4L60E tuning question -- HELP my 1-2 shift is pretty harsh at light loads

[MxRace75]

I've been working on a friends suburban and I've got just about everything working like it should except I want to soften the 1-2 shift at light loads. He had the trans built way beyond what a suburban should need and it shifts hard 1-2..

What is the easiest place to alter this?? desired shift time vs tps?

If so I've posted the stock table as a jpg if you guys could make suggestions that would be great.. I've never messed with trans tuning.

[1BadAction]

line pressure modifier vs TPS vs gear.

Good idea making sure that thing isn't banging into gear, because he will break hard parts in a heavy ass suburban with it shifting like some of those built units shift.

[Roadknee]

I've been working on a friends suburban and I've got just about everything working like it should except I want to soften the 1-2 shift at light loads. He had the trans built way beyond what a suburban should need and it shifts hard 1-2..

What is the easiest place to alter this?? desired shift time vs tps?

If so I've posted the stock table as a jpg if you guys could make suggestions that would be great.. I've never messed with trans tuning.

If the transmissions pressures were boosted in the rebuild, adaptive learning won't be able to remove enough pressure to achieve the desired shift times in the table you posted.

Take a look at ramping pressure vs tps vs shift. You can remove pressure from the 1-2 shift to reduce shift firmness. A word of caution: don't get too crazy with the negative numbers or you risk burning clutches.

I've seen -100 from 37.5% TPS to 100% TPS in a built 4L60E with the big servos and Sonnax performance pack. This made for pretty lazy 1-2 shifts. Don't go directly to -100. Make small changes and see how the trans responds.

[Fast355]

line pressure modifier vs TPS vs gear.

Good idea making sure that thing isn't banging into gear, because he will break hard parts in a heavy ass suburban with it shifting like some of those built units shift.

Which is why the Express has an 80E. Got tired of shattering the glass like 4L60Es. It has a Transgo HD2 and I had to pull a little line pressure. With the 0411 the line pressure is controlled by calculated torque output. I increased the base line pressure slightly from Zero to make sure I had plenty of holding power off-idle and changed the pressure ramp slighly off-idle through the midrange of about 240 ft/lbs. From 240-320 ft/lbs it is roughly stock values and above 320 ft/lbs its bumped about 10% over stock. I suspect the 60E will like something similar. I would leave the 0% and 50% TPS and above 50% line pressure about stock and taper the off-idle through 50% to your liking.