Think back 15 years. Would you have predicted the popularity of CVT technology? It’s amazing to think of the change in perception of the Jatco CVT since it became available in the mid-2000s, not only by consumers but also by technicians. Way back in March and April of 2007, Gears Magazine published the first two articles I wrote about the JF011E/RE0F10a. This is the stepper motor type CVT that uses a ROM attached to the valve body that contains the solenoid and valve body calibration. That design was used for many years, and it’s pretty common in the shops right now.
It’s crazy to go back and re-read those articles. In my closing remarks on the second article, I mention that “although it may be a while before you see one of these CVTs in your shop, it’s definitely time to get ready for this technology. CVTs could very well be the next trend for the automatic transmission industry.” That was almost 14 years ago, and I’d say that prediction was mostly true! With that said, there are still plenty of shops that won’t work on CVTs or will only install reman-units. In my opinion, that really needs to change.
In this article, I’m going to briefly go over some of the obstacles that, in the past decade, a builder has needed to overcome to be successful at rebuilding these units. The bottom line is that the aftermarket has really stepped up to the plate and provided some excellent solutions.
In October of 2020, I had the privilege of working alongside Robert Bateman, Technical Advisor for Seal Aftermarket Products. He’s done a ton of research over the years regarding the various Jatco CVT units. We discussed many of the common CVT issues and failures along with their remedies while we were recording his CVT presentations for the ATRA Powertrain Virtual Expo. Those discussions became the motivation for writing this article, where I summarize some of the in-depth discussions and solutions.
First, let me mention that after doing a quick search on Gears Magazine’s website you will see that ATRA has done their due diligence covering the Jatco CVT tech over the years. There are many articles from Jarad Warren and Mike Souza covering Jatco CVTs, so don’t be shy and go ahead and start reviewing those articles as well. Also, there are quite a few Jatco CVT models. Although they share some obvious similarities, they also have some unique differences. If you’re like me, it’s easy to get confused with all the model and code designations, especially since Nissan and Jatco like to use different code names for the transmissions (Figure 1).
First obstacle: Parts availability – solved!
Early on, as with many new-to-market transmissions, parts were scarce and difficult to obtain. Aside from valve bodies and TCMs, Nissan didn’t offer many internal components. For example, trying to cross-reference a bearing became difficult. At times, you’d have to source a bearing from a different country designed for a different application. You can now find the primary and secondary bearings for pretty much all the Jatco CVT models (Figure 2).
When overhauling one of these units, do a good job cleaning the bearings and ensure that they spin smooth. If you come across one that doesn’t replace it. Don’t take the chance of reusing a marginal bearing. Also, realize that there will be metal throughout the unit if a bearing was failing, so proper disassembly and cleaning of the valve body, pulleys, and oil pump is essential.
Pulley/chain/belt. Disassembling the pulley halves is a must, not just for cleaning and inspection, but for replacing the ball or roller bearings that allow the movable pulley half to glide back and forth. Techs have been burned by a “good looking” pulley set, only to have them bind up and cause DTCs. If you don’t disassemble the pulley halves, you’ll have no idea if the ball/roller bearings are perfect or on their last leg and on the verge of self-destruction.
A failed set of ball bearings will cause the pulleys to stick/bind and potentially break, plus the metal from the failing bearings will take-out the seals (Figure 3). If you purchase a used pulley set, make sure you ask your supplier if they’ve been disassembled, cleaned, and inspected. Like I mentioned before, the ball bearing damage is hidden from view, so a pulley set that looks perfect on the outside could be a ticking timebomb on the inside.
Disassembling the pulley assemblies requires a special puller (Figure 4). As you can see, some pullers use a band that fits around the pully, while others grab the lip of the pulley sheave. Check your local parts distributor for availability. And make sure you check the “We’ve Got a Fix For That” section associated with this article on the Gears Magazine website.
One of the questions I ran past Robert involved reusing belt assemblies that still look good (Figure 5). My concern was that a belt that has 140,000 miles of flexing might not have much life left in it. He offered a few good points to consider. First, go ahead and pull the laminated bands out of each side of the belt (one side at a time to prevent a game of 400 segment pickup) to make sure there are no broken bands. He said, “You’ll know for sure when you pull the bands out if they’re broken because they will coil up like a clock spring.”
Second, inspect the belt segment edges to make sure they still have their “ridges.” It should look like the edge of a quarter or dime. Third, the high-quality steel used in the belts lasts for many miles, so running a used belt isn’t an issue.
When inspecting the pulleys, don’t assume the marks on the pulley is scoring or scuffing. The pulley surfaces often have a buildup of contamination (remember bearing failures?) that get smeared on the pulley surface by the extreme pressure between the belt and the pulley (Figure 6).
The pulley surfaces are very hard, so the material typically won’t embed into the pulley. Instead, it builds up on the surface of the pulley. This is why many techs will spin the pulley halves in a lathe and run sandpaper against them. Use the finest sandpaper possible that will remove the buildup, then work your way to 320 grit paper to polish the pulley surface.
When assembling the belt onto the pulleys, remember that the belts are designed to rotate in a specific direction. Usually, there is an arrow indicating rotation, but you can also tell by looking at the “P” shape of the segments.
