GEARS HELP PLEASE

[KEVINS800]

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

 

[Texas82GP]

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.




View attachment 219227 View attachment 219228

Correct, with a non-overdrive transmission.

 

[olds307 and 403]

Who would run tires that 30" or 32" size in a G body? The OP has a .70 overdrive and 4.8 LS, I say 3.42 minimum, probably 3.73 considering the 4.8 likes and needs to rev. I use the Olds Gmail calculator when using a lock up torque converter or manual transmission, I add 300ish rpm for no lock up with that calculator. With a 28" tall tire, my 2.78 gear and the current non lock up TH350, 60 mph is that 2300 rpm for me, a 3.42 would be around 2800 rpm at 60 mph. http://tech.oldsgmail.com/ch_axle.php

 

[Ernest]

Being that the stock 4.8L isnt exactly considered a performance engine(285hp), and with the 4L60E OD transmission used, its more of a daily driver of sorts with gas mileage in mind, i would go with 3.42 max if you want some pep moving from light to light, along with an average of a 27" tall tire, you'll be keeing the engine around 1800rpm at 60mph, around 2100rpm at 70mph.

 

[spongbob]

For starts have been mulling over the lower gear swop myself .Speaking from the low end of cost prospects. I've found out a few things .1 s10s have the 7.5 gear in the 7.5 config. 2. S10 2 wheel drives have the 26 spline side gears and unusable axles...3 years being safe on these facts are 85 to say 92 for 2 wheel drive equipt...4. The s10s with 4.10 rearends were the 4 cylinder equipped ones .5 to swop the gears you need the carrier that's in the Doaner housing.obviously with the matching pinion if your useing used stuff. 6. S10s have that still having the rop sticker with codes inside the dash glovebox door. To put new gears when you change say from the 2.90 say to the mentioned 3.44 ect you have to change the carrier or find the thicker ring gear for use on the 2 series carrier. THER IS SOME MENTIONING about spacers for ring gears that are not made thicker so probaly thin gears availible (need spacer ring?..I'm just mentioning some of the process for swopping thr 7.5 series 2 ring and pinion 7.im not mentioning any shimming miking or sanding of shims to fit new bearings . Or 28 spline axles being bigger (93 up)around ...or suggesting you change to disc brakes lol