Keep your 4x4 Duramax on the road, on the track, and pulling heavy loads without fear. When you add tuning, larger tires, or heavy towing to a 4WD 6.6L Duramax, the massive traction of a 4x4 configuration forces your Allison LCT1000 transmission to absorb extreme torsional stress. The stock Allison is plagued by low line pressure, slipping clutch packs, and fragile shafts that quickly trigger "Limp Mode."
The ATS 4WD Allison Performance Transmission Package is a complete engineering solution designed to eliminate these weak points. Tailored specifically for 4WD platforms, these packages combine upgraded clutch capacities, re-engineered hydraulic controls, and high-strength billet shafts to deliver maximum power directly to your transfer case with absolute reliability.
2001-2010 4WD Stage Comparison Chart
Component
Stage 1
Stage 2
Stage 3
Stage 4
Stage 5
ATS Performance 4WD Transmission
✅
✅
✅
✅
✅
ATS Deep Transmission Pan
✅
✅
✅
✅
✅
ATS TruLok Performance Torque Converter
✅
✅
—
—
—
ATS Five Star Performance Torque Converter
—
—
✅
✅
✅
ATS Co-Pilot Transmission Controller
—
✅
✅
✅
✅
ATS Billet Input Shaft
—
—
✅
✅
✅
ATS Billet Output Shaft
—
—
—
✅
✅
ATS Billet Intermediate Shaft
—
—
—
✅
✅
Billet P2 Carrier, C2 Hub and Sun Gear
—
—
—
—
✅
2011-2019 4WD Stage Comparison Chart
Component
Stage 1
Stage 2
Stage 3
Stage 4
ATS Performance 4WD Transmission
✅
✅
✅
✅
ATS Deep Transmission Pan
✅
✅
✅
✅
ATS TruLok Performance Torque Converter
✅
✅
—
—
ATS Five Star Performance Torque Converter
—
—
✅
✅
ATS Billet Input Shaft
—
✅
✅
✅
ATS Billet Output Shaft
—
—
✅
✅
ATS Billet Intermediate Shaft
—
—
—
✅
Notable Transmission Build Specs
Premium Foundations: All new gaskets, bushings, seals, and pistons are used during assembly.
P1 Sun Gear Bearing Upgrade Kit: Addresses a prominent wear-induced failure point inside the factory gear train.
ATS Allison Pump Modifications:
Upgraded high-volume Line-to-Lube Pressure Regulator Valve and shim kit (safely elevates line pressure and enhances lubrication throughout the hydraulic circuit) - 2001-2002 Models Only.
ATS Allison Cut Back Valve Upgrade - 2001-2002 Models Only.
ATS Valve Body Modifications:
2001-2005 (5-Speed): ATS F-Trim Solenoid and block upgrade, performance A and B trim valves, performance shift kit, and a modified internal wiring harness explicitly wired for Co-Pilot functionality.
2006-2010 (6-Speed): Full ATS Solenoid Block upgrade featuring Performance A and B trim pressure control solenoids and a Performance Torque Converter Clutch (TCC) solenoid.
2011-2019 (6-Speed): Performance A and B trim pressure control solenoids, Performance TCC solenoid, and the proprietary ATS G-Block Solenoid Upgrade to enable seamless high-line pressure control functionality.
Heavy-Duty Engineered Clutch Packs:
Performance C1 Pack: Modified C1 pressure plate accompanied by (8) internal and (8) external C1 performance friction clutches.
Performance C3 and C4 Packs: Modified C3 and C4 pressure plates featuring (12) C3/C4 performance friction clutches, (4) C3/C4 steels (.0747” thick), and (7) C3/C4 selective steels (.105” thick).
Performance C5 Pack: Includes (6) C5 performance friction clutches paired with (6) thick C5 steels (.1046” thick).
Filtration: Complete kit includes both brand-new internal filters and external spin-on filters.
Case & Core Preparation: Transmission cases and critical hard parts are thoroughly disassembled, inspected, and solvent-cleaned. Valve body and pump castings are checked and machined to ensure perfect flatness.