The “P”s face in the direction of rotation (Figure 7). On most Jatco units, except the JF015e, the pulley rotation is clockwise as viewed from the engine side, which is the same as the engine rotation. On the JF015e, the pulleys rotate counterclockwise because the pulleys receive input from the input shaft through a transfer gear. So, it’s very important to note the rotation of the belts!
As I mentioned earlier, the aftermarket has stepped up to the challenge and developed some great upgrades to make these units last. The JF015e has an issue with their small inner piston. The inner diameter wears a large step and could possibly wear completely out. The aftermarket offers a nice billet upgrade to this piston, which is worth installing on every unit (Figure 8). The JF015e also traps the reluctor wheel for the speed sensors between the pulley and the piston housing. If the piston housing gains some clearance, the reluctor won’t spin with the pulley, resulting in gear ratio and speed sensor codes.
When overhauling the JF015e pulley assemblies, re-press the housing onto the pulley and place a small dab of solder or tack weld with a tig welder. Try to keep the heat off the pulley surfaces to avoid altering the hardness of the pulley surface. It doesn’t take much to hold that reluctor wheel to the pulley. The only reason why that reluctor wheel spins free is when the housing pulls away from the pulley, which releases its grab on the reluctor wheel. So just a simple tack will suffice.
A major root-cause failure on the Jatco CVTs is traced back to a worn Flow Control Valve found in the oil pump assembly (Figure 9). The pump gets scored and can cause sticking, which will cause very low pressure in the transmission. Low pressure can destroy any automatic transmission, but with a Jatco CVT where the pressures can hit 800psi+, low pressure won’t be tolerated at all.
The aftermarket has repair kits for the flow control valve. Check with your local parts distributor, and check it on every rebuild. Vacuum test the valve body to determine whether you need to ream and rebuild or just address the valve body with some drop-in valves (Figure 10).
If you find a severely worn-out valve body, check with the dealer for the cost of a new valve body. Many valve bodies from Nissan are still relatively cheap, and they come supplied with the solenoids. Here’s a little tip: Check to see if there are any service bulletins related to the problem. If the TSB directs you to change a valve body, then use that part number. It’ll be substantially less expensive.
The included picture shows the valve body for a 2015 Altima pulled from repairlinkshop.com. The site allows you to view manufacturer parts catalogs and access dealer pricing and availability. You can see that this valve body is less than $200, complete with solenoids! This might not always be the case, but it’s always worth trying (Figure 11a, 11b, and 11c).
When overhauling a JF015e, you’ll notice that Jatco is now using rollers instead of ball bearings inside the pulleys (Figure 12). If you have ever disassembled Honda CVT pulleys, you probably noticed that the Honda units use rollers as well. Since rollers have more contact area across the grooves than ball bearings, many consider it to be a good upgrade to convert a pulley assembly that uses ball bearings to roller bearings if possible.
Some kits come with replacement rollers. Just size up the number of ball bearings to determine the proper length of the roller bearing. There are three different sizes. If your CVT pulley comes equipped with three sets of two ball bearings (six total), then use the short roller. If the CVT comes equipped with three sets of four bearings (twelve total), then use the longer roller. The beauty of the roller is that it’ll work in a slightly worn groove since its design doesn’t require anything to roll in the groves. In discussions with Robert, he mentioned that some pulley sets are manufactured slightly different than others, and the rollers won’t always fit. Some pulleys have a slightly smaller diameter groove, and the rollers just won’t slide in. In those units, the builder will need to go back with ball bearings. Bearing damage is very common, so regardless of the pulley condition as viewed from the outside, each pulley assembly needs to be disassembled to clean, inspect, and replace the ball bearings with either rollers or new high-quality ball bearings.
Third Obstacle – Electronics and Programming – work-arounds
Another learning curve involves the electronics, adapting, relearning, and programming. The JF009/11/15/20 and some JF010 units have a ROM assembly in the valve body harness that contains information related to the solenoids and valves for calibration purposes. Issues might arise when swapping new or reman valve bodies. In discussions with Robert, he recommends keeping the ROM with the vehicle and simply resetting adapts and driving the vehicle to let it relearn. Using the ROM that comes with the new or swapped valve body can, at times, cause DTCs and drivability issues that are often resolved by simply using the vehicle’s original ROM.
The JF015e still uses a ROM, but it also has a “clutch point relearn” procedure that allows the vehicle to learn the shift characteristics of the two-speed gearset found in the JF015e. Search the Gears Magazine archive, or Google “clutch point relearn” to find the instructions. It’s basically a scripted test drive, but it’s necessary for the TCM to properly learn the transmission.
The JF016/17/18 models don’t use a ROM, but they are known for setting the infamous Judder DTC P17F0, which cannot be cleared using an aftermarket scan tool. If the TCM sets this code before overhaul or replacement, the code will still remain. Obtaining the Nissan Consult 3+ (and you need to make sure it’s a “3+”) or sourcing a new or used TCM are the only options for clearing to DTC.
Some major obstacles have been solved for you to be successful while overhauling the Jatco CVT. It’s time to test the waters if you haven’t already. Stop for a second to think that basically, every front-wheel-drive Nissan vehicle since 2007 has a Jatco CVT. That’s in addition to the many Mitsubishi, Suzuki, Jeep, and various other manufacturers. So what are you waiting for? Give it a try! What’s the worst that could happen?