Wayback Machine

Now to begin the disassembly, I'm going to remove all of these hoses and this cooler on the front half of the transmission, turn that off as well. Okay, I'm starting to do it. There's a mess in here so I just wore my brother's old pants let's soak up some of this mess this is going to be a very dirty video we're just going to take out that cooler and there's the filter that looks like a normal oil filter that you would find . in a car, but like a mini version, I'll just unplug that electrical connector and it will come out of the dipstick, at least this one actually comes with a real dipstick, unlike those newer Nissans where the dipstick is sold for separated now it is It is always recommended to start with the valve body at the bottom, which means we have to turn it over and make a big mess.

Next, I'm going to remove all of these 10 millimeter bolts that hold this transmission pan on and remove them. that transmission pan this is a nice thick cast aluminum pan that I like you can see the bottom here we have these two magnets it has a little bit of a slope inside here now on the bottom of the transmission under the pan Transmission This valve body is now responsible for directing fluid flow to do different things throughout the transmission, like adjusting gear ratios or what mode you're in. Here we have the electronic part, which is the eprom with which it will communicate. the transmission control module here, the steel part is a transmission filter with the pickup tube, so it will actually collect the transmission fluid that's in this pan here and filter it before it goes through the

entire

transmission and now I can remove that filter and You can see that the filter is like a screen-like material.

I'm going to go ahead and remove all the electrical connectors from here. This is the control rod that goes to the top half of the transmission and connects to the transmission shift lever. and it's basically controlling this manual valve to manually select the transmission's park, reverse, neutral, or drive functions. You can see when I move the knob from the other side. Here how to control that and I'm just going to remove this nut and then I'm going to remove the secondary nut, they were double screwed and now I'm going to remove all the 10 millimeter bolts that I can see, it looks like we have the sensor because it moves back and forth depending on the gear your selector is in and you're going to send that signal to the transmission control module you should be able to just lift the valve body out of the transmission housing and you can take a closer look now.

Here's a good look at the bottom of this valve body and you can see there's so much. There are a lot of little holes and ports here where fluid will flow into the transmission housing underneath and that's because this controls all of the individual hydraulic circuits within the transmission to do various things. Now you'll

notic

e that there are also only four solenoids in the Here on the front, a typical automatic transmission may have six or eight solenoids and the reason is that there are not as many clutches inside this transmission. Now, if we take a look at the hydraulic aspects of the CVT control system, you will see that the transmission control module is located here at the front and takes inputs from numerous electronic components in the vehicle and converts them into hydraulic outputs.

There are numerous solenoids and valves here, such as the stepper motor that will ultimately adjust the valves and the size of the pulleys. Here we have the pressure regulators, we also have the valves that will control whether it goes forward or reverse, as well as the torque converter lockup. Now if we take a look at the electrical aspects of the CVT, we have the transmission control module which interacts with the other computers in the system through the CAN communication bus. It will take things like throttle position as well as wheel speed and other things, calculate them, and convert them into electrical signals here and there.

The signals can be inputs or outputs, such as the temperature, pressure and speed sensor or solenoid valves to control the fluid. Here's a look inside the transmission case. There's a lot of liquid here now, so I'll wear my brother's old gym pants again. to absorb some of that transmission fluid, now very similar to an automatic transmission in the front, we have this bell here that houses the torque converter inside, here is the feed for the torque converter lockup and control and this another one here spins the oil. pump inside here that rotates with the speed of the engine that way the transmission always receives fluid flow to perform its operation now there are several 14 millimeter bolts on the inside and outside of this belt housing here so I'm just going I'm going to go ahead and start removing them all nice and with all the bolts free and I'll just lift that housing up to reveal the inside of the transmission.