Advanced Quality Validation: Comprehensive vacuum and air checks are executed throughout the build process. Valve bodies are hydro-tested on our in-house SuperFlow valve body machine, and every completed transmission and torque converter is dyno-tested together as a matched pair.
The Deep Dive: Inside the ATS Engineering Advantage
To safely manage the massive output of a tuned Duramax, an upgraded transmission requires absolute hydraulic stability. Every ATS Allison pump is modified with a high-volume, completely redesigned Pressure Regulator (PR) Valve assembly. This specialized configuration stabilizes line pressure around a powerful 275–300 PSI. Please note that our dedicated pump line-to-lube modification and the cutback valve upgrade inside the PR valve are implemented on 2001–2002 models only. For these specific early model years, this exclusive modification allows full line pressure to consistently reach the clutch packs rather than venting away, keeping vital components fully lubricated and cool under load.
The C3 & C4 Non-Vented Steel Advantage
The C3 and C4 clutch packs are notorious failure points on stock Allison transmissions due to heat and severe holding loads. While several aftermarket replacement kits utilize generic vented steel plates, ATS deliberately utilizes a solid, non-vented steel design. Vented steels drastically reduce the effective friction holding surface area by 20%. This structural reduction places extreme structural strain on the friction clutches, encouraging heat buildup and causing the clutches to start slipping much earlier in the power band. Our non-vented steels retain 100% surface area engagement for maximum thermal dissipation and unmatched holding power.
Valve Body Engineering & True Line Pressure Architecture (2001-2010 Gen 3 & Gen 4)
A common mistake in the diesel industry is relying on basic drop-in pump kits (such as Transgo kits) to boost pressure. In reality, generic pump modifications fail to provide the necessary pressure increase to the entire transmission. On 2001–2010 Gen 3 and Gen 4 builds, the factory valve body acts as a strict bottleneck; it limits the actual volume of pressure that reaches the clutch packs, regardless of what the pump generates. To circumvent this restriction, Gen 4 systems must run the ATS Co-Pilot Transmission Controller to route full line pressure straight to the clutch packs where it is actively required to hold power. This hydraulic pathway is completely updated through our proprietary ATS separator plate, unlocking the total power-holding potential of the Allison platform while delivering fast, clean, and positive gear changes.
We do not guess at electrical or hydraulic performance. Before final assembly, every single shift solenoid is extracted and tested individually on our specialized in-house solenoid test machine to verify proper electrical resistance and mechanical speed. Furthermore, we dyno test our valve bodies on a high-end hydro-test valve body test machine. This allows our technicians to completely balance the A and B trim solenoids under real-world pressure scenarios, eliminating cross-leaks and ensuring perfectly timed clutch-to-clutch handoffs before the valve body is bolted into the casing.
ATS Five Star Torque Converter (Standard on Stage 3+)
The patented ATS Five Star Torque Converter features an industry-leading 2.4:1 torque multiplication factor, completely overshadowing the weak factory ~1.25:1 ratio. This allows the Cummins or Duramax engine to spool the turbocharger instantly, eliminating off-the-line lag.
Patented Viskus Clutch Drive System: Features CNC laser-cut clutch plates designed for maximum efficiency.
Square Tab Construction: Employs a robust square flank drive design on the billet cover and piston, ensuring internal clutches remain perfectly intact under high-torque engagement.
Proprietary Bonding Technology: Our exclusive clutch formulation guarantees a 100% chemical bond to stop friction material delamination in its tracks.
Bulletproof Construction: Reinforced with a 4340 hardened turbine spline, a high-flow CNC-machined stator with optimized oil windows, full roller-bearing internals, and a plasma-welded impeller housing.
The Co-Pilot functions as a closed-loop electronic sub-computer that continually monitors engine and vehicle dynamics to eliminate the dreaded Allison "Fail-Safe" Limp Mode. By monitoring real-time Boost Pressure (MAP), Vehicle Speed (VSS), and Throttle Position (TPS), it dynamically spikes clamping force to allow clutch packs to receive full line pressure (up to 230 PSI) right when the truck demands it.
