I have a 1987 chevy z28 camaro
I was wondering what the differential ratio was on my car ... ? i think thats what i want to know. I wasn't sure what people have changed theirs to, anyone have any suggestions? i was told that 4:11 or 4:12 might be good.


thanks again

 

Not sure what you got. Whats the RPO. anyway I went from a 2.73 to a 3.73, then blew that up and now I have 3.42s. I wouldn't recommend 4.11s on a street car.

 

The ratio could be 2.73, 2.77, 3.23, 3.27, or 3.45...

What engine does it have (305 carb auto, 305 TPI manual, etc.) and we can guess at what it probably came with stock. Count the bolts on the cover, it would help to know whether it has a 9-bolt or a 10-bolt.

There's a 4.10 available for the 10-bolt, and I think also for the 9-bolt; it's too much gear for most of these cars. The car will usually go fastest with 3.42 or 3.73 gears depending on motor & trans.

 

K, Im quite un experienced with this part of the car. do i just go out and count the bolts on the midle of the axle between my rear tires? I have a 305 with a Carb, Instead of throwing money into a supercharger i was swayed to fix up this thing and modify other parts of my car before supercharging it. What does it mean when i have a higher number? and what would it mean if i had a lower number? If i went with the 4.10 what would i get? or if i went with the 3.42 what would i get? sorry for the laman questions Im still trying to learn


I also have the 4 speed overdrive transmission if that helps

 

That's what you'd count...

If it originally came that way, it's probably a 10-bolt, probably 2.73s if it's auto trans or 3.23 if it's a 5-speed.

The number is the ratio of how many times the driveshaft turns, to one revolution of the wheels. The higher the number, the higher the engine speed will be at any given car speed. Since engines produce more power at a higher RPM, this translates to faster acceleration, possibly at the expense of top speed and gas mileage although those things vary quite a bit from one car to another.

If the motor is still stock, 3.42 if you have an auto trans or 3.73s if you have a 5-speed are about as far as you would want to go. That engine doesn't breathe well enough to support really high RPM operation; with too much gear what you'll get is a trmendous grunt off the line, then the motor will tach up to however fast it can possibly go and hang there without accelerating the car. Plus with too much gear, you'll find yourself at 3000 RPM or more in normal freeway driving.

The things to do to that car are, in order of importance, the exhasut all the way from the heads to the street; the cam, you have the lamest cam ever installed in a small block Chevy; the heads, which respond fairly well to porting; and the gear.

 

Where should i look for a 3.42 rear differential? Any places you guys know that sell them? any place i ca rip one out of ? ... im kinda clueless. lol But I want to learn, and about how much time do you think it would take someone helping me do it? thanks again

 

if your refering to changing the entire rear its quite simple, changing the gears is also not that hard but it helps to know what your doin.. with your tranny i'd personally go with 373's... proformance with reasonalble top end and gas mileage..also if you plan on supercharging it i'm guessin your goin for proformance.. i'd recommend puttin a 350 in it first.. a 305 just doesnt seem to make any sense to me.. hehe

 

my car is a street car and it's got 4.33's with a 26" tall tire not that my car is any ordinary street car lol.

 

fast how did ya run the duals? my car has way too much back pressure with the ****ty flowmaster single pipe pos n i want to run real duals...any suggestions would be appreciated

 

Heh, I wanted to get the rear end of my car and my transmission up to par for a 350 and a turbo, just wanted to prepare it... 3.73 sound like a nice good reasonable number? lol