Cascade Crew

83Z28BlackBetty · Posted: Fri Apr 07, 2006 2:40 am Post subject: Rear end swap

So if I get some extra money and want to swap out my rear-end, what set up would you recomend? gear ratio, year, and the like. I have never worked with gear ratio stuff so I know nothing, im just trying to learn something here Smile

rjmcgee · The Hammer Joined: 08 Jan 2004 Posts: 2328

What is in it now? Might be worth pulling the cover to see what the ratio is.

Xophertony · Posted: Fri Apr 07, 2006 10:54 am Post subject:

if you are planning on building it up the rear end get a 10 bolt, there are more parts available for them. if you are planning on leaving the rear end stock get a 9 bolt, they are stronger fromt he factory. 3.23 or better. i kinda wish i had gone with 3.42s now... Sad

so if anyone is selling a 9bolt posi 3.42 i want it Very Happy

Quasi-Traction · Posted: Fri Apr 07, 2006 3:07 pm Post subject:

Put a 9" in it ! Thumbs up

Seriously though.....here's a couple things to consider:

1) you have a 700R4 Auto........are you going to keep that transmission and do you rear gear change first or put in a different transmisson then consider a rear end swap? Are you gonna change to another automatic, say a TH350? Or are you considering a 4, 5 or 6 speed manual?

2) Assuming you keep the 700R4, do you want something that gets good highway mileage, or something that is fast off the line and going through the gears.

Higher Numerically the gear number in the rear, the larger your final drive ratio is, Final drive ratio is figured like this:

Transmission gear X Rear end gear = Final drive ratio

lets take OD gear in the 700R4

.74(Overdrive gear in trans)x 3.42 (rear end gear size)= 2.53:1 Final drive.

Do the same with every gear in your transmission and you know your final drive in every gear.

Higher numerically final drive ratios mean faster acceleration, but also mean higher engine rpm in operation, especally in your last drive or overdrive gear.

Check out Febuary 06's Chevy High Performance if you get a chance. its got a great article about engine rpm operation and gear ratios and how it factors into fuel economy and performance and achieving the best of both worlds. The article is called "Fight Back Oil Prices"

aaron_sK · Posted: Fri Apr 07, 2006 4:14 pm Post subject:

Also depends on what type of engine you have, what type of intake you have, how much HP you're shooting for, and what your torque curve looks like.

If you run a carb or a high-revving intake like an LT1 or an HSR, you can go quite a bit higher than if you run, say, TPI.

LB985IROC · Posted: Sat Apr 08, 2006 11:34 am Post subject:

i would go wiht a set of 3.73 gears and a new possi and get one form a 85 or newer oric or trans am so you can convert to rear disc

rjmcgee · The Hammer Joined: 08 Jan 2004 Posts: 2328

Xophertony · Posted: Sat Apr 08, 2006 8:36 pm Post subject:

you could actualy get disc rear brakes on a thirdgen since 82. it is just more rare in the early 3rd generation. if you get an 89 or newer disc rear you will have the larger 11.75" rotors.