2.73 to 3.42s
Thread Starter
Burning Brakes
Joined: Jun 2004
Posts: 1,211
Likes: 0
From: Nesconset NY
St. Jude Donor '04 & '05
2.73 to 3.42s
Hi all
I am changing my differential from 2.73 to 3.42
I have an a4 and I know you have to change the shift points does any one out there have a recommended setting?
Thanks in advance
Tom
I am changing my differential from 2.73 to 3.42
I have an a4 and I know you have to change the shift points does any one out there have a recommended setting?Thanks in advance
Tom
Team Owner
Joined: Apr 2001
Posts: 54,204
Likes: 180
From: S.W. Ohio. . . . . . NRA Life Member
Hypertech is out - unless they fixed the C5 gear scaling bug.
The Diablosport Predator will make the necessary changes. I do believe there's one or two additional handhelds out there; I'm just not familiar with them.
The Diablosport Predator will make the necessary changes. I do believe there's one or two additional handhelds out there; I'm just not familiar with them.
Team Owner
Joined: Apr 2001
Posts: 54,204
Likes: 180
From: S.W. Ohio. . . . . . NRA Life Member
this goes back a few years, but the HPIII doesn't alter the TCC Slip table. So, within 50 - 90 miles after the A4 rear ratio upgrade you will get a P1870 error and the tranny will go into a limp mode.
Hypertech did admit to the problem, but then refused to correct it - or offer firmware upgrades to those already sold.
But I can't tell you whether they eventually corrected this in latter production models.
It will work as-is if changing from 2.73 to 3.15; but beyond the 3.15 is where the error will raise its ugly head.
Burning Brakes
Joined: Aug 2001
Posts: 1,206
Likes: 21
From: Roswell GA
Adjust the down shift tables also
The up shift changes are fine by just scaling them in proportion to the gear change. But remember that for each different 5% of peddle there can be different shifting.
I especially did not like the fact that to get it to drop back down into 1st from 2nd it took almost a complete stomp of the gas, so I made more changes to the down shifting curves than to the up shift. I can now get it to drop back a gear most of the time with little more than 50 to 70 percent gas. I have attached the chart view of both my original 3.15 shift patterns and the current 3.73 ones. Pay particular attention to the down shift changes.
http://team-meidl.com/c5/shift view/3.15 Orig.rtf
http://team-meidl.com/c5/shift view/3.73 Cur.rtf
Hope that helps - that Mike is so fast on these gear questions he always beats me to the answer.
I feel like a good sotp feeling is from either a 2.73 / 3.42 jump or a 3.15 / 3.73 jump - but that is just one guys experience.
I especially did not like the fact that to get it to drop back down into 1st from 2nd it took almost a complete stomp of the gas, so I made more changes to the down shifting curves than to the up shift. I can now get it to drop back a gear most of the time with little more than 50 to 70 percent gas. I have attached the chart view of both my original 3.15 shift patterns and the current 3.73 ones. Pay particular attention to the down shift changes.
http://team-meidl.com/c5/shift view/3.15 Orig.rtf
http://team-meidl.com/c5/shift view/3.73 Cur.rtf
Hope that helps - that Mike is so fast on these gear questions he always beats me to the answer.
I feel like a good sotp feeling is from either a 2.73 / 3.42 jump or a 3.15 / 3.73 jump - but that is just one guys experience.
Last edited by KingTut; Apr 3, 2008 at 02:23 PM.
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