View Full Version : 3:43 to 3:73


Bad98SS
12-22-2009, 07:28 PM
Will this change make me run a faster Quater mile?

BriancWS6
12-22-2009, 08:22 PM
Going from 3.42s to 3.73s isn't a significant change. I am assuming you have an m6 although you could have an auto that's already had the gears swapped.

If you have a manual, go with at least 4.10s. Steeper gears will help you get off the line quicker which will give you a quicker et.

shtnfrds
12-22-2009, 08:29 PM
X2, m6's should be 4.11 from the factory and A4's 3.73.

however i'm going 3.90 when i get a rear.

and a gear swap isnt going to get you much of a gain at all.

when i went from 3.23 to 3.73 in my old car, i gaind .5 mph and like .05 et.
small gains like that are filed under better weather, launch etc etc in my opinion.

Slvr00Bird
12-22-2009, 08:44 PM
I am assuming you have an m6 although you could have an auto that's already had the gears swapped.

Auto's came with 3.42's as well.. My A4, 6 cylinder Y87 Firebird came with them.. ;)

BriancWS6
12-22-2009, 10:18 PM
Auto's came with 3.42's as well.. My A4, 6 cylinder Y87 Firebird came with them.. ;)
My V6 knowledge isn't up to par with the V8s, and for some reason, it doesn't bother me :lol:

TAtoad
12-22-2009, 10:56 PM
w68 V6s came with 3.42s, but no auto V8s

BriancWS6
12-22-2009, 11:07 PM
w68 V6s came with 3.42s, but no auto V8s

:confused: he said V6..

00pooterSS
12-23-2009, 05:38 PM
w68 V6s came with 3.42s, but no auto V8s

My SS was supposed to have 3.23's but for some reason actually had 3.42's the guy at the rear end shop said he has seen stranger things come from the factory.

Hemi2Slo
12-23-2009, 09:32 PM
My 98 A4 TA came with 3.42 gears from the factory. I went to 3.73 gears and felt a significant difference. Never ran it with the stock gears in it though so I can't say about the actual gains, it just felt better.

cambirdracing
12-24-2009, 06:12 AM
V6 A4's came with 3.23-V8 A4's came with 3.42

I had a 77 Bird with a 455 and 2.41 gears, went to 3.42 and wasted my time doing the work, then I went to 3.73 and was super pleased.

So now you have 2 people saaying that 3.42 to 3.73 is worth it. Ecspecially if you have an A4.

01ssreda4
12-24-2009, 09:16 AM
V6 A4's came with 3.23-V8 A4's came with 3.42


That is 100% incorrect. Stop spreading false information :bang:

Pseudonym
12-24-2009, 09:18 AM
I did 3.23s to 3.73s in my Trans Am. It will make your quarter mile times faster.

nomoneyz
12-24-2009, 09:23 AM
I say 4.10's or go home. I have them in my A4 and it is bad ass. As long as your not into doing highway pulls way up there they are awesome. No track times though.
But yes gears "should" make your times a little better.

cambirdracing
12-24-2009, 09:46 AM
That is 100% incorrect. Stop spreading false information :bang:

Sorry, just going by the Chiltons manual. Of course,they are not 100% either. Can you post what car came with what rear gear? 93-02!

Squirts11
12-24-2009, 09:57 AM
Like everyone has said, go 4.10s to make it worth your while.

01ssreda4
12-24-2009, 12:08 PM
Its not difficult to remember, and I dont do V6s so dont ask me about them.

All 4th gen V8s came with:
3.42 if an M6, SS or Z it doesnt matter
3.23 if an auto SS, some Zs got this as well
2.73 if a non SS auto, and didnt get the 3.23 as an option.<---these cares got steel driveshafts, non z rated tires, and no 1st gear selector on the console.

I think the first year M6 Z 4th gen got 3.23 then the very next year they switched/stayed with the 3.42.

dlandsvZ28
12-26-2009, 01:57 AM
My SS was supposed to have 3.23's but for some reason actually had 3.42's the guy at the rear end shop said he has seen stranger things come from the factory.

