3:27 Chevy SS Diff' vs. 3:45 Camaro

[elc32955]

(Up onto the soapbox I go!)

SO.... I'm still trying to figure this out after all this time..... WHY do people insist on upgrading to the 3.27 over the 3.45?

WHY WHY WHY!!!

Is it availability of the pumpkin? Cost difference?? Difficulty with the install??? Urban legend that this is the "hot" setup???? Compromise for fuel economy?????

Roll back the history to 2009-2010. The PPV Caprice with the L77 was originally destined to have the 3.45 ratio as standard equipment for police pursuit use. The accountants and the Federal CAFE standards are what made GM/Holden take a hard look at things and stick 2.92's in to conform with CAFE. The stock L77 with 3.45's hauls major heiney!! The 3.27's.... respectable, but not near what the 3.45's give you as far as line performance. You only lost 1-2 MPH off the very top end with the 3.45's, based on actual data from owners that have done the swap. And got there quicker. If people go back and look at threads from the early days of the system, we've discussed & debated it time and time and time again. And with that ratio, bye bye drone.

Unless you need the 3.27's for a specific calibrated build that calls for that ratio the 3.45 is the hotter setup. Now it's irrelevant for me driving a V6 Grocery mobile (albeit with 301HP, lol!), but when I did the swap with the 2011 9C3 w/L77 it was a night & day difference. Lining up against cars with 3.27's, I won EVERY time. Just because something comes out of an SS doesn't necessarily make it the best fit for our cars. And we all don't have the budget for blowers, et al... so most of the time 70-80% of the people that mod are doing intake, exhaust, tune, gears, DOD delete - maybe cam to get what they can out of the car.

If you listen to the smack talk we all drive 4-door Camaros by owning a Caprice. The Camaro SS has 3.45's. Drive it like you stole it, not borrowed it!

HOP! (off the soapbox)

[BluesBro]

I think its mostly an availability thing elc,

From what I can gather the SS camaro with a manual got the 3.45 but all the autos got 3.27s. At least in my searching, 3.27s are much easier to find and usually cheaper.

[bstoner]

The Camaro SS (manual) has 3.45 rear gear with a 3.01 first gear and 28.7" tire verse our 4.027 first gear and 27.3" tire. That's a huge difference! The Camaro SS is running a larger tire and less aggressive first gear trans ratio. A total 10.38 ratio in the Camaro verse 13.89 if you run a 3.45 gear in our Caprice. If you jump down to a 3.27 gear it bring you to a total 13.16 which is still very aggressive. Our stock 2.92 gears gives a total of 11.75 which is still more than the Camaro SS. If you run a 3.45 in a Caprice it is like running a 4.61 gear in a Camaro!

I have a 3.45 gear and love it. I am cammed and run Mickey Thompson Street S/S with 305 tires and still have to peddle it out of the hole in 1st gear to maintain traction. If you are staying mostly stock, or a mild cam and do mostly city driving then 3.45 is amazing. I love mine. However when I go LSA 3.45 will be too much and I will go back down to 3.27. If you do more freeway driving I would also get 3.27 gears. With 3.45 gears it feels like the car needs to shift when I am cruising at 70 mph compared to most other cars. It runs at too high rpm and gets a little annoying.

Side note the 3.27 rears are easy to find and much cheaper. They made probably 10x as many as the 3.45. The 3.45 only came in the SS and are not nearly as common.

As far as acceleration there was someone over on the SS forum who ran both gears and didn't get much improvement on the 3.45 over the 3.27. You just blow through 1st gear so fast. It is also harder to get traction. Even running the MT ET Street S/S in a 305 I can blow the tires off in 1st gear if I just punch it on the street.

[elc32955]

LOL, remember I was the NewCaprice poster child for the 3.45's since I had the first set documented on a Caprice (at least on this forum - which predates Facebook forums). My results are in other threads way back, but I fell into the category of "mildly modded". In addition to the 3.45's I left the DOD intact since it had never given me any problems, I did mufflers (SLP PowerFlo with the trap tips) that were originally on a G8, a RotoFab intake (again, G8-style intake), and a Chris Henry trans/ECM tune. I spent a LOT of time up & down on Interstate 95, the Florida Turnpike, State Road 50 into Orlando & back, and a few other smaller wide-open paved roads... heh....

From what I recall my 70 MPH setting was 2 MPH lower than the set point which took DOD to full-time 8-cylinder operation. I left the cruise on right at 70 and the car was nice & happy running in 4 cylinder mode. At 73 MPH all 8 kicked in and the fuel economy took the noticeable hit. I remember when we did my gears that Chris had a PILE of 2.92 diff's removed from cars that no one wanted, I just stuck my old one on the pile rather than tote the old diff spooging gear oil all the way home and stick it in my shed for lord knows how long. At 70 with 3.45 in lieu of 2.92's my RPM was about 250-300 or so higher, went from 1400 to 1700 I believe from memory at steady-state cruise with DOD enabled. So it was a very manageable hit, a bit less boggy than the 2.92's but that was the objective!

But to this day I still maintain that 3.45's were a very good solution for my particular mods coupled with my desire to pep the car up in the most economical fashion possible. I know the gears were only put in manual Camaros 2010-2015, BUT gear sets are still available if you decide to stick with your pumpkin and not run the beefier one (pics are still up of the two side by side). I forklifted as opposed to taking the lid off the pumpkin, but the capability is still out there in the wild to get the ratio you want. Give it a little HP Tuner action after the surgery and you're good to burn 'em out another day!

Eric