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      02-20-2011, 12:31 PM   #1
chachacha28
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Automatic Diff into 6MT?

would it be possible to swap a rear diff from an auto car (bolted ring gear, and 2.56:1 instead of 3.08:1)? I do a lot of high speed cruising, and my mpg is killing me. I realize this would make the car accelerate slower, but it would give me a much needed drop in cruising RPM's. I could always make more power to make up for the 17% drop in torque, shoot, most tunes make at least 50 ft. lbs over stock, so with only a tune, i would break even and then some.

I think it seems like a good idea because of the cruising rpm's like i mentioned, and it has a bolted ring gear, so it would be easier to upgrade to a quaife down the road.
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      02-20-2011, 12:37 PM   #2
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The auto diff is a 3.46...
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      02-20-2011, 12:38 PM   #3
chachacha28
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http://www.bmwusa.com/Standard/Conte...fications.aspx
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      02-20-2011, 12:41 PM   #4
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Quote:
Originally Posted by BrokenVert View Post
The auto diff is a 3.46...
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      02-20-2011, 04:28 PM   #5
chachacha28
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so do the regular auto and the dct have different diff's then? the spec sheet i linked to didnt say anything about that. if it is the dct diff that has the 2.56, would it still have the bolted ring gear?

thanks.
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      05-28-2011, 12:13 PM   #6
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Quote:
Originally Posted by ezeedee View Post
so do the regular auto and the dct have different diff's then? the spec sheet i linked to didnt say anything about that. if it is the dct diff that has the 2.56, would it still have the bolted ring gear?

thanks.
Auto is 3.46
DCT is 2.56
M/T is 3.08

You can install an auto diff into a manual as long as the auto diff is from a 08/2007 or earlier car. 09/2007 and later auto diffs are much smaller and requires a longer drie shaft.
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