This post is going to be similar to the comparison blog I created on the C150 vs C50, I believe the C160 is super rare so I jumped at the opportunity to document my findings. The first thing you will notice about the case is again, just a bit more width on the newer C60 version. You will see in this blog how slight changes in a few places results in that outcome. In the picture above we notice the cases are very different, on the outside. The bell housings have different starter locations since they are used on different engines. The center case is different due to the C160 being a 1/2 inch shorter, thus requiring a different upper mount. Then end cap for 5-6 seems to be the only compatible part.

The C160 1st gear tooth width is 3mm narrower than the C60, and the overall gear with is 4mm less. That's a huge difference if you do any drag racing, The synchronizer seems to be the same part between the two.

The 2nd gear is a similar story to 1st gear, the C160 is 4mm narrower at the teeth and overall. The C60 has a superior 3-piece synchronizer as well, so that means the 1-2 shift hubs will be different.

The 3rd gear set is where things start to become close, at this point, there is roughly a 1mm difference between the two transmissions. The shift hubs are almost identical and the synchronizers are also the same size, you can use the 2000-2003 C60 synchros with the C160 3rd gear for an upgrade to bi-metal friction material! 

Just like the C150, the measurements of the 4th, 5th, and 6th gears are all the same. The only differences are the synchronizer and hub designs.

Here you can see the C60 shafts are longer than the C160 by roughly 0.6 inch. The differences all occur between the clutch splines, pinion and bearing race, 1st, 2nd, 3rd, and 3-4 hub.

The bearings have the exact same differences as the C150 did, 2mm less width. The good thing is I recently ordered a set of these bearings from Japan, so they are still available.

This is really cool, the C160 actually came with a torsion LSD! The only downside to this is that it requires a 110mm ring gear, that means you can only use it with the C160, Yaris/xA C50, xB1 C50, or MR2 C52. All other gearboxes(except C150) require the 115mm ring gears and have fewer axle splines.

The differential bearings and seals are different, and so is the spacer in the bell housing. 

The biggest takeaway here is that Toyota paid attention to what was failing and seriously beefed up those areas. The final drive, the bearings, 1st, 2nd, 3rd, the differential, and axles...the only thing unchanged was the ratios and the 4-5-6 gears. Too bad we still have a problem breaking 3rd and the final drive on stock 2zz's, its better but not a complete solution. I'm sure you know by now that Toyota doesn't even use the C60 in any modern cars, they all use the EC transmissions now like in the new Corrolas. This is why I recommend the WPC treatment on these weak points on all of my builds, and I haven't seen one break yet! Check out the comparison below:

The C150 is one of the first 5-speed transaxles made by Toyota, here in the US this gearbox would be used in the Echo, Tercel, Paseo, and 80's Corolla. These cars were smaller and made a lot less power than they do now, so it makes sense that the C150 is more compact than the modern units. This was my first time building one of these for an Echo track car, so I logged all of my findings:

The bell housing is the foundation of these C transmissions, since this is where the differential and main bearings reside. After inspecting and measuring, the C150 and Yaris C50 bell housings are very similar. Both have the 4.5in distance from the Output shaft to the differential, and all of the internal features are identical. The main differences are the threaded holes on the C150 for a rear mount(C50 uses a pitch stop mount at the bottom), and the Yaris C50 has threaded holes for the shift cable mount(C150 does not). So use the bell housing for your cars engine and mounts, then build upon that.

The first thing I noticed was the compact design. The whole C150 is almost the same length(5/16ths shorter) as a C5x, but the middle case and end caps are completely different. The C150 center case that houses the shafts and gears 1-4 is a half inch shorter than the C5x case, this also means the shift rails are different since the detents are a half inch closer to the shift selector. The C150 end cap is a 1/2 longer, because it houses the same size 5th gear components but has to reach that extra 1/2 in due to the shorter center case. This is where I started comparing the internal parts.

Because this is an older economy transmission, a lot of what's inside is low budget. What I mean is that the 3-4 shift hub uses the C-clip style dog spring, 2nd gear has a 1 piece syncro, and it uses the most common ratios. 

Same thing here with 2nd gear, the only difference is gear thickness.

Third gear is where they start to look similar, only a 1mm difference and the synchros aren't that different either.

I also measured 4th and 5th gears from the 2 transmissions, and they seem to be the same so we'll skip over them.

