• Low line pressure
  • Burnt clutches
  • Soft upshifts
  • Delayed Reverse


Leakage between the boost valve and sleeve.


Sonnax drop-in boost valve kits are available in three different ratios to restore pressure control in most OE applications.

4L30-E, AR25, AR35

Boost Valve Kit
Part No. 54200-01K

Medium ratio, OE code 448

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In GM 4L30-E, AR25 and AR35 units, the OE boost valves are made of steel, whereas the sleeves are made out of aluminum. Over time the valve wears against the sleeve and causes boost pressure leakage. The result is low line pressure during boost, with associated burnt clutches. Sonnax boost valve 54200-01K restores pressure control to the boost circuit.

  • Sleeve is made from wear-resistant aluminum and incorporates annular oil passages to distribute boost oil evenly to the valve and reduce side loading
  • Hardcoat anodized aluminum valve combats premature wear
  • Valve includes oil grooves which allows the valve to ride on a film of oil, further reducing wear
  • Valve and sleeve are made from the same material to help reduce leakage due to thermal expansion
  • Drop-in Zip Valve parts install quickly and easily
Sonnax Part No. Boost Ratio Sonnax I.D. Mark OE/Euro I.D. Mark Large Spool Diameter Small Spool Diameter
54200-14K Small to Medium 067 067 .634" .570"
54200-01K Medium M 448 .662" .630"
54200-06K Large L 264 .697" .649"
Learn More About Zip Valve™ Drop-In Repairs

Medium boost ratio kit. Please see chart to verify.

  • Valve
  • Sleeve
  • 4L30-E, AR25, AR35 Boost Valve Kit 54200-01K
  • 4L30-E, AR25, AR35 Boost Valve Kit 54200-01K
  • 4L30-E, AR25, AR35 Boost Valve Kit 54200-01K