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Changing from 3.45 to 3.9 in XR8 


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 Post subject: Changing from 3.45 to 3.9 in XR8
Posted: Wed Jun 09, 2010 8:54 pm 
Oompa Loompa
User avatar

Age: 28

Posts: 35

Joined: 9th Mar 2005

Ride: AUIII XR8 ute

Location: melbourne
VIC, Australia

Hey guys, i am thinking about changing my diff gears in my XR8 ute from the 3.45's to 3.9's, the ute is auto and i need something to get it going a bit quicker and to help with towing.

other than the obvious swap what do i need to do with the speedo to make it read properly and shift at the right points? Ive heard there isnt a speedo gear up to 3.9?

Will the electronic speedo corrector from jaycar work? or will it just be a headache?

The diff is only 20,000km old which i had Northern differentials build a new one which was in my manual XR6 ute, so i swapped the diff's over from the XR6 to the XR8 as they were exactly the same setup, only one was woth $2500 so i wasnt selling that only to have the XR8 diff go. bit of piece of mind
 Post subject: Re: Changing from 3.45 to 3.9 in XR8
Posted: Wed Jun 09, 2010 8:56 pm 
Getting Side Ways

Age: 29

Posts: 2563

Joined: 19th Feb 2007

Gallery: 21 images

Ride: 98 EL Futura

Power: 199 rwkw

Location: Lilydale
VIC, Australia

I just bought a 3.9 diff with an auto so im interested to know as well.



EL Futura: CVE head, Wolf V500, ICE Ignition and Coil, 36lb injectors, Walbro 255lb, Paci comps, 3" exhaust, T5, Harrop Truetrac with 3.9s. Now with 198.9rwkw, (~185rwkw and 13.80 @99.1mph) with more power to come

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