My dad just bought an 89 Iroc tonight but it is missing the RPO code sheet. It is a well optioned car with-

5.7/Auto(of course)
T-Tops
PW/PL/PM
Rear disc breaks
Gray Interior

So I was wondering how i could find out the rear gear ratio without taking it apart. Do rear disc cars come with only one gear ratio? Or does it also have to do with the 5.7?

Any help would be great.

Ryan

 

If you look on the rear end cover there is alittle tag that will tell you the ratio.

 

ok cool, and did all 5.7L cars get rear discs? or was it an option?

 

Yes in 89 all 5.7's should have the rear disks.... this was suposed to be true from 87-92 however there was a short time in 91 where the Disks were not available. But this will not effect yours.

John

 

Look on the rear end cover for a rubber fill plug, this would be the Australian nine bolt rear and probably a 2:77 ratio positraction.

 

I have an 89 IROC and its 3:45

 

And I would bet its not a stock 350 or a Auto.

 

the highest ratio for the 350 was 3.27 for 3rd gens.

3.45 would have been a 305 LB9/M5 car.

John

 

The highest ratio for a stock 350 car is 2:77 which is the majority and the lowest would be the optional 3:27 which are both BW 9-bolt rears that were only offered.

 

so if there is a rubber plug its a 2.77? btw....what are the ratios of the G80 and G92?

 

Easy way to tell BW is by the nine bolts holding the rear housing cover on and the rubber fill plug.

RPO G80=limited Slip rear.
RPO G92= performamce rear, which varied in content over model years. It did have different ratio gears also depending on engine and tranny. 9-Bolt 3:27 & 3:45 and 10-bolt 3:23 & 3:42.

 

No its factory 350 auto, and I changed the rear. Just saying do not judge a book by its cover.

 

Would been just as easy to say so, and not look like you didn't know what you had.

 

http://www.camaro3rdgen.20m.com/ try this!!!!!!!!!!!