Real-Time Diagnostics: Features a built-in display with sequence lights to provide real-time feedback on transmission activities.
4340 Billet Hard Part Upgrades (Input, Intermediate, & Output Shafts)
When punishing your truck with boosted launches or extreme towing weights in a 4WD vehicle, there is no "tire slip" to relieve driveline shock—the tires dead-hook. This sends 100% of the engine's torque straight through the internal hard parts, making weak factory cast components highly susceptible to shattering. Our billet input, intermediate, and 4WD output shafts are CNC-machined from premium 4340 high-strength alloy steel. This structural material delivers deep hardenability, maximum fatigue resistance, and exceptional toughness to comfortably withstand extreme shock loads without twisting, fracturing, or shearing splines under heavy 4x4 strain.
The ATS Diesel Difference
"True transmission performance isn't built on a standard workbench with off-the-shelf parts; it's born from precise engineering and exhaustive validation. By analyzing every hydraulic constraint inside the factory Allison, we created a system that completely redefines power transmission. When you buy an ATS package, you are getting a transmission and converter that have been dyno-tested together as a matched pair, ready to deliver flawless operation out of the box."
ATS LIMITED PRODUCT WARRANTY
ATS Transmission packages carry a standard THREE YEAR Warranty. There are several exceptions, so refer to the Warranty’s specific terms and conditions . All labor, shipping, or any other charges associated with the product and the product’s failure are not covered under Warranty. Labor and/or shipping charges will not be refunded under any circumstance. After the one-year anniversary date of the original purchase, there is a limited parts replacement Warranty only. Transmissions that are purchased separately outside of a transmission package / stage and are installed without an ATS torque converter carry a 1 year parts only warranty and there is no labor or shipping allowance for transmission only purchases.
In the event of a product failure, the consumer must return the defective product to ATS for inspection before a replacement is sent to the consumer. After ATS inspects the product and completes the failure analysis, the inspection officer at ATS will provide written documentation stating the condition of the product and determine, to the best of his or her ability, what caused the malfunction or complaint. Based on the findings of the inspection report, ATS will determine whether there is a valid Warranty claim. Should a consumer require immediate service, and chooses not to wait for their product to be returned to ATS for inspection, service, and potential repair or replacement, the consumer can purchase a replacement product from ATS. The consumer must pay the full current MSRP, the applicable core charge, and shipping to and from ATS’ shop. When the defective product arrives, ATS will refund the core charge and inspect the product. During inspection, ATS will assess the product for warrantable damage. If the original product has indeed failed under the terms of the original Warranty, ATS will refund the full purchase price for the replacement product only. If the product has failed due to any issue not covered under the original Warranty, ATS will assess charges to the consumer based on any parts necessary to return the product to nominal ATS standards. ATS will deduct the total cost of required parts from the replacement product’s purchase price, and the consumer will be refunded the difference (if any) between the purchase price paid for the replacement product and the cost of parts.
If the consumer can wait for their product to be returned to ATS for inspection, service, and potential repair or replacement, the consumer pays shipping to and from ATS’ shop. When the defective product arrives in Colorado, ATS will inspect the product. ATS will then assess the product for warrantable damage. If the product has failed under the terms of the original Warranty contract, ATS will repair or replace the product – at ATS’s discretion. If the product has failed due to any issue not covered under the original Warranty, ATS will assess charges to the consumer based on any parts necessary to return the product to nominal ATS standards. ATS will bill the consumer for the total cost of parts required for repair of the product, and shipping to and from Colorado, prior to the repaired/replaced product being sent to the consumer.
ATS Manual Transmissions Warranty
This section incorporates Section 2, entitled “In the Event of a Failure.” ATS manual transmissions carry a 1-year/12,000 mile Warranty. ATS will not pay for any fluids replaced in the event of a transmission failure. There is no labor or freight warranty coverage on standard transmissions. Manual transmission shafts and gears are not covered by this Warranty on any transmission due to the capability of certain situations to cause stress-loads beyond the structural ability of the shaft or gear.
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