how low can i safely lower shift firmness in 4R70W with SCT?

04ctd · 10-08-2009, 11:00 PM

had my tranny rebuilt in the 99,

and put a mild shift kit in it.

due the number of variables in a 135k mile tranny that has been rebuilt once at least,

it came out a LOT firmer than we thought.
not too firm for one of us,

but too firm for my Dad.

i have them down 10%, it goes in five % steps down to 25.

it also allows you to change the MPH, but i have not monkeyed with that.

??

gearmesh, inc. · 10-10-2009, 12:21 AM

Are you saying that your programmer can decrease line pressure below factory program levels? If so, I am surprised that a company would take the liability risk of lowering line pressure below factory standard.

A programmer can't increase maximum line pressure at all. All they can do is modify the ramp of the pressure rise curve in relation to engine load. They can also take out any torque management strategies.

04ctd · 10-12-2009, 12:35 AM

http://www.sctflash.com/X3.php

it changes it in 5% increments, up/down to a range of 25.

at negative 25, it made the 1-2 shift bearable.
but it will still bark 2nd at WOT

it never did really ease up the 3-4 shift, you just kinda have to "peddle" the gas, and feather it to get a soft 3-4 shift.

AverageJoe · 10-12-2009, 07:16 AM

Don't try to change it with the tune, take it back to whoever built the tranny and they should be able to soften it up for you the right way.

Illusions · 10-12-2009, 07:24 AM

^^ x2

gearmesh, inc. · 10-12-2009, 07:55 AM

Sounds like the shift kit may be set up for full kill instead of just "stun". A shift kit set up for full kill with a stock or tight converter will be rather harsh around town.

I agree on consulting with the trans builder to soften you shifts up some. Which shift kit was installed? Different things are done with different shift kits to get firmer shifts.

04ctd · 10-12-2009, 10:31 PM

Quote:

Originally Posted by gearmesh, inc.

Sounds like the shift kit may be set up for full kill instead of just "stun". A shift kit set up for full kill with a stock or tight converter will be rather harsh around town.

I agree on consulting with the trans builder to soften you shifts up some. Which shift kit was installed? Different things are done with different shift kits to get firmer shifts.

he told me which shift kit, and i forget now.

lot of stuff going on.

that's the craigslist pic in my avatar, in 2 months, i pretty much replaced everything on the car.

and i just ran OUT of time to take it back down and put in a new valve body, so that option was out.

turning down the pressures with the programmer was my only choice due to my tight schedule.

my builder gave me a year warranty, but advised against using the programmer to lower the pressures, due to unknown side effects.

we decided to let Dad have it, and tow it back down, over the holidays, if he can't live with it.

i delivered the car this weekend, and my dad LOVES it.

he really likes being able to catch second in it, and I told him harsh shifts under part throttle were part of the trade off.

between now and the holidays, he will get in some prime cruising in the Blue Ridge Parkway, and he is supposed to decide what he wants to do.

i believe, once something is together, and running like you want, within 90% of your expectations, you are best to leave it alone. he pretty much agreed,
so we will see what he thinks in a few months.

thanks for the advice.

john

10-08-2009, 11:00 PM	#1
04ctd Senior Member Join Date: Aug 2009 Location: Ladson SC Posts: 4,388	how low can i safely lower shift firmness in 4R70W with SCT? had my tranny rebuilt in the 99, and put a mild shift kit in it. due the number of variables in a 135k mile tranny that has been rebuilt once at least, it came out a LOT firmer than we thought. not too firm for one of us, but too firm for my Dad. i have them down 10%, it goes in five % steps down to 25. it also allows you to change the MPH, but i have not monkeyed with that. ??

10-10-2009, 12:21 AM	#2
gearmesh, inc. creepy azz cracka Join Date: Nov 2008 Location: Summerville Posts: 1,587	Are you saying that your programmer can decrease line pressure below factory program levels? If so, I am surprised that a company would take the liability risk of lowering line pressure below factory standard. A programmer can't increase maximum line pressure at all. All they can do is modify the ramp of the pressure rise curve in relation to engine load. They can also take out any torque management strategies. __________________ "I came into this world kicking, screaming,and covered in someone else's blood, I have no problem leaving the same way!" ÔÇ£If you carry a gun, people will call you paranoid. ThatÔÇÖs ridiculous. If I have a gun, what in the hell do I have to be paranoid about?ÔÇØ -Clint Smith, Thunder Ranch.

10-12-2009, 07:24 AM	#5
Illusions Senior Member Join Date: Apr 2008 Location: In the Pits Posts: 2,247	^^ x2 __________________ Illusions Grafix A Pair of "Jackstand" 01 Xtreme Blazers

10-12-2009, 07:55 AM	#6
gearmesh, inc. creepy azz cracka Join Date: Nov 2008 Location: Summerville Posts: 1,587	Sounds like the shift kit may be set up for full kill instead of just "stun". A shift kit set up for full kill with a stock or tight converter will be rather harsh around town. I agree on consulting with the trans builder to soften you shifts up some. Which shift kit was installed? Different things are done with different shift kits to get firmer shifts. __________________ "I came into this world kicking, screaming,and covered in someone else's blood, I have no problem leaving the same way!" ÔÇ£If you carry a gun, people will call you paranoid. ThatÔÇÖs ridiculous. If I have a gun, what in the hell do I have to be paranoid about?ÔÇØ -Clint Smith, Thunder Ranch.

10-12-2009, 12:35 AM	#3
04ctd Senior Member Join Date: Aug 2009 Location: Ladson SC Posts: 4,388	http://www.sctflash.com/X3.php it changes it in 5% increments, up/down to a range of 25. at negative 25, it made the 1-2 shift bearable. but it will still bark 2nd at WOT it never did really ease up the 3-4 shift, you just kinda have to "peddle" the gas, and feather it to get a soft 3-4 shift.