spinky Posted February 5, 2008 Share Posted February 5, 2008 Hi guys.......now i havn't looked into this too much but i have a dodgy gearbox (now lying by the side of tilly) when the time comes to pop the gearbox back in i have the choice of 3 transfer boxes to fit.....the first is the original one still attatched to the old gearbox(a defender unit i think).....the second one is one i purchased which is originally from a discovery.....the third one is attatched to the gearbox that is going back in(also a defender unit...apparantly)......now...i cant remember what the ratios are that is on the boxes but i think all 3 are different.......which transfer box is best for my 110 running 285/75/16's powered by a 200tdi......and if some kind soul wants to explain the science behind the ratios i'd be muchly appreciative!!! Quote Link to comment Share on other sites More sharing options...
smo Posted February 5, 2008 Share Posted February 5, 2008 Hi guys.......now i havn't looked into this too much but i have a dodgy gearbox (now lying by the side of tilly) when the time comes to pop the gearbox back in i have the choice of 3 transfer boxes to fit.....the first is the original one still attatched to the old gearbox(a defender unit i think).....the second one is one i purchased which is originally from a discovery.....the third one is attatched to the gearbox that is going back in(also a defender unit...apparantly)......now...i cant remember what the ratios are that is on the boxes but i think all 3 are different.......which transfer box is best for my 110 running 285/75/16's powered by a 200tdi......and if some kind soul wants to explain the science behind the ratios i'd be muchly appreciative!!! Most transfer boxes are 1.4's - commonly found in 90's. Disco's had 1.2's (better cruising speed at lower revs) and 110's had 1.6's. For a 110 you might well be best off with a 1.6 box, however if you do a lot of miles and need better top end at lower revs then consider a 1.4. Your best bet is to check the serial numbers on the box, and refer to the ashcroft website for identification. Quote Link to comment Share on other sites More sharing options...
spinky Posted February 5, 2008 Author Share Posted February 5, 2008 ah yes.....option 3 is a 1.6............is the disco 1.2 no good then??? Quote Link to comment Share on other sites More sharing options...
smo Posted February 5, 2008 Share Posted February 5, 2008 1.2 on a 200tdi is a bit of a no go really. youll find acceleration a dog but if you ever wind it up she will cruse at about 1500rpm doing 80mph...except a 200tdi 110 will never make it there!! Quote Link to comment Share on other sites More sharing options...
ThreeSheds Posted February 6, 2008 Share Posted February 6, 2008 Could i jump in on this thread with a couple of closely related questions please? When figures of 1.2, 1.4 and 1.6 are quoted above, is that referring to them being a (for example 1.4:1) reduction ratio when in high box? If that is the case then how much do low ratios differ on different vehicles? TwoSheds Quote Link to comment Share on other sites More sharing options...
Mark90 Posted February 6, 2008 Share Posted February 6, 2008 Low ratio is the same in all (standard) LT230's, can't recall off the top of my head what it is but IIRC it's 3.something. 200tdi 110's would be fitted with a 1.4 ratio transfer box as standard. 2.5NAD 110's where fitted with the 1.6 ratio box. Quote Link to comment Share on other sites More sharing options...
Simon Smith Posted February 6, 2008 Share Posted February 6, 2008 My old 110 hardtop 200tdi ran fine with a 1.2 and would happily cruise to Italy at 85 to 90 mph and 30+mpg. If yours wont there is something wrong with it. Quote Link to comment Share on other sites More sharing options...
Gromit Posted February 6, 2008 Share Posted February 6, 2008 From ashcrofts: List of Serial numbers and corresponding Ratios All stock LT 230"s have a low ratio of 3.321, the following list refers to the high range ratio. 12D = 1.667 LT 230R 13D = 1.410 LT 230R 14D = 1.003 LT 230R 15D = 1.192 LT 230R 20D = 1.667 (2.5 N/A 110), 22D = 1.410 (all 4Cyl 90/110 bar above), 25D = 1.410 (V8 110 LT 85), 26D = 1.003 (RR Classic 3 speed auto), 27D = 1.192 (early RR Classic), 28D = 1.222 (RR and Disco I), 29D = 1.192 (V8 90 LT 85), 32D = 1.222 34D = 1.410 (2.0 Disco I), 36D = 1.211 38D = 1.211 40D = 1.211 (NAS/Japan 90&Disco), 41D = 1.211 (Disco II, diff lock stud), 42D = 1.211 (Disco II, diff lock stud), 43D = 1.410 (90/110 TD5), 57D = 1.410 (90/110 TD5), 61D = 1.211, 62D = 1.211, 68D = 1.211, 69D = 1.211, 70D = 1.211 (Disco II, no diff lock), LT 230 Transfer case comparisons 1.003 > 1.222 = 17.92% Drop 1.003 > 1.410 = 28.86% Drop 1.003 > 1.667 = 39.83% Drop 1.222 > 1.003 = 21.80% Raise 1.222 > 1.410 = 13.33% Drop 1.222 > 1.667 = 26.70% Drop 1.410 > 1.003 = 40.57% Raise 1.410 > 1.222 = 15.38% Raise 1.410 > 1.667 = 15.41% Drop 1.667 > 1.003 = 66.20% Raise 1.667 > 1.222 = 36.41% Raise 1.667 > 1.410 = 18.22% Raise For those considering a ratio change the following may prove useful. MPH per 1000 rpm = 2.976D/ MTR D Tyre diameter in inches (more accurate to use 2 x rolling radius) M Typical 5 speed manual box, select a ratio 1st 3.60 These ratios will vary a little between box types 2nd 2.11 3rd 1.40 4th 1.00 5th 0.77 Rev 3.43 T Transfer ratio select a ratio High 1.003 1.222 1.410 1.667 Low 3.321 R Differential select a ratio 4.70 S 4.11 L 3.54 S L Special S stock Quote Link to comment Share on other sites More sharing options...
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