Gear ratio help

[SS_Malibu]

Here’s a calculator I used to figure out what gears I want. This may help you narrow down what you want depending on how you will be using your car. I currently have a 2.29 7.5 posi unit in my ‘79 Malibu with a TH400 which makes freeway driving very comfortable. Street driving is decent as I have an ample amount of HP. I will switch to low 3.00 when the rear end is replaced.
Hope this helps.

Calculate RPM for Given Speed(MPH), Rear Gear Ratio, and Trans Gear Ratio

Calculate RPM for Given Speed(MPH), Rear Gear Ratio, and Trans Gear Ratio

purperformance.com

 

[Montecarlo79]

Here’s a calculator I used to figure out what gears I want. This may help you narrow down what you want depending on how you will be using your car. I currently have a 2.29 7.5 posi unit in my ‘79 Malibu with a TH400 which makes freeway driving very comfortable. Street driving is decent as I have an ample amount of HP. I will switch to low 3.00 when the rear end is replaced.
Hope this helps.

Calculate RPM for Given Speed(MPH), Rear Gear Ratio, and Trans Gear Ratio

Calculate RPM for Given Speed(MPH), Rear Gear Ratio, and Trans Gear Ratio

purperformance.com

So I could basically just change my carrier to a post unit to accommodate my 2.29, I just heard for my setup it’s going to be really bad on acceleration

 

[jcelk]

i had the same idea to put in a posi carrier but my bearing were shot so i had to rebuild my rear

 

[Montecarlo79]

i had the same idea to put in a posi carrier but my bearing were shot so i had to rebuild my rear

So what would you recommend with what I picked out?

 

[Montecarlo79]

i had the same idea to put in a posi carrier but my bearing were shot so i had to rebuild my rear

Here’s a calculator I used to figure out what gears I want. This may help you narrow down what you want depending on how you will be using your car. I currently have a 2.29 7.5 posi unit in my ‘79 Malibu with a TH400 which makes freeway driving very comfortable. Street driving is decent as I have an ample amount of HP. I will switch to low 3.00 when the rear end is replaced.
Hope this helps.

Calculate RPM for Given Speed(MPH), Rear Gear Ratio, and Trans Gear Ratio

Calculate RPM for Given Speed(MPH), Rear Gear Ratio, and Trans Gear Ratio

purperformance.com

Think I found the solution

 

[jcelk]

what carrier and gear you use is up to you what one person likes another person won;t . i also have a th350 trans and up graded to a 28 spline axle and 3.08 gears it makes cruising down the highway nice and it;s not to bad off the line others won;t like that combo back in the day i had a buddy that put a 411 gear with a 4 speed muncie trans i was great off the line but you didn;t even want to drive it down the highway ..take your time and do some research because it;s gona cost some coin .and when ordering parts there is a difference between the 78 -81 rear and the 82 and up an easy way to tell is the factory started using metric lugs in 1982 but read up on the differences . good luck

 

[Montecarlo79]

what carrier and gear you use is up to you what one person likes another person won;t . i also have a th350 trans and up graded to a 28 spline axle and 3.08 gears it makes cruising down the highway nice and it;s not to bad off the line others won;t like that combo back in the day i had a buddy that put a 411 gear with a 4 speed muncie trans i was great off the line but you didn;t even want to drive it down the highway ..take your time and do some research because it;s gona cost some coin .and when ordering parts there is a difference between the 78 -81 rear and the 82 and up an easy way to tell is the factory started using metric lugs in 1982 but read up on the differences . good luck

I just want something that has decent acceleration for what I’m running/good highway driving or fuel economy somewhat, because I find with the setup with my motor it’s going to be running around 1800-5800 rpm and with my 2.29 rear end it just seams that it would take so long for the powerband to get up to par, so far I have seen for recommendations, the 3.08, 3.23, or the 3.42, anything that I have heard below 3 is not good for a somewhat high rpm engine because of the powerband.

 

[86LK]

What do you mean new? The whole kit I showed accommodates 26 spline, I shouldn’t have to swap out my axles

I was referring to if you did a junkyard swap instead of buying new. iirc, the 26-spline was not as common as the 28-spline

 

[Sweet_Johnny]

If on a super tight budget then grab these and an install kit (2 gear choices shown). The Chinese posi is for 26 spline axles so it'll drop right in, and it's available from 20 different sellers on Amazon as well as eBay. Motive makes great parts and has at least two performance levels that I recall- the parts listed are the cheap ones and their others are $100 more, Richmonds sometimes whine on the street, U.S. Gear and Yukon are about equal, and sometimes 3 of the above brands show up in each other's boxes (same manufacturer):

 

[olds307 and 403]

Another source is the mid 80's, up to 89 Astro van. I got a set of 3.42 gears with an open carrier from one, wrecker said most were 3.23 gears. We actually have some old crap still here in Saskatchewan. Nothing wrong with a open rear and used gears for a street car. Just count the axle splines. The stock spider gears are soft and did explode a set. It took out the pinion gear. The replacement were showing wear as well. I used the Yukon replacement open spider gears at the track with slicks and they held up great. Honestly the small spider gears can be issue on a 7.5" posi. A Trutrac or a used Zexel Torsen posi uses a worm gear in place of the spider gears, is another option.