Put a new fuel pump in today ( what a pain ) and noticed my rearend was rusted to hell. What rearend do these cars have? RPO says G80 but our 91-92 verts all have drum brakes. 92 Trans Am WS6 convertible

 

According to Compnine's database, which has all 663 1992 T/A Convertibles:
All 1992 T/A Convertibles with the LB9/MM5 show GU4 (3.08)
All 1992 T/A Convertibles with the LB9/MX0 show GU2 (2.73)

None of them, WS6 or not, received J65 (rear disc brakes).

G80 is the code for GM's positraction. All 1992 Trans Am Convertibles that came with the LB9 engine also came with G80. Only the L03s had the non-G80.

 

I have only seen them with 10 bolt, drum brakes and from 273 to 323 gears. I put a 9 bolt in mine with 327 gears and PBRs. Had to change e-brake cables.

 

put in a 10 bolt 3.42 posi disc brake with 1-le/11.5 disc in my 1990 irocz

 

I think G80 means posi or it does in my late 70s early 80s trans ams and Z28s. I think
GU4 means 342 gear, GU3 323- GU2 308- GU1 273 and the late 70s early 80s F cars even had a 243 gear or 240 something to try and meet the gas mileage rule from the govt back then. I had a 4 wheel disc rear from a 81 trans am that was factory 243 I think and the carrier would not work with the 373 gears I had without this huge spacer. At least those old 10 bolt rears were strong and never broke. The third gen cars came out and were lighter, better handling, had overdrive and fuel injection. My cousin worked rebuilding transmissions back in the early 80s and when the 82s came out the early 700r4 had a life expectancy of 6000 miles. That is all he did for 3 years was rebuild warranty 700r4s at the local pontiac GMC Buick dealership. I blew up three turbo 350 transmissions in 6 months in my 81 Z28 back then untill I installed a muncie 4 speed. The good ole days.

 

My 92 Z28 vert came with 2.73 gears. I just picked up a rear end off of Craigslist out of a 90 Iroc that had disc brakes and 3.23 gears for $200. It even had the sway bar still attached. This will be my winter project for next year. I might even change out the gears to 3.42 is I have the funds.

 

Mine is an automatic that had open diff with 3.42 gears when I bought it used 10 yrs ago with 100k miles. Bought from original owner, my then-girlfriend's dad, who stated no work to the rear-end was done. Loved that ratio- could bark the tires even with the stock 305.

 

3.42s? Definitely swapped at one point, maybe even out of a V6 car considering the open diff with that kind of ratio.

 

My 88 IROC vert had 3.23 and a weak posi. I changed to 3.73 soon after. I auto-x the car and the posi blew out on my first run (4 years ago). I am now running a Moser 9" with a Detriot True Trac. When I installed the Tremec TKO (converted from the 700R4) I used a 3.20 ratio in the 9". No problems with the rear, the trans, or the posi after many races.

 

If I were going to buy a set of gears I would go 370 with the overdrive trans we have. You only gain a few hundred RPM in overdrive and gain a ton from a stop sign or red light.

 

i've actually never seen a vert with factory 4 wheel disc, doesn't mean it doesn't exsist, just saying that my understanding was that if you ordered a vert the 4 wheel disc was not an option for whatever reason

 

Mine had 10 bolt open diff 2.77 drum brakes... I quickly replaced it with a borg lsd 9 bolt 3.08 disc brake off an 80 something 'maro from the junkyard

 

Do you mean 2.73? I see no records for a 2.77 for that application.

 

The answers to this question can vary greatly depending on what year and model the convertible is. The original poster of this thread asked about a 1992 T/A. A 1992 T/A would have been considered a "factory" convertible, and as such, was subjected to guidlines by the factory as the car was built to be a convertible. None of 1992 T/As had the option for J65 (rear disc brakes) and they only had two rear-end options (3.08) or (2.73) - depending on the drivetrain.

 

yes, but i was just stating that i have never saw an ASC vert with the J65 option

 

Mine originally had a 2.73 posi drum rear... I hated that thing.

 

You're correct... I don't know why a put 2.77... it was 2.73 and it was the first thing I changed on my car.