3.42 rearend, need a reprogram?
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From: Pembroke Pines, FL, USA
3.42 rearend, need a reprogram?
Going to put 3.42 gears in a friends 2001 C5.... I know hypertech used to sell a reprogrammer for the 97s and 98s. Where can I get a reprogram for him to use the 3.42s? Thanks in advance.
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From: S.W. Ohio. . . . . . NRA Life Member
Re: 3.42 rearend, need a reprogram? (Metlegleo)
need a reprogram?
The speedometer is not affected, so you don't need a reprog because of that.
What ratio carrier is currently in the car now? If it is a 3.15 (and you are going to use the stock torque convertor) then you don't have to reprogram at all. There is some better performance if you reprogram arounf the A4 torque management; but was trying to directly answer your question.
there is info on my web page about this specific upgrade:
mikemercury.home.att.net/342.htm
The speedometer is not affected, so you don't need a reprog because of that.
What ratio carrier is currently in the car now? If it is a 3.15 (and you are going to use the stock torque convertor) then you don't have to reprogram at all. There is some better performance if you reprogram arounf the A4 torque management; but was trying to directly answer your question.
there is info on my web page about this specific upgrade:
mikemercury.home.att.net/342.htm
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From: Boynton Beach Florida
St. Jude Donor '07-'12, '20
Re: 3.42 rearend, need a reprogram? (Metlegleo)
Just did this swap in my 2001. You will need the program! Hypertech does not make one. I went with SUPERCHIPS Love it. The reason for the program is not the sppedometer it is the shift points and lock-up of the convertor. I tried to get away without the program but, the codes that it was throwing told me otherwise. Runs like a champ. Check my signature. :D
Bob
[Modified by 16Again, 12:19 AM 3/1/2002]
Bob
[Modified by 16Again, 12:19 AM 3/1/2002]
Team Owner
Joined: Apr 2001
Posts: 54,204
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From: S.W. Ohio. . . . . . NRA Life Member
Re: 3.42 rearend, need a reprogram? (Metlegleo)
. I tried to get away without the program but, the codes that it was throwing told me otherwise. Runs like a champ. Check my signature.
Team Owner
Joined: Oct 2001
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From: Boynton Beach Florida
St. Jude Donor '07-'12, '20
Re: 3.42 rearend, need a reprogram? (Mike Mercury)
. I tried to get away without the program but, the codes that it was throwing told me otherwise. Runs like a champ. Check my signature.
Bob, what ratio was originally in your car? Did you replace the stock TC as well?
Bob, what ratio was originally in your car? Did you replace the stock TC as well?
Bob
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Joined: Oct 2001
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From: Boynton Beach Florida
St. Jude Donor '07-'12, '20
Re: 3.42 rearend, need a reprogram? (Mike Mercury)
. I tried to get away without the program but, the codes that it was throwing told me otherwise. Runs like a champ. Check my signature.
Bob, what ratio was originally in your car? Did you replace the stock TC as well?
Bob, what ratio was originally in your car? Did you replace the stock TC as well?
Bob
[Modified by 16Again, 4:10 AM 3/1/2002]
Burning Brakes
Joined: Aug 2001
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From: Roswell GA
Re: 3.42 rearend, need a reprogram? (16Again)
Mike's point is that your car was "set up" for the 2.73's. To change to 3.42's is quite a large percentage change - that is why you needed a reprogram. If a car is set up from the factory for 3.15's it already has different shift points than yours did and to change from 3.15's to 3.42's is only abouy 9% and that does not require a reporgram.
Several others besides Mike have proven this out. Thus again back to the original question:
From 2.73 to 3.42 - yes reprogram.
From 3.15 to 3.42 - no need to.
Several others besides Mike have proven this out. Thus again back to the original question:
From 2.73 to 3.42 - yes reprogram.
From 3.15 to 3.42 - no need to.
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Team Owner
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From: Boynton Beach Florida
St. Jude Donor '07-'12, '20
Re: 3.42 rearend, need a reprogram? (KingTut)
I understand what your saying however, I still don't feel the TC will lock up at the right time as there is a RPM change of (on my car 400 rpm) has to be a couple hundred on his. Then there is hitting of the rev limiter again I feel a program change is in order. Just my opinion, as always do what is needed for your particular application.
