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| AdamN |
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I've been looking at changing my diff for the last couple of months. With the final drive ratio of the auto being lower than that of the manual, I don't see a problem with running a 4.1:1 ratio diff in my daily driver.
What do you guys/girls think? |
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| 67RCE |
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Do you do alot of highway milage? if yea then eithe 3.73:1 or 3.9:1 would be better, if not then 4.11:1 will get better launches, and use less fuel around town because you need to do less heavy accelleration
_________________ ILL60 - EF XR8, Sunroof, Ticky Kit, 19x8.5/19x11 TE37's, 347, AFr185's, TFS BoxRcustom converter, Hurst Quarterstick, huge billet cam. |
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| AdamN |
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Mon-Fri is peak hour twice a day. Weekend is about 50km of highway driving (100km/h) and driving on 60-70km/h roads.
Edit: Approximate revs @ 100km/h 3.23:1 (current) - 1800rpm 3.45:1 - 1920rpm 3.73: 1 - 2080rpm 3.9:1 - 2170rpm 4.11:1 - 2290rpm Approximate revs @ 60km/h 3.23:1 (current) - 1080rpm 3.45:1 - 1160rpm 3.73: 1 - 1250rpm 3.9:1 - 1300rpm 4.11:1 - 1370rpm |
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| 67RCE |
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the 3.45:1 revs are pretty accurate... for a manual
_________________ ILL60 - EF XR8, Sunroof, Ticky Kit, 19x8.5/19x11 TE37's, 347, AFr185's, TFS BoxRcustom converter, Hurst Quarterstick, huge billet cam. |
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| AdamN |
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67RCE wrote: the 3.45:1 revs are pretty accurate... for a manual
Those calculations are based on 205/65R15 tyres in 4th gear in my 4spd auto. Final drive is 0.68. As a comparison 5th gear in the falcon manual is 0.72 or 0.73. Can't remember which, but it's one of those. So the manual in any gear will rev higher than the auto in 4th with the same diff/tyres. The question is.. what revs are reasonable for daily driving? |
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| kezz |
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AdamN wrote: The question is.. what revs are reasonable for daily driving?
haha i guess thats up to you and what you think is acceptable. imagine 4.11 in my car with the 5sp?!?! stuff that, i do about 300 km on the highway a week so i think that ratio would be out of the question for me....
_________________ Kezz's 5sp Box Car ---> RPD enhanced with a bunch of other stuff |
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| AdamN |
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That's where the 6spd autos and manuals come into their own.. can put in 4.11 diff and still have low revs at 100km/h lol
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| bowsaw |
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Look what the factory does, cooking models are around 3:08, which would be a daily driver, 3:2.... for heavier stuff, 3:45 for sportier.
4:11 arent a daily driver ratio, if you want to conserve fuel etc, why bother, unless you want to traffic light drag. |
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| AdamN |
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Well with 3.7:1 gears.. it'd be 2000rpm@ 100km/h.. don't see any problem with that.
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| Mechan1k |
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I am looking at either 3.45 or 3.7 for daily driving and highway.
Have been told for 3.45 LSD is easier to come across ... and gives a bit of a better boost off launch with auto. Ute has crap take-off with auto and 3.23:1 single spinner ... such a dog ogg the line with load on.
_________________ 04 Territory TX AWD - Winter White - optioned up |
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| bowsaw |
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The revs might be only 200 odd apart, but thats extra 200 every minute, for how many years? has to be less wear surely? you want fuel economy? or extra legs down low? be fine for the city, but where i live, that would kill me, doing 140/160.
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| Mechan1k |
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If you are contantly on the highway/freeway ... definitely stay with the longer gearing.
I do a combination of city/metro/highway/freeway ... but do a lot of load work too. I think 3.45 LSD is going to be the go (for me anyway) ... easy to come across ... and a lot of people seem to be happy with them on autos as well ... gotta be better than trying to take off with 3.23s under load with an auto.
_________________ 04 Territory TX AWD - Winter White - optioned up |
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| AdamN |
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I've done all my country trips in this car already. It's now going to be a city only car.. so rarely going to be hitting anything over 100km/h.
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| 4dlvr |
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with an auto will the ecu be ok with the shorter ratios???
or will you have to change to a xr6 ecu???
_________________ 96 EF FAIRMONT |
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| Mechan1k |
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Just change the speedo gear on the auto and all should be fine ... from what I could tell.
_________________ 04 Territory TX AWD - Winter White - optioned up |
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