In previous articles I have explained the important part that adaptations play in the shift quality and proper operation of a transmission. I have corrected many shift complaints from other shops that just could not get the transmission to shift properly simply by resetting the adaptations.
In this article I’ll use the VW 01M 2-3 shift to explain the hydraulic part of the adaptation. Let’s use the most-recent case I had, a ’99 VW New Beetle with a 01M transmission that had a slight binding feel on the 2-3 shift.
A no-move 1992 Mazda MPV van was towed into a shop, where it was determined that the planets inside the R4A-EL transmission were toasted. One look at the vehicle and you can see why (see Figure 1). This van recently had been involved in a front-end collision that collapsed the oil-cooler line, causing a lack of cooler flow, and there ya go – wasted planets.
For those select few of you who have taken on the task of either rebuilding or installing a Volkswagen 01M transmission, you know that these units can be difficult. This transmission is very easy to rebuild, and usually the internal parts are in good shape.
One step many technicians take in diagnosing transmissions that have electronically controlled line-rise problems is to unplug the pressure-control solenoid. If the solenoid, pressure-regulator valve and pump are in good working order, line pressure will rise to about 150 to 170 psi at 1,000 rpm in Park. If it rose to only 80-90 psi or didn’t rise at all, this would indicate that a problem existed inside the transmission.