Shift point corrrection

[billybob]

Running 38s on my LLY and want to change shift points to match bigger tires. Efilive's built in shift point correction is working, it brings up a pop up that says access denied? How do I manually adjust shift points?

[THEFERMANATOR]

You don't need to change them. The ALLISON isn't like the GM PCM. It doesn't care what size tires your running or gear ratio. It will shift at the same RPM VS TPS and speed with 38's or 28's. Changing the speedometer settings in the TCM can result in some funky shifts and unpredicteable grade breaking.

[billybob]

Hmmm, yea it still shifts at same rpm but i wanted to change it cause with the big tires it feels a bit lazy at lower rpms. i thought it might help if it downshifted earlier?

[THEFERMANATOR]

You can make changes to it to keep it higher up in the RPM's. Just remember to change both your upshift and downshift tables accordingly or else you will get some very awkward and busy shifts that can lead to trans trouble. I would reccomend flashing in an 01 TCM file and see how it does. you will lose overdrive lockout, but other than that you will be fine.

[killerbee]

The larger tires do require higher rpm shift points, and you can universally scale them up with adjustments to

{H0137} Vehicle Speed Ratio (going from memory here)

I have found that to be very effective.

[THEFERMANATOR]

The larger tires do require higher rpm shift points, and you can universally scale them up with adjustments to

{H0137} Vehicle Speed Ratio (going from memory here)

I have found that to be very effective.

I went to 3.42 gears in my BURB which is the equivalent of putting 33" tires on a stock truck, and I lowered my shift points as well as running a tighter converter. Couldn't be happier with it setup this way.