Now taking a look at this CVT transmission, we have the input shaft where The torque converter screws in over here and now it also spins this oil pump because the torque is so high that you can't turn it by hand, but if I spin this intermediate gear here, you can see that between here and here is the variator and the belt. located for the cvt part of the transmission, you have this intermediate gear here and then the final drive differential here. Now I'm going to remove this intermediate gear here. You can see that this one actually has the gears at this angle here and that's to prevent any squealing when the transmission is in gear.

Here we have the front differential and that just pops. I already have a video on how differentials work. You may want to see the de

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ion and link below. The only difference to note here is that this is an all-wheel drive model, which means you will need an extra axle to power the transfer case and power the rear wheel for the all-wheel drive transfer case you have. an additional set of splines here that connects to this carrier and therefore the final drive to send power to that transfer case to the rear wheel. Now here on the CVT output variator we have the lock here that controls your parking pawl that connects inside here and completely locks the transmission when you have it in park, when you take it out of park it will open it again to allow it to spin okay now I'm going to remove all the 12 millimeter bolts that hold this oil pump and its housing in the transmission, now I'm just going to lift this up and then I can remove this assembly here, now this clutch pack has a little snap ring here that I'm going to try to remove and then now I can remove this clutch pack.

Now this smaller shaft on the inside here forms the input shaft to the transmission and this other shaft on the outside here is what drives this oil pump and you can see that the input shaft here is. then it's going to be splined directly into this clutch over here, so this clutch is going to move as part of the transmission input. Now the oil pump is located inside this housing. I'm going to remove these six millimeter hex bolts so we can take a closer look now with all those bolts free. I'm going to split this oil pump and inside this oil pump you'll

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e that there are a lot of other fluid passages for the fluid to go in and route and also provide pressure. to other things in the transmission here we have the heart of the fuel pump here, it basically rotates around this shaft that is offset from the housing and as it rotates like that, you can see that the fluid will travel in the middle here . and it's forced between these teeth as it rotates and that's what provides that fluid flow.

Now at the top we have these two hex bolts that have a spring inside here and that is to regulate the pressure. Now if we take a look, I have a planetary gear set and a CVT transmission like in an automatic transmission. Now the real reason this is here is to give you reverse steering so you can reverse your car instead of just changing gear ratios like an automatic transmission now the first part of that planetary gear set is made up of this package clutch is now turned off by the oil pump it has these holes here that are going to press against this piston here to tighten this clutch inside here now this assembly here houses the ring gear for the first part of the planetary gear set and it has these teeth inside here which are teeth for this gear inside here, so essentially when this clutch locks up, it's going to lock the ring gear to these teeth inside here and that's going to attach it to this piece here now this piece here is the sun gear from the planetary gear set and then in here you have the planet carrier and you can see the little planets inside here now this The planet carrier is splined here to this clutch that's on the inside of the housing, so it's actually going to lock the housing to this planet carrier when it's engaged, there's just a little retaining ring here that I'm going to remove and then I can remove this clutch assembly.

Next, we have another clip here that I'm going to remove and then I can remove this return spring over here and this just helps return the clutch pack to its proper position once the fluid pressure is released. Then the next thing I'm going to remove is this piece that has a little bit of liquid on it. Now we're going to turn the transmission around and create a mess. I'll go with my brother's old underwear to mine it. I don't want to ruin my cardboard studio. It's going to be a very dirty video. I'm going to use a crowbar.

Shit, it's heavy. So here we have the heart of the continuously variable transmission. This is the input pulley and this. one is the output pulley, it has this gear that will connect with the intermediate gear and then the differential that now connects the two pulleys is a steel belt that has to be flexible enough to go around these pulleys but strong enough to transfer the torque now. Looking from the side, the way this continuously variable transmission is going to vary its input to output ratio is by changing the effective diameter of the pulleys from the input to the output, for example, in this case the pulley is adjusted so that the The belt has the smallest diameter at its entrance here and the largest diameter at the exit, so this will give you a very low gear ratio, which is good when you want to start from the top.

