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3.45s to 4.11s? 

 

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 Post subject: 3.45s to 4.11s?
Posted: Fri Feb 20, 2009 11:54 pm 
Smokin em up
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I'll possibly be buying either an XHII XR6 or EL XR6 manual Falcon in a few months, my first upgrade planned is diff gears, I'm thinking of changing out the stock 3.45s out for 4.11s when i get the car. How much of an improvement will it make?

What will i be revving at in 5th at 110km/h? 90% of my driving will be highway.
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 Post subject: Re: 3.45s to 4.11s?
Posted: Sat Feb 21, 2009 12:38 pm 
Getting Side Ways
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I personally wouldn't put 4.11's in a manual, you wouldn't even use first. 3.73's are probably better suited for a manual

 

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 Post subject: Re: 3.45s to 4.11s?
Posted: Sat Feb 21, 2009 3:14 pm 
Getting Side Ways
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Personally I would stick with the 3.45's, as if you jump right up, not only will you ever use first gear in the manual, it's not suited for it either, your speedo will be way off, and highway driving, well, I would say that the revs would be in the 3000's or there abouts.

 

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 Post subject: Re: 3.45s to 4.11s?
Posted: Sat Feb 21, 2009 3:25 pm 
Smokin em up
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Ride: WS Ford Fiesta CL manual

Location: Melbourne
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Would the 4.11s make first useless? Or would it go up to 20km/h or so? Or do I just take off from second gear? I'd be after a faster 0-100 time, I hear diff gears help with that. But I think spinning at about 3000 RPM would be a bit much for highway driving.

Speedo could be corrected with that kit from Jaycar I suppose, so that isn't really an issue.

But if i did change diff gears, 3.73s would be the most ideal? Would that be much of a step up from 3.45s?
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 Post subject: Re: 3.45s to 4.11s?
Posted: Sun Feb 22, 2009 11:50 am 
Parts Gopher
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WA, Australia

hey mate iv just put 3.89's in my el xr6. they are a great ratio the car feels awesome!
1st gear is still very usefull, still get to around 50k's with it, and really really fast!

i bought the jaycar kit and it works very well, sitting on 110 im reving at about 2700. the car doesnt seem to mind it at all, still cruises nicely

 

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 Post subject: Re: 3.45s to 4.11s?
Posted: Sun Feb 22, 2009 11:56 am 
Getting Side Ways
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i had 3.73's behind an EA manual box and 1st gear was a bit of a pig around town, but went like a cut snake. In the end the super short ratios were enough to make me sick of driving a manual.

but with the later model T5's having a longer 1st and taller 5th, i reckon 3.73's would be ok and would not go any higher in my opinion.
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 Post subject: Re: 3.45s to 4.11s?
Posted: Thu Mar 19, 2009 9:42 pm 
Oompa Loompa
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easy way to convert diff change in RPM is: take the current RPM@ 100kmh divide by the current diff ratio, then times it by the ratio you want

Mine is 2050Rpm @100kmh with 3.45
it would be 2198rpm @100kmh with 3.7's
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