The C150 bearings are essentially identical copies of the C5x, just 2mm smaller.

The differentials are very different in the two transmissions. Although they both have a 67 tooth ring gear, they are not interchangeable with other pinions. This is because the Echo has a 3.5FD compared to the C50's 3.7FD, and that means an extra tooth on the C150 output shaft. The extra tooth adds an extra 2mm to the pinion diameter and that leaves no room for any backlash(ZERO). If thats not enough, the C50 ring gear is 2mm thicker so it wont clear 1st gear on the C150 output shaft. 

The other areas the differential is different is in the bearings. The taper on the C50 and C150 bearings is different, AND the size of the bearing. The ring gear attachment is also different, the C150 has threads in the differential where the C50 has threads in the ring gear.

Now that we know what the parts look like, let's discuss upgrade options.

RATIOS:
 Because gears 1-3 are different from the C5x/C6x, you cannot swap in any other ratios except those from the C160. That requires importing a whole C160 from Canada or Japan, since many of these parts were discontinued. Alternatively, you can retrofit to a C5x/C6x, but you need to make room for fitment and sometimes new axles as well. Honestly though, the 3.5/1.9/1.3 1-3 ratio spread is not that bad. You may be able to fit a C56 1.03 4th gear and instantly have a close ratio box. 

FINAL DRIVE:
Again, since the ring gear and pinion are proprietary in the C150, there are no simple options. A C5x/C6x retrofit is the only option that I know of, that takes you from the 3.5 to either a 3.7, 3.9, 4.3, or 4.5(6-speed).

DIFFERENTIAL:
I believe there are only 2 options here for the C150, Quaife or Cusco. Many companies advertise they have the correct LSD, but usually it's really an 8-bolt for the Yaris...

I feel like the C56 retrofit is still the best option for every 5-speed, and this will remain my recommendation. You can install the Cusco C110 LSD and do the WPC treatment to the C150 and have a nice build, but the 3.5FD means the gears will feel super long. Check out the chart below:

I remember back in 2010 when Subaru started using the 1st Generation CVT in the Legacy and Outback. Of course, we mourned the passing of the 4AT, but hey fuel economy is more important right? All of us Subaru technicians were in for a surprise though, somehow there was a disconnect between the sales department explaining how the CVT's operate. We had so many people coming in to service with complaints of "transmission slipping in 1st gear". We would perform tests and drive the vehicle, only to tell the customers this is normal. 

Once we started seeing actual issues arise, they surfaced as noises, electrical faults, and stalling. A vast majority of the CVT problems are covered in either a recall or TSB, so the odds are good the repair will be covered under warranty.  There isn't much you can do to prevent the electrical issues, since they all occur inside the valve-body solenoids. However, you can do your part in fluid and software maintenance...

Over the course of my day as a Subaru technician I would take CVT fluid samples from vehicles at different mileage intervals that had a CVT issue, and after several months I had a collection of fluid samples ranging from 11,000  to 100,000 miles. What I noticed is that the fluid stays very clean all the way up to 25,000, then you can start seeing the change. Not only does the fluid start changing to a brown color, but you can see a lot of suspended material moving around. I don't know for sure what the debris is, but we can assume is wear from the input/reverse/AWD clutches.

New fluid on the left, 30k fluid on the right...

​I change my CVT fluid every 30,000 miles, because its right there where the fluid starts looking bad. Also, knowing that the valve-body can become clogged with that debris makes even more sense to just stay on top of it. The other very important element I would suggest is that you pay attention to your shift lag time. When you shift from reverse to drive, does it take a long time to actually move the vehicle? If so then you need to have the clutches re-learned, this is where the wear on the clutch packs is compensated for. If you neglect this issue it can slip the clutches every time you take off before feeling the CVT engage drive or reverse. 