That's interesting. You would assume the factory would have had to reprogram the PCM to account for the different gear ratio.

Did you ever do a read to see what ratio had been programmed into the PCM by the factory?

00pooterSS
12-26-2009, 08:37 PM
That's interesting. You would assume the factory would have had to reprogram the PCM to account for the different gear ratio.

Did you ever do a read to see what ratio had been programmed into the PCM by the factory?

Im sure they probably did, and no I didnt BUT I havent had it changed yet to read 3:73's so I will try to remember to do that cause that will be interesting to know. I drove the car 10 miles from the rear end shop to the body shop so when I get it back I will take it to the tuner to change the gear ratio in the computer. I do know that the speedo read properly before though.


The shop that did the rear end has been a rear end only shop for something like 30-40 years and he said "hell they just throw whatever is laying around in em sometimes" which I wouldnt be surprised, or say for instance if they ran out for some reason they may have substituted, just like some F body's ended up with LS6 blocks in them..

dlandsvZ28
12-26-2009, 11:09 PM
Im sure they probably did, and no I didnt BUT I havent had it changed yet to read 3:73's so I will try to remember to do that cause that will be interesting to know. I drove the car 10 miles from the rear end shop to the body shop so when I get it back I will take it to the tuner to change the gear ratio in the computer. I do know that the speedo read properly before though.


The shop that did the rear end has been a rear end only shop for something like 30-40 years and he said "hell they just throw whatever is laying around in em sometimes" which I wouldnt be surprised, or say for instance if they ran out for some reason they may have substituted, just like some F body's ended up with LS6 blocks in them..

I doubt seriously that GM took the time to reflash the PCM with all of the parameters to necessary to change the rearend ratio from 3.23 to 3.42. Because they would have had to change the shift points too.

If you are not the original owner then I suspect the 3.42 gears possibly found their way into your car via other means - maybe a dealership warranty where the dealership ordered parts, discovered they were wrong but installed them anyway. Can a dealership change the settings in the PCM with a Tech II - to account for the different ratio - I don't know.

What does the label on the door post say for the rearend ratio - 3.23 has a special code as does the 3.42 code?

00pooterSS
12-26-2009, 11:52 PM
I doubt seriously that GM took the time to reflash the PCM with all of the parameters to necessary to change the rearend ratio from 3.23 to 3.42. Because they would have had to change the shift points too.

If you are not the original owner then I suspect the 3.42 gears possibly found their way into your car via other means - maybe a dealership warranty where the dealership ordered parts, discovered they were wrong but installed them anyway. Can a dealership change the settings in the PCM with a Tech II - to account for the different ratio - I don't know.

What does the label on the door post say for the rearend ratio - 3.23 has a special code as does the 3.42 code?

I dont doubt at all that they would program the ECU for the parts that were installed....As far as if the gears were switched there is no absolute way to say yes or no but it is highly doubtful, because a lady owned the car before me and the carfax showed service at the dealer up until I owned the car and there was no reference to rear end repair and the car was completely untouched when I bought it except maintanence. So who really knows, but I do know the speedo was accurate so its safe to assume the ratio in the ECU was correct.

I wish I knew at what point of assembly the gears are changed in the auto car when the SS option is designated and maybe I could answer your question a little better, but that im aware of SLP does the modifications that change the car from a Z28 to a SS so im kinda under the impression they may have been the ones to do the gear change in which case they would have had to have changed the ratio in the ECU from 2:73 to 3:23 so why would it not be just as easy for them or even chevrolet to program it for 3:42's

In any case there is a seperate tune done by one of them because they have two auto flashes with different gear ratio's. Im sure it wouldn't be difficult for either company to implement a third.

After seeing the gears I am as curious of this as you...

