3.91 gear talk - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

judkins75 · 10-03-2019, 06:36 PM

My dealer quoted me a price on gears. $429 for gear kit and $693/6.3 hours install. I think I'm going to pull the trigger this winter. I've read a lot of post on 3.91, but does anyone have more up too date info and ride info on using 3.91 gears on a daily driver...

IWANTA(ss) · 10-03-2019, 07:16 PM

I’m in the middle of a gear swap from 3.91 to 4.11. I do have a big cam, but I think the most popular answer is 4.11 manual cars and 3.91 for the L99. But search for acammer on here and read his great write ups and you’ll find some good info. If you can swing it look into the true-trac, lpw cover and some bushings for the diff since your opening it open anyway.

lemontwist · 10-03-2019, 08:02 PM

there is a guy on here selling 391's from his 1le for 1k i would just buy that and put it in.

KerseySS · 10-03-2019, 08:35 PM

It’s a lot more fun to drive with the 3.91 but you will lose about 1.5 mpg

Sent from my iPhone using Tapatalk

TheFlyingBananaSS · 10-03-2019, 09:08 PM

Besides a tune, it's the best bang for buck mod you can do. You car will wake up and you will have fun driving it again.

Black_SS10 · 10-03-2019, 09:28 PM

3.91 gear is a great upgrade. You will lose a few mpgs but the car will feel lighter and accelerate quicker. If you want to go all out, go straight to 4.11. I should have, so when I rebuild the diff in my garage it will get a 4.11 gear.

zlathim · 10-04-2019, 08:46 AM

Is the car a manual or automatic? If it's a manual, you should consider 4.10s or 4.11s. acammer convinced me to do the same and I am really glad I listened. An even lower ratio would be better, but in my case, the cost was prohibitive.

pnwdan · 10-04-2019, 01:03 PM

My car is a LS3/M6
TSP stage 3 cam
I daily it with 3.91s

4.11 would be better for the strip but the 3.91 is a good middle ground for my setup

GK_2012_SS · 10-04-2019, 01:59 PM

Everyone seems to love the 3.91. My question: is there any concerns over the stock SS differential and transmission? My understanding is that the 1LE (which includes the 3.91) has a stronger differential and a different version of the TR6060. My car is a manual SS (not 1LE), I would hate to do this mod then start breaking parts. BTW - I don't race, just street.

anthony.martinez · 10-04-2019, 03:38 PM

Yes the trade off is miles per gallon for Smiles per gallon!!! It is a great gear for cruising the highway too.

Black_SS10 · 10-04-2019, 04:08 PM

Quote:

Originally Posted by GK_2012_SS

Everyone seems to love the 3.91. My question: is there any concerns over the stock SS differential and transmission? My understanding is that the 1LE (which includes the 3.91) has a stronger differential and a different version of the TR6060. My car is a manual SS (not 1LE), I would hate to do this mod then start breaking parts. BTW - I don't race, just street.

The diffs are the same just different gearing. The trans are the same, different gear sets because of the 3.91 gearing. The SS tr6060 will have a very short 1st gear with 1LE 3.91 vs the SS 3.45.

This is a good read about adding 3.91 to a manual SS.

https://www.camaro5.com/forums/showthread.php?t=284343

acammer · 10-04-2019, 08:20 PM

If you have a M6 car that doesn't have a power adder then anything less than a 4.10 gear is leaving performance on the table. There are really no significant drawbacks to a 4.10. You will gain a couple hundred RPMs at cruising speed in top gear, 70mph is right around 2000rpm - which is a still completely reasonable. I lost 1.5mpg at 70mph. It was no different in mixed/city driving, that all depends on the driver.

From a drag race perspective, you definitely want the 4.10. These are heavy cars, and they need all the help they can get to get moving. Additionally, with the 1:1 4th gear you need to get the RPMs up.

Like Zlathim said, if we could get more gear in the rear end, I would have a 4.56 back there. Zane and I run 26" tires (stock is 28.66") at the track specifically to increase the final drive ratio. It makes the car easier to launch, and helps down the back half of the track, getting the car back up into the power sooner after you make the 3-4 shift.

lemontwist · 10-04-2019, 08:31 PM

boom 1200
used 3.91
https://www.hawksmotorsports.com/201...-3-91-used-gm/

mbesman · 10-04-2019, 11:47 PM

Quote:

Originally Posted by judkins75

My dealer quoted me a price on gears. $429 for gear kit and $693/6.3 hours install. I think I'm going to pull the trigger this winter. I've read a lot of post on 3.91, but does anyone have more up too date info and ride info on using 3.91 gears on a daily driver...

