After rebuilding an RE5R05A transmission an engine flare up through the third to fourth shift is observed followed by a neutral or slipping condition in 5th gear. Often times this condition is accompanied with fourth and fifth gear ratio codes P0734 and 735.
One common cause for this complaint has to do with poor sealing ring pressure retention for the Input Clutch circuit on the turbine shaft. The OE rings are plastic in style with internal scallops to assist the oil to get under the ring and expand it. This style ring is not the easiest rings to get onto the shaft. If the ring is spread open too far, the spine part of the ring kinks causing it to be deformed. Once the ring is deformed, it can no longer conform to the inside of the pump stator to adequately seal Input Clutch pressure.
The same damage occurs with the rings on the sun gear shaft. This causes the High/Low Reverse Clutch to slip affecting the second to third shift. It could also cause it to continue to slip throughout third, fourth and fifth gears. A reverse delay and/or slip complaint will accompany these complaints.
If an application chart is consulted, it shows that this clutch is also applied in first gear. This causes many to overlook this area as there are no problems being exhibited with first gear. The reason for this is, the clutch is used for engine breaking in first gear. It does not complete the drivetrain to produce first gear. If it never applies, first gear will still function due to the sprags.
When making correcting by carefully replacing the rings, be sure to also inspect the sleeve area of the pump that it is not grooved, and the support bearing is good. Air test the Input Clutch to be sure the piston seals are good.
Note: Some techs have chosen to use aftermarket Teflon rings on the Turbine Shaft from those used in the VW 09G transmission. For the sun gear shaft, the nickel plated rings from Ford’s 4R70W are being used.
Subscribe to Motor Age and receive articles like this every month…absolutely free. Click here