Spartan7
12-27-2009, 12:45 AM
^^^
If you are not the original owner, then there is no way you can accurately claim your A4 car came with 3.42's from the factory.

hitmanws6
12-27-2009, 02:49 AM
my friends 2000 Z28 A4 came with 3.42s from the factory, so those cars are out there. but to the OP of you are an auto dont bother changing them, focus on other mods. my friends LS1 i just mentioned with 3.42s is running mid 11s in the 1/4 with Heads/cam/boltons. but if you are a manual at least do 4.10s, if you are more of a track car 4.30s would work well

01ssreda4
12-27-2009, 10:14 AM
^^^
If you are not the original owner, then there is no way you can accurately claim your A4 car came with 3.42's from the factory.

Agreed, everyone claiming this is full of it.....:bs:

ThoR294
12-27-2009, 11:50 AM
I went with 3.73s in my M6 car. 4.10s seemed really steep for a car that I drive on the road a lot. I woulda prefered like 3.90 :) 4.10s seems to me pretty steep and I would have to start messin with tire sizes and need some sticky tires :P

LT1Formula007
12-27-2009, 12:46 PM
If you check the rpo codes sticker (usually in the glove box) look for these codes...
gu2 = 2.73's
gu5 = 3.23's
gu6 = 3.42's

I've done alot of research on these cars in the past 5 years, and all I have been able to come up with is that all of the V8 A4 cars had 2 options 2.73's and 3.23's.
In 93 TA's and Z28's with an M6, they had a 3.23 gear and the transmission had a steeper 1st gear.
In 94 and up TA's and Z28's, they used a less steep 1st gear in the 6 speeds and bumped up the rear gear ratio to 3.42's.
In this time period nothing was changed in the A4 cars though. Still the same 2 options from 93-02. (2.73's or 3.23's only)
And to verify on the v6 cars, YES the 3.42 rear gear ratio was offered as an option. (My 44,xxx mile 96 RS has this option as well) It has a GU6 rpo code on the label in the glove box to verify.

With that said, IDk wether or not ANY V8's did slip out of the factory with 3.42's or not, but it isn't documented anywhere that I have seen. Is it Possible??? YES! But they would have to note it in the RPO codes label as well as use a whole different tune as for the shift points and etc. It would not be able to use the same as the V6 due to the fact of the power difference, the car will not shift in the same spot. The mph and rpm's would vary slightly.
If I have said anything that you disagree with, please lmk.

And to answer your question, 3.42's to 3.73's will not help very much, but in some cases have shown a little improvement in some cars. If I were you I would look more into either making power or adding some suspension. (IMO)

However; There's no reason to have a high horsepower car if you can't plant the power to the ground. It becomes more of a PITA at the track when a car with half the power walks right by you, b/c your spinning and they are hooking. :( All I'm saying is suspension makes a world of difference. I'm having the same issue with my car now, not enough suspension to plant 550-600hp! It pretty much speaks for itself once you do suspension mods. The car will drive completely different and actually do something with the power.

Best of Luck

James

dlandsvZ28
12-27-2009, 02:58 PM
If you check the rpo codes sticker (usually in the glove box) look for these codes...
gu2 = 2.73's
gu5 = 3.23's
gu6 = 3.42's

I've done alot of research on these cars in the past 5 years, and all I have been able to come up with is that all of the V8 A4 cars had 2 options 2.73's and 3.23's.
In 93 TA's and Z28's with an M6, they had a 3.23 gear and the transmission had a steeper 1st gear.
In 94 and up TA's and Z28's, they used a less steep 1st gear in the 6 speeds and bumped up the rear gear ratio to 3.42's.
In this time period nothing was changed in the A4 cars though. Still the same 2 options from 93-02. (2.73's or 3.23's only)
And to verify on the v6 cars, YES the 3.42 rear gear ratio was offered as an option. (My 44,xxx mile 96 RS has this option as well) It has a GU6 rpo code on the label in the glove box to verify.

With that said, IDk wether or not ANY V8's did slip out of the factory with 3.42's or not, but it isn't documented anywhere that I have seen. Is it Possible??? YES! But they would have to note it in the RPO codes label as well as use a whole different tune as for the shift points and etc. It would not be able to use the same as the V6 due to the fact of the power difference, the car will not shift in the same spot. The mph and rpm's would vary slightly.
If I have said anything that you disagree with, please lmk.