That's no too bad of a deal and you get a full warranty with the dealer install. I had mine installed at dealer. They did not tune the car though (adjust for speedometer) I have a Diablo tune that I was able to use to adjust the speedo so that didn't concern me. If you don't own one, you will need to get it tuned to adjust for the gears at a minimum.

10-03-2019, 06:36 PM	#1
judkins75 Silver Shark Drives: 2014 2SS GM Npp 6 speed manual Join Date: Nov 2014 Location: Wyoming Posts: 131 View My Garage	3.91 gear talk My dealer quoted me a price on gears. $429 for gear kit and $693/6.3 hours install. I think I'm going to pull the trigger this winter. I've read a lot of post on 3.91, but does anyone have more up too date info and ride info on using 3.91 gears on a daily driver... __________________ Silver Shark2010,2011 Z28 black gloss replica wheels, 285/305 tires, BMR Strut brace,Kooks lt headers/hfc, CAI cold air intake/air scoop

10-03-2019, 07:16 PM	#2
IWANTA(ss) Drives: 13 1LE 1SS/05 ZX10/02 Silverado/14 Join Date: Nov 2014 Location: Brandon,Mississippi Posts: 487 View My Garage	I’m in the middle of a gear swap from 3.91 to 4.11. I do have a big cam, but I think the most popular answer is 4.11 manual cars and 3.91 for the L99. But search for acammer on here and read his great write ups and you’ll find some good info. If you can swing it look into the true-trac, lpw cover and some bushings for the diff since your opening it open anyway. __________________ 02 Stepside Silverado 05 ZX-10 13 1LE 14 Nightrod Special

10-03-2019, 08:35 PM	#4
KerseySS Joey Drives: 2011 Camaro 2SS/RS L99 Cyber Grey Join Date: Feb 2017 Location: GA Posts: 113	It’s a lot more fun to drive with the 3.91 but you will lose about 1.5 mpg Sent from my iPhone using Tapatalk __________________ 2011 Cyber Grey L99 SS/RS- 3.91 Gear MRR 228 Wheels-Hurst shifter/base plate LT Headers no CATS-Magnaflow 16582 Axle Back RoboFab intake-Dyno Steve tune ZL1 Rocker Panels-SLP Splitter Lowered on Phastek springs Pray Performance ported TB

10-03-2019, 09:08 PM	#5
TheFlyingBananaSS Evil Genius of Chevrolet Drives: 2017 Z06, 2019 XTS, 2013 SS Join Date: Feb 2017 Location: New York Posts: 3,260	Besides a tune, it's the best bang for buck mod you can do. You car will wake up and you will have fun driving it again. __________________ GPI SS2 VVT cam, ECS Novi 1500 supercharger, Corsa Extreme, Detroit Speed and BMR suspension, Circle D triple disc, Melling oil pump, LS2 chain tensioner, ATI 10% UD, DSX E85 kit, High Energy coils, BTR springs, LS2 Lifter trays, Titanium retainers, hardened push rods, FIC 1000 injectors, ZL1 pump, Mighty Mouse catch can, AEM gauges, Tial BOV, Richmond 3.91 gears, Custom gauge bezels, Speed Engineering headers, Stainless Works HF cats, DSX Aux pump, 710rwhp on E85.

10-03-2019, 09:28 PM	#6
Black_SS10 SomeguyK Drives: 2010 Black 2SS/RS Join Date: Nov 2014 Location: FL Posts: 1,947	3.91 gear is a great upgrade. You will lose a few mpgs but the car will feel lighter and accelerate quicker. If you want to go all out, go straight to 4.11. I should have, so when I rebuild the diff in my garage it will get a 4.11 gear. __________________ TMS 427, Dart iron Block, Forged assembly, Frankenstien heads, AGP TT 62/62 BB turbo's, AGP/Fore triple fuel system, Tilton clutch, Holley 1 7/8 shorties, Technostalgia tail lights,Oracle, Aeroforce, MGW shifter,Flowmaster, Pegasus subframe bushings,BMR trailing & toe arms,Z28 UCA bushings,Zl1 rear sway bar,Prothane,BMR,Goodridge brake lines,Ridetech HQ coilovers,3.91,Trutrac,billet caps,DSS axles,HE offest,built TR6060,1LE diffuser,Havoc spoiler,SSclones,20in MRR 017, Pirelli P Zero, Nitto NT555RII More to come.

