Symptoms:

Poor line pressure control
Low line rise in Drive
Soft shifts
Burnt clutches
Premature clutch failure
Low pressure

Cause:

Wear between the reducing valve and sleeve allows line pressure fluid, acting as cutback pressure, to exhaust to the sump. Wear between the pressure regulator valve and bore allows line pressure fluid to exhaust to sump. This combination of wear prevents proper hydraulic control of the pressure regulator valve and can cause high/low and erratic line pressure.

Correction:

Restore proper hydraulic control and renew line pressure performance by reconditioning the bore and installing Sonnax oversized pressure regulator valve kit.

ZF8HP50, ZF8HP75, ZF8HP95

Oversized Pressure Regulator Valve Kit
Part No. 35740-40K

Tooling:

F-35740-TL
VB-FIX

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Vehicles with ZF8HP50, ZF8HP75 and ZF8HP95 transmissions may exhibit insufficient line rise in drive ranges, soft shifts and/or burnt clutches. These problems may be caused by continuous oscillation of the reducing valve in the sleeve, creating excessive wear and a path for critical line pressure fluid to exhaust to sump. Reconditioning the bore and installing Sonnax oversized pressure regulator valve kit 35740-40K restores proper hydraulic control and prevents wear by utilizing upgraded materials and minimal clearances.

Sleeve is manufactured from highly wear-resistant billet aluminum to prevent future wear
Hardcoat anodized aluminum valves combat premature wear
O-Ringed sleeve provides positive seal to prevent critical line pressure fluid from leaking to exhaust
Annular grooves help center the pressure regulator valve in the bore to reduce future side-load wear

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