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History / OriginalityGot a question about 1982-1992 Camaro or Firebird history? Have a question about original parts, options, RPO codes, when something was available, or how to document your car? Those questions, answers, and much more!
So does a G92 optioned car have the same gear ratio?
G92 depends... If you have a situation like the 87 Irocs with 5.7L TPI engines, they all came standard with 3.27 gears. Since there was no other gear ratio offered with that engine that year, there was no G92 code used. I'd still considering 3.27 gears to be a "Performance Axle Ratio", but it didn't need the code because there was nothing they needed to differentiate from.
Same goes for 91-92 Firebirds with the 5.7L, the only gear ratio available was 3.23. Therefore there's no need for the G92 code, and most of them don't have it. But there's an exception. 91-92 Firebirds with the 5.7L and 1LE have G92. They have G92 to help keep service parts straight, because GM cataloged a lot of (1LE) parts based on the G92 code.
Edit to add: So if a large variation, like an engine/transmission combo was available with standard gear ratio, or a performance gear ratio, the performance gear ratio version of the car would carry the G92 code to identify it as having the optional gear ratio.
I gotcha. So my brothers 87 GTA is a 305 tpi with a 5 speed.
The second SPID is a 1990 IROC with the 305 tpi and 5 speed, but shows the G92. So I assume, then that they are for sure the same gear ratio then. Just optioned a little differently..
G92 just designates an optional performance gear ratio, it doesn't specify the gear ratio, only that it's the optional of the two or more available. The second spid is a 10-bolt, 3.42 ratio. Effectively the same as a 9-bolt with 3.45, but two different rears, and Borg Warner chose a slightly different tooth count, therefore a slightly different ratio. It's minor enough to come out in the wash.
The 9-bolt is a larger ring gear, therefore somewhat marginally stronger rear. But with the caveat of being impossible to find parts for. The 10-bolt is tiny 7 5/8" ring gear, and weak, but has the benefit of being a GM rare in so many platforms there is no shortage of parts support.
Specifically, note how in the chart, there are two different LB9s listed. The standard LB9 auto or 5spd was rated 210hp, the same LB9 with the 5spd and G92 axle ratio got 230hp along with the upgrade from a 3.08 to 3.42 gear ratio.
If we back up to 1989, notice there are two 5.7L auto options, a 230hp version with 2.77 gears (no G92) and a 240hp version with 3.27 gears (G92). We see the same with the LB9 5spd, a 220hp version with 3.08 gears (no G92) and a 230hp version with 3.45 (G92) gears. The car will always have the G?? code for the specific gear ratio, and if there were more than one optional gear ratio, the "performance ratio" version would have G92. If the G92 gear ratio was standard, there wouldn't be a reason to show G92 because they all were the same.
Further, G92 doesn't really mean the car has the more powerful engine, or any other options. It just means that the "performance gear ratio" was selected, which often triggers or requires the more powerful engine. Where this gets really confusing is people considering G92 to be a "performance package" when it's not. In some cases, you can have a G92 and non G92 with the exact same engine, the only difference is the gear ratio.
Touching back on what I mentioned earlier, in 87 all 5.7L cars had 3.27 gears standard. Since there wasn't a higher or lower gear ratio offered, those cars don't have G92 on the SPID. But on the LB9 auto and 5spd there were optional "performance gear ratios", so a LB9 M5 with 3.45 gears would have G92 on the spid, the same car with 3.08 gears wouldn't have G92. Same for the LB9 auto with 2.73 gears, it wouldn't have G92 on the sticker, but with 3.23 gears it would.
Probably too much information, and all kinds of confusing, but it really depends on the year and available options. Consistently, always, G92 = Performance Gear Ratio. It can just be an indicator of other things in some circumstances.
