Tales From the Bench - August - 2017

The Ins and Outs of the RE0F08B Jatco CVT

CVTs may still be a bit unfamiliar to some, but they’re certain to be a big part of your future. Covers the procedures for disassembling and inspecting the Jatco RE0F08B CVT.

It’s time to start jumping in and learning about the Jatco CVTs. By being able to handle these transmissions, you’ll bring in more jobs and more profit to your shop.

In this article, we’ll cover the sensor and solenoid locations. We’ll tear down the valve body and examine the valve layout. And we’ll remove the primary and secondary pulleys and see where you’re most likely to find wear.


The secondary speed sensor, or output speed sensor, sits above the differential and uses the gear on the secondary pulley shaft to create a signal (figure 1).

The range switch mounts to the shift rail on top of the transmission, and creates a signal based on shifter position, just like most other transmissions.

The primary speed sensor, or input speed sensor, mounts in the back of the case and uses the primary pulley to create a signal (figure 2). There’s also a pressure port on the rear cover for measuring pressure to the secondary pulley.

To pull the valve body:

  • Remove the four Allen bolts that hold the filter housing in place. This filter comes with the housing.
  • Remove the linkage arm nut, linkage arm, and the spacer that slides on behind the linkage arm.
  • Remove the thirteen valve body bolts (figure 3).

The valve body should lift right out of the transmission.

RE0F08B case view

The line pressure A, line pressure B, and TCC converter clutch solenoids should all have 5.6–6.6 ohms resistance. The select solenoid should have 12.3– 13.5 ohms resistance.

Remember, these solenoid specs are for the RE0F08B transmission (figure 4). The RE0F08A transmission solenoids are different and have different resistances.

There’s little factory information on this transmission. In most cases, if a car comes into the dealer with a solenoid issue, they’ll replace the transmission: That’s the factory recommendation. It’s a sloppy choice, but it’s one that’s likely to send more work to your shop.

RE0F08B valve body

A lot of parts aren’t yet available, but that’s changing quickly. Solenoids aren’t easy to get, but there are a lot of cores where you can find good, used solenoids.

There are no factory valve body exploded views or valve names for the RE0F08B transmission. So we’ve put together our own valve names, based on their function or operation. The valve body is broken down into three sections: lower, middle, and top.

Lower Valve Body — The lower valve body houses the main regulating valves (figure 5). This transmission uses two regulating valves: one for main pressure and the other for secondary pulley pressure. Always check these valve bores for wear.

The secondary pulley valve controls oil to the secondary pulley to adjust gear ratio.

The lower valve body houses the TCC limit valve, which also affects lube. If the transmission is overheating, this is one of the first areas you should check for wear.

Middle Valve Body — The middle valve body houses the clutch control, select, torque converter control, clutch regulator, secondary pulley control, and the solenoid regulator valves (figure 6).

There are four checkballs and two screens in this part of the valve body (figure 7). The stepper motor also bolts to this section of valve body.

Top Valve Body — The top section of valve body houses a lube relief valve (figure 8). The other side has four solenoids, the ratio control valve, and a pressure switch (figure 9).


The pulleys in this transmission stay with the rear cover. When you remove the pulley from the case, always wrap two zip ties around the belt to keep the belts and chain together.

Notice the arrow on the belt and what direction it’s pointing. This belt is directional; make sure you reinstall it with the arrow pointing in the same direction.

You’ll need to attach a puller to the secondary pulley to relieve the pressure on the belt. Then you can remove the belt and pulleys from rear cover.
RE0F08B pulley assembly
To remove the secondary pulley (figure 10):

  1. Remove the 40mm, left-handed nut, and use a bearing puller to remove the bearing.
  2. Press the gear and park gear off the shaft.
  3. Reinstall the park gear and nut to keep components from flying apart while you’re removing the pulley.
  4. Remove the snap ring and piston. There are no seals on this piston.
  5. Remove the retainer ring by tapping upward.
  6. Remove the two half-moon retainers that hold the piston in. The piston is spring loaded, so be careful!
  7. Use a puller or press to pop the piston off.
  8. Remove the spring and pulley sheave. Watch out! There are twelve balls between shaft and pulley.

Inspect the area where the balls ride in the pulley and on the shaft. This area often wears and develops grooves. You’ll want to check all other bearings in the transmission for similar wear or damage.

Always check the seals on CVTs. They tend to collect metal and debris in the pulleys. Just think of the pulleys like clutch packs that need to be cleaned and inspected.

To remove the primary pulley (figure 11):

  1. Use a bearing puller to remove the bearing.
  2. Remove the right-hand threaded nut.
  3. With a puller, pull up on pulley sheave and it will pull off the piston. There’s no spring behind this pulley. Watch out! There are six balls between the sheave and the shaft.

Inspect the pulley surfaces, balls, and grooves for wear.

There you have it: In this article, we’ve examined some of the basics for the Jatco RE0F08B transmission. The RE0F08A and RE0F09A/B are basically the same transmission, with a few minor differences.

These CVTs don’t have much to them and are easy to rebuild. The hardest part is finding parts. For now, you’ll need to depend on a supply of good used parts; it shouldn’t be long before the aftermarket catches up and begins handling the parts you need for these units.

We didn’t look at the pump, planets, or the forward or reverse clutches. These components are similar to the ones you’re already familiar with, so there shouldn’t be any surprises there.

Learning these Jatco CVTs is just one more way to help improve your business. They’re reliable and reasonably easy to rebuild, and are highly profitable when they do go bad.