Diagnosing 62TE, 68RFE Low/Reverse Switch Valve Issues

Chrysler 62TE and 68RFE transmissions continue to be popular for rebuilds. Because of that, we here at Sonnax are constantly looking for new problems to see if there is anything we can do to share our knowledge with others. One example is wear in the low/reverse switch valve bore and the low clutch switch valve bore.

In these units, the low/reverse switch valve acts as a one-way valve for the low/reverse clutch in Reverse and Drive. Also, in the 62TE, the low clutch switch valve similarly functions as a one-way valve for the low clutch in Reverse and Drive (Figure 1).

Figure 1 – 62TE OE L/R Clutch Switch Valve Locations & Lineup

In both cases, wear in this bore and to the valve will result in leakage past the one-way valve exhausting through the manual valve, resulting in low apply pressure that will cause burnt clutches and delayed — or even no — Reverse or 1^st and 2^nd Gears (Figure 2).

Figure 2 – 68RFE L/R Hydraulic Circuit

Wear is caused by the valve being heavily side-loaded, likely because the diameter of the valve is too close to its total length.

The Sonnax repairs for these units utilize inboard and outboard sleeves and a checkball that allow fluid to move only one way through the orifice. For 62TE, Sonnax offers drop-in low/reverse switch checkball sleeve kit 92835-43K and an oversized version 92835-47K for bores with extreme wear. Similar kits are available for the 68RFE, drop-in 92835-41K and oversized 92835-45K.

Sonnax Low/Reverse Switch Checkball Sleeve Kit – 92835-41K

If you are unsure whether you need to replace the OE valves, we have found that vacuum testing those bores is difficult. In the 62TE, there is a very long port that you will need to cover the back and front of to properly test. Covering the back of the valve body casting with a rubber mat is one way to make this process a bit easier. You will also need to manually shuttle the valve into the port you are testing to get accurate readings. We have found that it is extremely likely if you test port #1 and find excessive leakage, then leakage in port #2 is almost assured. You can safely assume that both OE valves will need to be replaced (Figure 3).

Figure 3 – 62TE L/R & Clutch Switch Valve Vacuum Testing

Outlined areas must be covered while vacuum testing to receive results. In addition, the holes highlighted within those areas must be plugged to achieve an accurate reading. The long worm track outlined in port #2 is extremely difficult to get a reading from due to the length of the track and the exhausts that need to be filled. During vacuum testing, the user must manually shuttle the OE valve to whichever worm track they are testing to see results.

Testing in the 68RFE is a bit easier, but you will still have to manually shuttle the valve to each worm track area to get results (Figure 4).

Figure 4 – 68RFE L/R Switch Valve Vacuum Testing

In all cases, a result of 18"-Hg is satisfactory, and anything below is worn and should be replaced.

Chris Leach is a Sonnax product line manager. He is a member of the Sonnax TASC Force (Technical Automotive Specialties Committee), a group of recognized industry technical specialists, transmission rebuilders and Sonnax Transmission Company technicians.