You can see when I rotate this input shaft twice. full rotations this output shaft here turns one rotation so there's a two to one ratio here now a low gear ratio like this is ideal when you want to start from a standstill because your engine can spin faster than your wheels and that will give you you are a torque multiplication of course in the opposite scenario this diameter here would be the largest diameter and this will be the smallest diameter and that will give you an overdrive ratio so let's say for example if this was the driving gear and this one being the driven one. gear, you can see that just one rotation of this gear here will give me two rotations of this gear here for a gear ratio of one to two, so that will work when you're on the highway and you want your rpm to stay nice and low for good fuel economy, so now we need to look at how this pulley actually varies the effective diameter of this belt.

Now, if you look at the cross section of the strap here, you can see that it has a width and that width. is always fixed, withoutHowever, the pulleys themselves here where the belt actually hits have a smooth taper shape and this taper shape is the key to allowing this belt to tighten when you tighten it, this belt will then be forced outward. this taper here and it effectively changes the diameter from the inside of there to the outside of here and that's because the width of this belt here has to stay the same, you can't tighten the belt, so you're actually forcing the belt back out this way now.

Of course, as this belt goes up to the outside, its girth will increase and that slack needs to be corrected somewhere because the belt itself is a fixed length, there are no adjustment pulleys or anything and that will be done by the secondary. pulley over here now this driven pulley is responsible for doing the opposite of what the driving pulley does and that is if the diameter increases on this side it will decrease the diameter on this side and that allows it to maintain the same length of chain on both because center-to-center distances are fixed, therefore any increase in this diameter must be imitated by a decrease in this diameter for everything to work correctly.

Now in some CVTs these actuators are adjusted by hydraulic systems and in some they are adjusted by an electric servo motor that actually moves them in and out. Here it is hydraulically operated. You can see that these are the ports where oil will flow from the transmission housing to these hydraulic actuators to vary their widths accordingly. Now I'm going to remove these pulleys from this housing here and of course. I've got more oil dripping around here, so I'm going to go in with some of my wife's and clean this up. I hope this video doesn't get flagged for being too dirty and here we have the pulley system removed. the CVT housing now these brackets here are the ones that held it to the housing and at the end here we have this bearing and this bearing over here now there are two big nuts on this side here and then a big nut on this side here that I need remove it, but I don't have any bushings that big, so I may have to improvise time for the angle grinder.

There we are going to break it and then we just take out that bearing. The driven side has this little circlip here that I'm going to use. To remove I just made a small incision here on the driven side, I'll remove this cover here, this looks like a fluid chamber or something, so I was able to pull this belt off the pulley here so I can separate these two there. come on here now we have the actual belt here we have the driven actuator and this is what's going to change its width with that taper shape and here we have the driving actuator coming from the input shaft now taking a look at the input and the drive actuators outlet are hydraulically actuated.

You've got the tapered pulley part here where the belt rides and adjusting this width here using hydraulic pressure inside this cylinder is what's going to pull it back or push it forward for variety. that belt diameter now the hydraulics on the input shaft come in through this part of the shaft here where the planetary gear set actually attaches to the oil pressure and then it's going to come in here and fill this chamber here that's going to slide this back here reducing the effective diameter over here now the hydraulic pressure from the output side variator is going to come in through here and it does it through the transmission housing where you have this port here that feeds it directly and that actually leads to this port here that goes back to the valve body of the transmission now the belt here is probably the star of the show, it's made of these little individual pieces of steel that form around this belt and that generally make this band steel be very flexible and still strong and able to transfer torque now unlike a rubber belt where there is always tension on this belt but because it is a pull style system these belts are a push style system where the driven part actually pushes these little steel membranes together to transfer torque to the driven side, I'm just going to pull out this little steel band here so we can see better now, taking a look at these little elements here, you have these two slots here for the steel bands to hold. all together you also have this little dot at the top here now this little detent will connect to this little tread on this side just like that and that's what will give the belt a gap at the bottom there when it's in a straight section but allow it to compress when it needs to curve around the pulley.

