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Swapping transfer box


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Hi all,

I've mananged to located a discovery transfer box to replace my whining defender box which was ruined by bad workmanship when installing the 1.222 ratio gears. the teeth are all worn out due to the failed bearing. 2yrs on the road and this has to happen.

The question is, just to be very sure, will any discovery LT230 fit a defender? The seller can't exactly be sure which year is the box but the box is from a discovery with a 3.6L engine. He mentioned it was either a 92 or 98 discovery. the box does have a center diff lock.

If it does fit, is it a straight bolt on?

I believe i need to port over the electronic speed transducer from the defender box as mine is a Td5, rite?

Thanks!

I need to confirm with the seller as soon as possible before he sells it off as it's going at a very reasonable price, which is cheaper than replacing the 2 gears.

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after a long trip across the border and back, i've hauled the t-box back.

to my horror, i've noticed that the 2002 Td5 T-box has an additional sensor mounting which looks like this picture.

the box that i've gotten doesn't have it.

Now my guess is that sensor tells the ECU if it's in low or high range and if in high range to activate FTC (fast throttle control). Anyone has any ideas? Assuming that this is correct, if i leave out this sensor, will the ECU think that i'm in high or low? if it's default to high, i can just install a flip switch in the cab to use the full throtle range when in low by closing the circuit, rite?

Failing which, i can try to port over the gears to my original box. Will i further mess up the box by moving the gears around?

Thanks!

Andrew

post-8868-126762916203_thumb.jpg

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regardless of which way it defaults, you can use a switch just like you describe, the default just sets which "way up" the labelling goes...

To find out the default, use a multimeter with the switch fitted to the original box, and see which gear closes the switch.

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Ralph: Tis only the TD5's that use the low range switch.

i've had a poke at my box, it seems that with the selector arm pulled fully back, the switch is closed, and in neutral and forward its open.

You'll need to compare the linkage positions with the selector on the box to work out which is which.

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After doing a lot of reading, i've come to realise that the above item is the low detect switch fitted on a LT230T late model. The LT230T early model has a different low detect switch fitted in another place.

The box that i have a is LT230Q. This model doesn't have any options to fit the low detect switch.

This switch does the following :

A high/low detect switch is fitted in the front output housing and connects to earth when low is selected. The switch is connected to the engine ECM, the SLABS ECU and the BCU. The purpose of the switch is to enable selection of the hill descent feature and to modify the engine fueling and automatic gearbox gearshift maps stored within the respective ECM's and ECU's.

The main difference between the T and Q boxes :

The LT230Q, while similar to the LT230T differs mainly in the following areas:

• Helix angle of gears increased to 31° together with an increase in the number of gear teeth thus giving quieter running and an increase in power transmission efficiency.

• Increased length mainshaft input gears together with increased thickness bearing housing and repositioned bearing.

• Redesigned intermediate gear bearings. Redesigned high gear bush giving quieter running

Now i'll have to try to figure out how to move the entire front output housing from the original box over to the box that i just bought.

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The box i have is an LT230Q from a Disco2, and it defo has the switch, its identical, down to the wiring tail and plug on the end

I dont see why you cant just use a switch like you suggested? Switch just needs to join the two wires to select low, and open when in high...

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If you are even more curious, there is an LT230SE.

These boxes are fitted on a discovery II with a V8. they have 1.211 ratio high. these boxes are more electronic controlled and do not have a manual select of the diff lock. (hence most people believe that they do not have a diff lock)

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Interesting. The box i have was apparently from a D2 V8, however there is no electronically controlled gubbins on it. The difflock lever is present but wasnt connected in the D2, because the D2 relies on traction control rather than CDL.

Looking at this: http://www.muddyoval.com/articles/generalinfo/LT230.htm

It seems that i do infact have the "SE" version, i'm sure my box is coded 41D, i'll check in a bit. Wonder what that means for connecting it to a 90...

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ok, my defender 90 is back on the road and i'm $900 poorer.

Swapped the front output housing around and now the switch can be fitted.

I can hear the stereo while driving now. no more whines.

The reason for the problem was that the gears were fitted without preloading and gaskets were fitted where there was not supposed to be. Hence the bearings started to move around and then after the gears followed. Hence when the t-box is in neutral and the g-box is in 5, the gears all started rattling terribly like the box was going to fall off.

I've damaged the 1.222 gear (largest gear, 3 section) and the low range gear (largest diameter, with the dog collar pins) in this exercise. Hence, if the shop you go to doesn't do it properly, they screw you up big time.

Anyway, i'm going to overhaul the damaged box and put back the 1.410 gear and replace the bearings. But that's another project in all. maybe i'm better off at selling the entire box which is now in pieces for the next interested party to overhaul. It's all been washed nicely and the entire case looks so clean and slivery.

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  • 8 years later...
On 3/4/2010 at 9:27 AM, Andrew Chua said:

If you are even more curious, there is an LT230SE.

These boxes are fitted on a discovery II with a V8. they have 1.211 ratio high. these boxes are more electronic controlled and do not have a manual select of the diff lock. (hence most people believe that they do not have a diff lock)

How would you know if diff lock is in the box if no nipple present on the top?

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