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

81ratrodc10 · 05-13-2010, 11:11 PM

how do you decide what gear ratio is best for one self dont know what my truck has and was just wondering how some of you guys decied

Keith Seymore · 05-14-2010, 07:43 AM

I always start at 3.42:1.

Then, if you want more performance, go up numerically (ie, 3.73, 4.10, etc).

If you want more fuel economy, go down numerically (3.23, 3.08 etc).

K

LONGHAIR · 05-14-2010, 10:03 AM

It depends upon several factors. Tire size, transmission type, % of highway driving, intended use, etc.

81ratrodc10 · 05-14-2010, 10:06 AM

im not going to be running huge tires im looking into 275/60r15 drag radials th350 trans with stall converter average highway driving mostly my dd and weekend play truck

blazer2007 · 05-14-2010, 10:07 AM

I used the Richmond gear calculater,just punch in tire size or gear ratio and it will tell you rpm at a certain speed or what you need to achieve rpm ,tire size etc.sorry I don,t know how to post a link but should be easy to find

Mike C · 05-14-2010, 08:36 PM

Great advice from all above. 275 60 15 are 28" tall. With TH700, would probably be happy with 3.73 or maybe even 4.10. With T350/400 would probably be better served with 3.42 or 3.73 on the big end. But it depends on the motor and what your intended use is as well. Plenty of gear ratio calculators out there to help you, start by figuring out what you have now to begin.

81ratrodc10 · 05-14-2010, 09:42 PM

how do i tell by looking at them what ratio it is

81ratrodc10 · 05-14-2010, 09:53 PM

buy the calculater is says i havr 2.08 does that sound right i know nothing about gears

slugish · 05-14-2010, 10:54 PM

3.42 with a 3 speed 350 or 400 is the best of all worlds for you . Had a 3.73 in mine & took it out > then put in a 3.08 < ( good highway gear ) wasnt satisfied > ended up with A 3.42 . WITH A TALL TIRE 30 in or so a 3.73 would be ok .

81ratrodc10 · 05-15-2010, 12:16 AM

thats what i was told from a buddy of mine who has that ratio in his mustang

3r!c84 · 05-15-2010, 01:27 AM

i got 3.42 gears in mine with a th350 and 28in tall tires.it was a big improvement from the 2.7 somthings that where stock

LONGHAIR · 05-15-2010, 09:24 AM

Quote:

Originally Posted by 81ratrodc10

buy the calculater is says i havr 2.08 does that sound right i know nothing about gears

2.56 is the highest I have ever seen, you must have one of your input numbers wrong. Speedometer or tach readings may not be accurate?

dan76 · 05-15-2010, 04:25 PM

http://www.grimmjeeper.com/gears.html

This is a link to a road speed/gear ratio/trans type/rpm/tire size calculator. You can plug in different combinations and see the results.

05-13-2010, 11:11 PM	#1
81ratrodc10 house of chevy's Join Date: May 2010 Location: New milford, CT Posts: 583	rearend gears ? how do you decide what gear ratio is best for one self dont know what my truck has and was just wondering how some of you guys decied

05-14-2010, 07:43 AM	#2
Keith Seymore Registered User Join Date: May 2009 Location: Motor City Posts: 9,177	Re: rearend gears ? I always start at 3.42:1. Then, if you want more performance, go up numerically (ie, 3.73, 4.10, etc). If you want more fuel economy, go down numerically (3.23, 3.08 etc). K __________________ Chevrolet Flint Assembly 1979-1986 GM Full Size Truck Engineering 1986 - 2019 Intro from an Old Assembly Guy: http://67-72chevytrucks.com/vboard/s...d.php?t=342926 My Pontiac story: http://forums.maxperformanceinc.com/...d.php?t=560524 Chevelle intro: http://www.superchevy.com/features/s...hevy-chevelle/ Last edited by Keith Seymore; 05-14-2010 at 07:43 AM.

05-14-2010, 10:06 AM	#4
81ratrodc10 house of chevy's Join Date: May 2010 Location: New milford, CT Posts: 583	Re: rearend gears ? im not going to be running huge tires im looking into 275/60r15 drag radials th350 trans with stall converter average highway driving mostly my dd and weekend play truck

05-14-2010, 10:07 AM	#5
blazer2007 Registered User Join Date: Jan 2007 Location: vernon b.c. Posts: 3,022	Re: rearend gears ? I used the Richmond gear calculater,just punch in tire size or gear ratio and it will tell you rpm at a certain speed or what you need to achieve rpm ,tire size etc.sorry I don,t know how to post a link but should be easy to find

05-14-2010, 08:36 PM	#6
Mike C Registered User Join Date: Dec 1999 Location: Austin, TX, USA Posts: 7,715	Re: rearend gears ? Great advice from all above. 275 60 15 are 28" tall. With TH700, would probably be happy with 3.73 or maybe even 4.10. With T350/400 would probably be better served with 3.42 or 3.73 on the big end. But it depends on the motor and what your intended use is as well. Plenty of gear ratio calculators out there to help you, start by figuring out what you have now to begin. __________________ 44 Willys MB 52 M38A1 64 Corvette Coupe 68 Camaro 'vert LT1 & TH700 69 Z/28 355 12.6's @110 69 Chevy Short Step 4 1/2"/7" drop 72 Jimmy 4WD 4spd 4" & 35's 02 GMC 2500HD 4x4 Duramax

05-14-2010, 09:42 PM	#7
81ratrodc10 house of chevy's Join Date: May 2010 Location: New milford, CT Posts: 583	Re: rearend gears ? how do i tell by looking at them what ratio it is

05-14-2010, 09:53 PM	#8
81ratrodc10 house of chevy's Join Date: May 2010 Location: New milford, CT Posts: 583	Re: rearend gears ? buy the calculater is says i havr 2.08 does that sound right i know nothing about gears

05-14-2010, 10:54 PM	#9
slugish Slugish Join Date: Jan 2005 Location: Earlysville, Va. Posts: 1,024	Re: rearend gears ? 3.42 with a 3 speed 350 or 400 is the best of all worlds for you . Had a 3.73 in mine & took it out > then put in a 3.08 < ( good highway gear ) wasnt satisfied > ended up with A 3.42 . WITH A TALL TIRE 30 in or so a 3.73 would be ok .

05-15-2010, 12:16 AM	#10
81ratrodc10 house of chevy's Join Date: May 2010 Location: New milford, CT Posts: 583	Re: rearend gears ? thats what i was told from a buddy of mine who has that ratio in his mustang

05-15-2010, 01:27 AM	#11
3r!c84 Badass Join Date: Jan 2009 Location: lox. fl Posts: 4,586	Re: rearend gears ? i got 3.42 gears in mine with a th350 and 28in tall tires.it was a big improvement from the 2.7 somthings that where stock __________________ Think outside the box? -84c10 (1stcar)→My Build← -00 Saturn 5spd drop a gear and disappear! 1/4:13:90

05-15-2010, 04:25 PM	#13
dan76 Registered User Join Date: Mar 2008 Location: Salt Lake City UT Posts: 441	Re: rearend gears ? http://www.grimmjeeper.com/gears.html This is a link to a road speed/gear ratio/trans type/rpm/tire size calculator. You can plug in different combinations and see the results.



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