Bob
Bob
Burning Brakes
Joined: Aug 2001
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From: Roswell GA
Re: 3.42 rearend, need a reprogram? (16Again)
3.42 / 2.73 = 25% increase in rpm for a given speed.
3.42 / 3.15 = 9% increase.
Given the car used to shift at 5400 rpm - yours would now shift at 6750 (big problem - over rev limit) and Mikes would shift at 5886 still under - no problems.
There are several other posts confirming these facts.
3.42 / 3.15 = 9% increase.
Given the car used to shift at 5400 rpm - yours would now shift at 6750 (big problem - over rev limit) and Mikes would shift at 5886 still under - no problems.
There are several other posts confirming these facts.
Pro
Joined: Oct 2001
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From: OH
Re: 3.42 rearend, need a reprogram? (KingTut)
Okay, here's another question for you experts...I have the 2.73s right now in my '01 coupe (:cry) and Mike M.'s 3.15s are sitting in my van waiting to be installed. Will I need to reprogram the computer to go from the 2.73s to the 3.15s? My primary concern is hitting the rev limiter at WOT.
And Mike, you're not allowed to answer this one! :jester
And Mike, you're not allowed to answer this one! :jester
Pro
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From: OH
Re: 3.42 rearend, need a reprogram? (Mystery Fan)
Mystery Fan-
Can you be a little more specific by what you mean by "optimally?" I'd like the car to behave as if it came stock with 3.15s. I do not intend to drag race the car, but I'd like a little more pull off the line than what the 2.73s can provide. Mike M. has reported NO problems on his car from going from the 3.15s to the 3.42s -- if I could have similar results I'd be happy.
[Modified by Schwa72, 6:13 AM 3/1/2002]
Can you be a little more specific by what you mean by "optimally?" I'd like the car to behave as if it came stock with 3.15s. I do not intend to drag race the car, but I'd like a little more pull off the line than what the 2.73s can provide. Mike M. has reported NO problems on his car from going from the 3.15s to the 3.42s -- if I could have similar results I'd be happy.
[Modified by Schwa72, 6:13 AM 3/1/2002]
Instructor
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Re: 3.42 rearend, need a reprogram? (Schwa72)
As far as my car goes, It current shifts at 6,000rpm at WOT. I have the powerloader and it is set up for that shift point. Before the powerloader the car shifted at 5,800 at WOT. By switching to 3.42, your shift points are going to move higher by 9%. So if your WOT shifts are at 5,800 now, effectively it will move closer to 6,400. At 6,400 you are moving closer to the pushrod bending danger zone. Going from 2.73 to 3.42 is a much bigger gain. I am not a mechanic and this is all based on what I have read on the forum.
Basically, your computer is setup for your current gear, any changes to your setup should dictate a change in the PCM for optimal results.
Basically, your computer is setup for your current gear, any changes to your setup should dictate a change in the PCM for optimal results.
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From: S.W. Ohio. . . . . . NRA Life Member
Re: 3.42 rearend, need a reprogram? (Mystery Fan)
Before the powerloader the car shifted at 5,800 at WOT. By switching to 3.42, your shift points are going to move higher by 9%
What is not factored into this is torque convertor slippage & torque management that are both being controlled by the PCM. If the TC was locked up at WOT, then "percentage added" would give exacting results.
I was so worried that my non-reprog'd 3.42 upgrade would be borderline rev limiter... but was pleasantly surprised that it didn't happen.
My local dealer said they can reprog (for $60) if the new ratio is a factory available one. Going from 2.73 to 3.15 stays within a factory available configuration. The 3.42 is not available with the A4 and their GM Tech Tool II will not allow them to assign a 3.42 to an A4 VIN.
[Modified by Mike Mercury, 12:34 PM 3/1/2002]
Burning Brakes
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From: Roswell GA
Re: 3.42 rearend, need a reprogram? (Mike Mercury)
I want to re-emphasize that.
2.73's to 3.15's is a stock factory option. Just go to the dealer and have you PCM reprogrammed for the 3.15's for the $60-65 fee. No problem - it will be just like you had ordered the option on the car in the first place. :cheers:
2.73's to 3.15's is a stock factory option. Just go to the dealer and have you PCM reprogrammed for the 3.15's for the $60-65 fee. No problem - it will be just like you had ordered the option on the car in the first place. :cheers:
