93 Yukon Lugs trying to go from 4th gear lockup to 3rd

[scott2093]

Means your shift points should be ~8% more aggressive than stock if you have the DRAC/VSSB corrected and the OE sized

Thank you!
I also have 285-75-16 but have calculated and adjusted everything as directed in the charts. Computer speed, gps and speedo are really close....
Sounds like I need to make some changes or a tune? I can't just drop a prom from the same truck with 3.73 option in I'm guessing?? Does that even exist?

I need to figure out this tuning thing.....

 

[L31MaxExpress]

Thank you!
I also have 285-75-16 but have calculated and adjusted everything as directed in the charts. Computer speed, gps and speedo are really close....
Sounds like I need to make some changes or a tune? I can't just drop a prom from the same truck with 3.73 option in I'm guessing?? Does that even exist?

I need to figure out this tuning thing.....

Considering a stock L05 has ~30 ft/lbs and 20 hp and ~2 mpg to gain in stock form from tuning, I would suggest tuning. That being said I would look at the overall gear ratio, tire size factored in to figure out what memcal to run if stock. What size tires were on it stock? 245/75R16s? At any case if you want the part-throttle shifting to be more aggressive use a memcal from a truck with 3.08 gears.

 

[scott2093]

What size tires were on it stock? 245/75R16s?

Yes

 

[L31MaxExpress]

You can download TunerproRT and then get a $OD or $E6 definition file and matching bin files on Gearhead-EFI. Then you can look at the shift patterns in a specific Memcal by the BCC number such as BJYL, BJYM, BJYN, etc. There will be many differences in the OE calibrations. Since you have an early non PWM 4L60E you are limited to 93 or 94 calibrations. None will compare to using Blucats and making your own though. Generally speaking GM neutered even a stock L05 shifting it at ~4,000 rpm in stock form. Peak power is at 4K and they maintain good power until 4,500 which is where the yellow band on the tach starts.