JumpingFrog Posted September 12, 2022 Report Share Posted September 12, 2022 Does anyone know for sure what the difference is between the following part numbers: 154479 UKC1450 TKC3002 They're all listed as second gears for Spitfire Mk. IV & 1500 and Toledo/Dolomite gearboxes. My hunch is as follows, 154479 is the original version, with a flat back. UKC1450, I really don't know. I suspect it's just a renumbering of an old Triumph number into the new BL scheme, it seems like this part number is seldom used. And then TKC3002 is the final second gear, I've never seen one, but from photos online it seems to have a dished back. I'm hypothesising that it's to work with the late UKC933 top hat bush? It's probably one for the anoraks, but I'm curious! Are these gears interchangable e.g. can I fit 154479 with the earlier bush and thrust washer arrangement (no UKC933?). Link to comment Share on other sites More sharing options...
johny Posted September 12, 2022 Report Share Posted September 12, 2022 I know Triumph changed gear teeth angles during the manufacturing life of some gearboxes but not sure which ones and when. Presumably it was for quieter running and/or thrust considerations and of course makes certain gearsets non mixable.... Link to comment Share on other sites More sharing options...
Clive Posted September 12, 2022 Report Share Posted September 12, 2022 I would take great care here. Chap I know who has built many gearboxes has a good selection of gears, they all look interchangeable, but are not. At least 2, possibly more, gear cuts. On top of that, a brand new "matched pair" of TR input shaft and laygear was not even close..... horrendous noise when turnng by hand. Link to comment Share on other sites More sharing options...
JumpingFrog Posted September 12, 2022 Author Report Share Posted September 12, 2022 24 minutes ago, johny said: I know Triumph changed gear teeth angles during the manufacturing life of some gearboxes but not sure which ones and when. Presumably it was for quieter running and/or thrust considerations and of course makes certain gearsets non mixable.... This is true for the close-ratio gearsets (1850, GT6 etc.), but as far as I can see these part numbers are all quoted alongside the same laygear - 154829. Although TKC3002 was also used for the later TKC5799 laygear with the bigger reverse teeth. So I'm not sure gear cut explains it. It's always some deep, dark rabbit hole when you start cross-referencing gearbox parts... Link to comment Share on other sites More sharing options...
johny Posted September 12, 2022 Report Share Posted September 12, 2022 Rimmers seem to think 154479 and UKC1450 are the same and TKC3002 is for single rail(?) but I would want to bet on it... Link to comment Share on other sites More sharing options...
JumpingFrog Posted September 12, 2022 Author Report Share Posted September 12, 2022 6 hours ago, johny said: Rimmers seem to think 154479 and UKC1450 are the same and TKC3002 is for single rail(?) but I would want to bet on it... This seems to explain it, thanks. TKC3002 suits the revised "top hat" thrust washer (UKC933) and bush arrangement used in single-rail boxes. Moss has a better parts diagram:https://www.moss-europe.co.uk/internal-gearbox-3-rail-spitfire-mki-iv-1962-74.html The changes are shown along side one another (boxes A and B), showing the different gear and thrust washer arrangement. However, I don't completely trust it as it lists UKC3364, instead of TKC3002 - UKC3364 is actually a late TR7 gear for the closer ratio gearset... Looks like TKC3002 was also fitted to late Spitfire Mk. IV 1300s on the 3-rail box as well as the 1500 on the single rail. Link to comment Share on other sites More sharing options...
Josef Posted September 12, 2022 Report Share Posted September 12, 2022 If you need a source, this was the cheapest I found for the MkIV 154479 http://www.leacyclassics.com/154479.html Link to comment Share on other sites More sharing options...
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