Having researched myself into a bit of a pickle I am after the benefit of your experience.

A transfer box rebuild is on the cards, so looking in to changing the ration while I'm there. Or not, whatever the outcome of this thread may be.

2.4 TDCi 110, BAS map and 33's... Which ratio? 1.1, 1.2, 1.3 or 1.4? And why/what is the benefit?

Thanks > 110 XS Double Cab
> Instagram @simonlanemind

Sooooo not a TDCI but a TD5 110 with 33s and an IRB remap;

Returned back from a 1:1.2 (Discovery gearing) to the standard 1:1.4 (Defender gearing) because the extra weight of the cage, roof rack and gear makes the shorter gears make sense. The Defender is now so much easier around town and doing hill starts (lots of those hills up here in NW) and the super bonus is that the EGTs are 100 or so degrees lower than before at 60 and 70 mph. Really the only down side is the slower top speed on the motorway, due to the noise mostly as it will pull and pull if necessary. I plan to fit an overdrive to compensate for this though.

1.3 best of both worlds. Love mine to bits. Happily cruises at 70 "as if its 60" and so forth Instagram @defender_ventures

TD5 110/ with 235/85 R16 ATs

I was running a 1.4 t/c and then went to a 1.2 t/c for 18months/two years. Ended up back at a 1.4 t/c and now much happier.

If I went along the line of a g/box rebuild I might consider the 5th gear cluster change instead.

I found (much the same as geobloke) that hill starts, around town driving and for me towing cars in forests much better at 1.4 ratio. 1999 Defender TD5 110

Regards
John M0VAZ
Do you know what a nemesis is?

First question should be: what do you want to achieve? How do you use the car? The Puma has the 1.2 transfer box, so anything shorter will be undergeared.

Vehicle's predominant use is around town with some motorway. Occasional off road and towing.

I think I might be approaching this the wrong way round actually.

So factory is 1.2...
If I move to 1.3 or 1.4 then output revs decrease at the same engine speed. So first becomes shorter and motorway cruising speed engine revs higher.
If I move to 1.1 then output revs increase at the same engine speed. So first becomes longer and motorway cruising speed engine revs lower.

Around town I find I am between third and fourth a lot. Plus first is so short, and reducing motorway cruising revs would be a bonus. So, perhaps moving to 1.1 would achieve this?

Perhaps I'm overthinking this and the 1.2 is the best compromise?

Thoughts welcome! > 110 XS Double Cab
> Instagram @simonlanemind

Last edited by hank on 13th Sep 2019 8:11am. Edited 1 time in total

Ashcrofts have a calculator on their website that will show rpm vs mph which might assist you? 1999 Defender TD5 110

Regards
John M0VAZ
Do you know what a nemesis is?

https://www.ashcroft-transmissions.co.uk/calc/ratio_calc.html 1999 Defender TD5 110

Regards
John M0VAZ
Do you know what a nemesis is?

hank wrote:

Vehicle's predominant use is around town with some motorway. Occasional off road and towing.

I think I might be approaching this the wrong way round actually.

So factory is 1.2...
If I move to 1.3 or 1.4 then output revs decrease at the same engine speed. So first becomes shorter and motorway cruising speed engine revs higher.
If I move to 1.1 then output revs increase at the same engine speed. So first becomes longer and motorway cruising speed engine revs lower.

Around town I find I am between third and fourth a lot. Plus first is so short, and reducing motorway cruising revs would be a bonus. So, perhaps moving to 1.1 would achieve this?

Perhaps I'm overthinking this and the 1.2 is the best compromise?

Thoughts welcome!

Move to 1.3 or 1.4 - high box gearing is lower- more revs on the motorway- first gear is lower so easier to pull away with a heavy load on a steep hill.

Move to 1.1 - high box gearing is higher - less revs on the motorway - first gear is higher so less easy to pull away with a heavy load on a steep hill

HTH
Mo The Land Rover 90 - Many are called, few are chosen.

Puma comes with 1.2 as standard.
Mo The Land Rover 90 - Many are called, few are chosen.

Thanks Mo

excossack wrote:

https://www.ashcroft-transmissions.co.uk/calc/ratio_calc.html

Really depends on how many motorway miles you do, that's where you'll see the difference I suspect.

I've had a 1.2 transfer box in my 300Tdi 110 on 32" tyres for the last decade or so and wouldn't go back to a 1.4 although I do do long motorway journeys. The only minor downside is that first is quite tall now (but they dropped first on the Puma) and that makes hill starts with 3.5 tonnes behind you a little tricky.

I've found that with the 1.2 it's moved the gears into more optimal locations. A gentle pootle around town and it's basically 3rd gear all the way. If you go out into the countryside and move along a little faster then 4th is the main gear. Cruising along the motorway then 5th. If you've got 3.5 tonnes behind you on uphill motorway stretches then 4th is ideal at 60mph and sits about the same as 5th used to (with the 1.4) at 70mph.

Interestingly quite a few years ago I went to a clay competition (when I lived in Surrey and he was still from back in South Wales) so we met up at the shoot in Bicester. Both joined the dual carriageway back down to the M4 and he commented afterwards that he (in a 2.4 Puma) struggled to keep up with me. Since then I've snapped two crankshafts but the last build with a lower half from someone in Devon has obviously had the pump tweaked a fair bit. I had previously been thinking about fitting a VNT to help with bottom end boost for when towing with the 1.2 but that simple tweak has utterly transformed the vehicle.

Retroanaconda and I have discussed this at length and the main benefit which isn't often described with the move to 1.2 is that, certainly for me, it moves the gears into nicer positions. E.g. 60mph is quite comfortable for long periods in 4th which means that you've got the strongest (at least in the R380) gear for towing. 5th effectively becomes an overdrive but not quite. Although the 300 has so much more torque now that I'd even consider an overdrive to drop the revs even more on the motorway, having said that the noise is probably mostly my KM2s... Ed
95 Defender 110 300Tdi
96 P38 4.6 HSE