And to answer your question, 3.42's to 3.73's will not help very much, but in some cases have shown a little improvement in some cars. If I were you I would look more into either making power or adding some suspension. (IMO)

However; There's no reason to have a high horsepower car if you can't plant the power to the ground. It becomes more of a PITA at the track when a car with half the power walks right by you, b/c your spinning and they are hooking. :( All I'm saying is suspension makes a world of difference. I'm having the same issue with my car now, not enough suspension to plant 550-600hp! It pretty much speaks for itself once you do suspension mods. The car will drive completely different and actually do something with the power.

Best of Luck

James

It's my understanding a dealership can reflash a PCM with the Tech II. If that is so and if there are a few (but not many) 98-02 F-Body A4 3.42 rearend ratio Camaro/Firebirds in the system then there should be a 'Flash' file for it: one file for 2.73, a second file for 3.23, and a third one for the 3.42.

Any GM tech on this forum should be able to easily find that out and report back with the information.

As for the owners in this thread who report that they do own such a rare vehicle IMO a call to a dealership asking if their car can be reflashed since it has the 3.42 would also answer the question if there really are factory completely stock A4 3.42 Z28/SS f-bodies.

pillarpod
12-27-2009, 07:30 PM
put that 4.10 in there ;)

00pooterSS
12-28-2009, 05:34 PM
^^^
If you are not the original owner, then there is no way you can accurately claim your A4 car came with 3.42's from the factory.

Agreed, everyone claiming this is full of it.....:bs:

If you weren't there when the car was built you cant accurately claim they didnt either.....


Just how like a very low amount of LS1 F body's ended up with LS6 blocks, shit happens at the factory that isn't necessarily supposed to, but it does so :gtfo:

Spartan7
12-28-2009, 05:40 PM
If you weren't there when the car was built you cant accurately claim they didnt either.....

:lol: Were you?

00pooterSS
12-28-2009, 05:54 PM
:lol: Were you?

No I was at home talking shit to people on the internet about what they can accurately claim, were you there?



Really though for whats its worth I never said the car with no doubt in jesus's name came with 3:42's I said thats what was in there and that its doubtlful they were changed by the condition the car was in when I got it, and the guy that has been building rear ends and only rear ends for somewhere around 40 years said he had seen it before from the factory, and others on here have had it happen to.

Spartan7
12-28-2009, 11:30 PM
No I was at home talking shit to people on the internet about what they can accurately claim, were you there?

Now who's talking shit?

My SS was supposed to have 3.23's but for some reason actually had 3.42's the guy at the rear end shop said he has seen stranger things come from the factory.

Whether you meant it or not, everyone read this and assumed that is what you meant. Without hard evidence, which you don't have, you should not even be insinuating that your car came with those gears from GM. If you were the original owner and the rear had never been serviced before, you would have something. But that's not the case here.

After I bought my car, I found the inside of my passenger door is red (my car is silver). So should I assume that GM, just for the hell of it, painted it a different color? Or should I more accurately assume the previous owner did something to the door?

I wasn't talking shit, I was bringing up a legitimate argument to your statement. If you don't like what I have to say, then ignore it.

01ssreda4
12-29-2009, 10:34 AM
Bottom line is it doesnt really matter.:givesfuck

davith
12-29-2009, 02:22 PM
How big of a change will I see on an auto going form 3.23 to 3.73?

dlandsvZ28
12-29-2009, 03:02 PM
How big of a change will I see on an auto going form 3.23 to 3.73?

There is a thread on this forum where the OP posted his results with different gear changes. Contrary to what you might think his results were measured in tenths in the quarter mile.

For example: if you are running mid 12's it's not like likely you will be running mid 11's with a gear change all other things being equal.

Suspension work, torque arm, sticky tires, and weight reduction dollar for dollar will get you better peformance than the cost for parts and labor to change gears (probably around $700).

If its a daily driver and you don't race street or dragstrip - IMO stay with the 3.23 and spend the dollars on something else.

