Swap D2 transfer case for defender.

OwnTheRoad · 12th July 2015, 02:39 PM

G'day I've often wanted to know if others have done this swap, the plan is to increase my wheel size = to 235/85/16 defender spec or slightly larger by use of 16x8 p38 rims and slightly wider tyres to suit , to counter the wheel size increase so as to retain normal rpm and speedo readings id fit the Defender transfer case.
With this swap id like to know will my rpm be the same as before or will the motor be spinning harder.
What will it be like to pull away in 1st gear on hills.? it's a manual trans and I tow.
The increase in wheel size would be valuable as I have often wanted to dual cab my D2 wagon and the lift will help with ramp over angle.
It's already lifted 50mm with OME suspension.

Any feed back or costs complications etc on this is greatly appreciated.

**Fast Freddie** · 12th July 2015, 10:06 PM

The Disco came with 2 'standard' 16" tyre sizes - 235/70 and 255/65.
235/85/16 (a tyre size, not a wheel size) is 9.1% or 9.5% bigger in diameter than the standard tyres when new, and will lower you revs by that amount at any given road speed (that's a lot).
The width of the rim won't make a real difference to the diameter of the tyre and so won't affect the gearing.
(235/85-16s are the same width as 235/70-16s)
I've no idea what difference a replacement transfer case would make but I hope this helps.
Good luck.

**loanrangie** · 12th July 2015, 10:28 PM

The 1.4/1 deefer tc is good for 33" plus tyres , any smaller and it will be revving its tits off.

Sent from my GT-I9300 using AULRO mobile app

**strangy** · 13th July 2015, 07:48 AM

There are many threads on trans case swaps to be explored.
IIRC Your D2 will have around 200 more RPM with a Defender 1.4 TC fitted and 235/85 tyres compared with 235/70 and the D2 case.
Go to Ashcroft transmissions website in the UK for a "ratio calculator"
The swap is easy and straight forward but, you need a speedo interface unit to ensure correct speedo and Cruise Control function.
Low range remains the same ratio as the D2. D2 take speed sensing from the Wheel Speed Sensors.

Just adding a bit more as loanrangie said
33's are the go and a Defer case will see you almost identical to the original RPM/ km/h

**Fast Freddie** · 13th July 2015, 12:25 PM

Tyre sizes quoted in inches of diameter can be a bit confusing, so fyi, 235/85-16 tyres are 31.7" in diameter (not 33).
33 inch tyres (at 16 inch diameter) include:
255/85 (33.1")
295/75 (33.3")
265/85 (33.7")
345/65 (33.7")
All these tyres are significantly wider than the 235/85s that you are proposing.

**MR LR** · 13th July 2015, 05:45 PM

Change your diff ratios to 3.90:1 GBR gears if you want to use a 31.7" tyre, that is about 0.5% under stock if i remember rightly from when I ran the numbers.

The Defender high range gears are too low.

**mrapocalypse** · 15th July 2015, 04:04 PM

TD5 or V8?

I have a V8 running 265/75/16 and I wouldn't drop the revs if you paid me.

10% less revs is money in the bank and low range work seems relatively unaffected.

I

**gezza** · 18th July 2015, 11:32 AM

Originally Posted by mrapocalypse

TD5 or V8?

I have a V8 running 265/75/16 and I wouldn't drop the revs if you paid me.

10% less revs is money in the bank and low range work seems relatively unaffected.

I

I have a td5 with the same tyre size well happy with it just don't like kumhos bad tyre

**DaveP** · 18th July 2015, 02:38 PM

I have 235/85R16-LT's on my TD5 D2, and honestly the last thing I would have thought about is changing the ratio's. Is better on the highway, seems the same in low-range. Even when towing I barely notice it, the only thing is my speedo is about 10% out but meh

OwnTheRoad · 2nd August 2015, 04:25 PM

Sorry forgot to add its a manual TD5 for those that have added their info many thanks.
In an ideal world I was trying to increase wheel diameter size yet not upset the overall gearing too much whilst keeping the speedo as close to stock as possible.
It would seem then that if the speedo reads from the ABS an increase in wheel diameter would need to be changed in the engine management system id guess.
Even with the standard gearing and wheel sizes I've often wanted a shorter first gear ratio for towing ,usually with caravan on the back and a hill start from standstill I've found its either painfully slow to get moving or it's grab a handful of rpm and boost and toast the clutch to get off the line up a hill.
As for 5 th gear my disco is stock so far as engine mods go and I really think it could drop at least 250 rpm at 100kph, I think Ashcroft in the UK can fit the .73 v8 ratio instead of the .77 , anyone here tried this mod ? TIA. Jase.

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