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LT77 Def/Disco


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The gearbox in my 110 is a bit rattly and a few more noises have evolved lately. As I have bought myself a Disco as a donor of a 200Tdi, maybe I could get some use of its gearbox too. :unsure:

It has an LT77 as well, but AFAIK with some differences to my 110 box - bellhousing, gearlever mechanism and input shaft. correct so far? Please fill in if otherwise. ;)

My plan would be to overhaul the innards of the Disco box, then when it's time to shift it, move over the necessary parts from the 110 box and install it.

Is this possible, or are there more differences that make it a no-no?

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you will need to fit the shorter def bellhousing and shorted def mainshaft plus change the remotes for the def variants.

you coudlalso use the disco t box if you wanted 1.2 ratios, depends what you will use the truck for as to whether it would be beneficial.

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Just what I wanted to know. ;):)

I think the Disco transferbox will be a bit too long legged, so I'll probably be out hunting for a 1,4 as in a Defender when the time comes. At first I will just lift over the engine and drive around with my 1,67 gearing. :closedeyes:

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Been there done that - or rather didn't do it 'cos none of it bluddy fits <_< the shifter shaft & end on the Disco/RR unit is different, and so it the tail casting of the box which means basically you have to take both boxes apart and swap tail castings. At that point I decided it was:

a) A lot of aggro

b) More involved than I wanted to get with gears and springs and things

c) Risky ground unless you really know what you're doing

And got on the blower to Ashcrofts instead who built me a latest-spec box (R380 suffix L) that fits, has their improvements included in it and if it breaks / doesn't work I can blame someone else :lol: you can always sell the good box to go towards the recon work.

For reference, this is a defender tail casting & shifter linkage:

Def_Back.jpg

And this is a Disco/RR one:

RR_Back.jpg

No amount of tinkering is going to make one shifter fit the other :( bear in mind I have no idea if you need to change other things apart from the tail castings once you are in there, could be a right old minefield especially if the boxes are not of the same year of manufacture (as I found when I tried to swap bits between LT230's) <_<

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Thanks guys for putting me off this idea! ;):) I thought that it could save me some time by renovating the loose box so it just could be switched over. Want as little downtime as possible on my preferred means of transportation, see...

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Hi Lars

Would stay clear of a complete transplant (i have such a combo 300tdi with all disco transmission) all in all more trouble than its worth ref transmission tunnel etc etc

However:

Seriously consider the disco transfer box - I have mine running through classic RR diffs to 265/75 tyres and although long-legged its not too bad - remembering back to the a Series IIa with a perkins on 750/16?s as a kid and how low that seem to be geared at the time

On mine i have a larger intercooler & more recently removed the cat but once up to speed it sails along at about 100kph at about 2,000- 2100RPM with about +5-8psi on the boost.

Its not written in any law that you can have to get to 5th ASAP use 4th - yep you could over-stretch the motor it if you wanted to trundle around in 4th or fifth at low speed but iam sure you would notice that before you did any real damage!

with regard to off road - its still capable and thats why the gods at Solihull put a low box on it.

Try the transfer box - you can always go back

one thing if you do go for a transfer box to make sure you keep the mainshaft (into the transfer box) well lubricated consider installing a extra oil splash plate on the back end of the box (easilly done - remove the back plate of the transfer box put the splash plate between the box and the back plate 30mins work tops) (its basically a disk the same profile as the back plate with a horse-shoe shape protrusion to throw oil down the mainshhaft) will cst you about 20GBP from somewhere like steve Parkers . will give you that extra piece of mind and ensure your mainshaft and bearing are constantly oiled.

happy trails

Abe

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Or fit a cross-drilled input gear as LR did later on (just another option) although you can't get them for very early LT230's apparently.

Using the disco LT230 will give you higher range on-road and keep the same low ratio (all LT230's are the same low ratio)

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Hiya Fridge

I think mine was already cross charged as the boxes are off a 1996 300tdi - i just wanted the extra piece-of-mind

stangley enough although the mainshaft didnt have any serious wear, after putting on the extra splash plate the box seems to have gone a little quieter

when I can get my hand on a R380 V8 remote oil mount - I will endevour to put a oil cooler on the main box

but thats stuff for another day

happy trails

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I think Mr Ashcroft posted up the thread sizes for the oil takeoffs, IIRC you unbolt the little bypass tube piece and screw in the fittings for a remote cooler. If you can find the right ends you can use stock cheap hydro hose (as it won't be taking anywhere near it's design pressure) and an oil cooler from a scrap car.

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Hiya Again Fridge

thanks for the info

as the main problem to date was sourcing the bypass gubbins to route in a oil cooler

regarding the routing i will probably get some besoke Hydraulic pipes made and put a new non LR "mocal" cooler where the orginal intercooler was up front as now there a space as i have the full size intercooler (sitting infront of the normal rad)

my other worry was the pump presseure to get oil to the front & back (luckerly its ATF fluid abs so is pretty viscuss)

great info thanks

happy trails

Abe

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Jez has the genuine LT77 cooler setup (and he's not letting it go) and it uses the standard pump. I can't remember if it has a thermostatic valve in it or a replacement bypass cover thing, your best bet is to ring Ashcrofts (or post up here and hope he spots it) to get a definitive answer.

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you could also use the disco t box if you wanted 1.2 ratios, depends what you will use the truck for as to whether it would be beneficial.

Slightly O/T, but in the region of t boxes, im in the middle of building up an '86 td90, with rangie tdi, lt77 and lt230, my question is, my lt230 came from a 70's rangie 3spd auto, therefore is a 1.003 ratio, is this going to be too high geared for my tdi? the vehicle will be used 90% on road as i have a series 3 plaything, occationally towing said series 3 on a trailer...

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