Symptoms:

  • Burnt Reverse clutch
  • Burnt Low/Reverse clutch
  • No Reverse
  • No Manual 1st
  • Slips in Forward & Reverse
  • Low line pressure in Reverse

Cause:

Wear in the bore of the low overrun valve can lead to critical oil loss and reduced apply pressure at the reverse input and low and reverse clutches.

Correction:

Recondition the bore and install Sonnax oversized low overrun valve kit to restore valuable clutch apply pressure.

4L60-E, 4L65-E, 4L70-E

Oversized Low Overrun Valve Kit
Part No. 77754-62K


You need this if... View Instructions Find a Distributor

The low overrun valve directs line pressure to the reverse input and low and reverse clutches. As the bore deteriorates, line pressure at the inboard location cross-leaks into the low/overrun circuit and to exhaust. Line pressure can also cross-leak to exhaust at the outer spool location, in both cases the loss of line pressure reduces clutch apply pressure in Reverse and Manual 1st, resulting in burnt clutches. As the bore wear becomes significant, the low overrun valve can become stuck in the bore resulting in loss of Reverse or Manual 1st Gears.

Reconditioning the bore and installing Sonnax oversized low overrun valve kit 77754-62K restores hydraulic integrity of the circuit and salvages worn valve bodies in GM 4L60-E, 4L65-E, 4L70-E transmissions.

  • Hardcoat anodized aluminum valve combats premature wear
  • New spring provided for proper calibration
  • Includes oversized bore plug

  • Plug
  • Valve
  • Spring
  • 4L60-E, 4L65-E, 4L70-E Oversized Low Overrun Valve Kit 77754-62K
  • 4L60-E, 4L65-E, 4L70-E Oversized Low Overrun Valve Kit 77754-62K

You need this if...

Vacuum testing at the port(s) indicated fails to hold the recommended minimum in-Hg, or if wear is visually detected.

4L60-E, 4L65-E, 4L70-E Oversized Low Overrun Valve Kit Vacuum Test Locations