Differential Options for my 2013

Drivetrain discussion including Transmission, Differential, Driveshaft, and related items.
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jpalmer
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Differential Options for my 2013

Post by jpalmer »

OK, so I'm looking around the forum and notice that several guys are upgrading the 2.92 rear ends to 3.45s from a Camaro. I was wondering what options are out there for these cars. I have found rear ends w/3.27, 3.45 and 3.91 gears but no mention as to whether or not they are open or limited slip. The 3.27s came out of a v6 car, does this mean they are not as stout as the 3.45s, also the sales description says "I upgraded to an LSD." so it seems the 3.27s are an open diff, can this be upgraded to a limited slip and would it be a good replacement? I was thinking it would be a good compromise between the 3.45/3.91 and the 2.92s but what do I know.

I guess what I am looking for is a source to learn what I can use (do's & don'ts) as a replacement for my car's rear end.

What say you?
Jeff

1996 Caprice LT1 B4U - Sold - So long my friend - it was a great 17 years!
2001 Silverado LS 3500 DuraMax Dually 4x4
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storm9c1
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Re: Differential Options for my 2013

Post by storm9c1 »

For the sake of argument, back in the B-Body days, most guys recommended a jump from 3.08 (on 9C1 cars) to 3.73. I always thought this was too big of a jump, revs too much on the highway, impacts MPG, etc. So I used the same logic as you and went with 3.42. I never regretted that decision. In fact, it was the single best mod I did IMO. It was the perfect ratio for performance plus some economy.

So using this same logic (which could be flawed when it comes to the PPV with a 6 speed trans versus 4 speed on the B-Body), I'd say a jump from 2.92 to 3.45 would put you in that same sweet spot. But what do I know.

If I were to change the gears on my PPV, I'd go with 3.45 on a street car/daily driver. Which happens to make the Camaro swap a no-brainer. Unless of course I had a big power adder, a high-stall converter, trans brake, and was at the track every week...if you know what I mean...then a bigger ratio would make more sense.
Tom (AKA: Storm)
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Navy Lifer
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Re: Differential Options for my 2013

Post by Navy Lifer »

My perfect setup would be to keep the 2.92, and figure out how to make the 8-speed (8L90) trans work. It has a 4.56 first gear, vs the 4.03 in 6L80. Winner at both ends.

6 speed (4th is 1.15, 5th is 0.85, 6th is 0.67)

2.92 x 4.03 = 11.77
3.27 x 4.03 = 13.18
3.45 x 4.03 = 13.90 (18% change from stock)


8 speed (6th is 1.00, 7th is 0.85, 8th is 0.65)

2.92 x 4.56 = 13.32 (13% change from stock)

At present, 8L90 is not compatible with previous engine/trans controllers, only works with GenV (DI) engines. 8-speed is same footprint as 6-speed, and is LIGHTER!
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jpalmer
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Re: Differential Options for my 2013

Post by jpalmer »

storm9c1 wrote:For the sake of argument, back in the B-Body days, most guys recommended a jump from 3.08 (on 9C1 cars) to 3.73. I always thought this was too big of a jump, revs too much on the highway, impacts MPG, etc. So I used the same logic as you and went with 3.42. I never regretted that decision. In fact, it was the single best mod I did IMO. It was the perfect ratio for performance plus some economy.

So using this same logic (which could be flawed when it comes to the PPV with a 6 speed trans versus 4 speed on the B-Body), I'd say a jump from 2.92 to 3.45 would put you in that same sweet spot. But what do I know.

If I were to change the gears on my PPV, I'd go with 3.45 on a street car/daily driver. Which happens to make the Camaro swap a no-brainer. Unless of course I had a big power adder, a high-stall converter, trans brake, and was at the track every week...if you know what I mean...then a bigger ratio would make more sense.
I am with ya on this. I have had a '96 B-Body for 17 years so I am firmly entrenched in this philosophy. I am also in the same camp with you about the 3.73s being too much for the B-Body (for daily drivers at least) and like you was applying this logic to my current car.

