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Mopar HEMI NAG1 Transmission

Weight:125.0 lbs
Manufacturer:Mopar Performance
Mopar Performance
Base Price: $3,530.00
Price with Options: $3,530.00

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NAG1 Replacement Transmission with Torque Converter  

If the transmission in your Dodge Challenger, Charger, Magnum, or Chrysler 300c has seen better days, replacing it with an OEM unit from Mopar is a good option. These HEMI transmissions are built by Dodge / Chrysler to ensure that they comply with all of the original specifications. A stock transmission replacement and torque converter are included in this package. No core charge. After installing a new Mopar transmission your vehicle will shift like new.

If you broke your transmission due to aggressive driving or your high-power modified motor is too much for your transmission to handle, you should get a higher performance transmission from Arrington's list of NAG1 upgraded replacements.

NAG1 Mopar Transmission 

The NAGI automatic transmission (NAG1 Automatic Transmission) is an electrically controlled 5-speed transmission with a lock-up clutch in the torque converter. The ratios for the gear stages are obtained by 3 planetary gear sets. Fifth gear is designed as an overdrive with a high-speed ratio.

NAG 1 identifies a family of transmissions and means "N"ew “A”utomatic “G”earbox, generation 1. Various marketing names are associated with the NAG I family of transmissions, depending on the transmission variation being used in a specific vehicle. Some examples of the marketing names are: W5A300, W5A380, and W5A580. The marketing name can be interpreted as follows:

  • W = A transmission using a hydraulic torque converter
  • 5 = 5 forward gears
  • A = Automatic Transmission
  • 580 = Maximum input torque capacity in Newton Meters

The gears are actuated electronically/hydraulically. The gears are shifted by means of an appropriate combination of three multi-disc holding clutches three multi-disc driving clutches and two freewheeling clutches.

Electronic transmission control enables precise adaptation of pressures to the respective operating conditions and to the engine output during the shift phase which results in a significant improvement in shift quality.

Furthermore it offers the advantage of a flexible adaptation to various vehicles and engines.

Basically the automatic transmission with electric control offers the following advantages:

  • Reduces fuel consumption
  • Improved shift comfort
  • More favorable step-up through the five gears
  • Increased service life and durability
  • Lower maintenance costs
Transmission Identification

The transmission can be generically identified visually by the presence of a round 13-way connector located near the front corner of the transmission oil pan, on the right side. Specific transmission information can be found stamped into a pad on the left side of the transmission, above the oil pan rail.

Transmission Gear Ratios

The gear ratios for the NAG I automatic transmission are as follows:

  • 1st Gear - 3.59:1
  • 2nd Gear - 2.19:1
  • 3rd Gear - 1.41:1
  • 4th Gear - 1.00:1
  • 5th gear - 0.83:1
  • Reverse - 3.16:1
Transmission Housing

The converter housing and transmission are made from a light alloy. These are hooked together and centered via the outer multi-disc carrier of multi-disc holding clutch, B1. A coated intermediate plate provides the sealing. The oil pump and the outer multi-disc carrier of the multi-disc holding clutch, B1, are bolted to the converter housing. The stator shaft is pressed into it and prevented from rotating by splines. The electro-hydraulic unit is bolted to the transmission housing from underneath. A sheet metal steel oil pan forms the closure.

Mechanical Section

The mechanical section consists of an input shaft, an output shaft, a sun gear shaft, and three planetary gear sets which are coupled to each other. The planetary gear sets each have four planetary pinion gears. The oil pressure for the torque converter lock-up clutch and clutch K2 is supplied through bores in the input shaft. The oil pressure to clutch K3 is transmitted through the output shaft. The lubricating oil is distributed through additional bores in both shafts. All the bearing points of the gear sets, as well as the freewheeling clutches and actuators, are supplied with lubricating oil. The parking lock gear is connected to the output shaft via splines.

Freewheeling clutches F1 and F2 are used to optimize the shifts. The front freewheel, F1, is supported on the extension of the stator shaft on the transmission side and, in the locking direction, connects the sun gear of the front planetary gear set to the transmission housing. In the locking direction, the rear freewheeling clutch, F2, connects the sun gear of the center planetary gear set to the sun gear of the rear planetary gear set.

Electrohydraulic Control Unit

The electrohydraulic control unit comprises the shift plate made from light alloy for the hydraulic control and an electrical control unit. The electrical control unit comprises of a supporting body made of plastics into which the electrical components are assembled. The supporting body is mounted on the shift plate and screwed to it.

Strip conductors inserted into the supporting body make the connection between the electrical components and a plug connector. The connection to the wiring harness on the vehicle and the transmission control module (TCM) is produced via this 13-pin plug connector with a bayonet lock.

Shift Groups

The hydraulic control components (including actuators) which are responsible for the pressure distribution before, during, and after a gear change are described as a shift group. Each shift group contains a command valve, a holding pressure shift valve, a shift pressure shift valve, overlap regulating valve, and a solenoid.

The hydraulic system contains three shift groups: 1-2/4-5, 2-3, and 3-4. Each shift group can also be described as being in one of two possible states. The active shift group is described as king in the shift phase when it is actively engaging / disengaging a clutch combination. The 1-2/4 -5 shift group controls the BI and KI clutches. The 2-3 shift group controls the K2 and K3 clutches. The 3-4 shift group controls the K3 and B2 clutches.

NAG1 Stock Transmission Section Diagram
NAG1 Stock Mopar Transmission Section Diagram
  1. Torque Converter
  2. Oil Pump
  3. Driveshaft
  4. Multi-disc Holding Clutch B1
  5. Driving Clutch K1
  6. Driving Clutch K2
  7. Multi-disk Holding Clutch B3
  8. Driving Clutch K3
  9. Multi-disk Holding Clutch B2
  10. Output Chaft
  11. Parking Lock Gear
  12. Intermediate Shaft
  13. Freewheel F2
  14. Rear Planetary Gear Set
  15. Center Planetary Gear Set
  16. Electrohydraulic Control Unit
  17. Front Planetary Gear Set
  18. Freewheel F1
  19. Stator Shaft
  20. Torque Converter Lock-up Clutch
  • 1st Gear - 3.59:1
  • 2nd Gear - 2.19:1
  • 3rd Gear - 1.41:1
  • 4th Gear - 1.00:1
  • 5th gear - 0.83:1
  • Reverse - 3.16:1
  • Dodge Challenger 5.7L & 6.1L LC 2008 to 2010
  • Chrysler 300 5.7L & 6.1L LX 2005 to 2010
  • Dodge Charger 5.7L & 6.1L LX 2006 to 2010
  • Dodge Magnum 5.7L & 6.1L LX 2005 to 2010
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