Its a 86 firebird transam, had a v8 305 and 700r stock... not posi

wondering if someone knows what rear gears this car normally had in it

i want to look myself but always forget to when i have time

appreciate any help

 

check the tech data on this site.

 

imy 86 ta had the lg4 305, 700r4 and 2:73 open rear

 

Looking is the only real way to tell. When you get time and remember, jerk the diff cover and look--and you might consider changing the fluid.

The numbers are stamped on the ring and pinion:

41 : 15 = 2.73
40 : 13 = 3.08
42 : 13 = 3.23
41 : 12 = 3.42
41 : 11 = 3.73

JamesC

 

jack up the rear of the car, chock the front wheels, set the parking brake, and put it in neutral. Make a mark with chalk on a tire and the driveshaft. rotate the tire one full revolution and count how many times the driveshaft turns. If the driveshaft turns roughly 2.75 turns, you have a 2.73 ratio. If it turns about 3.25 times, you have a 3.23 gear etc. etc. This is probably the easiest way to check Your ratio.

 

If you set the parking brake, you wont be able to turn the rear wheels very easily.

 

oh man, it has 2.73s.

305 + 2.73s = instant win? lol

yeah no wonder why this car launches like a school bus from a tar pit.

so what should i put in it? 3.73s? higher?

i want it to be as fast as possible at lower speeds like 0-60, maybe destroy a tire every if i feel like it. it doesn't go on the highway much, and gas milage is no concern. and i'd get a posi if i had that much money right now.

like i said its a 305 though... its slightly better than stock, it has a cam and intake, im gonna get a real engine sometime soon

till then, would a gear change like this help me out? i mean, the way it is now this car is unbelieveably slow from the start, it feels like i get better acceleration around 80-100 then anything and thats not what i want

thanks everyone

 

3.73 would be a great gear coupled with the 700R4's 3.06 first gear.You will need to change the carrier as you have a 2 series carrier and need to go to a 3 series.So this would be the best time to change to an good grade posi unit.Dot it once and be done with if you can.

 

you dont have to change the carrier, you can get 3:73 gears that are made to work with the 2 series carrier

 

Ok maybe i will just get a posi then, while i'm doing this

This brings me to more questions though, like what parts do i get? lol

How can I make sure everything will fit? Like I know my rear end is a 10 bolt, but thats about it. I see there are items to fit a 10 bolt 7.5 and a 8.5 as well. Is that the diameter, so I can just measure it to check?

And then I see there can be either 26 spline or 28 spline. I have no idea what this is. How can I check which mine is?

So what I need to get is the posi carrier, the gears, and an installation kit right?

And yes I have a good mechanic to hook it up

Also, while I remember, the rear end has been making a slight klunk noise when turning... is that bad bearings or what

 

You have a 7.5. It has 26 splines.

JamesC