Changing Diff Ratio's in the D1

**TerryO** · 29th March 2011, 02:25 PM

Hi everyone,

I have been contemplating fitting crawler gears in the trusty old D1 but it looks like the gears are way to expensive and then getting them fitted will also cost a arm and leg.

That leaves me with the other option of changing the diff gears to a lower ratio. My D1 is a V8 with manual gearbox and has 33's fitted and the standard gearing in low first is way to high for trying to climb the side of some of the more challenging hills.

The usual ratio selected by people with 33's is 4.11's I beleive but given that I don't use the D1 for anything other then going off road I'm not the worried about the gearing being to low for long distance highway cruising or fuel economy and would like something lower then standard gearing which 4.11 gears give I believe.

The ratio's available from lucky8 are 4.12, 4.37 and 4.75. My problem is I don't know how to work out what engine rpm the old girl would be pulling at 100 kph compared to the standard gearing with 33's which it has now.

I have not driven a standard D1 so its hard for me to compare what it would be like with 4.11's or if changing to 4.37's or 4.75's is going to low?

If anyone could please assist I would appreciate it very much thanks.

cheers,
Terry

**Psimpson7** · 29th March 2011, 02:29 PM

Hey Terry,

The awesome ratio calculator on Ashcrofts site should give you all the answers you need:

Ashcroft Transmissions - Ratio Calculator

Rgds
Peter.

**isuzurover** · 29th March 2011, 02:35 PM

Firstly, apparently Lucky8 no longer sell to Australia unfortunately, so you will need to buy from ashcroft.

I think that if you need lower gearing with 33's your engine may be a bit tired??? There are lots of defenders with 33's and almost the same gearing (V8 R380 ratios (assuming you have a manual) are very slightly taller).

If you don't know how to calculate ratios and revs it is probably easiest to use the calculator on the ashcroft website.

**101RRS** · 29th March 2011, 03:38 PM

Don't Defender transfer cases have lower gearing than Discos - if so is this an option????

**isuzurover** · 29th March 2011, 08:49 PM

Originally Posted by garrycol

Don't Defender transfer cases have lower gearing than Discos - if so is this an option????

Low range is the same (3.32:1) - I read it as being offroad that is the issue.

Disco high range is 1.22:1 for most of D1 and 1.21:1 for D2 and late D1 (Q-case). Defenders are 1.4:1.

**TerryO** · 29th March 2011, 10:45 PM

Originally Posted by isuzurover

Firstly, apparently Lucky8 no longer sell to Australia unfortunately, so you will need to buy from ashcroft.

I think that if you need lower gearing with 33's your engine may be a bit tired??? There are lots of defenders with 33's and almost the same gearing (V8 R380 ratios (assuming you have a manual) are very slightly taller).

If you don't know how to calculate ratios and revs it is probably easiest to use the calculator on the ashcroft website.

Thanks I'll try Ashcroft directly, as for a tired engine it has much more poke then my D2a.
It's not a horsepwer thing rather being able to go slow enough to crawl up very rough rutted steep hills.

If you tried to follow Max / Tusker on one of his little Sunday drives you would understand where I'm coming from.

cheers,
Terry

**roverv8** · 30th March 2011, 03:45 PM

My problem is the other way,
My 94 Disco V8/auto is reving at 2600rpm @ 100kph (doesn't help my fuel bill)
most Disco's only sit on2200rpm @100kph

I don't know whether to blame the diff ratio or the tranfer case ratio,
Although im suss on the transfer case, it has a bit of a whine to it, like the gearing is higher

**Scouse** · 31st March 2011, 07:38 AM

Originally Posted by roverv8

My problem is the other way,
My 94 Disco V8/auto is reving at 2600rpm @ 100kph (doesn't help my fuel bill)
most Disco's only sit on2200rpm @100kph

I don't know whether to blame the diff ratio or the tranfer case ratio,
Although im suss on the transfer case, it has a bit of a whine to it, like the gearing is higher

It could be the alternator. If the wrong model or pulley is fitted, the tacho will get the wrong signal.

**Scouse** · 31st March 2011, 09:47 AM

There's a set of 4.7s on OL at the moment:
Outer Limits 4x4 Board • Login

ITEM: 2X Range Rover Classic Diff Gear sets 4.7:1 Ratio ! New In box !

PRICE AND PRICE CONDITIONS: $450

CONDITION:New in Boxes

REASON FOR SELLING: No more rangies

EXTRA INFO: 2X Range Rover Classic Diff Gears 4.7:1 Ratio New In box !
Includes one spacer

LOCATION: Brisbane

CONTACT: Chris 0419480419

Might be too low for 33's though so you can use that as an excuse to go to 35's or bigger to give Max a run for his money

.

**roverv8** · 31st March 2011, 03:58 PM

Originally Posted by Scouse

It could be the alternator. If the wrong model or pulley is fitted, the tacho will get the wrong signal.

Not the alternator, been down that road,
it's the gearing for sure

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