I'm tempted on sticking a Disco Transfer Box in my 90, but...

...do they have the option to select diff lock?

The reason I ask is that I stripped a RRC 200tdi which had a Borg Warner T/box. I was very tempted in putting this in my 90, but because there was no option to select diff lock at my own discretion, I chose not to.

Do any 1.22 T'boxes have the same set up as my Defenders' LT230 in terms of pushing the stick to the left to select diff lock?

yes mate ,did mine this week 300tdi disco onto 19j 90 and mine all seems the same.

yes ive done two ,they are the same from the 300tdi discovery

Cheers lads...will look out for one off a Disco 300tdi then.

any manuel disco lt230 transfer box will be ok (200 and 300),it was only the borg warner (rrc)that had the viscous coupling rather than manuel diff lock

forgot you dont want 1 off a v8 disco as the ratios are too high

and what ratio is the v8 one ,1.2 i believe same as 300 ,200 ,only early rrc with 3 speed auto had higher ratio at 1.oo3

jamesmartin said:

and what ratio is the v8 one ,1.2 i believe same as 300 ,200 ,only early rrc with 3 speed auto had higher ratio at 1.oo3

Click to expand...

Yes I put a 1.003 transfer box out of a 3 speed auto on to a LT77 box in a RR I
had at the time, because I had fitted a Perkins 4236 T and it was very slow revving at 3000 rpm, but I remember still getting a ton out of it.

jamesmartin said:

and what ratio is the v8 one ,1.2 i believe same as 300 ,200 ,only early rrc with 3 speed auto had higher ratio at 1.oo3

Click to expand...

I stand corrected maybe this will help people in the future
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
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D Tyre diameter in inches (more accurate to use 2 x rolling radius)
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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
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T Transfer ratio select a ratio

High 1.003 1.222 1.410 1.667 Low 3.321
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R Differential select a ratio 4.70 S 4.11 L 3.54 S L Special
S stock

as i said only 3 speed auto has 1.003,and there very rare as are most roller brg types as well