. Quote Link to post Share on other sites
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