I think a few of us are trying to overthink this apparent anomaly???
The reality is the SPC details by part number the three different Number Plate Panel Assemblies for the Home Market, and all rest-of-world export markets, so Australia (the largest export market after North America), NZ, South Africa, Europe, Scandinavia, Middle East, South America, Asia etc etc; plus the three different Number Plate Panel Assemblies for USA and Canada only (so not all of North America as it seems as though Mexico was considered RoW).
The reality is during the XK120 period of interest there was zero standardization of Number Plate size and mounting holes position. In UK you were simply issued with a Number, and then it was up to you (or the selling dealership) to get your number plates made (to certain specifications re size of numerals and colours), so not a standard government issued plate. In Australia the various states and territories, did issue their own State/Territory plates, but each state/territory was a different size and hole mounting position (it was not until 1954 that the Australian Government specified a standard plate size and holes position for all states and territory issued plates). In USA, similar problem in 1949-54 - each sate and territory issued different size plates, and some only a rear plate and no front plateā¦ Europe during 1949-54 was equally all over the placeā¦
So really looking at the actual plates is a red-herring.
No knowledge of RoW, but for the UK there has never been a regulation regarding size or shape of a number plate. As Roger P. points out, the regulations relate solely to the size of digit, spacing of digits, and the minimum distance between digit and border. These have changed slightly over the years, and are easy to research online.
My daily driverās plate is an old one from the sixties with just six digits, and therefore has a correspondingly reduced plate size. The MOT chap scratched his head first time it went in, then looked it up and said āno, youāre OKā.
Any owner of a Rover P5 can vouch for this! The rear number plate is hugeā¦
Forget the Number Plates, at least for a while as Iām still curious why Jaguar opted for the 4 screw mounting facility if none of the plates would fit. There must have been a reason for that choice. In that respect, I noticed that some UK companies offer new Number Plates for the āOld XKā in the dimension 20.5 x 5" so that would fit the arrangement Jaguar opted for.
The next question is why 15" changed into 12.5" and for what reason. Would this distance have any effect at all on the mechanical fixation of the Number Plate Panel to the Boot Lid? Or are there other āstandardizationā reasons to do so? But the (contemporary) Saloons all had āsquareā number plate panels. So in short: Iāve no clueā¦
I believe it to be the mechanical fixation. The new spacing might have the tendency to pull down the panel to the boot lid better, or pull up the boot lid to the panel, either way, they were probably looking to improve the poor fit they were getting.
I mentioned having to glue my piping to the panel. We really have no evidence that the factory ever had to do that. In fact, if they had found a problem there, my guess is they would have pop-riveted the piping on, as they did with Mark V front wings. My previous rubber piping fit nice and I never had to glue it.
Following your line of thinking, I would assume that the farther away, the better the possibility would be to get the two curves (Boot Lid vs Number Plate Panel) together. Jaguar made the distance between the two bolts shorterā¦ Still unclear what the reason was for the change from 15 to 12.5".
Looking at the earlier models like the Mk V and Mk IV: they had separate panels but fitted on a flat surface so a different principle (but you are the expert in Mk Vās).
It looks like Lyons opted for a new construction when designing the XK120 model. Clausager (āJaguar XK 120 in Detailā) shows some ādesign experimentsā with on one occasion using an old Mk IV Rear Number Plate Panel but a second attempt had a simple Number Plate just hanging at the bottom edge of the Boot Lid. Later design versions had only a Number Plate fitted on a (much flatter) Boot Lid, but no clear ādeep drawnā Number Plate Panel yet. All versions still without rear bumpers. It looks like this was also the way the XK 120 was introduced at the London Motor Show in November 1948. Trying to find original pictures of early cars like HKV 455 but hard to tell what is still original and what has been replaced over the past 7 decades.
The first version of the Rear Number Plate Panel was apparently C.2941 made for the US export market. The circumference of this Panel was identical to the later versions as the Piping length remained the same (5 ft). Like Rob R. mentioned earlier, this construction used four 2Ā½" long BSF Ā¼" setscrews with nuts, so the setscrews went through the Panel and Boot Lid.
