Gear ratio when in 3rd....
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Gear ratio when in 3rd....
Ok, I am trying to learn more about the dif. I have a 2.73 A4. From a dead stop, as I go through the gears, what are my ratios? AT highway speeds when I put it in 3rd it is much more responsive...this tells me I am in a different ratio, but what is it? This all has to do with my decision to move into a 3.42 setup.
Le Mans Master
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From: York PA
No matter what rear gear you have, 3rd gear in the trans will always be 1:1
At 75 mph in 3rd gear with 2:73's your RPM will be 2,730
At 75 mph in 3rd gear with 3:42's your RPM will be 3,420
No problem though, since you have OD
At 75 mph in 3rd gear with 2:73's your RPM will be 2,730
At 75 mph in 3rd gear with 3:42's your RPM will be 3,420
No problem though, since you have OD
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aw yes, I get it...I was getting the gears in the rear end confused with the gears in the tranny.
So, the extra time gain comes from the combination, right? If someone posts the numbers for the 3.42 it should be evident, right?
So, the extra time gain comes from the combination, right? If someone posts the numbers for the 3.42 it should be evident, right?
Safety Car
Joined: Oct 2004
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From: Plano TX
The transmission gear ratios will never change no mater what rear end axles ratio you have. You have an 4l60e automatic transmission.. They all have the trans ratio that MUNCH posted above. The auto trans either had a standard 2.73 or optional 3.15 ratio from the factory.. The 3.42 rear end was standard on all manual trans mission c5 corvettes... The manual Transmission ratios are also different than the auto trans ratios Also the transmission gearing is shorter on the z06 than on the regular c5 6 speeds.. Both have the same 3.42 rear end.. The z06 has a close ratio transmission, which provides for quicker acceleration than the wide ratio 6 speed found on the coupe,frc and convertble.. The close ratio tranny keeps the engine in the "sweet spot"
of the powerband for optimal power at all times. So all said you are stuck with the same tranny ratios regardless if you havee a 2.73,3.15,3.42,3.73,4.10 axle ratio. The 3.42 gears will help your acceleration times out quite a bit.. I think you will be really happy with it.. A 3200 rpm stall converter woul be a nice addition as well
of the powerband for optimal power at all times. So all said you are stuck with the same tranny ratios regardless if you havee a 2.73,3.15,3.42,3.73,4.10 axle ratio. The 3.42 gears will help your acceleration times out quite a bit.. I think you will be really happy with it.. A 3200 rpm stall converter woul be a nice addition as well
Safety Car
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From: You can't get there from here NJ
St. Jude Donor '08-'09
I went from a 2.73 to a 3.42 ZO6 rear.There was a huge difference in performance. There also was a difference in gas mileage. With the 2.73, I averaged about 29 mpg straight highway. Now, I get about 25mpg. HOWEVER, that may be due to the fact that it is WAY MORE FUN TO DRIVE THE CAR NOW, and the tune I have is pretty aggressive. I have a hard time not getting on it from time to time just for the kick it gives me.
Also, if you switch to a different rear, you MUST GET A TUNE. Get one from someone famliar with A4 trans. I know folks will say any good tuner can handle this. NOT. The first guys that did the rear install did a tune that sucked. Chuck, at Corvettes of Westchester got the car running great.
I did not get a different TC ( torque converter), and the car is still fine for the street. Everyone claims you need this, but it is not true.If I spent alot of time at a drag strip, a different TC like a 2800 0r 3200 would probably be the way to go. It will also cost you about another grand to get this too.
Also, if you switch to a different rear, you MUST GET A TUNE. Get one from someone famliar with A4 trans. I know folks will say any good tuner can handle this. NOT. The first guys that did the rear install did a tune that sucked. Chuck, at Corvettes of Westchester got the car running great.
I did not get a different TC ( torque converter), and the car is still fine for the street. Everyone claims you need this, but it is not true.If I spent alot of time at a drag strip, a different TC like a 2800 0r 3200 would probably be the way to go. It will also cost you about another grand to get this too.
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From: Should this thoughtful, valuable contribution meet with no acknowledgement or 'thanks' this post----
Great stuff...just wondering, couldn't my dealer's corvette mechanic do the shift point adjustments with the tech 2? I may have him install it...
