any way to quicken shift speed?

[sarg]

I have been trying to learn more, but was unable to find a thread that dealt with this specifically. Is there a way in the transmission to speed up how fast (not mph, but time) it takes for the 4l65 to downshift or upshift? When my friend hits the gas it seems like it takes forever for the transmission to actually downshift into the next lowest gear at wot.

[firefly9r68]

what type of car are you working with?

[sarg]

2007 Trailblazer SS.

[08RED2500HD]

Is there a way in the transmission to speed up how fast (time) it takes for the 4l65 to downshift or up shift?

for up shift, you would just decrease the shift times
Example .500 to .300
down shift doesn't have a table, so i normally just increase line pressure a bit.

[sarg]

Ok, so no table that effects downshift speed other than line pressure? Does the upshift time not have any relationship to downshift time?

[08RED2500HD]

I dont know, I wouldn't think so. But since there is no downshift time table maybe. Try it and please post results.

[sarg]

Will do. He did say when they bumped pressure a bit it helped a bit. Being that it is a truck that he tows cars with on occasion, I don't want to muck with the transmission much.

What is the max line pressure you generally call for on your truck?

[08RED2500HD]

depending on the application I'll max out the tables at 148psi, but from my understanding the Max Pressure in the "other" section under "Auto shift properties"-shift pressure in 93.
Again it depends on the app,yestarday i was working on a 4.8L silverado with the 4 speed, at lower RPM's the Customer didn't like much Psi over stock.

[sarg]

I have seen many performance tunes at 90+, but then some say that without upgraded internal components it is not advised to go much over stock. Seems that there is no clear answer, just a lot of opinions. But I do know that he wants to retain the ability to tow vehicles with it. He bumped it up 20 percent and still values are low 80s.

[01ssreda4]

I have a similar issue with mine. It downshifts instantly when in OD, as in a 4>2 shift. But when in D where it would make a 3>2 shift, its very delayed in comparison.

[sarg]

I am also going to try dialing in the shift speeds as well to make sure they are spot on. Right now the transmission settings are stock with a 20 percent increase in line pressure. He did say that before he adjusted that 20 percent increase it would almost redline before downshifting!