My PPV will be a daily driver and now that I am back in Morgantown after 20+ years in flat ol' Indiana a little extra grunt for the hills around here would make a difference. I just didn't know how much I would need due to the difference of the 6-speed and very low first gear compared to the 4L60E in the B-Body. So, with the open diff 3.27 at half the cost of the 3.45s seemed like a viable option depending on what it would cost to make it a limited slip, and if it was a stout as the 3.45s.

Probably shouldn't over think it and if a rear end swap is in my future sounds like a 3.45 is the way to go or at least until I find out more info. Now on to Bill's response! :o

Thanks Tom!
Jeff

1996 Caprice LT1 B4U - Sold - So long my friend - it was a great 17 years!
2001 Silverado LS 3500 DuraMax Dually 4x4
2004 Suburban 2500 6.0L 4x4
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jpalmer
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Re: Differential Options for my 2013

Post by jpalmer »

Navy Lifer wrote:My perfect setup would be to keep the 2.92, and figure out how to make the 8-speed (8L90) trans work. It has a 4.56 first gear, vs the 4.03 in 6L80. Winner at both ends.

6 speed (4th is 1.15, 5th is 0.85, 6th is 0.67)

2.92 x 4.03 = 11.77
3.27 x 4.03 = 13.18
3.45 x 4.03 = 13.90 (18% change from stock)


8 speed (6th is 1.00, 7th is 0.85, 8th is 0.65)

2.92 x 4.56 = 13.32 (13% change from stock)

At present, 8L90 is not compatible with previous engine/trans controllers, only works with GenV (DI) engines. 8-speed is same footprint as 6-speed, and is LIGHTER!
Now here is some food for thought, an 8-speed! Hopefully it's just a matter of time before some propeller-head figures out how to make the older electronics talk to the new trans. Or, I know that there are trans builders out there that are turning 4L80Es into 6-speeds by engaging different clutch packs, wonder if this can be done with our current 6-speed? Of course it wouldn't be a 4.56 first gear. Looking at the math this would be a good solution for the extra grunt for stop and go/ hills and maintaining fuel mileage on the highways.

My fear is that with PPV model coming to an end and the GTOs/G8s fading into automotive history, there won't be any real development from the aftermarket. I'll keep a good thought, like....
An 8-speed w/ tap shift!

Thanks Bill!
Jeff

1996 Caprice LT1 B4U - Sold - So long my friend - it was a great 17 years!
2001 Silverado LS 3500 DuraMax Dually 4x4
2004 Suburban 2500 6.0L 4x4
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9C1fanatic
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Re: Differential Options for my 2013

Post by 9C1fanatic »

I may be wrong but I thought from previous posts here that the 3.45 diffs came from V8 Camaros with manual trans and the 3.27 diffs came from V6 Camaro and V8 automatic Camaros with the L99 engine which I would bet only came in limited slip on V8 auto equipped versions.
Garner Ames



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jpalmer
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Re: Differential Options for my 2013

Post by jpalmer »

9C1fanatic wrote:I may be wrong but I thought from previous posts here that the 3.45 diffs came from V8 Camaros with manual trans and the 3.27 diffs came from V6 Camaro and V8 automatic Camaros with the L99 engine which I would bet only came in limited slip on V8 auto equipped versions.
That's what I thought too, but on the Camaro forum I have read that the V6 Camaro w/ manual transmissions and 3.27 rear end has a limited slip differential (LSD), it's the V6 w/ auto trans that are open rear ends. The V8 Camaros have the 3.45, but can be ordered with optional 3.70 or 3.90 gears.