Also, the angle of these elements here has to be equal to the angle of the cone here so that it can move freely up and down, so now I have taken this nissan cvt apart, let's take a look at some of the failure modes starting, by Of course, with this strap, which is probably the weakest link in this system. This is just a steel belt here, there are no hard gears like in a manual transmission or even planetary gears like in an automatic transmission and transferring too much torque to one of these could eventually cause it to fail.

Now one of the worst things is that Nissan chose to plug this into higher horsepower vehicles. CVTs are mainly known for light vehicles such as economy ones. cars, but for some reason they chose to pair the vq-35 engines with this one, which is a pretty powerful engine and that's what will make these things fail. People are going to charge those vehicles and that's not going to work well for this transmission. Now, another factor that can cause this belt to slip or clog on these cones here is, of course, wear. Now not only can wear occur on these cone surfaces or on the belt, but slipping or plugging can also occur if these drives are not operating.

They are not doing their job correctly, for example, if this variator fits differently than this variator, suddenly the diameters are not in the correct proportion and then this belt starts to slip and clog. Perhaps one of Nissan's biggest oversights was the cooling system and that's because it was inadequate for these CVTs, now these CVTs generate a lot of heat because you have this belt system and if the cooling system can't keep up and the Transmission fluid can't absorb heat well, then all of a sudden you have parts that start to disintegrate and wear out much faster because they are at much higher temperatures and they just disintegrate on their own.

Now one of the telltale signs of CBT failure is moaning. They definitely make a lot more noise than a conventional automatic transmission and that's because you have a steel on steel contact here there's a rotating assembly now all those things start to wear out pretty quickly they're known to keep a lot more noise now because you have a planetary gear set with this style of clutch just like an automatic transmission this can also be a point of failure and if this fails then your CVT will not be able to go into gear or will not be able to go into reverse or will get stuck in reverse and then literally goes a I'll go back to the dealership now, of course CVTs have their pros and cons.

With the belt system, you don't have to worry about any gears, which means you get a really smooth power delivery, unlike an automatic transmission where you have these. Clutches that keep locking and unlocking give you brakes in the power band when you're accelerating, also because you have less clutch packs, there's less friction and therefore CVTs give you better fuel economy and that's the number one reason why many economy creators. Cars are switching to CVT transmissions because drivers of these economy vehicles typically don't care about the driving experience they lose with the CVT, but they care more about the gas they're going to save now, of course, the fuel economy does. arrives. an expense and that's because this belt makes a lot of noise, but not only does it make a lot of noise, it also gives you a rubber band effect.

You see, the thing is, with a clutch pack you can lock and unlock it instantly. just a change in the pressure in the valve body, while this big drum here you have to fill this drum and therefore when you step on the accelerator, this variator will take a little while to change its ratio so that you accelerate fast now nissan. markets its CVTs as more reliable than conventional automatics because they now have fewer moving parts, while that's true, they're definitely not more reliable. There have been tons of these failing so much that Nissan has been involved in many lawsuits and settlements over owners with cvt transmissions that don't even last the warranty and unlike an automatic, you see, everything I've done here I've done on my end There really isn't any manual on how to take apart a cvt and diagnose it properly or anything else. parts available or any diagram other than this little cross section to give you in the owner's manual how this works or how to fix it when your CVT fails you are out three or four grand to replace it completely there is no rebuilding a cvt transmission As you would with an automatic now, in general, if you own a CVT vehicle, the only thing you can really do to extend its life is to keep up with transmission fluid and coolant changes. surfaces and to drive the car fairly easily, do not tow even if you have a Pathfinder or a Murano that is supposedly rated for it because you could easily damage these expensive components of your vehicle, so next time you use the paddle shifters.

To change your CVT transmission, think about all these components that have to go inside for it to work. Be sure to follow me on Instagram to see more behind-the-scenes images and subscribe to see more videos like this.