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D3 D4 Diff
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bazelk
 


Member Since: 07 Aug 2014
Location: Tamworth
Posts: 12

United Kingdom 2007 Discovery 3 TDV6 XS Auto Java BlackDiscovery 3
D3 D4 Diff

Although I am running a post on here about poss front diff problem (decided to take the chance and change it) not everybody might wont to read to the end of replies and miss this question that I could do with a quick answer to.

"Can I put a Discovery 4 front diff in my Discovery 3" (both auto box)

The breaker says yes but I'm not sure due to the different ratios Confused

Can anybody also enlighten me on what the ratio numbers mean.

Thanks
  
Post #138030227th Nov 2014 10:34 pm
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Lost for Words
 


Member Since: 03 Sep 2013
Location: Warminster, Wiltshire
Posts: 6703

United Kingdom 2006 Discovery 3 TDV6 HSE Auto Zambezi SilverDiscovery 3

I think the answer is probably yes but I'll let others answer.

The ratio is how many turns of the prop shaft give one turn of the wheels. Auto and manual models have different ratios, affected by the relationship in size between the pinion and crownwheel, while petrol models have a different one again. They compensate for the differences in the auto/manual gearbox ratios and the higher revving nature of the petrol engines.

The auto ratio is 3.54:1; the manual is 3.07:1. The petrol models are 3.73:1 I believe.

Hope this helps. Thumbs Up

(Edit: Updating this post for future reference due to later clarification from LR - the V8 petrol uses a 3.54 diff, the 3.73 diff is for the V6 petrol Wink )
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Previous: FL2 56 reg SE Manual Black (written off Sad )
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Last edited by Lost for Words on 20th Mar 2015 9:42 am. Edited 1 time in total 
Post #138042828th Nov 2014 9:33 am
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bazelk
 


Member Since: 07 Aug 2014
Location: Tamworth
Posts: 12

United Kingdom 2007 Discovery 3 TDV6 XS Auto Java BlackDiscovery 3

So I guess that would mean the front and rear wheels would be rotating at different speeds through the transfer box if I was to use the D4 diff as that ratio is 3.21, which I also guess would result in the transfer box being damaged due to the props rotating at slightly different speeds ?

Am I right in my assumptions Sad
  
Post #138080828th Nov 2014 6:43 pm
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Spooky
 


Member Since: 02 Jun 2009
Location: Swindon, Wilts
Posts: 1013

United Kingdom 

You are. Furthermore, once the centre diff locks up when off-roading, you'll cause enough transmission 'wind-up' to stop the car ... and possibly break something! Shocked

You MUST have the same ratio in both axles ...
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Mick

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Post #138091328th Nov 2014 9:36 pm
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Allan_T
 


Member Since: 10 Sep 2012
Location: Northampton
Posts: 1034

United Kingdom 2007 Discovery 3 TDV6 GS Auto Java BlackDiscovery 3
Re: D3 D4 Diff

bazelk wrote:
Although I am running a post on here about poss front diff problem (decided to take the chance and change it) not everybody might wont to read to the end of replies and miss this question that I could do with a quick answer to.

"Can I put a Discovery 4 front diff in my Discovery 3" (both auto box)

The breaker says yes but I'm not sure due to the different ratios Confused

Can anybody also enlighten me on what the ratio numbers mean.

Thanks


My front diff is from a 2010 D4 auto with the 3.54:1 ratio.
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Post #138094728th Nov 2014 10:58 pm
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Martin
Site Admin and Owner 


Member Since: 06 Nov 2004
Location: Hook Norton
Posts: 18439

United Kingdom 2006 Discovery 3 TDV6 SE Manual Buckingham BlueDiscovery 3

The front and rear diffs MUST be the same ratio, otherwise the centre diff is working all the time which it is not designed to do.
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Post #138096728th Nov 2014 11:50 pm
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Lost for Words
 


Member Since: 03 Sep 2013
Location: Warminster, Wiltshire
Posts: 6703

United Kingdom 2006 Discovery 3 TDV6 HSE Auto Zambezi SilverDiscovery 3

The 3.21:1 diff is for the 8 speed box. So, no, you can't use that. Older 6 speed D4 diffs will have the correct ratio. Thumbs Up
 Current: Discovery 3 06MY (55 reg) HSE Auto Zambezi Silver Zambezi Silver Allisport Fast Road Intercooler, V8 Brakes, Silicone IC Hoses, EGRs Blanked, Remapped, De-Cat pipe, FBHIC
Freelander 2 2007 HSE Manual Tambora Flame
Previous: FL2 56 reg SE Manual Black (written off Sad )
Disco 3 06 reg B7S Manual Rimini Red Rimini Red
Disco 2 TD5 Y reg ES Manual Blue - Chipped Very Happy
Several Discovery 300 TDis
 