The second generation of Number Plate Panels of March 1950 (with BD.4256 as the earliest new version for the US Export market) got the āblindā construction with ācage nutsā. This one had the 15" bolt (horizontal) distance, probably taken over from the previous model C.2941 used up to March 1950. Can anyone confirm this?
Bob, I mentioned earlier that I have a spare original (steel) XK120 number plate panel in need of restoration. I dug it out of my spare parts collection so I could provide a measurement of the narrowest point at the bottom of the panel. Using a solid ruler pressed against the bottom edge of the central weld-on plate, I have a distance of approximately 11/16 inch to the point were the panel should touch the boot lid.
I mentioned earlier that this panel had some rust issues on the inside of the lower edge where it meets the boot lid. Iām guessing when new the measurement would have been at least 3/4 inch.
Are you sure about the wood screws? Or could they have been the four countersunk slotted 2Ā½" long BSF Ā¼" setscrews (FS.504/20H) the SPC refers to?.
If they would have been wood screws, they should screw into wood but (as far as I can see) the wooden ribs are much further apart (almost 19 inches i.s.o. 15). This is valid for the steel XK 120s.
If the very early alloy versions had the wooden ribs spaced at 15 inches, then that would be an important message.
Thatās interesting information. Remember that I had a gap of 5/16" and what was still there was about 3/8". If we add these two values, we end up with exactly 11/16" which is what you measured!!
So I have to widen that section by 5/16" in the middle of the Plate and the corner sections were about correct.
So thatās solved and we have to change my first attempt to list the various versions.
My second attempt is based on the XK 120 SPC publication J.8 reprinted (and updated?) in January 1958. Earlier SPCās (AL.1, AL.2 or AL.3) may contain other information.
First version of the Rear Number Plate Panel was C.2941 made for the US export market and C.2946 for other countries and only used on Alloy cars. This Panel was made of aluminium and its dimensions were identical to all later versions as the Piping length remained the same (5 ft circumference). These early Panels were fitted to the Boot Lid using 4 countersunk slotted (nickel plated?) wood screws probably 2Ā½" to 3" long, screwed in the lower vertical wooden ribs of the Boot Lid spaced at about 19 inches and about 5 inches in vertical direction.
The XK 120 SPC refers to the same panels as above but now using four 2Ā½" longBSF Ā¼" setscrews with nuts, so the setscrews went through the Panel and Boot Lid. According the SPC this would be a continuation of the aluminium version C.2941 and C.2946, still used on the Alloy bodies but now spaced at 15" (as 19" would be impossible for using bolts and nuts. .
The next generation of Number Plate Panels from March 1950 onward (with BD.4256 as the new version for the US Export market and BD.4257 for other countries) had a āblindā construction with ācage nutsā. These panels were made of steel and used four Ā¼" UNF x Ā½" hex head set screws and nuts, spaced at 15" (horizontal) distance.
The final version was introduced in (1951?) and was basically identical to the previous version, except for the set screw distance which had become 12.5 inches. This refers to Panels BD.4655 for US Export and BD. 4654 for other countries.
Thatās excellent information, XKSS (Mike?). The alloys do tie in after all in this discussion, though it mostly is about the steel cars. It makes some sense that the panel started life as aluminum, but was changed to steel when they decided to weld some tabs on it.
So if I understand right, you mean tapered rough thread wood screws through the panel into the wood, and not emerging through. Sometimes called lag bolts, not used with a nut.
Possibly the BSF screws and nuts listed in the SPC are intended to replace worn wood screws and/or deal with worn wood in the boot lid, as you might expect for parts supplies intended for a dealerās shop or other repair shop back in the day. (wood chewed up? just drill it through and use a long bolt and nut)
The two wood frames in my '51 FHC are spaced at 21 inches on centers, thus we can conclude that the framing was not changed in that particular aspect, though I see other differences.
