What gears should I use in my rear end? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Kerlijah · 09-07-2011, 05:40 AM

So I'm saving up my nickels and dimes, hoping to get different gearing soon. Unfortunately, when it comes to gearing, I dont know jack

I drive my truck every day, mostly just in town, but I also drive it a lot on the highway. I dont have a tach, so I cant say exactly how many rpm's I'm turnin at 65 down the highway,(way high though I'm sure) but I can tell you Ol Yeller really doesnt like goin that fast at all, it's practically screamin!!

So my question is, what would yall recommend for gearing in my truck? It's 2-wheel drive, has the stock 4-speed with granny low--it's so low geared right now it could pull my house off the foundation, but since I just drive it, I dont really work it, I'd REALLY much rather be able to get up and go, but cruise at highway speeds without feeling like I'm gonna blow my engine...

Any help would be awesome, thanks guys!!

ont_guy_38 · 09-07-2011, 07:36 AM

You probably want a 3:42 gearing . That is a good all around ratio

Goldfinger · 09-07-2011, 07:46 AM

2.73 for mpg. the acceleration is a little less but has a high top speed and will run highway at low rpms

MalibuSSwagon · 09-07-2011, 08:17 AM

I have the stock SM465 and 2.73 gears. Its not a screamer but it drives and tows fine. Highways rpms are 2k rpm at 60-65. Just needs more power to get up and go!

**N2TRUX** · 09-07-2011, 11:21 AM

No one can properly answer your question with out more data to input. What motor do you have? What size tires are you running? Exactly what transmission do you have? Answer these questions and we can offer our best advice.

James McClure · 09-07-2011, 12:27 PM

N2, thankyou. I was waiting to see if someone asked these critical questions. Kerl, we need to know everything thats in front of the diff as well as tire sizes and current diff ratio. (more on this later) Without good information you can't get a good logical answer. What works for driver "A" or "B" may not be good for you or your truck. We also need the current ratio because you can't put series 3 gears on a 4 series carrier, so if you have 4:10 gears in there now 3:73 or 3:08 ect won't fit without a spacer or a 3 series carrier. If you can't decode the diff from the numbers on top of the R\S axel tube or suspect a previous diff change the most accurite way to determine ratio is to pop the cover aand look for numbers on the ring gear. The numbers you seek look like this, "00:00". They will be arranged that way. 15:41 is 2:73 ratio, where 15 represents # of teeth on the pinion & 41 the number of teeth on the ring gear. Divide 41 by 15 and you get 2:73. jim

09-07-2011, 05:40 AM	#1
Kerlijah Registered User Join Date: Feb 2011 Location: Boise, ID Posts: 293	What gears should I use in my rear end? So I'm saving up my nickels and dimes, hoping to get different gearing soon. Unfortunately, when it comes to gearing, I dont know jack I drive my truck every day, mostly just in town, but I also drive it a lot on the highway. I dont have a tach, so I cant say exactly how many rpm's I'm turnin at 65 down the highway,(way high though I'm sure) but I can tell you Ol Yeller really doesnt like goin that fast at all, it's practically screamin!! So my question is, what would yall recommend for gearing in my truck? It's 2-wheel drive, has the stock 4-speed with granny low--it's so low geared right now it could pull my house off the foundation, but since I just drive it, I dont really work it, I'd REALLY much rather be able to get up and go, but cruise at highway speeds without feeling like I'm gonna blow my engine... Any help would be awesome, thanks guys!! __________________ ~Wooden Indian~ 1979 C10 SWB, shaved bed rails, drip rails, tailgate handle. 350 w/ Comp cam, hydraulic lifters, Edelbrock Performer intake, Edelbrock 650 carb, Flowtech headers, Flowmaster 40s, turbo 350 w/stage 2 shift kit...so much fun!

09-07-2011, 07:36 AM	#2
ont_guy_38 Registered User Join Date: Jul 2007 Location: Ontario Canada Posts: 1,006	Re: What gears should I use in my rear end? You probably want a 3:42 gearing . That is a good all around ratio

09-07-2011, 07:46 AM	#3
Goldfinger Registered User Join Date: May 2010 Location: laurel hill Fl Posts: 645	Re: What gears should I use in my rear end? 2.73 for mpg. the acceleration is a little less but has a high top speed and will run highway at low rpms __________________ 1985 C10 Custom Deluxe LWB 305/700r4 [ Goldfinger ] 1999 k3500 crew cab dually 6.5tdi/4l80e

09-07-2011, 08:17 AM	#4
MalibuSSwagon Registered User Join Date: Sep 2009 Location: Weare,NH Posts: 1,591	Re: What gears should I use in my rear end? I have the stock SM465 and 2.73 gears. Its not a screamer but it drives and tows fine. Highways rpms are 2k rpm at 60-65. Just needs more power to get up and go! __________________ Eric 1992 Oldsmobile Custom Cruiser 1986 Chevrolet C10\|5.3L\|TKO600\|Shortbed\|Custom Deluxe 1983 Malibu Wagon\|TPI 305\|T5 5 speed\|3.73 non-posi

09-07-2011, 11:21 AM	#5
N2TRUX Happy to be here Join Date: Mar 2000 Location: Cypress, TX Posts: 39,023	Re: What gears should I use in my rear end? No one can properly answer your question with out more data to input. What motor do you have? What size tires are you running? Exactly what transmission do you have? Answer these questions and we can offer our best advice. __________________ Follow me on Facebook and Instagram @N2trux.com Articles- "Jake" the 84 to 74 crewcab "Elwood" the77_Remix 85 GMC Sierra "Scarlett" "Refining Sierra"

09-07-2011, 12:27 PM	#6
James McClure One shot, one kill. Join Date: Dec 2007 Location: Saratoga Springs NY Posts: 859	Re: What gears should I use in my rear end? N2, thankyou. I was waiting to see if someone asked these critical questions. Kerl, we need to know everything thats in front of the diff as well as tire sizes and current diff ratio. (more on this later) Without good information you can't get a good logical answer. What works for driver "A" or "B" may not be good for you or your truck. We also need the current ratio because you can't put series 3 gears on a 4 series carrier, so if you have 4:10 gears in there now 3:73 or 3:08 ect won't fit without a spacer or a 3 series carrier. If you can't decode the diff from the numbers on top of the R\S axel tube or suspect a previous diff change the most accurite way to determine ratio is to pop the cover aand look for numbers on the ring gear. The numbers you seek look like this, "00:00". They will be arranged that way. 15:41 is 2:73 ratio, where 15 represents # of teeth on the pinion & 41 the number of teeth on the ring gear. Divide 41 by 15 and you get 2:73. jim __________________ 1984 K20 350M engine with 465,000 miles. Well, it's finally done!! Almost 2 years of work, but it was really worth the effort. Little stuff left to do is mount winch, wet sand & buff out and build belly pan\running boards. Body work takes lots and LOTS of beer!!!! God, Guts and Guns made America and God, Guts and Guns will preserve it! The worst thing you could do is get into my sights, but that don't matter, you'll never know it, cause you'll never hear the shotJim or Paladin whichever you choose.



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