Diesel Tuner's Blog

Upgrade Your LB7 or LLY Duramax To a 6-Speed

Posted by Ben Lawson on Oct 5, 2022 11:58:01 AM



As technology gets better, we see transmissions in trucks with more and more gears. Recently the Allison 6-speed was replaced with the 10-speed version. For older trucks, this can set them behind the competitors, both in terms of performance and fuel efficiency. A 6-speed conversion kit can take LB7 and LLY trucks to a whole new level of performance and drivability. 


If you are already in need of a valve body replacement due to slipping gears because of a weak or bad solenoid this kit is exactly what you'll want to swap in its place. The kit comes with an upgraded valve body combined with a 6-speed TCM. This upgraded TCM comes with updated shift schedules customized to your truck for the new gearing . Calibrated Power has been able to design one of the smoothest shifting 6-speed conversion kits there is. This kit will have your 15-year-old truck shifting like a 2018 model. It's also relatively simple to install and can easily be installed by someone who knows what they're doing in the shop or at home. Another option is to have Calibrated Power install it themselves in one of their upgraded transmissions (DT550, DT750, or DT1000), which is what you'll want if you're trying to make big power. 


DT550 Tranmissions


If you're looking for any of these qualities out of your transmission then a 6-speed conversion is for you:

  • Better MPG's
  • Quieter Exhaust Drone On The Highway
  • Smoother Shifting Transmission 
  • Engine and Transmission Longevity
  • Narrower Cruise Range to Meet Emissions Requirements


Noise Reduction

Say goodbye to loud exhaust resonance while driving your truck for long periods on the highway. Most trucks hover around 2000-2200 RPM when cruising at highway speeds. However, with the addition of another over-drive gear your RPM while cruising will be decreased by about 14%. This will bring your engine speed back down to that sweet spot of 1850 RPM, benefiting you with far less exhaust drone. Noise, vibration, and harshness will decrease drastically. Making long-distance driving a more enjoyable experience. 


Better MPG

Upgrading to a 6-speed conversion kit will double the number of over-drive gear ratios your transmission has to work with. This means your engine will be able to operate in a higher gear ratio while cruising on the highway resulting in 14% lower RPMs. Lower RPMs mean less work being put into rotating the mass of the crankshaft. Meaning better MPG and more range out of your tank. Below is a chart that shows the difference we were able to record in engine RPM while testing between the standard 5-speed Allison and the 6-speed conversion kit equip trans. 

6 speed conversion Shot

Powertrain Durability

With the use of an upgraded valve body, the line pressure is increased which increases the holding capacity of the transmission. This will improve the overall durability of your transmission in lugging or high output scenarios. the added gear also helps take the wear and tear off your engine while cruising at high speeds. Further improving the durability and reliability of your truck's entire powertrain. 

This kit is the prefect option for anyone looking to replace the valve body in the transmission of their LB7 or LLY truck. But we've found that in general this is a great option for anyone who wants to get better all around drivability out of their truck.  This kit will improve fuel milage, the smoothness of shifts, drivetrain durability, and soften the drone of the exhaust while cruising at high speeds. These are all things that anyone who's taking their truck on long distance trips want's. Which is really who this kit is prefect for. 


Upgrade To A 6 Speed Allison Transmission

The 6 Speed Conversion Kit Come's With:

  • Custom Tuned TCM 
  • Upgraded Valve Body 



Related Articles:

Unleashing The Brand New Duramaxtuner Built Transmission




Topics: better performance for lly, how to get better fuel mileage with LLY, LLY mpg, LB7, Transmission Duramax, LLY TCM Tuning, LB7 TCM Tuning, 6speed, LB7 MPG