Product Description
Fits: 4R44E, 4R55E, 5R44E, 5R55E
Increased Ratio
Some typical problems in Ford 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 boost valve 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
- Harcoat anodized aluminum valve combats premature wear
- 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
- Drop-in Zip Valve® parts install quickly and easily
Pressure Comparison Between OE and Increased Ratio Boost Valves
| EPC PSI | 37947-01K (OE Ratio) | 37947-03K (Increased Ratio) | ||
|---|---|---|---|---|
| Line | Reverse | Line | Reverse | |
| 30 | 107 | 135 | 114 | 143 |
| 75 | 178 | 224 | 194 | 243 |
| 120 | 250 | 313 | 275 | 343 |
Notes
OE sleeves may come in either a 3- or 2-circuit design. Boost valve kits 37947-01K and 37947-03K may be used to replace either version.
Symptoms
- Delayed Reverse
- Soft shifts
- Low line pressure
- Poor modulator control
Cause
A worn boost valve or boost valve sleeve.
Correction
Restore proper line pressure control and prevent future wear Sonnax drop-in boost valve kits.
Contents
- Valve
- Sleeve
Valve Body Layout
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.
Ford 4R44E, 5R44E, 4R55E, 5R55E Valve Body Layout
