what gears??? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Jmiller022 · 09-09-2013, 12:06 PM

My truck is for running around town, and enjoying with my family. It won't see a drag strip. So Im looking for the highest gears that I can run to improve mileage as best as possible.

Im running 3.73s now on a 28" tire. I average about 18mpg. I will be swapping in a LSD soon and would like to look at some 3.23s or possibly even 3.08s.

its a regular carb short bed with a 5.3/4l60e. I believe it weighs around 3300lbs(could be wrong).

What are you running in your "driver"?

Indian113 · 09-09-2013, 02:09 PM

I have 3:42's and a 700R4 behind my 5.3 in my S10 and get around 20 mpg's on the HY. I still have plenty of pickup and go, I don't think I would go much lower with a OD trans as it might bog due to low RPM's.

**Hart_Rod** · 09-09-2013, 02:18 PM

Quote:

Originally Posted by Indian113

I have 3:42's and a 700R4 behind my 5.3 in my S10 and get around 20 mpg's on the HY. I still have plenty of pickup and go, I don't think I would go much lower with a OD trans as it might bog due to low RPM's.

+1. Low rpms can be as bad as high rpms on mpg.

**oldman3** · 09-09-2013, 08:04 PM

jmiller022, I agree with indian113 and hart rod. 3:73 with OD {approx 70%) would be 2:61 and 3:42 with OD would be 2:39. Anything lower than that and I think your tranny will be shifting back and forth and mileage may suffer, just my 4 cents worth (inflation)

...Jim

Blackpony · 09-09-2013, 11:12 PM

I am running 3.73 with my 5.7 4l60 combo and i average around 19-20 hwy. 3.42 might net a tick better but i doubt it. at 70 mph im around 2200 rpms

Ryan Hubbard · 09-09-2013, 11:43 PM

I don't have an LS engine but I am running a blown 350 with a 4l80e and am running a 3.55 rear gear with 29" tires and I find it a great combo. I am averaging 16 mpg doing 75-80 mph or sitting in traffic in So Cal.

solidaxel · 09-10-2013, 12:46 AM

Have you considered a taller tire on the rear?

**Clyde65** · 09-10-2013, 07:51 AM

I have a 4.8/4l60e/28" and now I have 3.73's getting about 19.5 on the hwy. before I rebuilt the rear, I had 3.8's and the same combo and got 18.5mpg hwy.

homemade87 · 09-10-2013, 08:17 AM

I have a 82 with a 04 5.3 and 4l60. Factory set up with a tune. I am running the 3.23 gear and does great. It has 28" tires. I get no shifting problems. Around town it does great and on the road I did a 350 mile trip ( interstate) and got 22.3 mpg. I could not be happier with the 3.23. If you plan on towing you may concider a higher number gear.

cjohnson6772 · 09-15-2013, 10:09 PM

I am running a cammed 6.0L/4L80e with 28" tire in a 72 swb with 3.07 gears. I can run at 60-65 mph and it never shifts out of OD. You can definitely hear the torque convertor locking and unlocking which is annoying. When the TC is locked, the RPMs are so low and the drone can be pretty obnoxious even with subdued mufflers.

Considering 3.73s with posi if I can find a factory unit. Would love 3.42s with posi, but I don't wanna spend $800 on my rearend at the moment.

I should also say that interstate cruising (80 mph give or take 10 mph) is great

09-09-2013, 12:06 PM	#1
Jmiller022 Registered User Join Date: Apr 2013 Location: Douglasville, Ga Posts: 212	what gears??? My truck is for running around town, and enjoying with my family. It won't see a drag strip. So Im looking for the highest gears that I can run to improve mileage as best as possible. Im running 3.73s now on a 28" tire. I average about 18mpg. I will be swapping in a LSD soon and would like to look at some 3.23s or possibly even 3.08s. its a regular carb short bed with a 5.3/4l60e. I believe it weighs around 3300lbs(could be wrong). What are you running in your "driver"? __________________ 68' c10 stepper 5.3/4L60e Build thread: http://67-72chevytrucks.com/vboard/s...d.php?t=578917

09-09-2013, 02:09 PM	#2
Indian113 Registered User Join Date: Sep 2009 Location: Monroe,Iowa Posts: 4,370	Re: what gears??? I have 3:42's and a 700R4 behind my 5.3 in my S10 and get around 20 mpg's on the HY. I still have plenty of pickup and go, I don't think I would go much lower with a OD trans as it might bog due to low RPM's.

