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Axle Ratios

Old 08-18-2002, 06:29 AM
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Question Axle Ratios

I know Z28s can be had with different axles, but how many were offered while they were in production and which axle is good for what?

- Good Launches
- Fuel Mileage
- Top Speed
- General All-Around Performance

Thanks.
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Old 08-18-2002, 09:00 AM
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The stock Z28 rearend (2.73) for automatics, and 3.42 for six speeds were installed by GM for one purpose only, "FUEL ECONOMY" to get around the gas guzzler tax. The term "Performance Axel" (i.e. "GU5") option for the automatic, is a joke. The only cool thing you get is the aluminum drive shaft with that option.

IMHO, to get the car to perform the way it should (i.e. getting into the "power curve"), the automatics should have a 3.73 ring & pinion, and the six speeds should have a 4.10.

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Old 08-18-2002, 09:21 PM
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2.73's are standard on the Auto, 3.23's are optional. I thought the M6's came with 3.23's standard though.

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Old 08-18-2002, 09:52 PM
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The manuals used to come with 3:23 standard I believe. I know for a fact they are now 3:42.

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Old 08-18-2002, 11:46 PM
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Is 3.73 too high for a daily driven automatic? I was leaning towards 3.42 - right now, I got the stock 2.73. What about the torque converter and drive shaft - upgrade also at the same time?

------------------
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Old 08-19-2002, 08:34 AM
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<font face="Verdana, Arial" size="2">Originally posted by jgkinsofla:
Is 3.73 too high for a daily driven automatic? </font>
My '98 Z Auto, has 4.10s in it, and its a daily driver.

4.10s are a little much, and I have been thinking about going to 3.73s once I get the funds for it.

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Old 08-19-2002, 08:08 PM
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<font face="Verdana, Arial" size="2">Originally posted by gillbot:
2.73's are standard on the Auto, 3.23's are optional.</font>
What's the difference between the 2.73 and the 3.23 with the automatic?

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Old 08-20-2002, 11:45 AM
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<font face="Verdana, Arial" size="2">Originally posted by SFB767:
What's the difference between the 2.73 and the 3.23 with the automatic?

</font>
What's the difference? Uhmmm... a lower ratio.

But serious, I'm confused about the question. The optional lower ratio will help acceleration.



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Old 08-20-2002, 12:46 PM
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<font face="Verdana, Arial" size="2">Originally posted by TireSmoke:
What's the difference? Uhmmm... a lower ratio.

But serious, I'm confused about the question. The optional lower ratio will help acceleration.
</font>
Ok, so a Z28 A4 with 2.73s will be faster than one with the 3.23s?

If so, will it be faster by a big margin, or hardly noticeable? Will the axle ratio have more of an effect on a 0-60 time, or a top speed?

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Old 08-20-2002, 03:20 PM
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I have 3.23 ratio on my A4 so since im not a genius at what it does exactly, how much more acceleration would I get with 3.23 ratio compared to the 2.73 ratio?

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Old 08-20-2002, 03:24 PM
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With the 3.23's I would say on average your 1/8th mile time would be 1/10th or 2/10ths better than a similarly equipped 2.73 car.

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Old 08-21-2002, 08:44 AM
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You car won't be "faster"... it may actually be "slower", but "quicker". Man, for someone who knows so little, I'm totally filled with smart-a$$ answers, aren't I?

Being "fast" usually refers to top speed -- which actually will decrease in theory when you go with a lower gearing in a car that is gearing limited instead of drag limited. I'm thinking that doesn't apply to the f-body automatics so I don't know how it would directly affect your top speed.

As for what gearing means... the most simple way to explain it is that it's the ratio of times that your drive shaft will spin compared to your tires. For example, 4.10 gears in your rear end will mean that your driveshaft will spin 4.1 times for every 1 time your tires rotate.

What this means for you is simple... think of your gears as a complicated lever system. You know how the little kid can lift the fat guy on the seesaw if the little kid is way on the end and the fat guy is near the fulcrum? The little kid is lifting WAY more weight but he is also moving a significantly longer distance than the fat guy is being lifted. So... when the driveshaft spins more times in relation to the tires, it's moving a longer distance but think of it as putting more "power" to the ground (for lack of a better term).

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Old 08-21-2002, 08:47 AM
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One other thing that is confusing....

a higher number gearing is called a "lower" ratio. So a 4.10 is lower than a 3.42

Sorry about that complication.

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Old 08-21-2002, 09:12 AM
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<font face="Verdana, Arial" size="2">Originally posted by jgkinsofla:
Is 3.73 too high for a daily driven automatic? I was leaning towards 3.42 - right now, I got the stock 2.73. What about the torque converter and drive shaft - upgrade also at the same time?

</font>

no get a converter FIRST. Gears may suddenly seem less necessary!


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