Iv had this car for a while, an 86 TPI Iroc, and i know that the rear end ratio is not what it originally was. my speedo shows faster than the real speed, when it shows 65 in really going around 55ish. im not sure of the ratio though.

There are 9 bolts on the cover, 4 on the top, 5 on the bottom. im pretty sure 10 bolt is stock right?

There is a tag on one of the bolts that you cant see in the pic that says "SPIN RESISTANT DIFF USE APPROVED LUBRICANT ONLY"



If anyone can tell me what this rear end is then that would be great, and what kind of lubricant i would need for this. Id rather know before i take the cover off.

 

you answered your own question. "there are NINE BOLTs around the cover". it's a BW 9 bolt. put in limited slip additive and some syn gear lube.

 

BW? the first thing i think of when i see BW is 'backwards', but i dont think thats what BW is here.

My knowledge is very limited with rearends, so would this be a Ford 9 bolt? Do you know whether this is a better rearend than stock?

and thanks for replying

 

You have a Borg Warner 9 bolt. It's a stock GM rear-end, although a better one than the 10 bolt rear more commonly used on these cars.

The Ford rear is a 9-inch, not a 9-bolt.

 

I see now, thanks man. Although my gears still must have been changed. Ill find out when i count the teeth with the cover off.

One more, is this rearend still 7.625"?

 

No, 7.75". There's nothing interchangeable at all between the 9 bolt and 10 bolt, other than the brakes and wheels.

 

The bolt count is for ring gear bolts, not cover bolts. FYI.

 

you know, I've never actually counted the ring gear bolts to know if that's true or not... funny. Coincidentally, both rears have the same number of cover bolts.

 

Interesting, I didnt know that. thanks