DIESEL TRANSMISSION
UPGRADES
HOUSTON
68RFE, Allison 1000, and 6R140 diesel transmission upgrades for Cummins, Duramax, and Power Stroke builds. Valve body, torque converter, and fully built transmissions — sequenced into the build plan from the start.
Your Transmission
Doesn't Care About
Your Power Target.
The most common failure sequence we see: someone builds engine power — tune, compound turbo, injectors — and then discovers the transmission can't hold what the engine produces. Now they need an unplanned transmission rebuild on top of an already-stretched budget, and the truck is back in the shop when it should be pulling or competing.
The fix is simple: the transmission is part of the build plan before any work starts. At the consultation, we look at your power target and your transmission and tell you honestly what it can hold and what it can't. If a valve body upgrade or a built transmission is in the plan, it goes in at the right point in the build sequence — not as an emergency repair after the powertrain fails.
See how we scope a transmission build as part of the complete build process for each platform.
Three Platforms. Three
Different Transmission Plans.
The 68RFE behind the Cummins, the Allison 1000 behind the Duramax, and the 6R140 behind the Power Stroke are different transmissions with different upgrade paths, different failure modes, and different torque limits. We don't run the same build plan across platforms.
The 68RFE is behind the 6.7 Cummins in Ram 2500 and 3500 trucks (2007.5+) and is the most commonly upgraded transmission in the diesel performance world — because it needs it. Stock, it has documented torque converter shudder and clutch pack limits that performance work exposes quickly. 68RFE upgrades for the Cummins Ram are part of every serious Cummins build plan.
- Valve body upgrade — shift quality and firmness
- Torque converter — billet lockup, higher stall
- Clutch pack upgrade — holds elevated torque
- Aisin AS69RC alternative on 3500 DRW builds
The Allison 1000 is a more capable transmission than the 68RFE at stock torque levels, but compound turbo Duramax builds push it meaningfully. Rated around 850 lb-ft input before valve body and clutch upgrades become necessary. Allison upgrades for the Duramax are planned at the build consultation, not discovered after the rest of the build is already done.
- Valve body upgrade — shift pressure and response
- Torque converter — billet, higher stall option
- Clutch upgrade — increased torque capacity
- Full built Allison for 600+ rwhp targets
Ford's 6R140 SelectShift is an improvement over the 5R110 it replaced and handles moderate performance work better than the 68RFE at stock. But it has torque limits at compound turbo Power Stroke power levels — a valve body upgrade or built transmission is part of the high-power 6.7 build plan. 6R140 valve body for the Power Stroke addressed in the platform page.
- Valve body upgrade — shift quality improvement
- Torque converter upgrade — billet option
- Full build for high-power compound turbo builds
Diesel Transmission Upgrades
Have a Sequence.
Not every build needs a fully built transmission. The right upgrade level depends on the power target, the use case, and the platform. We scope the right level at the consultation — and a custom tune after the transmission upgrade is always part of the completion step.
Improved shift pressure, firmer lockup, reduced clutch pack slippage under load. The most common starting point on the 68RFE and Allison — addresses shift quality issues and extends clutch life under moderate performance work. Required before any tune that adds meaningful torque on a stock transmission. Right for Stage 1–2 tune builds without compound turbos.
Billet torque converter with higher stall, upgraded clutch pack capacity, and steel separator plates. Handles compound turbo power levels on the 68RFE and Allison 1000. The right level for builds targeting 450–550 rwhp with compound turbos and upgraded injectors. A tune revision after installation closes the loop on the drivetrain upgrade.
Complete rebuild with billet internals, upgraded drum, high-capacity clutch packs, billet torque converter, and valve body upgrade. Addresses every failure point in the stock transmission. Right for builds targeting 600+ rwhp, competition sled pull or drag applications, or any truck where the transmission is the known limiting factor in the drivetrain. Custom tune after is mandatory.
Diesel Transmission Upgrade FAQ
What performance diesel owners ask before the build consultation.
THE TRANSMISSION
IS PART OF THE BUILD.
Diesel transmission upgrades in Houston for Cummins, Duramax, and Power Stroke trucks. We plan the transmission into the build before the first part is ordered — not as an emergency repair after the drivetrain fails. Book a consultation and we'll scope the right upgrade level for your power target.
