johnnyar15

ok guys i just got my 85 vette auto, i traded my 87 iroc and my ar15 for it!!

what size is my rear end? is it posi? what is gear ratio? and what gear ratio should i replace it with?

what should i know about my car(problems)

car is stock except straight exhaust, really loud to(original owner put tru duals to center of car wit drop offs no cats), but what can i do to add hp?? all input will be appreciated

thanx

megtom2

Your rear will be in the rpo codes. As far as I can tell the choices were not near as wide as the fbody you had. Also if your 87 had the 350 the two engines are almost identical so any mod you did on your 87 that helped would probably carry over.

johnnyar15

no mods done to my iroc just exhaust and intake

Pwnage1337

Welcome to corvette world, I have an 85 too!

Hopefully you have the 3.07 performance axle. It kicks ***.

johnnyar15

it is the auto version, would that have been installed? also what about the 373 gears for this rear end??

Pwnage1337

The highest factory option was 3.07.

I think the base rear end ratio was 2.59 with automatics. 3.07 was a performance upgrade option

johnnyar15

but what size was the rear end?? and was it posi?

Pwnage1337

stock is D36. D44 was only on manuals for 85.

What exactly is posi? I don't really know lol

johnnyar15

can u tell me what d36 and d44 is?? lol

Pwnage1337

D44 is much stronger than D36. A lot of people with upgrades that make more power go to a D44 because the D36 can't take nearly as much abuse.

johnnyar15

but what is it??

megtom2

I doubt any vette in the last 30 years has come without posi. One side burnouts is what you have to look out for when purchasing fbody speed.

Blue 92

On late model C4s the D36 came from the factory with automatic transmissions. D44 was standard with manuals. No idea if the same held true in 85

Try here for more details

blkzr1

hi, one of the best ways to find out how your 1985 was equiped is to look at the rpo code list. you will find a small white sticker with alot of 3 digit codes like j55, kc4, and so on printed on this sticker. it will be stuck on the bottom of the compartment lid behind the seats or on the bottom of the center console lid. it will be about 2" by 3" in size. make sure that the vin number on the sticker is the same as the vin number on the car. if you can find it, post the codes for all to see. you can also search this forum under an rpo search and find them posted in another thread. see ya

cumbercr

If it has a G44 RPO code, then its a 3.07. Otherwise it will be a 2.59.

Welcome to the 85 club. You'll find there's a few differences from the later years. The codes are located on the underside of the rear compartment lid. Write em, down and post them here. We can tell you what you bought.

If your 85 is truly stock, you're looking at 230 Hp if tuned properly. A major difference with later years is that you have cast iron heads. GM went to aluminum heads midway thru the 86 year. So new aluminum heads should be near the top of you performance list.

BADDUCK

Read the Sticky C4 technical summary and FAQs at the top of the page.
There really are not any meaningful cheap mods for this car. Don't fall for the crap products that claim big power improvements. Valve train, porting the intake, and exhaust are the easiest to do. A 3.07 gear set will help your stop light times.

LD85

85's rock

eguyett1985

Pwnage1337

85's kick ***.

No air bags
No ABS
No third brake light

Lol

snowmanmdp

Hi and welcome,
I too have an 85 and after try everything....
K&N air filter, Magnaflow SS exaust and Smooth air inlet, ported and polished plenum, ported and powdercoated runners and Hooker ceramic super comp headers and airpump delete...So far I would say I have gotten it to around 300 horsepower it has woken up a lot with these mods. My next mod is a new roller create motor.