Revisiting Shifting

[Blown]

Yah, After looking at a stock power curve and the fact that the exhaust gets a bit small at high RPM, I have tuned my 1-2 shift to happen earlier. I commanded the shift at 4,200RPM and it actually happens by about 4600RPM. The "Shift Calc." has it dropping down too 2,466rpm when it catches second. There must be some TC slippage as you can see below in an RPM graph as it does not drop below 2,700. You are looking at 1-2 shift at WOT, datalogged and graphed with my Tweecer:

This is a useful tool to look at shift points: Gear Ratios, RPM and Tire Diameter to MPH with Shift Points Calculator

My output shifting at 5,000rpm:

Output shifting at 4,500rpm:

Inputs for 4R70W:

 

[CDW6212R]

That's a cool tool, especially the rpm's that each gear causes it to fall back to. That will show the wider gear spreads of some transmissions. In the 4R70W, the drop in rpm from 2nd to 3rd is a wide gap, which is where the W comes from. The AODE had the same gearing of the AOD, except the AOD forces lock up in 3rd and 4th, which was worse at that 2nd to 3rd shift.

The AODE would be the better gearing for accelerating, but those were rare and the 4R70W is slightly stronger. That's why I'm swapping AODE gearing into the 4R that's going in my Lincoln(AOD car).

I'll have to check that gearing calculator out for the 6R I want. I know the ratio drop from 1st to 2nd is a little more than most automatics.