10-03-2019, 08:02 PM	#3
lemontwist Drives: 12 2SS/RS L99,11 2SS/RS LS3totaled Join Date: Jun 2019 Location: mooresville nc Posts: 1,048	there is a guy on here selling 391's from his 1le for 1k i would just buy that and put it in.

10-04-2019, 08:46 AM	#7
zlathim Drives: 2010 Camaro 2SS/RS M6 Join Date: May 2009 Location: Idaho Posts: 726	Is the car a manual or automatic? If it's a manual, you should consider 4.10s or 4.11s. acammer convinced me to do the same and I am really glad I listened. An even lower ratio would be better, but in my case, the cost was prohibitive. __________________ GPI SS2; EE E2 catch can; SP 1 7/8" LT Headers w/ hfc; FM AT 3" cat-back; CAI Cold Air Intake; AEM Wideband Tuned by GPI McCleod RXT; MGW flat stick; Ram Clutch slave cylinder & hydraulic adjuster BMR cradle & diff bushings, trailing arms, toe rods & upper control arm bushings Hotchkis sub-frame brace Stop Tech Z-23 brakes 4.10 gears, Eaton Truetrac, LPW diff cover Best 1/4 mile 12.073 @ 115.68 mph 3,300 ft DA

10-04-2019, 01:03 PM	#8
pnwdan Drives: 2014 2SS/RS Join Date: Jan 2018 Location: Washington Posts: 848	My car is a LS3/M6 TSP stage 3 cam I daily it with 3.91s 4.11 would be better for the strip but the 3.91 is a good middle ground for my setup __________________ 2014 2SS/RS LS3/M6

10-04-2019, 01:59 PM	#9
GK_2012_SS Drives: 2012 Camaro LS3 2SS Join Date: Oct 2018 Location: Missouri Posts: 60	Everyone seems to love the 3.91. My question: is there any concerns over the stock SS differential and transmission? My understanding is that the 1LE (which includes the 3.91) has a stronger differential and a different version of the TR6060. My car is a manual SS (not 1LE), I would hate to do this mod then start breaking parts. BTW - I don't race, just street. __________________ Z/28 Cold Air Intake; ARH 1 7/8 Long Tube Headers, High-flow Cats, X-Pipe; Borla ATAK; 160 Deg. Thermostat; Craven Tune

10-04-2019, 03:38 PM	#10
anthony.martinez Drives: 2010 Join Date: Dec 2018 Location: texas Posts: 119	Yes the trade off is miles per gallon for Smiles per gallon!!! It is a great gear for cruising the highway too.

10-04-2019, 08:20 PM	#12
acammer GPI Sales Consultant Drives: 2011 Camaro 2SS SGM Join Date: Jul 2016 Location: Weedsport, NY Posts: 2,794 View My Garage	If you have a M6 car that doesn't have a power adder then anything less than a 4.10 gear is leaving performance on the table. There are really no significant drawbacks to a 4.10. You will gain a couple hundred RPMs at cruising speed in top gear, 70mph is right around 2000rpm - which is a still completely reasonable. I lost 1.5mpg at 70mph. It was no different in mixed/city driving, that all depends on the driver. From a drag race perspective, you definitely want the 4.10. These are heavy cars, and they need all the help they can get to get moving. Additionally, with the 1:1 4th gear you need to get the RPMs up. Like Zlathim said, if we could get more gear in the rear end, I would have a 4.56 back there. Zane and I run 26" tires (stock is 28.66") at the track specifically to increase the final drive ratio. It makes the car easier to launch, and helps down the back half of the track, getting the car back up into the power sooner after you make the 3-4 shift. __________________ GPI Max Package 2.0: Brodix BR7 heads/GPI porting, MAX3 cam, ST2116LSR, BSR Max Lift rockers, LS7 LSXR with 103mm TB, Vararam OTR, Mcleod RXT, G-Force/Strange 9" IRS setup with 4.63 gear. 551whp, 11.1@124mph. *Got a question about a GPI product? Feel free to shoot me a message!*

10-04-2019, 08:31 PM	#13
lemontwist Drives: 12 2SS/RS L99,11 2SS/RS LS3totaled Join Date: Jun 2019 Location: mooresville nc Posts: 1,048	boom 1200 used 3.91 https://www.hawksmotorsports.com/201...-3-91-used-gm/