09-09-2013, 08:04 PM	#4
oldman3 Senior Member Join Date: Mar 2011 Location: West Plains, Missouri Posts: 7,559	Re: what gears??? jmiller022, I agree with indian113 and hart rod. 3:73 with OD {approx 70%) would be 2:61 and 3:42 with OD would be 2:39. Anything lower than that and I think your tranny will be shifting back and forth and mileage may suffer, just my 4 cents worth (inflation)...Jim __________________ my build thread: http://67-72chevytrucks.com/vboard/s...d.php?t=459839 Jimbo's long bed step build:http://67-72chevytrucks.com/vboard/s...t=464626<br />

09-09-2013, 11:12 PM	#5
Blackpony Registered User Join Date: Feb 2013 Location: Aubrey, TX Posts: 308	Re: what gears??? I am running 3.73 with my 5.7 4l60 combo and i average around 19-20 hwy. 3.42 might net a tick better but i doubt it. at 70 mph im around 2200 rpms

09-09-2013, 11:43 PM	#6
Ryan Hubbard Registered User Join Date: Aug 2007 Location: Mission Viejo, CA Posts: 288	Re: what gears??? I don't have an LS engine but I am running a blown 350 with a 4l80e and am running a 3.55 rear gear with 29" tires and I find it a great combo. I am averaging 16 mpg doing 75-80 mph or sitting in traffic in So Cal.

09-10-2013, 12:46 AM	#7
solidaxel Registered User Join Date: Dec 2002 Location: Cactus Patch So. Az Posts: 4,749	Re: what gears??? Have you considered a taller tire on the rear? __________________ 53 TuTone Extended Cab 350 4-Spd 3:08 (SOLD) 53 Chevy Moldy pearl green ZZ-4 4L60E 9" 3:25 55 GMC 1st Black Mll (ZZ4) ZZ6 TKO 600 5 sp 3:73 62 Solidaxle Corvette Roman Red (327 340hp 4spd 3:36) C4 & C5 suspension tube chassis LS 3 4L70E 65 Corvette Coupe 327 350hp 4spd 4:11 78 Black Silverado SWB (350/350) 5.3 & 4L60E 3:42 2000 S-Type 3.0 (wife cruiser) 2003 GMC SCSB 5.3 4L60E 3:42

09-10-2013, 07:51 AM	#8
Clyde65 1965 Chevy C10, 2005 4.8L/4l60 Join Date: Aug 2004 Location: DFW Texas Posts: 8,546	Re: what gears??? I have a 4.8/4l60e/28" and now I have 3.73's getting about 19.5 on the hwy. before I rebuilt the rear, I had 3.8's and the same combo and got 18.5mpg hwy. __________________ Clyde65 Rebuild of Clyde http://67-72chevytrucks.com/vboard/s...84#post8338184 69 Aristocrat Lo Liner build http://67-72chevytrucks.com/vboard/s...84#post7561684 *support our troops!*

09-10-2013, 08:17 AM	#9
homemade87 Registered User Join Date: Apr 2010 Location: Guntersville Alabama Posts: 1,073	Re: what gears??? I have a 82 with a 04 5.3 and 4l60. Factory set up with a tune. I am running the 3.23 gear and does great. It has 28" tires. I get no shifting problems. Around town it does great and on the road I did a 350 mile trip ( interstate) and got 22.3 mpg. I could not be happier with the 3.23. If you plan on towing you may concider a higher number gear.

09-15-2013, 10:09 PM	#10
cjohnson6772 Registered User Join Date: Dec 2010 Location: NC Posts: 666	Re: what gears??? I am running a cammed 6.0L/4L80e with 28" tire in a 72 swb with 3.07 gears. I can run at 60-65 mph and it never shifts out of OD. You can definitely hear the torque convertor locking and unlocking which is annoying. When the TC is locked, the RPMs are so low and the drone can be pretty obnoxious even with subdued mufflers. Considering 3.73s with posi if I can find a factory unit. Would love 3.42s with posi, but I don't wanna spend $800 on my rearend at the moment. I should also say that interstate cruising (80 mph give or take 10 mph) is great



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