Disco to 90 Transfer box change?

Paul D · May 13, 2018

Having a little difficulty here.

In my 90 I have an LT77 (50 314459F) with an LT230 (22D104860C) The transfer box is fubar ..

I want to change it to my old Disco 300 Tdi transfer box LT230 (28D547603F), but when I try to stick the 28d onto the LT77 it appears not to fit! The splines look similar but shorter and everything else seems similar, so what am I doing wrong? Or are there shaft differences that stops me doing this?

jamesmartin · May 13, 2018

check t/box hasnt got an oil thrower fitted behind pto cover,if thats not it there are 2 length of spline in input gears

Paul D · May 13, 2018

Cheers @jamesmartin

Paul D · Jun 10, 2018

Thanks @jamesmartin all sorted now, with your help ..

Paul D · Jun 11, 2018

Hit another issue on this ... speedo cable.

The original transfer box has a wire speedo drive cable, the 300tdi t-box has an electronic feed to the speedo .. and the wire cable doesn't fit intot he drive output! Small video to show the problem .. I'd be grateful for any advice ..

jamesmartin · Jun 11, 2018

it doesnt fit you fit your old speedo drive

Hicap phill · Jun 11, 2018

Hi @jamesmartin do you have to turn the old drive as well as pull towards you to remove?
Thanks for your on going help.
Also is there much difference betweeen the speedo drives for 205/7.50?

jamesmartin · Jun 11, 2018

just prise out if your lucky if not housing needs to come off to get it out,there is a difference in number of teeth to match tyre size

Paul D · Jun 11, 2018

jamesmartin said:
it doesnt fit you fit your old speedo drive

Many thanks, I knew you'd know ..

So is that prop and handbrake off and remove the housing to change to change the drive unit inside?

jamesmartin · Jun 11, 2018

if it wont prise out it is draining box removing prop and hand brake and the 6 bolts,housing will prise off between the lug for the older type hand brake bracket and the case
you can then tap the speedo out from the inner side

Hicap phill · Jun 11, 2018

@Paul D
Have you got a pair of long nose pliers & tried to pull the drive out the 300 TB?

jamesmartin · Jun 11, 2018

this is the bit you need to prise out

Paul D · Jun 11, 2018

Hicap phill said:
@Paul D
Have you got a pair of long nose pliers & tried to pull the drive out the 300 TB?

Not yet, but I will shortly, working right now ...

Paul D · Jun 12, 2018

As a thought, I've taken the housing off the old LT230, which confirms my belief that the main shaft splines are absolutely worn out, hooked, not square teeth and a lot of movement, but would it work if I take the newer LT230 housing off and simply swap both the housings?

Neither of the speedo drives want to come out, I suspect dissimilar metal welding! They simply aren't moving, either from pulling with pliers or tapping from inside ...

callisr · Jun 13, 2018

I can offer no help or advice whatsoever but I am about to do this same swap on mine so reading with interest as I have an early lt 230 which is soon to be replaced by the disco unit whilst i overhaul my original one....

flat · Jun 13, 2018

I
To am
Thinking of doing this swap for motorway cruising.

Interesting stuff, does it really make a
DOfference? I mean my 410 transfer box is fine but I just want to lower the revs a tiny bit

Hicap phill · Jun 13, 2018

It does make a difference. I used to tow 3.5t horse trailers & needed to pull away. My 1.4 box is good for 50mph cruising in 4th & 5th.
5th gets me to a noisy 70mph on 7.50 tyres
I'm changing to a 1.22 to drop the revs as no more towing.
I'm watching this thread as I have the same electo pick up on the TB
Just need to decide if I'm going to fit an x-eng handbrake.

flat · Jun 13, 2018

Hicap phill said:
It does make a difference. I used to tow 3.5t horse trailers & needed to pull away. My 1.4 box is good for 50mph cruising in 4th & 5th.
5th gets me to a noisy 70mph on 7.50 tyres
I'm changing to a 1.22 to drop the revs as no more towing.
I'm watching this thread as I have the same electo pick up on the TB
Just need to decide if I'm going to fit an x-eng handbrake.

i have 7.50 tyres, and 5th is the same, i would like to be less noisy at 70mph!!

Paul D · Jun 13, 2018

Hicap phill said:
Just need to decide if I'm going to fit an x-eng handbrake.

Mine is being changed because the old one has issues, noisy, rattly and 'very' loud, so pointing to a potential breakdown and I had the 300 Disco gearbox/Transfer box spare and laying around!

I wouldn't hesitate to recommend the X-eng ... it just works! Not had a problem since fitting it and it's way stronger than the standard drum, whatever state of repair the drum is in.

Clunkbucket · Jun 13, 2018

flat said:
i have 7.50 tyres, and 5th is the same, i would like to be less noisy at 70mph!!

Rough maths suggests that changing from a 1.4 to a 1.22 will give a 14% gain, which in reality will mean that at the revs you were doing at 70mph you will then be doing 80mph. Sounds like a reasonable gain.

Disco to 90 Transfer box change?

Old, nackered 'n broke, but the Landy is fine . :)

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Old, nackered 'n broke, but the Landy is fine . :)

Old, nackered 'n broke, but the Landy is fine . :)

Old, nackered 'n broke, but the Landy is fine . :)

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Old, nackered 'n broke, but the Landy is fine . :)

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Old, nackered 'n broke, but the Landy is fine . :)

Old, nackered 'n broke, but the Landy is fine . :)

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Old, nackered 'n broke, but the Landy is fine . :)

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