I think the 3.27 would be a nice compromise to the 3.45s, extra grunt down low and still decent fuel mileage in OD, and they can be had for about 3/4 the price. I just don't know if the v6 rear ends would hold up behind a V8 Caprice. I guess the Caprice is about the same weight as a Camaro, but the L77 has a bit more umph than the V6. And, I can't find out if an open diff can be converted to a LSD. I see the V6 rear ends for sale for about 400 - 500 bucks.
Jeff

1996 Caprice LT1 B4U - Sold - So long my friend - it was a great 17 years!
2001 Silverado LS 3500 DuraMax Dually 4x4
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orgdnr
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Re: Differential Options for my 2013

Post by orgdnr »

What is the ring gear diameter of the 3.27 units you're looking at? The 3.45 I put in my caprice is 218mm. I think the stock unit was 198mm. Leadfart is running the smaller gear with a maggi at 500 rwhp so unless you are making big power I would run the gear you want. I have the 2.92 posi out of my car and might be good candidate for 3.27 gears. How $100 + shipping sound?
Dave
Chatsworth Ca

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jpalmer
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Re: Differential Options for my 2013

Post by jpalmer »

orgdnr wrote:What is the ring gear diameter of the 3.27 units you're looking at? The 3.45 I put in my caprice is 218mm. I think the stock unit was 198mm. Leadfart is running the smaller gear with a maggi at 500 rwhp so unless you are making big power I would run the gear you want. I have the 2.92 posi out of my car and might be good candidate for 3.27 gears. How $100 + shipping sound?
I dunno Dave, I don't know what parts would cost. Ebay has the 3.27 rear ends for about $550, just remove and replace.

Good price though....
Jeff

1996 Caprice LT1 B4U - Sold - So long my friend - it was a great 17 years!
2001 Silverado LS 3500 DuraMax Dually 4x4
2004 Suburban 2500 6.0L 4x4
2013 Caprice PPV 6.0L
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elc32955
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Re: Differential Options for my 2013

Post by elc32955 »

Jeff,

Just to discuss the 3.45 a little, we've had a few threads on here on the swap from 2.92, if you search back in the older threads you'll find a lot of detailed information and pictures. I did the pumpkin swap on my car and overall I've been relatively happy with the performance, Either a 3.27 or a 3.45 would be a good compromise gear if you don't want a full track car. I also had a B-Body that I went from 2.73 to 3.73 with (ex- 95 Virginia State Police) and that was quite a jump. An old wise man told me once though that unless you're talking .5 or more on a ratio change it wouldn't be worth the expense and hassle. Take that into consideration.

With the 3.45, fuel economy will go down a bit but not so much as to be unpalatable. With city driving I'm seeing an average of 300 miles on a tank, I can jump that to 400-425 or so miles on the highway with steady-state driving (I did 430 once but had the "low low fuel" warning on for about 10 miles, that was worrisome in that the pump was probably uncovered). One thing that we didn't have in the B-body was AFM, mine is still enabled with a 72 MPH max cut-on threshold. So, for long distance Interstate driving I set the auto throttle to 72 and cruise down the road in the right lane. Only thing irritating about that is all the people that think you're a cop and refuse to pass you...

If you're after max top-end, you will lose a few MPH if you make the 3.45 swap. "In Theory" a car of my gearing and with my tune will do at least 150 in 5th before it goes and shifts to 6. 6th gear will hold it pretty much steady state, but you're not going to see much of an increase unless you've got a LONG road ahead of you. Of course I would have no personal knowledge of this :)

My diff was out of a 2010 Camaro SS that only had 1800 miles on it, if I remember correctly I paid just under $1K for it. Chris Henry (another board member and a very good tuner) did the swap and can discuss more of the in's and out's of things to look for technically.

Hope this helps.
Eric
System Manager and your tour guide for the day. 2015 Caprice w/LFX, former NC DPS staff car. Partial hybrid G8/SS/Camaro SS interior mods, SS MyLink radio upgrade, 2016 Camaro V6 rims, GMPP Malibu chrome exhaust tips, otherwise bone stock for now.
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