• If you currently own, previously owned or want to own an Avalanche, we welcome you to become a member today. Membership is FREE, register now!

Hard 1-2 Shifting



I have noticed that my Av will shift very hard when going from 1-2. It is a jerky shift and sometimes there is a clunk noise. It stared doin this after I put on duals, hypertech, and FPIK. But before I put these mods on the truck had a hard time shifting into third when it was around 0 degrees. Does anybody have the same problem or know whats wrong?

I had the same situation with my ?01 Silverado. I did some researching on the WEB and found a recall site stating that Chevy, in an attempt to get better MPG, had set the shift point in the transmission really low in the RMP before going to second gear. Therefore if the driver were nursing the fuel feed they would not have enough momentum when going to second. (Sorry I tried to find that again, but no luck yet after a year.)

I did try driving with a little heaver foot on take off, and no it wasn?t hammer down ;D, the problem did not reappear.

The site also continued to state that Chevy was correcting the sifting problem as the vehicles come back in for maintenance. I do my own maintenance so I just called up my dealer a scheduled an appointment for him to do this modification for me. It took a whole 5-10 minutes.

FYI: I am having the same thing with my ?02, just not as hard. I plan to buy a Super Chip reprogrammer so I can adjust for the bigger tiers I am planning on buying and tune in any performance pieces I add. I will adjust my shift point myself at that time.

Hope this helps

I ment to state that the '02 is an avalache.... Kinda important to your question.
I have a 2500 4x4 and have the 8.1. I also have added Superchip and this adds the firm shift. Very noticible 1st to second. Enhanced the overall performance. Very happy with the mod. Also lowered the trans temp approx 10 degrees.

I had the same problem shifting from 1st to 2nd in my 2003.

Dealer replaced a module (not sure what it was) near my alternator. It fixed the problem.. There is a TSB out on this issue. It takes about an hour to install.
I mentioned this the other day in a transmition forum. My '03 does it when I accelerate from a dead stop. I drive slow and in style, so when I leave from the dead stop very easy on the gas this happens. I am taking mine in for an oil change soon and I am going to ack about the replacement that Bonecutter mentioned.