differential swap
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Instructor
Joined: Feb 2004
Posts: 198
Likes: 9
From: Loveland Colorado
differential swap
I am planning to switch out the 2.73 rearend in my 2000 A4 for a 3.42 or a 3.73, is this a clean swap or does it require any modification to my existing unit? 
Team Owner
Joined: Apr 2001
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From: S.W. Ohio. . . . . . NRA Life Member
Le Mans Master
Joined: Aug 2005
Posts: 5,375
Likes: 328
From: CA.
St. Jude Donor '13-'14-'15
I would recc getting a 3.42 take-off complete rear end assy off a Z06
do a gear only change on a C5 is difficult and very technical even for a rear end shop-Doing 3,73's would require an aftermarket set to be installed as GM doesn't offer a 3.73--I got mine for only $600 on E-B__Y
did the install myself--not that difficult--With the $$ you save get a stall converter--
PS: while there only about 6 more bolts and you have have the tranny out---In my opinion the BEST mod you can do on an A4 is a stall converter--If you want something mild using a stock GM diameter converter -something in the 2400-2800 range--If you are more performance oriented then go to a smaller diamter 3000-3600 range
A 2800 stall will get you about 4-6 tenths in the 1/4 mi without touching the engine !!
PSS: with a gear change on a C5-- a speedo adjustment is NOT required as the speedo pick-up is on the output shaft of the diff and not on the input shaft on the trans like on a Camaro-- However a shift point adjustment should be done with a full tuner (HP orEFILIVE)
do a gear only change on a C5 is difficult and very technical even for a rear end shop-Doing 3,73's would require an aftermarket set to be installed as GM doesn't offer a 3.73--I got mine for only $600 on E-B__Y
did the install myself--not that difficult--With the $$ you save get a stall converter--
PS: while there only about 6 more bolts and you have have the tranny out---In my opinion the BEST mod you can do on an A4 is a stall converter--If you want something mild using a stock GM diameter converter -something in the 2400-2800 range--If you are more performance oriented then go to a smaller diamter 3000-3600 range
A 2800 stall will get you about 4-6 tenths in the 1/4 mi without touching the engine !!
PSS: with a gear change on a C5-- a speedo adjustment is NOT required as the speedo pick-up is on the output shaft of the diff and not on the input shaft on the trans like on a Camaro-- However a shift point adjustment should be done with a full tuner (HP orEFILIVE)
