80-81 4-speed id.
Burning Brakes
Joined: Aug 2000
Posts: 925
Likes: 1
From: LT1 and LS5 Coupes... New Orleans, LA
Re: 80-81 4-speed id. (81vette)
Yep, and it had a new ratio set compared to the 74L-79 T-10s, and had a 300 lb-ft torque rating.
2.88
1.91
1.33
1.00
In 1980, it was used with a 3.07 axle; in 81 it got a 2.72. There were no otional ratios.
2.88
1.91
1.33
1.00
In 1980, it was used with a 3.07 axle; in 81 it got a 2.72. There were no otional ratios.
Burning Brakes
Joined: Dec 1999
Posts: 924
Likes: 1
From: Houston Texas
Re: 80-81 4-speed id. (Allan71)
Hi Alan,
That is an interesting topic (for me anyway) that I have never been able to figure out to my satisfaction. I've read many places that the 81's only came with 2.72 for the 4spd, and 2.87 for the automatics. However, there was an optional G92 Performance Axle Ratio available that year of which there were 2400 purchased. I've oftened wondered if that performance option was the 2.87 ratio, and if so it must have only been available with the MM4 (4spd) option as the automatic already had it. If it was the 2.87 then it wasn't much of a performance option. :) Additionally, my owners manual list a 3.07 axle ratio in a chart and refers to it as a high performance axle ratio which leads me to believe that the G92 option may have been the 3.07 rear that was first installed in the 80' rear axle. I'm stretching here, but maybe GM had 2400 3.07's left over from the previous year, and decided to offer it as a performance option on the 81'. I've never read anywhere what the ratio actually was for the G92 option. Does anyone have any additional information on this?
[Modified by 81vette, 11:55 AM 11/20/2001]
That is an interesting topic (for me anyway) that I have never been able to figure out to my satisfaction. I've read many places that the 81's only came with 2.72 for the 4spd, and 2.87 for the automatics. However, there was an optional G92 Performance Axle Ratio available that year of which there were 2400 purchased. I've oftened wondered if that performance option was the 2.87 ratio, and if so it must have only been available with the MM4 (4spd) option as the automatic already had it. If it was the 2.87 then it wasn't much of a performance option. :) Additionally, my owners manual list a 3.07 axle ratio in a chart and refers to it as a high performance axle ratio which leads me to believe that the G92 option may have been the 3.07 rear that was first installed in the 80' rear axle. I'm stretching here, but maybe GM had 2400 3.07's left over from the previous year, and decided to offer it as a performance option on the 81'. I've never read anywhere what the ratio actually was for the G92 option. Does anyone have any additional information on this?
[Modified by 81vette, 11:55 AM 11/20/2001]
Burning Brakes
Joined: Aug 2000
Posts: 925
Likes: 1
From: LT1 and LS5 Coupes... New Orleans, LA
Re: 80-81 4-speed id. (81vette)
Yes, and the only reference to this info was found in a 1981 Corvette News article. I have never seen the article myself, but this is the way it happened.
All 4-speed cars used a 2.72 axle
All Federal Emissions Automatic cars used the 2.87 axle
All California Emissios Automatic cars came standard with the 2.72 axle
Now heres where G92 comes into play. Those California Automatic buyers were allowed to order RPO G92 and this in turn would give them the 2.87 that all Federal cars already got. With roughly 10% of all new Corvettes going to CA every year, you will see that about half the cars got the G92. Probably just a cheap way for Chevy to get another MPG or so in the average for the buyers that didn't know or that had a dealer that could figure it out. Well thats it. The G92 option will only be found on cars that were originally ordered with the CA Emissions.
All 4-speed cars used a 2.72 axle
All Federal Emissions Automatic cars used the 2.87 axle
All California Emissios Automatic cars came standard with the 2.72 axle
Now heres where G92 comes into play. Those California Automatic buyers were allowed to order RPO G92 and this in turn would give them the 2.87 that all Federal cars already got. With roughly 10% of all new Corvettes going to CA every year, you will see that about half the cars got the G92. Probably just a cheap way for Chevy to get another MPG or so in the average for the buyers that didn't know or that had a dealer that could figure it out. Well thats it. The G92 option will only be found on cars that were originally ordered with the CA Emissions.
Burning Brakes
Joined: Dec 1999
Posts: 924
Likes: 1
From: Houston Texas
Re: 80-81 4-speed id. (Allan71)
Oh well....your story sounds better than mine. :cry :cry :cry :cry :cry
I'll see if I can find the reference to the 3.07 in my owners manual again. Thanks for your help Allan.
[Modified by 81vette, 12:42 PM 11/20/2001]
I'll see if I can find the reference to the 3.07 in my owners manual again. Thanks for your help Allan.
[Modified by 81vette, 12:42 PM 11/20/2001]
