Member Since: 07 Aug 2014
Location: Tamworth
Posts: 12
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
Can anybody also enlighten me on what the ratio numbers mean.
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.
(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 )Current: Discovery 3 06MY (55 reg) HSE Auto 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 )
Disco 3 06 reg B7S Manual Rimini Red
Disco 2 TD5 Y reg ES Manual Blue - Chipped
Several Discovery 300 TDis
Last edited by Lost for Words on 20th Mar 2015 9:42 am. Edited 1 time in total
28th Nov 2014 9:33 am
bazelk
Member Since: 07 Aug 2014
Location: Tamworth
Posts: 12
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
28th Nov 2014 6:43 pm
Spooky
Member Since: 02 Jun 2009
Location: Swindon, Wilts
Posts: 1013
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!
You MUST have the same ratio in both axles ...Regards,
Mick
- 2014 SDV8 Autobiography
- 'Vincent' - 2010 TdV8 Vogue SE
- 'Molly' - 2005 HSE Auto
'Dixie' - 2000 D2 Td5 ES
28th Nov 2014 9:36 pm
Allan_T
Member Since: 10 Sep 2012
Location: Northampton
Posts: 1034
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
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.GAP IID Pro Multi Vehicle Defender L316 2007-2015 - Discovery 3 - Discovery 4 - Discovery Sport L550 - Freelander 2 - Range Rover Evoque L538 - Range Rover L322 - Range Rover L405 - Range Rover Sport L320 - Range Rover Sport L494 Electrical Fault Diagnostics
28th Nov 2014 10:58 pm
Martin Site Admin and Owner
Member Since: 06 Nov 2004
Location: Hook Norton
Posts: 18439
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.06 D3 SE / 15 LR D90 XS SW / 88 LR 90 Td5 / 68 BMW 2000 ti
Any issues with the site let me know!
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. Current: Discovery 3 06MY (55 reg) HSE Auto 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 )
Disco 3 06 reg B7S Manual Rimini Red
Disco 2 TD5 Y reg ES Manual Blue - Chipped
Several Discovery 300 TDis
29th Nov 2014 9:50 am
Sidestick
Member Since: 22 Apr 2012
Location: Rome
Posts: 2286
I suppose that the ratio you are talking about is relative to the "transfer box" unit... - Easy-Lift suspension module 4.0
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- Compressor guard
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29th Nov 2014 10:24 am
bazelk
Member Since: 07 Aug 2014
Location: Tamworth
Posts: 12
Thanks for all the input.
Will continue the hunt for a low mileage diff with the correct ratio.
29th Nov 2014 10:28 pm
bazelk
Member Since: 07 Aug 2014
Location: Tamworth
Posts: 12
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
Thanks to all for the input and help
Now for the next job on the long list
9th Dec 2014 9:08 pm
Jimjimney
Member Since: 10 Jul 2016
Location: Spain
Posts: 40
Hi where do you get the ratio numbers from on the diff?Discovery 3 2.7 TDV6 2006
Discovery 2 V8 2004 Expedition Equipped (Drove 2 West Africa)
Honda S2000 2001
Ford Focus 1.8 2000
Hanix 1.5t digger 1994
1 tonne dumper 1992
Yanmar 3 cylinder generator (live off grid)
15th Jan 2018 9:54 pm
tomaszwodz
Member Since: 28 Feb 2020
Location: Luton
Posts: 3
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
Thanks to all for the input and help
Now for the next job on the long list
12th Jul 2020 5:52 pm
Globetrotter448
Member Since: 21 Mar 2017
Location: Londonderry NSW
Posts: 1771
Did you just change the diff or the shafts as well?
13th Jul 2020 5:59 am
tomaszwodz
Member Since: 28 Feb 2020
Location: Luton
Posts: 3
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??
13th Jul 2020 9:32 am
Discoveringcomfort
Member Since: 16 Sep 2015
Location: Berkshire
Posts: 637
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.
(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 )
Maybe the V8 Manual uses the 3.54 but the V8 Auto uses the 3.73.
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