Transfer box gear upgrade to LR90

Shabby Rover · Nov 28, 2016

Hello,

I was looking to fit a recon updated 1.2 instead of the 1.4 ratio output gears to my 1987 LR90. I am a bit concerned that my 19J diesel engine wont have enough HP grunt to be able to take advantage of the ration improvements. Does anyone have any experience of this job on and early 'defender' LR 90?

TheQ · Nov 29, 2016

You have 30% less power than the 200/300tdi, and that's if none of the horses have escaped in all this time since. I have the 200tdi disco engine and transfer box conversion so a lot more power but I can't change to 5th until 40 mph unless the engine is really warmed through. I some how doubt you would get into 5th unless down hill.

Turboman · Nov 29, 2016

Shabby Rover said:
Hello,

I was looking to fit a recon updated 1.2 instead of the 1.4 ratio output gears to my 1987 LR90. I am a bit concerned that my 19J diesel engine wont have enough HP grunt to be able to take advantage of the ration improvements. Does anyone have any experience of this job on and early 'defender' LR 90?

No point. 19j is just about adequate on standard gearing, goes up through the gears, and will cruise about 60-65 in fifth.

Like he says^^^^^^^^^^^, all you will do is make fifth redundant. And probably put extra strain on the rest of the trans as you pull away .

mojo247 · Nov 29, 2016

Ditto! I tried it on my old 19J and it felt like I was driving in treacle!

Stick to the 1.4 or better still stick a 200/300tdi in it!

Shabby Rover · Nov 29, 2016

Thanks to all, definitely lost some power anyway at 150K miles. I will stick with standard build until i need to swap engine then, cheers

300bhp/ton · Nov 29, 2016

Also what size tyres are you running?

The 1.2 transfer box kills performance in a Tdi. The reason is, stock 32" tyres on a Tdi 90 with the 1.4 box, give you about the same mph/1000rpm as a Disco on stock 29" tall tyres with the 1.2.

Meaning if you run a D90 on 32" tyres the 1.2 box massively over gears it.

If you want to lower rpm for cruising try some 255/85R16 tyres. It'll help a bit, but shouldn't completely kill performance.

Shabby Rover · Nov 29, 2016

Thanks 300bph/ton great advice cheers, I already hav tally tyres, Goodyear C90 M&S, so probably optimised. I will definitely stick to a standard 1:4 ratio set up

Transfer box gear upgrade to LR90

Shabby Rover

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TheQ

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Turboman

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mojo247

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Shabby Rover

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300bhp/ton

Well-Known Member

Shabby Rover

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