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3.42 diff question

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Old 05-22-2010, 11:02 AM
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btstone84
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Default 3.42 diff question

I have been told a 3.42 gear from an m6 will not work on my a4. What exactly is the difference? And is there a way to make it work?
Old 05-22-2010, 08:08 PM
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haljensen
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Originally Posted by btstone84
I have been told a 3.42 gear from an m6 will not work on my a4. What exactly is the difference? And is there a way to make it work?
From previous posts over the last couple of years;

The differential housings are different, the gears for the A4 are physically smaller as well as a different ratio. 3.42 gears are made for the larger housing manual trans. From what I understand somebody is making smaller 3.42 gears that will fit the smaller housing.

Also; The complete manual diff won't interchange either due to bolt patterns, input/output shaft diameters and lengths.

Your best bet is to contact any of the Forum Vendors that do rear gearswaps, they can explain the options better than I can.
Old 05-22-2010, 08:16 PM
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dennis50nj
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Originally Posted by haljensen
From previous posts over the last couple of years;

The differential housings are different, the gears for the A4 are physically smaller as well as a different ratio. 3.42 gears are made for the larger housing manual trans. From what I understand somebody is making smaller 3.42 gears that will fit the smaller housing.

Also; The complete manual diff won't interchange either due to bolt patterns, input/output shaft diameters and lengths.

Your best bet is to contact any of the Forum Vendors that do rear gearswaps, they can explain the options better than I can.
all the gear kits are the same 05-10
Old 05-23-2010, 08:43 AM
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c6 batmobile
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If they are from the same year they should work. I believe they changed the case and mounts in 06+ due to the "weak" rear in the 05 models. RPM sells and adapter or something of the sort so 05 guys can put 06+ rears in.
Old 05-23-2010, 08:52 AM
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dennis50nj
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Originally Posted by c6 batmobile
If they are from the same year they should work. I believe they changed the case and mounts in 06+ due to the "weak" rear in the 05 models. RPM sells and adapter or something of the sort so 05 guys can put 06+ rears in.
if i put the second generation rear in my c5 i have to use the rpm adapter and an 06-10 manual case housing and side covers, i can buy that from gene culley, and use my 05 ring and pinion with my 05 differential, what changed was the housing, the a6 housing is different
Old 05-23-2010, 06:13 PM
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c6 batmobile
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Originally Posted by dennis50nj
if i put the second generation rear in my c5 i have to use the rpm adapter and an 06-10 manual case housing and side covers, i can buy that from gene culley, and use my 05 ring and pinion with my 05 differential, what changed was the housing, the a6 housing is different
thats what I meant. I believe the spline on the a6 tranny maybe a different length too but I dont know for sure. You may have some more insight on that.
Old 05-23-2010, 06:43 PM
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dennis50nj
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Originally Posted by c6 batmobile
thats what I meant. I believe the spline on the a6 tranny maybe a different length too but I dont know for sure. You may have some more insight on that.
yea i don't know for sure, i just know RPM told me i need to use the manual not the 6 speed auto housing
Old 05-23-2010, 07:06 PM
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btstone84
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i wanna replace the entire rear, casing and all. will one out of a m6 work with my a4 wil the adapter you are talking about
Old 05-23-2010, 07:36 PM
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Originally Posted by btstone84
i wanna replace the entire rear, casing and all. will one out of a m6 work with my a4 wil the adapter you are talking about
yes if you buy the adapter from RPM and have an 05 a4 c6, your 342 manual stick housing will fit
Old 05-23-2010, 08:37 PM
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thank you
Old 05-23-2010, 09:26 PM
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glad i could help
Old 05-24-2010, 11:59 PM
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lgm118icbm
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The 3.42 differential from a 2005 mn6 will bolt right up to your 2005 a4, no modification required. You will have to reprogram the computer however. Everything is a straight remove and replace bolt on.

You only run into problems when you try to put a 2006+ differential onto a 2005 tranny.
Old 05-25-2010, 08:10 AM
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dennis50nj
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Originally Posted by lgm118icbm
The 3.42 differential from a 2005 mn6 will bolt right up to your 2005 a4, no modification required. You will have to reprogram the computer however. Everything is a straight remove and replace bolt on.

You only run into problems when you try to put a 2006+ differential onto a 2005 tranny.
you are correct, i am assuming he wants a second generation rear, its stronger, and if you buy the case and side covers new its cheaper, but you will need the adapter

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