[Z06] I Need Advice!
Thread Starter
Intermediate
Joined: Feb 2013
Posts: 39
Likes: 1
From: Alabama
I Need Advice!
So to make a long story short. I bought a 03 c5Z in december with 40k miles on it. well i figure its time for a full fluid change in the car if it hadnt been done yet. well when i get to the rear diff it shows a sticker saying 3.15 and reads a date of 10/04/2012. well when i look at the plat thats on it it also reads 3.15. So it seems to me the rear diff has been changed out and they didnt even replace it with the stock c5Z rear diff. Sooo my question is what would you do in my situation??
Le Mans Master
Joined: May 2007
Posts: 5,393
Likes: 17
From: Belleville Mich.
Check your RPM at different speeds.
With a 3:42 rear end your RPM will be
1479 RPM @ 60 MPH
1726 RPM @ 70 MPH
Only reason I say, is that perhaps a 3:42 ring & pinion were installed in that particular 3:15 case/pig.
If the RPM's do not correspond, take your car back to the dealer that you bought it from & see what they can do for you.
With a 3:42 rear end your RPM will be
1479 RPM @ 60 MPH
1726 RPM @ 70 MPH
Only reason I say, is that perhaps a 3:42 ring & pinion were installed in that particular 3:15 case/pig.
If the RPM's do not correspond, take your car back to the dealer that you bought it from & see what they can do for you.
Safety Car
Joined: Mar 2004
Posts: 4,434
Likes: 18
From: Bartlett IL
St. Jude Donor '07-'08-'09-'10-'11
Sounds like youre running a 3.15 gear... I'd verify to see what mph you top out at in 1st gear... in 1st you should roughly be hitting around 46mph at 6500rpm... with a 3.15 you'll probably be in the 55mph range.
Thread Starter
Intermediate
Joined: Feb 2013
Posts: 39
Likes: 1
From: Alabama
Check your RPM at different speeds.
With a 3:42 rear end your RPM will be
1479 RPM @ 60 MPH
1726 RPM @ 70 MPH
Only reason I say, is that perhaps a 3:42 ring & pinion were installed in that particular 3:15 case/pig.
If the RPM's do not correspond, take your car back to the dealer that you bought it from & see what they can do for you.
With a 3:42 rear end your RPM will be
1479 RPM @ 60 MPH
1726 RPM @ 70 MPH
Only reason I say, is that perhaps a 3:42 ring & pinion were installed in that particular 3:15 case/pig.
If the RPM's do not correspond, take your car back to the dealer that you bought it from & see what they can do for you.
Thread Starter
Intermediate
Joined: Feb 2013
Posts: 39
Likes: 1
From: Alabama
Im stepping out the door to try it now. Thanks for the info!
Thread Starter
Intermediate
Joined: Feb 2013
Posts: 39
Likes: 1
From: Alabama
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