2.73 > 3.42 diff change - tuning needed?
10-09-2020, 09:24 AM
#1
Burning Brakes
Thread Starter
2.73 > 3.42 diff change - tuning needed?
Hello all,
I would post this in the tuning thread but it gets so little traffic I'm going to post it here in the Tech section. If mods decide to move it, so be it. I posted the same on DiabloSport (*as I have a Trinity 2 tuner) and have included Mike's answer below my question.
I'm getting ready to do a 2.73 > 3.42 differential swap on my 2002 Corvette A4 base. It is currently running the 91 octane tune (always run 93 octane as that is what they have in my area) with no other adjustments. Car is stock other than cat back exhaust. Can I make the programming changes needed for the 2.73 > 3.42 differential swap or are the parameters locked so only a custom tuner can do it? If I can do it what are the parameters that need changes and what are the changes?
From Mike at DiabloSport - you can make them, and honestly most C5s as i recall do not even need any change in the tune as they measure speed after the diff.
But going through many threads here I find info like those below and I need to know if I need to do anything tuning-wise and can I do it with the Trinity 2 that I have?With a gear swap no speedo change is required However you will need a "shift point correction" for both WOT and P/T shifts
If your car had a 2.73 rear gear then you would need a MINUS 25% for both P/T up/down shifts as well as for WOT up/down shifts
If your car had a 3.18 gear then you MINUS 8%
and
For 3.42 Gears set the following parameters:
1-2 Upshift MPH 41
2-3 Upshift MPH 80
3-4 Upshift MPH 130
2-1 downshift 36
3-2 downshift 79
4-3 downshift 118
Rev limits @ 6480
Rev Limits ON @ 6479
I would post this in the tuning thread but it gets so little traffic I'm going to post it here in the Tech section. If mods decide to move it, so be it. I posted the same on DiabloSport (*as I have a Trinity 2 tuner) and have included Mike's answer below my question.
I'm getting ready to do a 2.73 > 3.42 differential swap on my 2002 Corvette A4 base. It is currently running the 91 octane tune (always run 93 octane as that is what they have in my area) with no other adjustments. Car is stock other than cat back exhaust. Can I make the programming changes needed for the 2.73 > 3.42 differential swap or are the parameters locked so only a custom tuner can do it? If I can do it what are the parameters that need changes and what are the changes?
From Mike at DiabloSport - you can make them, and honestly most C5s as i recall do not even need any change in the tune as they measure speed after the diff.
But going through many threads here I find info like those below and I need to know if I need to do anything tuning-wise and can I do it with the Trinity 2 that I have?With a gear swap no speedo change is required However you will need a "shift point correction" for both WOT and P/T shifts
If your car had a 2.73 rear gear then you would need a MINUS 25% for both P/T up/down shifts as well as for WOT up/down shifts
If your car had a 3.18 gear then you MINUS 8%
and
For 3.42 Gears set the following parameters:
1-2 Upshift MPH 41
2-3 Upshift MPH 80
3-4 Upshift MPH 130
2-1 downshift 36
3-2 downshift 79
4-3 downshift 118
Rev limits @ 6480
Rev Limits ON @ 6479
10-09-2020, 08:15 PM
#2
Safety Car
They shift by mph at part throttle. Not RPM.
so lower gears, the rpm will be high before it shifts.
Full throttle looks for mph, then waits for rpm.
Follow Diablosport advice. No changes needed. See what happens. Then report back.
so lower gears, the rpm will be high before it shifts.
Full throttle looks for mph, then waits for rpm.
Follow Diablosport advice. No changes needed. See what happens. Then report back.
10-09-2020, 08:22 PM
#3
Melting Slicks
get it tuned, you will damage your trans if you keep driving it, TCC slip table and the WOT shift MPH value need adjustment, your shift points will be off
the rpm vs mph will be way off and set a trans slipping code
the rpm vs mph will be way off and set a trans slipping code
Last edited by feeder82; 10-09-2020 at 08:25 PM.
10-10-2020, 01:04 AM
#5
Drifting
Yes. When I went from 3.15 to 3.73 rear drive on my A4, it would hit the rev limiter in second and still not shift. I had A&A Corvette re program the PCM, which fixed the problem.
https://www.aacorvette.com/
https://www.aacorvette.com/
10-10-2020, 09:47 AM
#6
Burning Brakes
Thread Starter
Quite a variety of replies and advice. Most indicate that some change will need to be made while others that I will be good to go, no changes necessary. We'll see in a week or so.
