GEARS HELP PLEASE

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KEVINS800

n00b
Oct 29, 2011
3
2
3
hello, put 2005 4.8 ls / 4l60 fuel injected into my 81 cutlass and i know i would like better gears i was thinking 355-373? just going to be a highway, town car, no racing! what would everyone recommend for gears, carrier, should i put disk on rear end? is there any thought? i am upgrading the front brakes right now to s10! i do have a small shop and do know the proper way to set gears up, don't do it a bunch but can do it! any insight would be great also where would u recommend buying parts at fair prices? thanks
 
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spidereyes455

G-Body Guru
Mar 6, 2013
781
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Anything in the 3's should do you just fine. I would probably lean more to 3.42 or 3.73 if red light to red light fun was your bigger concern and you would still be able to cruise the highway comfortably with the overdrive. If highway cruising is more your thing then I would lean more towards a 3.23 or maybe even a 3.08 to really get the most out of the overdrive.
 
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Texas82GP

Just-a-worm
Apr 3, 2015
7,986
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The 4L60E has a pretty steep first gear at 3.06:1 and a relatively tall overdrive ratio at 0.696:1 so I'd go with 3.42:1 rear gears. Rear discs are not needed unless if you are going to repeatedly stop hard like autocrossing. The drum brakes will stop the car just fine if in good shape and properly adjusted. Look into the S10 wheel cylinders and the wheel cylinder brackets. They may be worthwhile mods for you.
 
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dmac35242

Not-quite-so-new-guy
Dec 23, 2021
25
39
13
Birmingham, AL
One of my work trucks has a 4.8/4L60/3.42 combo.
It lacks throttle enjoyment down low because of engine size and gearing.
I would seriously consider a 3.73 gear to help put a smile on your face.
The final effective ratio with the 4L60 would be 2.60
That gives a 70 MPH cruise of 2352 RPM
80 MPH with 3.73 = 2688 RPM
These numbers assume a 26" tall tire.
 
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Built6spdMCSS

Geezer
Jun 15, 2012
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just going to be a highway, town car, no racing!
Marc Lamont Hill Wtf GIF by Identity
 
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-dw-

Greasemonkey
Mar 15, 2021
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Central MN
One of my work trucks has a 4.8/4L60/3.42 combo.
It lacks throttle enjoyment down low because of engine size and gearing.
I would seriously consider a 3.73 gear to help put a smile on your face.
The final effective ratio with the 4L60 would be 2.60
That gives a 70 MPH cruise of 2352 RPM
80 MPH with 3.73 = 2688 RPM
These numbers assume a 26" tall tire.

A truck could easily be 1000lbs heavier and the tires 4-5in taller. Not a fair comparison.

3.41 gear would be good all around.
 
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Dec 22, 2022
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hello, put 2005 4.8 ls / 4l60 fuel injected into my 81 cutlass and i know i would like better gears i was thinking 355-373? just going to be a highway, town car, no racing! what would everyone recommend for gears, carrier, should i put disk on rear end? is there any thought? i am upgrading the front brakes right now to s10! i do have a small shop and do know the proper way to set gears up, don't do it a bunch but can do it! any insight would be great also where would u recommend buying parts at fair prices? thanks

hello, put 2005 4.8 ls / 4l60 fuel injected into my 81 cutlass and i know i would like better gears i was thinking 355-373? just going to be a highway, town car, no racing! what would everyone recommend for gears, carrier, should i put disk on rear end? is there any thought? i am upgrading the front brakes right now to s10! i do have a small shop and do know the proper way to set gears up, don't do it a bunch but can do it! any insight would be great also where would u recommend buying parts at fair prices? thanks.
Ok Kevin, these are just opinions... 3.55 will still you SOME performance, but at the end of the day it's a highway car... 2nd question..
Big yes on rear disk conversion, did mine and it just feels better..
And 3rd comment... Save for the better products, you will be happier in the end. If it's a long term car..
Justy $0.02
 
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69hurstolds

Geezer
Supporting Member
Jan 2, 2006
8,191
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Throwing my 3 cents in (inflation adjusted).

Go with mid-3 gears within the range of 3.23 (mostly highway) all the way to 3.73 max (mostly in town). You pick 'em based on where you're planning on using it the most. It'll make any G-body more fun to drive without the extra revs on the highway. Remember that performance and street manners are a give and take. So you have to find your sweet spot.

Disc/disc is usually always better than disc/drum and street or highway, better braking is always welcome. The simplicity of the disc brakes alone makes it worth it, let alone the inherent increase in stopping power if done correctly. A bit of work involved but nothing serious. If you can do rear gears, you can do a disc conversion.

Good luck.
 
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Wraith

Royal Smart Person
Jan 13, 2013
1,602
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DFW, TX
What gear ratio do you have currently? Tire size?

I've always run 3.73 gears in my former naturally aspirated G Bodies, overdrive or not but always ran a 275 on the rear, 275/60/15 or 275/40/17.
 
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Max Headroom

Master Mechanic
Sep 8, 2011
420
389
63
Correct ,me if I am wrong but if you run 30" tall tires (15" rims), in order to run at 60 mph at around 2300 rpm, it would require around a 3.50 rear end ratio.
With a 32" tall tire at 60 mph and 2300 rpm you would be in the 3.73 rear ratio neighborhood.




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