3.23 gears won't break as easily a 3.73's if you still have a stock rear end.

Gas mileage will decrease going to 3.73.

I have a Moser 12 bolt and went from 3.73 back 3.42. Couldn't go back 3.23 and with the next lower ratio a 3.08 instead. So I chose 3.42 but hindsight tells me since car is a daily driver I should have went to a 3.08 because I have almost BIG rwhp (565). It's pretty easy to blow the tires.

My setup: ATI Procharged D1SC h/c bolt on stock bottom end 347 running 10 lbs of boost matched to a Yank PY3400 and Performabuilt Level III outputting 565 rwhp on a Mustange dyno with plans to replace with an LS2 forged 364 or iron block 370.

I want driveability and cruising at a reasonable rpm - 3.73 is too high for me.

Bottom line - depends upon how you to want to drive the car and its purpose.

00pooterSS
12-29-2009, 06:30 PM
:lol: Were you?

I considered this talking shit.^^ So thats where my comment came from.

But you wanna say I cant assume this and that blah blah, well accept the fact that you cant either, and quit acting like that just because something wasnt supposed to happen, that it cant.

Anyway, I understand your point, ill stop thread highjacking now and im outta here, along with my factory 3:42 gearset:engarde:

eseibel67
12-29-2009, 08:01 PM
I find this subject interesting. If I had to put money on it, I would say it is extremely unlikely that an auto was built with 3.42's. Especially if the speedometer is correct, since there is no factory calibration for this, and they certainly wouldn't do a custom change for 1 car.

I'm not sure how factories work, but I would assume that at the time of assembly the bar code on the "incorrect" 3.42 axle would conflict with the build procedure for an A4 and set off the alarms.

And yes, a Tech II can recalibrate to another STOCK axle ratio that was available on that model and year at the dealership.

Did we determine if the car in question had the GU6 RPO code?

snk-huntr
12-29-2009, 08:25 PM
maybe 0.5 if that.

snk-huntr
12-29-2009, 08:28 PM
woops read the gearing wrong ,thought it said 273 to 373 ,and I met to put 0.1. stupid beer.lol..

01ssreda4
12-29-2009, 09:22 PM
There is a thread on this forum where the OP posted his results with different gear changes. Contrary to what you might think his results were measured in tenths in the quarter mile.

For example: if you are running mid 12's it's not like likely you will be running mid 11's with a gear change all other things being equal.
This is true, rediculous in thinking but true
Suspension work, torque arm, sticky tires, and weight reduction dollar for dollar will get you better peformance than the cost for parts and labor to change gears (probably around $700).
Thats not true, me and my buddy split the cost of all tools needed ($200) and learned to do our own gear swaps for free. Then I did half a dozen other cars for profit.
If its a daily driver and you don't race street or dragstrip - IMO stay with the 3.23 and spend the dollars on something else.
once again, no logic used here bc we dont have 500+ hp. Gears are great bang for the buck SOTP mod.
3.23 gears won't break as easily a 3.73's if you still have a stock rear end.
You cant prove that
Gas mileage will decrease going to 3.73.
This is true, not a big deal really though
I have a Moser 12 bolt and went from 3.73 back 3.42. Couldn't go back 3.23 and with the next lower ratio a 3.08 instead. So I chose 3.42 but hindsight tells me since car is a daily driver I should have went to a 3.08 because I have almost BIG rwhp (565). It's pretty easy to blow the tires.

My setup: ATI Procharged D1SC h/c bolt on stock bottom end 347 running 10 lbs of boost matched to a Yank PY3400 and Performabuilt Level III outputting 565 rwhp on a Mustange dyno with plans to replace with an LS2 forged 364 or iron block 370.
We dont have these hp numbers. Smaller hp needs a gearing advantage
I want driveability and cruising at a reasonable rpm - 3.73 is too high for me.
Other people may not agree with you, I felt the same way at first about my 3.73s but I wouldnt trade back to 3.23s.
Bottom line - depends upon how you to want to drive the car and its purpose.

My thoughts in bold. Have a nice day :D