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Depending on who bought it when new-what I mean by this is if it was bought by the MOD then it'll have a 1:666 ratio transfer box and if it was a civilian vehicle then it would have a transfer box ratio of 1:410, However if someone's mucked about with it and swapped the original transfer box over for a discovery one then it will have a ratio of 1:222

HTH

John

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the lower ratio one ie: 1.667:1 has a lower speed to it-it was for military vehicles 90 and 110's that needed to pull heavy weights-thats from my own personal experience of when I was in the army many moons ago-top speed in a 2.5 NAD of about 60 mph

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the lower ratio one ie: 1.667:1 has a lower speed to it-it was for military vehicles 90 and 110's that needed to pull heavy weights-thats from my own personal experience of when I was in the army many moons ago-top speed in a 2.5 NAD of about 60 mph

thanks guys so the higher the number the lower the speed?

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The only way you'll be able to tell-if it's still on there is to look for a sticker on the rear of the transfer box by the handbrake drum telling you which one it is ie: 1.410, 1.222 etc etc and yes the higher the number the lower the speed

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Well looks like I have the 1.667 ratio on my 1990 defender 110 which had a 2.5NA and now I have replaced it with a Defender 200TDi engine plus a roverdrive DX overdrive. Yet to get the landy out from the garage, can you tell me what I can expect from this combination?

Does having a 1.667 ratio mean I have better torque for hauling stuff?

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Well if you want to change it for a 1.4 one then i would be after the 1.6 one.

a 1.6 is better for lower grunt yes, hence i want it as running an auto with 35 Fedimas and it needs the lower grunt.

if you do alot of heavy towing in hilly areas then a 1.6 with a tdi may suit. if you spend much time on main roads then a 1.4 would be better. a 1.4 with an o/d will give about the same as a 1.2 box. a 1.6 with o/d about the same as a 1.4 i would of thought.

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well, not everytime the sticker is correct. there was a time when i swapped the internals of a 1.410 to 1.222 so the sticker still said 1.410 but it's 1.222 internal.

to be 101% sure, take off the round cover and count the teeth of the largest gear (not largest diameter)(3 segments of teeth).

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well, not everytime the sticker is correct. there was a time when i swapped the internals of a 1.410 to 1.222 so the sticker still said 1.410 but it's 1.222 internal.

to be 101% sure, take off the round cover and count the teeth of the largest gear (not largest diameter)(3 segments of teeth).

The "largest gear" your on about is the intermediate shaft, the actual high gear is on the diff assembly, and you cant see it from inside the round cover.

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well, not everytime the sticker is correct. there was a time when i swapped the internals of a 1.410 to 1.222 so the sticker still said 1.410 but it's 1.222 internal.

to be 101% sure, take off the round cover and count the teeth of the largest gear (not largest diameter)(3 segments of teeth).

Thats interesting cos my transfer box has a serial number saying its a 1.4 but it always feels undergeared. Its an early 90 with a 200tdi fitted. Could you elaborate please? which cover and when I've counted what number means what ratio? Could I have 1.6 internals on a 1.4 box?

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Well if you want to change it for a 1.4 one then i would be after the 1.6 one.

a 1.6 is better for lower grunt yes, hence i want it as running an auto with 35 Fedimas and it needs the lower grunt.

if you do alot of heavy towing in hilly areas then a 1.6 with a tdi may suit. if you spend much time on main roads then a 1.4 would be better. a 1.4 with an o/d will give about the same as a 1.2 box. a 1.6 with o/d about the same as a 1.4 i would of thought.

I'll have a 1.667 going spare soon when I put the Isuzu into my defender.

I'm in Leicester JST.

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1.4 is standard. If you have a 1.6 you won't be able to do more than about 60mph before the engine is really screaming. I've a 1.2 in mine now and it's comfortable to drive but wouldn't like to tow anything massive over long distances. 17Foot trailer was my limit for 30 miles with the 1.2

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I have disco 200tdi conversion with 1.2 t-box.

With 2.5 petrol and 1.6 t-box top speed was 60mph. But let me say again TOP.

Now with 200tdi+ 1.2 top speed is the same. Is this normal?

Altough I still have some problems with a busted pipe from turbo to bosch pump...

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I have disco 200tdi conversion with 1.2 t-box.

With 2.5 petrol and 1.6 t-box top speed was 60mph. But let me say again TOP.

Now with 200tdi+ 1.2 top speed is the same. Is this normal?

Altough I still have some problems with a busted pipe from turbo to bosch pump...

60mph - nope it should do 80 or more.

you got the right speedo sender in it? and std sized tyres?

Edited by JST
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Prith, i would think that a 1.6:1 box with an overdrive will give you a final gear ratio similar to that of a disco box (1.2:1). It could work quite well really, as some say that the overdrove on 1.4:1 box leaves it a bit overgeared. So I would think you will have plenty of grunt low down and a reasonable top gear for cruising.

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Prith, i would think that a 1.6:1 box with an overdrive will give you a final gear ratio similar to that of a disco box (1.2:1). It could work quite well really, as some say that the overdrove on 1.4:1 box leaves it a bit overgeared. So I would think you will have plenty of grunt low down and a reasonable top gear for cruising.

Thanks Reb!

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Well I have 235/85 16 tyres. And the speed was checked with the GPS.

What can be the fault for this? It seems like the engine is quite on the end with the revs at 60mph...

check which speedo drive gear is fitted, for 7.50x16 or 235/85x16 or 255/85x26 tyres it needs the FRC3310 20tooth Blue gear.

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  • 1 month later...

check which speedo drive gear is fitted, for 7.50x16 or 235/85x16 or 255/85x26 tyres it needs the FRC3310 20tooth Blue gear.

Speed was checked with GPS. I even put the boost gauge on inlet manifold to see if the turbo is not working right, but the gauge shows me 11 psi.

I have disco 200tdi, LT77 and 1.22 transfer box, input gear with 26 teeth. It revs just fine, top speed is 60mph, but crusing speed is 55mph.

The exhaust is from petrol engine but I`m waiting original for 200tdi. Could this be exhausts fault?

Even with original petrol engine and 1.67 t-box I could reach 60mph... So it would be logical to have faster car with stronger engine and faster t-box.

Please help :D:blink:

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