Absolutely nothing to do with this, but Iād just mention that a couple of original AC Cobras I have had/worked on had some body elements screwed into the aluminium skin with sheet metal or even woodscrews. And thereās no wooden frame in a Cobra. AC Cars routinely used tapered steel thread-cutting screws alone to fix parts such as screenwashers, trim pieces etc. directly into the aluminium body. Hard to believe, but presumably cheaper and quicker than a BA screw and nutā¦
J.8 October 1950 (First Edition):
660001>660058/670001>670184: C.2946 Rear Number Plate Panel Assembly (not required for U.S.A. and Canada) C.2941 Rear Number Plate Panel Assembly (for export to U.S.A. and Canada)
660059 and subs./670185 and subs: BD.4256 Rear Number Plate Panel Assembly (for export to U.S.A. and Canada)
J.8 October 1952 (Amendment List No.1 - Second Edition):
660001>660058/670001>670184: C.2946 Rear Number Plate Panel Assembly (not required for U.S.A. and Canada) C.2941 Rear Number Plate Panel Assembly (for export to U.S.A. and Canada)
660059 and subs./670185 and subs: BD.4257 Rear Number Plate Assembly (not required for U.S.A. and Canada - Alternative to BD.5644) BD.5644 Rear Number Plate Assembly (not required for U.S.A. and Canada - Alternative to BD.4257) BD.4256 Rear Number Plate Panel Assembly (for export to U.S.A. and Canada - Alternative to BD.5645) BD.5645 Rear Number Plate Panel Assembly (for export to U.S.A. and Canada - Alternative to BD.4256)
J.8 May 1953 (Amendment List No.2 - Third Edition): - no changes re Panel Assembly.
J.8 June 1954 (Amendment List No.3 - Fourth Edition): - no changes re Panel Assembly.
J.8 February 1958 (Reprinted January 1958 - Fifth and Final Edition): - no changes re Panel Assembly.
660001>660058/670001>670184: C.2946 Rear Number Plate Panel Assembly (not required for U.S.A. and Canada) C.2941 Rear Number Plate Panel Assembly (for export to U.S.A. and Canada)
660059 and subs./670185 and subs: BD.4257 Rear Number Plate Assembly (not required for U.S.A. and Canada - Alternative to BD.5644) BD.5644 Rear Number Plate Assembly (not required for U.S.A. and Canada - Alternative to BD.4257) BD.4256 Rear Number Plate Panel Assembly (for export to U.S.A. and Canada - Alternative to BD.5645) BD.5645 Rear Number Plate Panel Assembly (for export to U.S.A. and Canada - Alternative to BD.4256)
So doesnāt help much, albeit interesting wording of āAlternativeā rather than superseded or similarā¦
And just to be completeā¦ J.11 for FIXED HEAD COUPE June 1953 (only one edition) is exactly the same as for J.8 (660059 and subs/670184 and subs)
J.13 for DROP HEAD COUPE June 1954 (only one edition) is exactly the same Part Nos as for J.8 (660059 and subs/670184 and subs), but changes emphasis of the notes, sayingā¦ BD.4257/BD.5644 now as āNot Suitable for U.S.A. and Canadaā BD.4256/BD.5645 now as āFor use in U.S.A. and Canadaā
I guess most information fits with what we had found already. The fact that the First Edition of J.8 only refers to one ānewā BD.4256 Rear Number Plate Panel and not the ānon-USAā version BD.4257 is interesting. A wild guess is that over the period March 1950 (intro steel bodies) and the date Jaguar engineers had to provide all input for printing of the October 1950 issued J.8 SPC, most XK 120s were destined for the USA. (I havenāt checked this āwildā idea yet).
Another question that remains is whether anything is mentioned in the First Edition J.8 regarding the 4 wood screws or the BSF replacement (FS.504/20H)? If Rob R. is correct, the latter could be a āservice solutionā for the original wood screws.(something like M.110/24R ā¦)
J.8 of October 1950 for 660059 and subs/670185 and subs showsā¦
BD.4256 REAR NUMMBER PLATE PANEL ASSEMMBLY - for export to USA and Canada
C.2954 Seal (Rubber) around Number Plate Panel (5ā long) - 1 off
NS.125/4D Screw, Set, securing Number Plate Panel - 8 off
FW.104/T Washer, Plain, on Setscrews - 8 off
C.724 Washer, Shakeproof, on Setscrews - 8 off
