I have a 2002 silverado with 4.8. I'm not happy with the way it shifts hard from 1st.to 2d. Had it checked by chevy and was told nothing wrong. It meets gm standards. I askedto drive another truck for comparison. They misstakenly gave me a 5.3 gmc which shifted much smoother than mine. They said that was because it was a 5.3 so they gave me a gmc 4.8 which shifted simalar to mine but still better. I was told the 5.3 is programed differently. I believe that programing might change when it changes but nothow it changes. My question. Is the trans. the same in a 4.8 and a 5.3. If so, is it programed differently and if it is, in what way?

 

the trans in the 4.8 is the same as the 5.3. it is a 4l60E. was your truck new when you purchased it? if not, then there is a chance it could have a vette servo, or a programmer installed on it. i have the 5.3 and it shifted slow and sloppy until i programmed the computer and installed the servo. now it shifts fast and snappy.

 

So you are upset that your truck has a bit of performance to it? If you wanted an easy ride you should have gotten a Cadillac.

 

if you change your tranny fluid to synthetic mobil 1 tranny fluid. Those $14 tranny tune up bottles help smoothen out the shift a little
I use the fuel primer from an outboard fuel hose to suck some fluid out of the tranny through the dipstick/ it makes life easier if you want to lower fluid level.

 

Dave, I don't know if you solved your hard shifting yet and I'm not an expert but.... if your tranny is a 4L60E, the 1st to 2nd shift is regulated by a spring in the valve body or in a section next to the valve body in a corner of the tranny. This can be serviced with the tranny still in the truck. If you bought the truck used somebody may have changed it for a firmer shift. Line pressure may also be a factor and can be checked with a Snap-On or like diagnostic tool and a line pressure gauge on a port on the tranny. If I recall correctly a softer spring is used to firm the 1-2 shift because it doesn't buffer the line pressure as much when your shift solenoid is triggered for the shift. This is something you could do yourself if you are comfortable opening up your tranny starting with dropping the pan. I would think a tranny shop would do it for under $150.00. Hope this helps. Al