2005 GMC Sierra shift kit

Striper80 · #1 05-23-2014, 05:55 PM

I've got an 05 GMC Sierra 1500 4wd with an autotrac transfer case and I believe a 4L60e trans. I've owned it since new. I have 91000 miles on it now. I changed the trans fluid at 50k and 75k, according to GM's guidelines. I've been using a hyper tech programmer since 06. I've been thinking of putting a shift kit in it but I'm not sure since I've got some miles on it. Any opinions?

THEFERMANATOR · #2 05-23-2014, 09:39 PM

It's not that hard to do most of a TRANSGO HD2 shift kit without pulling the trans. Keep in mind with a programmer you may want to see if you can put the trans settings in the PCM back to stock to keep from getting to hard of a shift with a shift kit in it. I personally prefer modifying the trans VS doing it in the programming, but don't ddo both unless it is setup for it in the programming. Not sure if the hypertech changes the shift firmness or line pressure, but it would be worthwhile to check and see.

Striper80 · #3 05-23-2014, 09:56 PM

It does increase the firmness but I've heard that its not that great for the trans. Not sure if that's true or not. I never could stand the shifting of the stock program, the way it holds first and second for a softer shift. I prefer a nice solid shift. The boat I picked up now is a bit heavier than my old one so that's why I was thinking of putting in the shift kit and adding a trans cooler.

THEFERMANATOR · #4 05-24-2014, 07:42 PM

They can get pretty firm depending on which kit you install. If you put a shift kit in it can and has made them shift to harsh depending on the electrical changes made. I've done a few TRANSGO HD2's, and they shift nice and crisp. If you install a corvette servo with it, you need to change the accumulator housing in the valve body to keep it from slamming the 1-2 shift. The key is to do one or the other(or make sure the electrical modifications are setup for the shift kit). I personally prefer to change shift firmness hydraulically instead of electronically, and is how I do them. The shifts with your 05 aren't going to be super snappy regardless of what you do because of the ETC and SEM built into the PCM programming. Most tuners still keep alot of defuel in for trans protection which keeps a soft shift. Depending on the shift kit it can bump up line pressure, as well as decrease shift times by altering the accumulator setups. About all a shift kit is going to do for you is to bump up line pressure some more, and change lockup to an on off instead of a pulsed style where it lockups soft.