I have a question about my Red 87 IROC, was thinking it had the G92 option, but not sure, really haven't checked RPO yet. It's a 305 TPI A4. With Dual fan and oil cooler, and rear drum. Any hints about RPO codes. I was thinking that all G92's had rear disc.

 

In 87, the G92 would have had discs all the way around.

 

Rear disc brakes option was RPO J65 and the standard was drums, The rear for you was 2:73 ratio. G92 was just a upgrade to 3:23 ratio in 1987 (note: the content of this RPO varied over model years). You should have
RPO G80 Limited slip. These were all extra cost options on the 87 IROC-Z

 

Since you're packing the common 305, your car wasnt factory equipped with the disk brake option.

 

Check your RPO codes. The oil cooler only came with the G92 option in 87 for 305's. So your car shouldn't have an oil cooler without disc brakes. All 87 305Iroc's that had the G92 option had four wheel disc's. And yes some of them were automatics. I have one.

 

Check your facts. In 1987 RPO G92 was a performance ratio only a $21.00 option with nothing else required.

 

In 1987 all options became part of groups and could not be ordered seperately.

The G92 option for the 305 with an automatic, included the engine oil cooler, four wheel disc brakes, and a 3.23 posi rear end. It could not be had any other way. The G92 was not a stand alone option as in previous years.

Source: Camaro White Book

 

I'm wondering if someone changed the rearend in it. When I toasted my 1st rearend in my 85, I got another one with 2:73, theses gears deffinitely aren't 2:73. It has to much torque at the bottom end and RPm is to high at 55 to be 2:73