Remember, transmissions have variations based on year, make, model and engine size, as well as for 2WD, AWD, 4x4, gas, diesel or hybrid and in some situations half years. We encourage you to chat or call toll free with one of our knowledgeable staff members that will assist you in finding the correct part the first time and answer any questions you may have regarding parts for your build. Our goal simply put, is to get you moving with one order.
4R44E 4R55E 5R44E 5R55E Transmission Boost Valve Kit Sonnax 37947-03K Large RatioSome typical problems in 4R44E, 4R55E, 5R44E and 5R55E units are soft shifts, delayed reverse, poor modulator control and/or low line pressure in reverse. A worn boost valve is often the cause, allowing reverse and/or TV pressure to cross leak or exhaust. Sonnax offers two replacement boost valve kits for these units: the OE ratio kit 37947-01K and the increased ratio kit 37947-03K. The 37947-01K has OE spool ratios, to return line rise to stock condition. The 37947-03K assembly has increased ratios for slightly higher line pressures.Sleeves are manufactured from highly wear-resistant aluminum alloy.Valves are made from hard-anodized aluminum for better wear resistance.Tight tolerances restore the hydraulic integrity of the assembly.Kits improve engagement related to loss of boost oil and increased line rise in forward and reverse.Pressure Comparison Between OE and Increased Ratio Boost ValvesEPC PSI37947-01K(OE Ratio)37947-03K(Increased Ratio)LineReverseLineReverse3010713511414375178224194243120250313275343NoteOE sleeves may come in either a 3- or 2-circuit design. Boost valve kits37947-01K and 37947-03K may be used to replace either versionContentsValveSleeveParts ship daily from our distribution center.FREE SHIPPING on US OrdersIn a hurry - expedited shipping is available for this item
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WARRANTY requests need to be accompanied with the appropriate code as diagnosed by a professional transmission shop. Vehicles must be professionally diagnosed for solenoid failure prior to purchase. We cannot guarantee any one item will fix all transmission problems. Solenoid failure is often accompanied by additional failures; for example valve body failures, internal wear or damaged hard parts.
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