What's your shift point tune?
 

Hello everybody, I'm interested in how your transmission is tuned, especially if you have big mods. Please include factors such as stall, gear, cam, valvesprings, and anything else that changes how the engine revs.

Please list your 1-2, 2-3, and 3-4 shift points in RPM and MPH, including programmed vs. actual, if you know off hand or have access to such information.

You could be a street driver or 1/4 mile racer with huge slicks, even better!

This is my attempt at trying to figure out how aggressive the tune should be with major mods like a stall, gear, cam, valvesprings, drag radials, etc. Especially the 2-3 shift, where apparently the 4L60E takes the most time to accomplish.



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2001 Firebird Formula A4
383ci 6-bolt 11:1 LS6 heads+cam, forged internals | Dana60 4.10 | BMR K-member | BMR control arms + Panhard + adj Torque arm | PST Custom driveshaft + 1350 yoke | FTI3500 stall 4L60E | stock air cleaner and exhaust! | P245/45R16 NT555R
345 rwhp / 391 rwtq
Built at Next Level Performance Orlando, FL

To give a simple explanation from my logs, 1>2 occurred within 50-100 rpm of commanded, and 2>3 takes about 250-300 to complete with the selector in 3rd. Shift time for 2/3 may increase when manually selecting third on the console due to fluid path differences. To deal with mph I would set that about 3 mph below the commanded rpm for that gear. Example:

1>2
Commanded: 6400 + 35mph
Actual completed: 6500 + 41mph
MPH @ 6400 (shift point): 38mph

2>3
Commanded: 6200 + 61mph
Actual completed: 6500-6550 + 67mph
MPH @ 6200 (shift point): 64mph

The commanded has to be padded more on the 2/3 for the increased shift time, especially using 3rd on the console. The simple way to do it for most cars would be plan your desired shift rpm, lets say like the above example around 6500. Find out mph vs. rpm from 6k to 6500. Use that as a reference to keep your mph lower then your rpm so the mph trigger is met first, and immediately after the rpm trigger is met. Most advise to leave some room for cushion here (hence my 3 mph above) and don't go crazy dropping the mph requirement either. Try to keep it close to accurate with a little bit of fudge room.

So, adjusting the 2-3 shift a whole 1700 rpm lower than limiter should be a red flag?
In my case :

Launch in 2nd WOT, 2-3 shifts at 5500, commanded at 5200.

Low-power shift 1-2 (manual or auto), WOT through 2nd, 2-3 shifts at 5500.

High power shift 1-2 (manual or auto), WOT through 2nd, 2-3 hits limiter at 6500. If kept at WOT at limiter, it will shift into 3rd. If I let off in 2nd (selector in 3 or D), trans stays in 2nd briefly, then goes into 3 or D.

Sounds like you have a trans issue. Holding manual 2 allows the clutches to grip, but making it shift the 1/2 makes them grab/control a WOT engine through second. Big difference.

That's what I was thinking. In all three cases (when shifting manually), I would move the selector into 3 or D early while accelerating in 2nd, not making the shift manually when it was time. This allowed the trans to be full auto during the 2-3 shift.