
falcongli6 



wats ur revs at when ur doing a 100
with 3.9 diff gears in a ebau falcon???
_________________ 04 BA XR6t auto 

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azza 



i just changed my diff to a 3:45 from a 3:08 and it went from doin roughly 17001800 to about 2200 with the new diff... so i would imagine urs would be close to the 3000
_________________ BA XR8 manual ute black 

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falcongli6 



hey azza wen u went to 3.45 gears did ur speedo go out 10ks
_________________ 04 BA XR6t auto 

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voids 



hey azza what sort of ecconomy did you loose with your 3:45 diff? much difference from a 3:08?
_________________ ' 96 Xh XR6 Ute 

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Damoz 6 



Falcongli6 ive got 3.73 diff gears in my auto ef 6 and it revs at 2200rpm with my 17's on it. And i got better fuel economy when i put the gears in kumn up from 3.08


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XR8Chic 



you can easily work it out yourself
Just need the ratio of the gear, and the circumference of the wheels, and the diff ratio (which you already have).
_________________ www.XR8Chic.com 

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XR8Chic 



oh... in case you dont know what I mean..
Engine RPM divided by gear ratio, divided by diff ratio = the number of spins of the wheel per minute multiply it by the circumference of the wheel = distance per minute multiply by 60 to get distance per hour. easy peasy
_________________ www.XR8Chic.com 

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Bassfreak55 



XR8Chic wrote: oh... in case you dont know what I mean..
Engine RPM divided by gear ratio, divided by diff ratio = the number of spins of the wheel per minute multiply it by the circumference of the wheel = distance per minute multiply by 60 to get distance per hour. easy peasy I think its time to bring out the calculator! 

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wild6 



in my xr8 the speedo is currently out about 15kms and when i sit on 115kmh it sits at 2400 rpm
regards from adam
_________________ series3 xr8 5 speed manual, pacemaker extractors, 3' exhaust, lowered cold air intake, k&n filter, interior, 3.9s


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jonbays 



You should be doing about 2400rpm at 100kmh in a 4spd auto with a 3.9 diff and 235/45ZR17's
Kmh/1000 rpm for a falcon BTR auto in fourth with 235/34ZR17 tyres and diffferent diffs are: 3.08 diff 54.8kmh/1000 rpm 100kmh = 1825 rpm 3.23 diff 52.4kmh/1000 rpm 100kmh = 1910 rpm 3.45 diff 48.8kmh/1000 rpm 100kmh = 2050 rpm 3.73 diff 44.2kmh/1000 rpm 100kmh = 2260 rpm 3.9 diff 41.5kmh/1000 rpm 100kmh = 2410 rpm 

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bowsaw 



Mine is doing nearly 1900 at 100.


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djmikey 



Mine is a stock ED and i sit on 1700 doing 100k/hr


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dark_realm 



my mates eb hardly rev's at 100km's its like 1500  1750, but its got a good top speed of around 220 i think.....


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azza 



sorry for late reply.. but yeh i noticed a drop in fuel economy..... i sat on around 12.8L per 100km with 3:08 and now im on about 14L per/100km.... so a small difference i would mostly say bcoz i do alot of freeway drivng and the higher revs is lifting me fuel consumption.... but a small increase in fuel consumption is a small price to pay for a LSD diff... it drives so much nicer... feels so tight around corners
_________________ BA XR8 manual ute black 

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NUTZEF 



i know u can buy different speedo gears but can u get speedo gears for a 3.9 ratio because that is not a standerd ford ratio and what color are the speedo gears for 15 inch rims and 17inch. also what happens to the computer controled shift does the speedo gear correct this.
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