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nickh90



Member Since: 19 Oct 2009
Location: Nr Horsham
Posts: 195
England 1989 Defender 90 V8 Petrol SW Auto Java Black
Overdrive options??
Hi all,.

Sorry back from hols and lots of questions have built up:-)

I have a v8 defender which I am "personalising"! it has a TH400 3 speed auto box and shifter, Quaife ATB2300 centre diff internals. I would like to have an overdrive for motorway work or long runs when I can let the big torque do the work.

currently just a touch over 3k rpm at 70mph

Without buying a 4 speed auto, any suggestions?

Thanks

Nick
Post #203847 21st Jan 2013 2:34pm
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SteveG



Member Since: 29 Nov 2011
Location: Norfolk
Posts: 659
2005 Defender 90 Td5 CSW Belize Green
What tyre size are you running. For example, moving from 235/85 to 255/85 give the same kind of effect as most overdrives. Obviously the effect happens in all gears, but unless you plan to tow really heavy loads you won't be bothered by it.

Cheers

Steve
Post #203855 21st Jan 2013 2:58pm
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MartinK



Member Since: 02 Mar 2011
Location: Silverdale (Lancashire/Cumbria Border)
Posts: 2665
United Kingdom 2011 Defender 110 Puma 2.4 USW Orkney Grey
Nick - I'm sure you'll already know them, but I would call Ashcrofts:
http://www.ashcroft-transmissions.co.uk/index.php

Steve's comments on tyres sound really good as well.

I assume you would prefer 2k RPM at 70 (more like modern 6-speed cars)...? Defender "Puma" 2.4 110 County Utility (possibly the last of the 2.4's)
Post #203860 21st Jan 2013 3:08pm
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nickh90



Member Since: 19 Oct 2009
Location: Nr Horsham
Posts: 195
England 1989 Defender 90 V8 Petrol SW Auto Java Black
Thanks chaps..

I am running 315 75 16 AT tyres so near as damn it 35" - don't think I can go any further down that route Smile

I will call Ashcrofts and see what they say... thanks

yes 1500-2000rpm would be better on fuel and noise for sure!


Its so torquey its in top within 50ft of pulling away anyway.. well unless I boot it Smile
Cheers

Nick
Post #203873 21st Jan 2013 3:50pm
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nickh90



Member Since: 19 Oct 2009
Location: Nr Horsham
Posts: 195
England 1989 Defender 90 V8 Petrol SW Auto Java Black
Ashcroft do not do an overdrive unit Sad

Will look at GKN
Post #203911 21st Jan 2013 4:54pm
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bpman



Member Since: 21 May 2008
Location: Oslo
Posts: 8069
2008 Defender 110 Puma 2.4 SVX Station Wagon Santorini Black
you might find roverdrive unit ... not sure if it would work with a V8
Post #203933 21st Jan 2013 5:27pm
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jst



Member Since: 14 Jan 2008
Location: Taunton
Posts: 8021
 2011 Defender 110 Puma 2.4 USW Stornoway Grey
although you said no to it, why not get a 4speed box, cheaper i would of thought. Cheers

James
110 2012 XS Utility
130 2011 M57 bespoke Camper
90 2010 Hardtop
90 M57 1988 Hardtop
Post #204017 21st Jan 2013 7:52pm
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Laurie



Member Since: 22 Feb 2008
Location: Sussex, England
Posts: 2897
England 2005 Defender 90 Td5 XS CSW Bonatti Grey
An overdrive in good working order is likely to cost £1K 
Post #204021 21st Jan 2013 8:01pm
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yobbie



Member Since: 15 Nov 2010
Location: Isle of Wight
Posts: 712
United Kingdom 1999 Defender 90 Td5 Heritage LE Bronze Green
I'm running a Roverdrive unit on a TD5 with a tune with similar power & torque to a V8 (190 bhp & 300ft torque). At just over 60mph in standard gearing is 3000rpm (I do have a rev counter) with overdrive its 2000rpm the noise levels are much more exceptable but I wouldn't say the fuel consumption it greatly improved.
Post #204027 21st Jan 2013 8:12pm
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nickh90



Member Since: 19 Oct 2009
Location: Nr Horsham
Posts: 195
England 1989 Defender 90 V8 Petrol SW Auto Java Black
I could get a 4l80e or similar box from a Bentley for about £500 plus adapter plate and then fitting - need to research more!

I am running 350bhp now but could end up at 500 in the future so needs to handle it..

Starting to think the box is a better option but this one is brand new!!!
Post #204045 21st Jan 2013 8:31pm
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yobbie



Member Since: 15 Nov 2010
Location: Isle of Wight
Posts: 712
United Kingdom 1999 Defender 90 Td5 Heritage LE Bronze Green
I doubt a Roverdrive would handle that sort of power Shocked they got me to fit a larger sump for more oil capacity due to cooling.
Post #204047 21st Jan 2013 8:35pm
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Lodelaner



Member Since: 04 Feb 2010
Location: Lambourn
Posts: 631
United Kingdom 1988 Defender 90 V8 Petrol ST Shire Blue
How about 1.003:1 transfer gearing from the 3spd RRC Auto? JB

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Post #205295 25th Jan 2013 6:17pm
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