What rearends do our convertibles have?
#1
Junior Member
Thread Starter
iTrader: (1)
Join Date: Nov 2009
Location: Humble, TX
Posts: 93
Likes: 0
Received 0 Likes
on
0 Posts
Car: 1992 Trans Am Conv.
Engine: 305 TPI
Transmission: Auto
What rearends do our convertibles have?
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
#2
Community Administrator
iTrader: (1)
Re: What rearends do our convertibles have?
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.
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.
#3
Supreme Member
Join Date: May 2005
Location: Malvern, Arkansas
Posts: 1,044
Likes: 0
Received 3 Likes
on
3 Posts
Car: 90 IROC 2-92 Zs blk vert & prpl
Engine: stealth ram brodix track 1 ful port
Transmission: 700r4 4l80e
Axle/Gears: iroc 375 lokr 92 Z 277 pos vert 327
Re: What rearends do our convertibles have?
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.
#5
Supreme Member
Join Date: May 2005
Location: Malvern, Arkansas
Posts: 1,044
Likes: 0
Received 3 Likes
on
3 Posts
Car: 90 IROC 2-92 Zs blk vert & prpl
Engine: stealth ram brodix track 1 ful port
Transmission: 700r4 4l80e
Axle/Gears: iroc 375 lokr 92 Z 277 pos vert 327
Re: What rearends do our convertibles have?
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.
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.
#6
Member
Join Date: Oct 2009
Location: Silicon Valley, CA
Posts: 105
Likes: 0
Received 0 Likes
on
0 Posts
Car: 1992 Camaro Z28 Z03 Vert
Engine: 5.7L Vortec TPI
Transmission: 700R4
Axle/Gears: 3.23 Posi
Re: What rearends do our convertibles have?
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.
#7
Supreme Member
Join Date: May 2002
Location: Texas
Posts: 1,332
Likes: 0
Received 0 Likes
on
0 Posts
Car: 1991 Z28 Convertible
Engine: 350 TPI
Transmission: 700R4
Axle/Gears: 3.23 with Eaton posi
Re: What rearends do our convertibles have?
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.
Trending Topics
#8
Supreme Member
iTrader: (1)
Join Date: Jun 2009
Location: Central Connecticut
Posts: 1,777
Likes: 0
Received 0 Likes
on
0 Posts
Car: 91 Trans Am 'vert
Engine: LB9
Transmission: T5
Axle/Gears: 3.45 9 bolt
Re: What rearends do our convertibles have?
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.
#9
Re: What rearends do our convertibles have?
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.
#10
Supreme Member
Join Date: May 2005
Location: Malvern, Arkansas
Posts: 1,044
Likes: 0
Received 3 Likes
on
3 Posts
Car: 90 IROC 2-92 Zs blk vert & prpl
Engine: stealth ram brodix track 1 ful port
Transmission: 700r4 4l80e
Axle/Gears: iroc 375 lokr 92 Z 277 pos vert 327
Re: What rearends do our convertibles have?
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.
#11
Senior Member
Join Date: Mar 2009
Location: Brick, NJ
Posts: 870
Likes: 0
Received 0 Likes
on
0 Posts
Car: 91 Trans Am
Engine: 355 TPI
Transmission: Built T-5
Re: What rearends do our convertibles have?
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
#12
Member
Join Date: Sep 2006
Location: Syracuse, UT
Posts: 170
Likes: 0
Received 1 Like
on
1 Post
Car: 1991 Vert Z28
Engine: 305... LS1 waiting to drop in
Transmission: 700-R4... soon 4L60E
Axle/Gears: 3.08 posi nine bolt
Re: What rearends do our convertibles have?
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
#14
Community Administrator
iTrader: (1)
Re: What rearends do our convertibles have?
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.
#15
Senior Member
Join Date: Mar 2009
Location: Brick, NJ
Posts: 870
Likes: 0
Received 0 Likes
on
0 Posts
Car: 91 Trans Am
Engine: 355 TPI
Transmission: Built T-5
Re: What rearends do our convertibles have?
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.
#16
Supreme Member
iTrader: (30)
Join Date: Sep 2005
Location: O'Fallon, MO
Posts: 6,258
Likes: 0
Received 4 Likes
on
4 Posts
Car: 1991 Z28 convertible built 3/1/1990
Engine: Cammed 6.0L LSX
Transmission: T56
Axle/Gears: custom Ford 8.8", 4.10 gears
Re: What rearends do our convertibles have?
Mine originally had a 2.73 posi drum rear... I hated that thing.
Thread
Thread Starter
Forum
Replies
Last Post