45RFE, 545RFE, 65RFE, 66RFE, 68RFE

Line Pressure Booster Kit
Part No. RFE-LB1

Fits gas and diesel units.

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Chrysler RFE transmissions have a unique, full range pressure transducer and real-time adaptive closed-loop pressure control system. Because of this, it is not possible to raise pressure in an RFE the same way you would in other transmissions. The typical method of installing a stronger pressure regulator spring or larger boost valve will not work because the RFE control module will simply adapt and return pressure to OE specification. An electrical booster option is the only way to raise pressure on an RFE without tuning.

Sonnax line pressure booster kit RFE-LB1 is an ideal performance and durability upgrade for heavy-duty and modified vehicles, and even stock transmissions when a little extra pressure is desired. Featuring an integrated chip (IC) circuit and a stronger pressure regulator spring, this unique kit delivers a progressive increase of 10 psi at lower pressure ranges and 25 psi increase at higher ranges. The results: smooth engagements and lower load on the pump at idle with improved clutch holding capacity and increased durability as the transmission is worked harder.

  • Electronic harness plugs in quickly and easily on outside of transmission case
  • Works just like a large-ratio boost valve for a progressive pressure increase of about 10–25 psi
  • Optional spring installed in the valve body helps optimize performance
  • Ideal for all heavy-duty work/sport vehicles and around-town daily drivers

Learn more about modifying transmission line pressure by reading Achieving a Progressive Pressure Boost in RFEs.

This kit is not recommended for use with transmission tuning mods. If you are unsure of the vehicle’s programming, use a scan tool to verify transmission line pressure meets stock levels (Drive at idle = 60 psi, Drive under heavy load = 160 psi). If desired line pressure values are greater than this, the system most likely has aftermarket tuning mods to the transmission pressure.

  • Pressure Regulator Spring
  • Wiring Harness with Connectors

Sonnax valve body layouts provide a detailed overview of individual units making it quick and easy to determine what’s available for the specific valve body you’re working on. See all Sonnax valve body layouts.

Chrysler 45RFE, 545RFE, 65RFE, 66RFE, 68RFE Valve Body Layout

Chrysler 45RFE, 545RFE, 65RFE, 66RFE, 68RFE Valve Body Layout

  • 45RFE, 545RFE, 65RFE, 66RFE, 68RFE Line Pressure Booster Kit RFE-LB1


How to Raise Chrysler RFE Transmission Line Pressure — No Tuning Required
Clean Up Your Shifts with Sonnax Line Pressure Booster Kits
Sonnax Line Pressure Booster Kit

Sonnax Line Pressure Booster Kits

Crisp, clean shifts without harshness

Sonnax booster kit components are uniquely designed for precision pressure control. At low-end pressures, they deliver normal engagements, normal light throttle shifts and smooth coastdown shifts. When vehicles are pushed harder, components progressively increase pressure for improved clutch holding capacity and increased durability.

Learn more about Line Pressure Booster Kits