Safety Car
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From: You can't get there from here NJ
St. Jude Donor '08-'09
I don't think dealers do this gear swap,since it is not an authorized option from GM to put a 3.42 in an A4. I don't know where you live, but there has to be a vette shop near that will do the swap and know how to tune it. Post up in your local area in the events section and ask who had this done, and where they went.
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Thread Starter
Tech Contributor
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From: Should this thoughtful, valuable contribution meet with no acknowledgement or 'thanks' this post----
I don't think dealers do this gear swap,since it is not an authorized option from GM to put a 3.42 in an A4. I don't know where you live, but there has to be a vette shop near that will do the swap and know how to tune it. Post up in your local area in the events section and ask who had this done, and where they went.
Safety Car
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From: You can't get there from here NJ
St. Jude Donor '08-'09
When they give you the bill, i'm sure "they" like that. The mods you refered to are minor things.
I would still take the car to a private "vette specialty" shop for gears and a tune. GM dealer will only give you a "GM" tune, not a custom tune .
I would still take the car to a private "vette specialty" shop for gears and a tune. GM dealer will only give you a "GM" tune, not a custom tune .
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From: Should this thoughtful, valuable contribution meet with no acknowledgement or 'thanks' this post----
Team Owner
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From: S.W. Ohio. . . . . . NRA Life Member
The 3.42 selection is grayed out.
Safety Car
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From: You can't get there from here NJ
St. Jude Donor '08-'09
the dealer won't be able to do the reprogram with this scenario. Oh yes... they each have the famed "Tech Tool 2" but the menu won't allow one to select a value for an unsupported upgrade. The TT2 - when connected to an A4 C5... will only allow the selection of 2.73 or 3.15 (because that was the available factory ratios on the A4).
The 3.42 selection is grayed out.
The 3.42 selection is grayed out.
Thanks Mike for explaining what I was thinking, I think ?
That's what I meant to say. GM only offers 2.78 or 3.15 as ratios for an A4. A 3.42 is not a GM option for an A4, so it would not be a mod a dealer would do, and their basic software would not give them the ability to account for this ratio in your car.
Like I said, talk to some local vette guys, and find out who they use in your area. That is the best way to go for this mod.
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From: Should this thoughtful, valuable contribution meet with no acknowledgement or 'thanks' this post----
Thanks Mike for explaining what I was thinking, I think ?
That's what I meant to say. GM only offers 2.78 or 3.15 as ratios for an A4. A 3.42 is not a GM option for an A4, so it would not be a mod a dealer would do, and their basic software would not give them the ability to account for this ratio in your car.
Like I said, talk to some local vette guys, and find out who they use in your area. That is the best way to go for this mod.
That's what I meant to say. GM only offers 2.78 or 3.15 as ratios for an A4. A 3.42 is not a GM option for an A4, so it would not be a mod a dealer would do, and their basic software would not give them the ability to account for this ratio in your car.
Like I said, talk to some local vette guys, and find out who they use in your area. That is the best way to go for this mod.
If I could find one that would let me help out or just hang around for the switchout I would jump on it. The labor and working overhead is just too much for an old man like me
Thread Starter
Tech Contributor
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From: Should this thoughtful, valuable contribution meet with no acknowledgement or 'thanks' this post----
the dealer won't be able to do the reprogram with this scenario. Oh yes... they each have the famed "Tech Tool 2" but the menu won't allow one to select a value for an unsupported upgrade. The TT2 - when connected to an A4 C5... will only allow the selection of 2.73 or 3.15 (because that was the available factory ratios on the A4).
The 3.42 selection is grayed out.
The 3.42 selection is grayed out.
Safety Car
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From: You can't get there from here NJ
St. Jude Donor '08-'09
Any good shop can do the gear swap in a few hours, and then do a tune for you. You go in first thing in the morning, and after lunch you are out the door.You just need to let the gears break in if you are getting a new setup. You have to wait a few hundred miles before you can jump on the GO PEDAL.
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From: Should this thoughtful, valuable contribution meet with no acknowledgement or 'thanks' this post----
I think the dealer will do it...I'll know for sure Monday...as long as I give them the VIN of the car it came out of the Tech2 will work...please keep your fingers collectively crossed for me! BTW, they use Pradators and Hypertechs, they have an extensive collection of them.
BTW, they use Pradators and Hypertechs, they have an extensive collection of them.
Last edited by $$$frumnuttin'; Jul 25, 2009 at 04:45 PM.
