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3:43 to 3:73

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Old 12-22-2009, 07:28 PM   #1
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Question 3:43 to 3:73

Will this change make me run a faster Quater mile?
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Old 12-22-2009, 08:22 PM   #2
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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.
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Old 12-22-2009, 08:29 PM   #3
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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.
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Old 12-22-2009, 08:44 PM   #4
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Originally Posted by BriancWS6 View Post
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..
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Old 12-22-2009, 10:18 PM   #5
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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
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Old 12-22-2009, 10:56 PM   #6
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w68 V6s came with 3.42s, but no auto V8s
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Old 12-22-2009, 11:07 PM   #7
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w68 V6s came with 3.42s, but no auto V8s
he said V6..
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Old 12-23-2009, 05:38 PM   #8
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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.
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Old 12-23-2009, 09:32 PM   #9
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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.
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Old 12-24-2009, 06:12 AM   #10
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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.
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Old 12-24-2009, 09:16 AM   #11
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V6 A4's came with 3.23-V8 A4's came with 3.42
That is 100% incorrect. Stop spreading false information
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Old 12-24-2009, 09:18 AM   #12
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I did 3.23s to 3.73s in my Trans Am. It will make your quarter mile times faster.
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Old 12-24-2009, 09:23 AM   #13
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I say 4.10's or go home. I have them in my A4 and it is bad ***. 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.
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Old 12-24-2009, 09:46 AM   #14
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That is 100% incorrect. Stop spreading false information
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!
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Old 12-24-2009, 09:57 AM   #15
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Like everyone has said, go 4.10s to make it worth your while.
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Old 12-24-2009, 12:08 PM   #16
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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.
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Old 12-26-2009, 01:57 AM   #17
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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?
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Old 12-26-2009, 08:37 PM   #18
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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..
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Old 12-26-2009, 11:09 PM   #19
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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?
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Old 12-26-2009, 11:52 PM   #20
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Originally Posted by dlandsvZ28 View Post
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...
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