Axle Ratios

[jd2b]

Hello all,

I was wondering if anyone knew of the Alero 3400 using different axle ratios starting in 2002. I used to have a black 2001 GL2 and am now purchasing a black 2004 GL2 and noticed a difference in the fuel economy. It went from 32 HWY to 29 HWY.

Does anyone know why it did this? According to the EPA, this change occured in 2002.

Thanks!

[overdrive75]

No change in axle ratios, they are the same.

[jd2b]

Does anyone know why the fuel economy is different then? It doesn't make any sense.


I cannot wait to pick this car up this weekend. B)

[wy3134]

There are too many factors at hand to pick out one specific and say thats the main reason....I dont know much about the 04s so I cant say what exactly it could be, but remember every car is unique in even a minute way, so until you refill a couple times, for all that matters, mileage can still be the same....

[overdrive75]

Originally posted by jd2b@Jul 8 2004, 10:01 PM
Does anyone know why the fuel economy is different then? It doesn't make any sense.


I cannot wait to pick this car up this weekend. B)
It could be something as simple as the shift pattern has changed between the model years, and it usually does slightly.

In my opinion the posted fuel economy numbers are useless anyhow as they are generated on a test schedule created back in the 50's and are no longer representative of how people currently drive.

I would not put to much faith in those numbers, cars tend to get slightly better than what is posted, depending on driving habits.

[mfuller]

Overdrive -

What are your thoughts on changing the 35 tooth drive/driven sprokets in a 4T45-E (3.05 FDR) car to 33/37 (effectively resulting in a 3.42 FDR)? Obviously, there's some computer work to be done, but do you think it may be too steep? Better to just use a GAGT 3.29 diff?

[overdrive75]

From a transmission durability and life, you would be better to go with the 3.29 and leave the sprockets alone. The reason that I say this, is by going to the other sprockets you will be feeding, while is doesn't seem like much, higher torque into the actual gear box/clutch pack area of the transmission. With a v-6 this would require the clutch packs and the gearsets to be upgraded.

So if you are looking for a better whole shot, go with the 3.29, while it still requires computer work, it is significantly less hardware (transmission) intensive.

[Mach1]

Anyone know where I can buy the 3.29 performance axle...

and if anybody knows, what were the axles that were put in the '99 aleros?
See I looked at a brochure for the 99's and I didn't see the 3.29 gears as an option so I guess that I don't have it

[overdrive75]

Originally posted by Mach1@Jul 12 2004, 01:57 PM
Anyone know where I can buy the 3.29 performance axle...

and if anybody knows, what were the axles that were put in the '99 aleros?
See I looked at a brochure for the 99's and I didn't see the 3.29 gears as an option so I guess that I don't have it
3.29 gears were never an option in the v-6 alero's.

[jturkey69]

mach 1 and jd...for the 3.29 gears you need to get a trans from a grand am GT only not an SE, once you get the tranny, you will need to go to DHP for a pcm tune right away.......

overdrive and fuller...is ther anything else that i need to finish my tranny swap?
i have a tranny only

[mfuller]

Originally posted by jturkey69@Jul 12 2004, 05:40 PM
overdrive and fuller...is ther anything else that i need to finish my tranny swap?
i have a tranny only
Should only need the tranny and the computer changes, although I'm sure overdrive will correct me if I'm wrong.

Out of curiosity, may I ask:

- where you got your 3.29 trans?
- how many miles are on it?
- did you get the torque converter that was attached to the trans also?
- what did it cost you?

[jturkey69]

i got it from a friend that works at a local wrecking yard for newer vehicles, it has about 30,xxx on it, got the converter, and total cost was just over 600.

i remeber talking with you about what issues i would have, and if it owuld drive to chicago to get a tune, or can i just get jason to send me one for a gagt?

[overdrive75]

Trans and an after market controller for the grand am GT is what you need. You may want to consider a Grand AM GT BCM too. Just incase there are some issues.

[jturkey69]

ok, sorry for this but i think i have an idea, what is BCM?
i thought i would maybe need the PCM, and have DHP tune it...is that what you mean by aftermarket controller?

[overdrive75]

BCM is Body Control Module, PCM is Powertrain Control Module.

Let me ask one question: I DHP going to give you an alero tune with a final drive change or are they giving you a GAGT PCM?

The reason I am asking, is that if you get the GAGT PCM, there is a minor chance of a VIN # conflict between the PCM and BCM and that point, and will it is the same BCM between cars, you may need to have a Pontiac BCM in there. I know it sounds dumb, but there is some stuff that happens.