Symptoms:

  • 2-4 Band burned
  • Low 4th Gear pressure
  • No 4th
  • 2nd Quality poor

Cause:

Continuous oscillation in relay valve and sequence valve bore causes wear that prevents proper hydraulic control.

Correction:

Recover hydraulic control and renew 2nd and 4th Gear operation by reconditioning the entire bore and installing Sonnax oversized 4-3 sequence valve kit.

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

Oversized 4-3 Sequence Valve Kit
Part No. 77964-14K

For use with OE valve/bore only.


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

GM 4L60-E, 4L65-E and 4L70-E transmissions often have trouble shifting into or holding 4th Gear due to excess wear in the sequence valve bore. This wear allows vital 4th servo feed and 3-4 accumulator oil to exhaust, resulting in deficient 4th servo apply pressure. Consequences are slipping or no 4th Gear operation followed closely by a burnt band.

Existing Sonnax kit 77964-04K does not address wear on the inboard two spools that is increasingly more common in these aging valve bodies. Wear at these spools can allow valuable 4th servo feed leakage, resulting in no 4th and 2-4 band wear, but can also allow leakage of 2nd clutch oil needed to apply the 2-4 band in 2nd Gear, resulting in poor 2nd Gear shifts. Leaking at the OE end plug also allows oil loss that can leave 4th Gear inoperable.

Re-establish hydraulic control and restore normal 4th Gear operation by reconditioning the entire bore and installing Sonnax oversized 4-3 sequence valve kit 77964-14K.

  • 3-4 Relay and 4-3 sequence valves are completely oversized
  • O-Ringed end plug helps prevent 4th Gear oil loss
  • Hardcoat anodized aluminum valves combat premature wear

Kit can only be used to replace OE steel valves in bore that has not been previously reamed for 77964-04K. See chart in instructions for details.

  • 3-4 Relay Valve
  • 4-3 Sequence Valve
  • Spring
  • End Plug
  • O-Rings (2) 1 Extra

June 06, 2018

All Over the Map: Attacking 4L60/E Burnt 3-4 Clutches with Confidence

Brian Wing

Topics: Shop Practices Transmission GM 4L70-E Transmission 4L60-E Transmission 4L65-E Transmission 4L60 Transmission

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  • 77964 14k combo
  • 77964 14k

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.

  • 77964 14k test