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


Leakage between the boost valve and sleeve.


Sonnax boost valve and sleeve 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

View Instructions

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 and sleeve kit 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
  • Valve is hardcoat anodized and includes oil grooves which allow 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
Sonnax Part No.Boost RatioSonnax I.D. MarkOE/Euro I.D. MarkLarge Spool DiameterSmall 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"

Medium boost ratio kit. Please see chart to verify.

  • Valve
  • Sleeve
  • 54200 01k alt
  • 54200 01k combo
  • 54200 01k