 
Post #138104929th Nov 2014 9:50 am
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Sidestick
 


Member Since: 22 Apr 2012
Location: Rome
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Italy 2008 Discovery 3 TDV6 HSE Auto Java BlackDiscovery 3

I suppose that the ratio you are talking about is relative to the "transfer box" unit... Idea
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Post #138107329th Nov 2014 10:24 am
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bazelk
 


Member Since: 07 Aug 2014
Location: Tamworth
Posts: 12

United Kingdom 2007 Discovery 3 TDV6 XS Auto Java BlackDiscovery 3

Thanks for all the input.
Will continue the hunt for a low mileage diff with the correct ratio.
Thumbs Up
  
Post #138134629th Nov 2014 10:28 pm
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bazelk
 


Member Since: 07 Aug 2014
Location: Tamworth
Posts: 12

United Kingdom 2007 Discovery 3 TDV6 XS Auto Java BlackDiscovery 3

Just an update to let others know who might read this post for reference.
The breaker got back to me with the all important ratio numbers 3.54.1 the mileage 46,000 , year 2010, model DS4.
So if the numbers match then yes a DS4 will fit a DS3.

Fitted it today took it for that all important test drive with fingers crossed Very Happy Thumbs Up

Thanks to all for the input and help

Now for the next job on the long list Rolling with laughter
  
Post #13865269th Dec 2014 9:08 pm
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Jimjimney
 


Member Since: 10 Jul 2016
Location: Spain
Posts: 40


Hi where do you get the ratio numbers from on the diff?
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Post #190196215th Jan 2018 9:54 pm
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tomaszwodz
 


Member Since: 28 Feb 2020
Location: Luton
Posts: 3

United Kingdom 
All works well??

Hi, i changed both diffs from disco4 to disco3 and well works?? No issiues?? No errors??
bazelk wrote:
Just an update to let others know who might read this post for reference.
The breaker got back to me with the all important ratio numbers 3.54.1 the mileage 46,000 , year 2010, model DS4.
So if the numbers match then yes a DS4 will fit a DS3.

Fitted it today took it for that all important test drive with fingers crossed Very Happy Thumbs Up

Thanks to all for the input and help

Now for the next job on the long list Rolling with laughter
  
Post #216060412th Jul 2020 5:52 pm
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Globetrotter448
 


Member Since: 21 Mar 2017
Location: Londonderry NSW
Posts: 1771

Australia 2007 Discovery 3 4.0 V6 Petrol SE Auto Java BlackDiscovery 3

Did you just change the diff or the shafts as well?
  
Post #216064713th Jul 2020 5:59 am
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tomaszwodz
 


Member Since: 28 Feb 2020
Location: Luton
Posts: 3

United Kingdom 

Yes i have change diff front and rear and all shaft plug&play installation all fits perfect, i havent Drive yet cose still working on suspension, im worried about ratio cos d3 is 3,54 D4 is 3,21 it not cause any issiues??
  
Post #216066713th Jul 2020 9:32 am
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Discoveringcomfort
 


Member Since: 16 Sep 2015
Location: Berkshire
Posts: 637

England 2005 Discovery 3 4.4 V8 HSE Auto Zambezi SilverDiscovery 3

Lost for Words wrote:
I think the answer is probably yes but I'll let others answer.

The ratio is how many turns of the prop shaft give one turn of the wheels. Auto and manual models have different ratios, affected by the relationship in size between the pinion and crownwheel, while petrol models have a different one again. They compensate for the differences in the auto/manual gearbox ratios and the higher revving nature of the petrol engines.

The auto ratio is 3.54:1; the manual is 3.07:1. The petrol models are 3.73:1 I believe.

Hope this helps. Thumbs Up

(Edit: Updating this post for future reference due to later clarification from LR - the V8 petrol uses a 3.54 diff, the 3.73 diff is for the V6 petrol Wink )


Maybe the V8 Manual uses the 3.54 but the V8 Auto uses the 3.73.

From LR manuals.

Rear 'Open' Differential
Item Specification
Reduction ratio:
V6 Diesel engine - Manual transmission 3.07:1
V6 Diesel engine - Automatic transmission 3.54:1
V6 Petrol engine - Automatic transmission 3.73:1
V8 Petrol engine - Automatic transmission 3.73:1

Front Differential
Item Specification
Reduction ratio:
V6 Diesel engine - Manual transmission 3.07:1
V6 Diesel engine - Automatic transmission 3.54:1
V6 Petrol engine - Automatic transmission 3.73:1
V8 Petrol engine - Automatic transmission 3.73:1
 Series 1 V8
Series 2 Hibrid V8
Discovery 3 HSE V8 
 
Post #216073313th Jul 2020 3:53 pm
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