Axle Ratios

[SFB767]

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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[SteveC]

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.

SteveC

[gillbot]

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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"GillZ28" 2002 Camaro Z/28 LS1 A4 (2.73's)
Sunset Orange Metallic
Fernco, SLP Airlid, K&N Filter, 17" SS 10 Spokes
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1995 Ford Aspire M5
!Torque & !Power, 40+MPG!!!

[davey]

The manuals used to come with 3:23 standard I believe. I know for a fact they are now 3:42.

[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?

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'99 Z28 A4 BLACK
▪ SLP air lid, K&N filter, air box mod, Borla exhaust, HPP3, 160* stat, Magnecor 8.5 mm wires, NGK TR55 plugs
▪ Pioneer DEH-P77DH, Polk speakers

[one wicked element]

<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.

[SFB767]

<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?

[TireSmoke]

<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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Steve
2002 Trans Am WS-6
M6, Pewter, Flowmaster 80 Series, Free Ram Air, and CAGS eliminator (FINALLY!)

[SFB767]

<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?

[Z28-CTYHNTR]

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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2002 Camaro Z28 AT
Stock for now until I decide what to install.

[96fbirdA4]

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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- Steve - 1998 Pontiac Firebird Trans Am
LS1 A4, 2.73's, Kumho Ecsta Supra 712 245/50/ZR16's, Direct Flow Lid, GMAF, !FRA, Loudmouth, 3" Y-Pipe, AIT Mod, Fan Switch Mod
13.774 @ 103.33, 300.5rwhp & 308.6rwtq, 97+ RPO Codes, Join The CamaroZ28.Com Users Webring

[TireSmoke]

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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Steve
2002 Trans Am WS-6
M6, Pewter, Flowmaster 80 Series, Free Ram Air, and CAGS eliminator (FINALLY!)
ASC Conversion: #10502 on 6/26/02

[TireSmoke]

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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Steve
2002 Trans Am WS-6
M6, Pewter, Flowmaster 80 Series, Free Ram Air, and CAGS eliminator (FINALLY!)
ASC Conversion: #10502 on 6/26/02

[Bull_in_a_china_shop]

<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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2000 Z28-Deep Maroon
Mac Headers With Off-Road Pipe
Vigilante Torque Converter 2800 stall 2.5 STR
Hooker 3" catback w/cut out & McCord
FTRA Kit
Dynamic Motorsports SFC's