Tales From the Bench - April - 2016

A Look Inside Subaru CVT Generation 2 Part 1

In this article, we’re going to look inside a Subaru 2nd generation CVT. We’ll inspect the front of the transmission, and look over the pump and its drive components.

Then we’ll cover the solenoid locations and case passages for testing. And we’ll tear down the transfer case clutch assembly and learn a testing tip for reassembly.

PUMP

The pump is chain driven at a ratio of 1.33:1 of engine speed, so the pump turns faster than the engine. This provides high pressure and volume at low engine RPM.

The pump is under the front cover. To access it, you’ll need to remove the front cover that supports the pump drive system. Remove the ten, 12mm bolts that hold the cover on. Then pry the front cover off to get access to the pump (figure 1).

There are three seals at the front of the transmission. Two are just like a normal transmission: the front torque converter seal and the input shaft seal for lockup control. The other seal is at the base of the stator shaft and seals the inside of the converter hub. This seals converter apply oil.

To remove the pump, remove the four bolts with an 8MM Allen wrench.
There are two O-rings and a gasket behind the pump: The larger O-ring seals the suction side of the pump and the smaller O-ring seals the pump output (figure 2).

To disassemble the pump, remove the four 10mm bolts and separate the pump halves. Notice that the ID marks on the pump gears aren’t showing. The ID marks go into the pump body first. Check the pump shaft and shaft bearings for wear and pitting (figure 3).

VALVE BODY AND OIL PASSAGES

On the Subaru Gen 2 CVT, the valve body is under the top cover. Remove the twelve, 10mm cover bolts and pry up on the cover. Be careful; you need to unplug the valve body wire harness under it. To remove the valve body from the case, just remove the nine valve body-to-case bolts (figure 4).

This valve body has six solenoids (figure 5).

  1. Secondary Line Pressure
  2. Forward/Reverse
  3. Lockup Duty
  4. Primary Up
  5. Primary Down
  6. AWD (All Wheel Drive)

The temperature sensor is part of the valve body wiring harness.

The case passages are under the valve body (figure 6). To air test the forward clutch, put the shifter in the drive position and apply 40 PSI to the manual valve port.

To test the reverse clutch, move the shifter into the reverse position and blow 40 PSI into the same port.

To air test the transfer case clutch, blow 40 PSI into the transfer case clutch port.

BOTTOM PAN

There isn’t much in the lower pan on this transmission; the valve body’s on top. But there are still some key items down there.

Remove the transmission pan and the three filter bolts. Pull the filter off and inspect the O-ring on the top of the filter neck.

While you have the lower pan off, you’ll need to get ready to remove the main case. Remove the three, 12mm bolts that hold the baffle to the case. The baffle won’t come out yet.

Next, remove the linkage and manual valve. Remove the two 10mm bolts and knock out the roll pin on the shift rail shaft (figure 7). Then remove the two bolts holding the range switch to the case. Now you can remove the range switch and shift rail together. Remove the park rod and pull out the manual valve.

The manual valve is different on this unit than on most transmissions: It’s located in the front of the transmission, not in the valve body. If you don’t remove the manual valve, it’ll bend when you try to remove the main case.

TRANSFER CASE CLUTCH

The transfer case clutch is in the same location as all other Subaru transmissions: under the tail housing. Remove the thirteen, 12mm bolts and remove the tail housing to reach the transfer case clutch.

You’ll find two sets of shims: one for the output shaft and the other for the transfer gears (figure 8). These shims have different outside diameters so you can’t mix them up. Don’t lose the O-ring seal; this is the seal for the transfer case clutch.

This is also a good time to remove the secondary pressure sensor so it doesn’t get damaged.

  1. Remove the park pawl, spring, and shaft.
  2. Pull the transfer case clutch drum straight out.
  3. Pull the transfer case clutch hub out.
  4. Pull the transfer shaft and gears out. There’s no need to remove the nut on the transfer gears.

The transfer case clutch has four clutch plates (figure 9). The stack up goes like this: apply plate first, then a steel, clutch, steel, clutch, steel, clutch, steel, clutch, pressure plate and then the snap ring. The transfer clutch clearance should be 0.028”–0.043” (0.7mm–1.1mm).

When air testing the transfer case clutches outside the tail housing, assemble the drum and clutch hub, and then put the whole assembly in a press (figure 10). You don’t have to put much pressure on the shaft. The press just holds it together; if you don’t put the assembly in the press, it’ll push the clutch hub off and cut the seal ring.

In the next Tales from the Bench, we’ll finish pulling this unit apart and inspecting the pulley system and the forward and reverse clutch systems.

It can be difficult to keep up with all the new transmissions coming out each year… but it’s also what makes this business fun and exciting.