391 gears

[bses48]

Have 2010 Camaro ss, would like to put 391 in it, I would like to find a complete rear end, also I think some years came with 391s stock would that rear end fit mine. thanks

[PROZ11]

They were the stock gears in the 1LEs.

[bses48]

thanks would they fit in a 2010ss, with my axles

[Hilflos]

If you're going with just gears, on the stock diff, in the stock housing, yeah, they'd fit, I would think.

I'm not an authority on the difference between the model years, but I'd suspect if you're buying a prebuilt diff, gear, housing set from one of the vendors, then it would be a direct swap out for your existing setup.

It was on my 2015 SS.

I got a eaton true-trac diff, with 3.91:1 gears, pre-built from the folks at JDP, and it was a pretty straight forwad swap.

I also upgraded the rear upper control arm bushings to Z/28 bushings, and did the subframe bushings, Detroit Speed solid aluminum, while everything was apart. You might want to think about doing whatever other upgrades you might want to do in that area of the car at the same time.

Mine's an LS3. Not sure if you're running manual or automatic. For the LS3, I'm of the opinion, this is how it should have come from the factory.

One word of warning though, 1st gear becomes ridiculously short if you get on it at all. Redline happens ridiculously quickly. If I'm looking to act like a civilized driver, then I sometimes just start in 2nd, or am very gentle with the throttle when starting from 1st.

[snizzle]

Originally Posted by Hilflos

Mine's an LS3. Not sure if you're running manual or automatic. For the LS3, I'm of the opinion, this is how it should have come from the factory.

I've heard this from a few folks. Considering going in that direction as well. So no regrets?

[esemjay56]

I don't know if anyone else had this issue, but the programmer I bought did not include 3.91 gears as an option to calibrate the speedo... I think 3.73's and 4.11's were the choices.

[frenchsquared]

Originally Posted by esemjay56

I don't know if anyone else had this issue, but the programmer I bought did not include 3.91 gears as an option to calibrate the speedo... I think 3.73's and 4.11's were the choices.

With some math work you could figure out the difference and add it to the tire size and get it accurate. Would suck every time you changed tires.

[bses48]

running manuel trans, thanks guys

[bses48]

if I understand this right in 2015 they went to 9 inch rear with 391s

[cc-rider]

You've got a few options for the 3.91...

Buy a complete 1LE diff (look in the classifieds here...or ebay)
Buy a 3.91 gear set and have it installed (cheapest option)
Buy a 3.91 gear set and Eaton Trutrac and have it installed

If you plan to go with big power build (500+ rwhp)...you should opt for the Trutrac.

And lastly...if you really want a robust rear end...you can go for a ZL1 differiential swap. You need the diff, driveshaft, and axles. This is extremely robust and can handle big power. But you've only got the gear choices of 3.23 or 3.73.

[Kopterman]

[QUOTE=bses48;9527943]if I understand this right in 2015 they went to 9 inch rear with 391s[/]


SS or 1LE?

[bses48]

not sure

[Hilflos]

Originally Posted by snizzle

I've heard this from a few folks. Considering going in that direction as well. So no regrets?

Nope, not a one.

Still got over 20mpg highway on the way home for Christmas and back, about a 1200 mile round trip.

For calibration's sake, mods so far are 1LE suspension, solid subframe bushings, Z28 rear upper control arm bushings, ported throttle body, Z28 CAI, and 3.91's on an eaton true-trac. Remote tune by Ted Jannetty.

[Avalnch]

If you are looking for a complete new rear end swap, you should look into the GMPP ZL1 rear end upgrade. That's what I did. You get everything (new rear end, axles & drive shaft) and it'll come with 373 gears (for the M6) which are a lot more street friendly than the 391s. Plus, it'll handle most power adders.