Rear end gears
Thread Starter
Racer
Joined: May 2006
Posts: 378
Likes: 11
From: DeBary Fl.
Rear end gears
2005 base 6 speed, I am curious as to the difficulty & process in changing rear gears, I feel this is one of the better upgrades for overall performance. Any thoughts or opinions is appreciated..
Burning Brakes
Joined: Jul 2002
Posts: 1,136
Likes: 100
From: Nova Scotia
Most people, myself included, buy a complete diff with whatever gear ratio we want, and swap the diff. It involves dropping the rear cradle, which I didn't find that difficult, but it depends on your abilities
Race Director
Joined: Oct 2004
Posts: 12,864
Likes: 4,667
Thread Starter
Racer
Joined: May 2006
Posts: 378
Likes: 11
From: DeBary Fl.
I do appreciate all your responses, but wonder where one might find a ratio as we have discussed????? If the safest / most popular way is to swap complete units in tact....what & where might the 3:73 or 3:90 ratio complete units be found??? Did any C6's or C5's come with those ratios??? Any & all responses are appreciated as always !
Burning Brakes
Joined: Sep 2012
Posts: 884
Likes: 301
From: KCMO
I do appreciate all your responses, but wonder where one might find a ratio as we have discussed????? If the safest / most popular way is to swap complete units in tact....what & where might the 3:73 or 3:90 ratio complete units be found??? Did any C6's or C5's come with those ratios??? Any & all responses are appreciated as always !
RPM Transmissions - complete differentials
Burning Brakes
Joined: Jul 2002
Posts: 1,136
Likes: 100
From: Nova Scotia
I do appreciate all your responses, but wonder where one might find a ratio as we have discussed????? If the safest / most popular way is to swap complete units in tact....what & where might the 3:73 or 3:90 ratio complete units be found??? Did any C6's or C5's come with those ratios??? Any & all responses are appreciated as always !
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Safety Car
Joined: Sep 2007
Posts: 4,009
Likes: 491
From: South Florida
I did a built diff by RPM in my C5 and switched from the stock 3.42 gears to 3.90 gears. That was hands down the best modification I did on that car, was good for 3-4 tenths at the track too. Totally changed the car, made it feel like it had a lot more power than it actually did.
Melting Slicks
Joined: Apr 2002
Posts: 2,397
Likes: 55
From: Dove Mountain, AZ
When I had my 04 I put 390's in it, loved them! Before the swap I could not use 5th in town very much (45 mph) but with the 390's no problem.
It made all gears pull better. I would do it again. I did not change the gears in my current 2012 because I supercharged it and do not track the car.
It made all gears pull better. I would do it again. I did not change the gears in my current 2012 because I supercharged it and do not track the car.
Race Director
Joined: Dec 2013
Posts: 12,502
Likes: 3,631
Problem with the 2005 diff, is it has the weakest case of all the C6 diffs (easiest to crack apart).
In later years, more internal webbing was added to increase the strength of the case.
Simply, if you going to be banging away at the diff, then first part of the upgrade is to change out the weaker case to a later stronger case as step one. The from here, internals are swapped out inside the case to create a stronger diff as well.
In later years, more internal webbing was added to increase the strength of the case.
Simply, if you going to be banging away at the diff, then first part of the upgrade is to change out the weaker case to a later stronger case as step one. The from here, internals are swapped out inside the case to create a stronger diff as well.
Pro
Joined: Nov 2013
Posts: 664
Likes: 320
From: Houston, Texas
Here is one place you can get a differential with gears installed
RPM Transmissions - complete differentials
RPM Transmissions - complete differentials
To the OP - if you remember any remember this ------ the 05 M6's weak link in the drive train is the rear diff. I had to replace mine when we took it to the track and my son dumped that clutch at the tree and the diff blew. Chevrolet fixed this in the 06+ models. RPM provides a special bracket for the 05's to be able to replace this OEM diff with all of their replacements.
BMF
Last edited by BMF_C6; Feb 20, 2022 at 04:53 PM.
Thread Starter
Racer
Joined: May 2006
Posts: 378
Likes: 11
From: DeBary Fl.
Thanks guys for all the thoughts & info..........looks like no matter how much I love my 2005 it comes with some serious baggage.....I will just juice it up & be careful!!!
Any thoughts as to the best choice to go to next? My 05 will be here for fun but if I want to have fun with other years (no Z06 level) what are the thoughts amongst the group???
Again, all is appreciated............................. ......
Any thoughts as to the best choice to go to next? My 05 will be here for fun but if I want to have fun with other years (no Z06 level) what are the thoughts amongst the group???
Again, all is appreciated............................. ......
Burning Brakes
Joined: Sep 2018
Posts: 1,023
Likes: 174
From: Auburn Al
Pretty sure the 3.42 is standard on all the 6 spd manuals. IMHO, a manual 6 speed benefits more than an A6, and the earlier cars with the A4s, when changing diffs/gears. If you do a search, a 3.73, or a 3.90 really livens up the car, and make 5th and 6th gear more responsive, especially 5th gear. I agree that it's usually best to change the entire diff, for a different one, with the ratio you want. My .02
6th gear is ONLY for fuel milage you would NEVER use it in racing or if you were doing the half or 1 mile speed runs, to do so would be flirting with disaster.
Burning Brakes
Joined: Jul 2002
Posts: 1,136
Likes: 100
From: Nova Scotia
I believe top speed is actually achieved in 5th gear. But what I think the poster means, because I noticed this, is that it makes 6th gear a lot more usable. It will actually accelerate and not be so luggy. With the stock gears I was only revving like 1600rpm on the highway. With 3.90s I'm revving like 1800, which the engine seems much happier about
Race Director
Joined: Oct 2004
Posts: 12,864
Likes: 4,667
Race Director
Joined: Feb 2006
Posts: 10,336
Likes: 14
From: Bellville OH
St. Jude Donor '06
IDK I have 3.90 hear in my Z06 with the LPE 660 HP package and honestly I wish it was the stock ratio. 1st and 2nd are basically useless past 60 percent throttle. I have the MPSS in 325 in the rear but I have 13 inch rim so i'm thinking of going to a 345 rear. With the 390 gear 65 MPH on the back country road is rite between 5th and 6th gears. 6 is too low and 5th is too high and drones.