The feel of a new rear

[LukeZ]

hey all,

You may or may not know me, but ive been posting a lot about rear ends lately. My car is an all stock 86 elco, V8. I've decided to go from my open diff 7.5in 2.56s to a performance set of 3.42s with posi, keeping the 7.5in size. Ive been reading a lot about gear swaps lately, and most people barely see a difference in quarter mile or 0-60 times with this prticular swap, but they say the car feels a whole lot different. I asked my friend who has a 77 firebird who went from 2.76s to 3.23s, and he said it's a completely different car. I'd like to have that feeling with my car. It does have overdrive, so my milage shouldn't suffer too much. I'm looking for some personal opinions here: do you think a swap like this will breath some life into my 100% stock g body?

 

[84_SS]

I went from 3.42 to 3.73 posi when i had the stock 305 with a few bolts on and it was a different car and needless to say I had to buy new tires before summer was over.

 

[LukeZ]

I went from 3.42 to 3.73 posi when i had the stock 305 with a few bolts on and it was a different car and needless to say I had to buy new tires before summer was over.

That's what I wanted to hear! I am trying to liven up this tired car as much as possible before I can get a proper engine swap, so I think this will be a good idea in the end.

 

[84_SS]

The only downfall to all of this is its never enough power. Once you get used to it you want more and more and then you end up doing a whole build lol.

 

[rad928music]

You have a Over drive so you are in good shape.
It should help performance.
I want to get a 3.41 but I have a 3 speed 375Thm.
May have to get a 200 r4 THM or 700 r4 but for now I have no real desire to do it.
The 700 r4 should fit because I'm running a long tail 375 THM with a shorted driveshaft.
I have 1980 GP\w a Pontiac 400 and 2.41 Granny gears, but the 375THM has a 2.41 first gear.
The 700 r4 has a 3.07 First gear.
Id love get a 3.41 and a Posi, I bet it would take a second off the 0-60 and Qt mile times.

 

[pontiacgp]

It's all about what you like, I had 2.41 rear with the 200 r4, I tried 3.42 gears and didn't like them so I put in 3.08 gears I changed the rear to an 8.2 and it came with 3.08 eaton posi which I really like especially with a stick.

 

[LukeZ]

It's all about what you like, I had 2.41 rear with the 200 r4, I tried 3.42 gears and didn't like them so I put in 3.08 gears I changed the rear to an 8.2 and it came with 3.08 eaton posi which I really like especially with a stick.

What was wrong with the 3.42s? I have be experience in this at all, so I'm trying to gather as much as I can before switching gears. I need to know if 3.42s are way too high, so that I can go with maybe 3.08s or 3.23s instead.

 

[pontiacgp]

What was wrong with the 3.42s? I have be experience in this at all, so I'm trying to gather as much as I can before switching gears. I need to know if 3.42s are way too high, so that I can go with maybe 3.08s or 3.23s instead.

There is nothing wrong with the 3.42 if you like them. I found the 3.42 too high and I have friends who think I am crazy.

 

[pencero]

You will sacrifice gas mileage and go through tires more often but it's worth it if you enjoy the car more. Supposedly the 700r4 works with the stock rear gears pretty well and doesn't really need a higher gear set. I had a 82 monte cl for a few months w/ 350 & 700r4 and it was pretty fast w the stock rear gears but a posi would have been a huge improvement - it would spin tire way too long before finally hooking up if you gave it more than half throttle. A posi is going to hook up basically right away w/o wasting your time, unless you add a lot more power after that, as someone already said.

 

[pontiacgp]

I don't like the 700 r4, it was geared for trucks with the 1st gear (3.06) being a granny gear. When you hit second gear (1.63) it's like hitting a wall.