The final element to CVT maintenance is the Differentials, well technically only the front differential is part of the CVT but you know what I'm saying. It's super rare for a differential to fail, but you should still change the fluid every 30k as well. Gears meshing together always creates some wear metals in the fluid, so you can't just never service them. If you don't believe me take a look at the fluid in a new car, there will be "some" metal debris and fluid discoloration straight out of the factory. This is because the gears create a matching pattern as they break-in, it's normal. Just like with a new engine, new driveline components can benefit from a break-in oil change. Take a look at the fluid from my Forester  below:

That's the new gear oil at the top right, 30k front diff oil at the top left, and 30k rear diff oil at the bottom left. I hope this write-up has helped you understand how to take care of your Subaru CVT and differential better, if you have any feedback just leave a comment below. Take a look at the short time-lapse video I made on this transmission:

A few days after removing the drivetrain from the Celica, I decided to get started on the engine tear down. The first step is to split the engine and transmission, this a pretty easy task with everything out of the car already. I was surprised however to see just how disgusting the transmission was, someone recently had this engine apart and decided to not fix the transmission leaks at that time. The saddest part is that it's just a bad axle seal, what kind of work ethic is that!  Anyway, let's move on...

In the image above you'll see the glued on seal proving this was a junkyard engine, although I knew this already just based on the infamous "silver paint job". Next, I put the engine on the stand, and anyone that has worked on a Toyota knows you need to source 5" bolts to mount the engine up. I started the disassembly by carefully removing the engine harness. The last person to touch this car had already broken most of the retention clips, so I tried to take extra caution not to break anything else. That didn't go as planned though, the connectors and wires in this harness were super brittle due to age, heat, and oil soaking. 

Next, I decided to remove the manifolds. The exhaust came off pretty easy, and I did notice a lot of soot build-up in the ports(something to keep in mind as improper combustion could be the possible cause of failure). The intake manifold was pretty difficult to remove though, it had sealant applied to essentially every contact surface and had to be pried off. I removed most of the other parts of the engine, finding excessive sealant and stripped bolts everywhere along the way. I even had to pry the water pump off due to the excessive sealant, and of course I dropped it on the floor and broke it....YAY! On a positive note, at least the clutch looks new!

I left the valve cover on to prevent more oil spillage, then turned the engine upside down. This is where I found the nastiest part of the whole project, for whatever reason the oil pan had been removed already. The amount of sealant on the pan was unbelievable, vast amounts of it squeezed inside and out of the flanges. Unacceptable, but somehow none of it was stuck in the oil pick-up. One good thing about this engine is that the rod bearing caps are accessible once the pan is off, so I removed them one at a time and took pictures:

Well thats gone wrong. 

It's clear something went wrong and caused #4 rod bearing to fail, I'm still not sure of the cause at this point though. I would suspect oil contamination since all of the bearings have some damage, but that could be collateral damage too. Maybe the engine did have a serious performance issue and detonation caused this, let's keep going and see what else is damaged.

The oil pump was another failure point. I didn't have the correct impact driver to remove to cover, but its definitely damaged based on the sounds it makes and inability to free spin. I know the 2ZZ has issues with the oil pump so this wasn't a surprise to me. There was sealant applied to every single contact surface on this too, including the oil pickup and pump gaskets. Take a look at the below picture of the timing cover to get an idea of what I'm saying...

On a positive note however, the cams and cylinder bores look great! All of the filters and screens must have done their job thankfully, if the rest of the engine was damaged this project would be much more expensive. You can see that the pistons look new and the engine is relatively clean inside, the timing components and oil pump also look like they were recently replaced. My original analysis on this engine was poor workmanship, and I'm going to stand by that based on what I found here. The patterns on these bearings resemble those that fell victim to contamination and subsequent lack of lubrication. 

Now I'll be taking the Crankshaft to a machine shop to inspect, I can measure it but I need to see if there are any cracks or distortion. Once I receive a response from them we can plan accordingly for reassembly. I'll also get a new oil pump, full bearing set, gaskets, water pump, lift bolts, lift screen, and fluids. Stay tuned for the next update!

To first understand wheel studs, let's look at the technical details behind them. The ARP studs are made from 8740 chrome moly and are cadmium plated, this results in a maximum tensile strength of 200,000psi. This would be the equivalent of applying 112ftlbs of torque to a regular Toyota passenger car 12mmx1.5 stud. The original Toyota 8T studs torque spec is 76ftlbs, but there is no data on their maximum tensile strength. So without using an oscilloscope and torque gauge to test each stud we can't definitively say witch studs are stronger. I will report that many people have lost a wheel or noticed their OEM studs cracked or broken after track racing. I've never heard one bad report of any ARP hardware, and I believe they are essential for those of us removing and installing wheels often.

I had originally purchased these studs for their length back when I had the JDM Vitz rear disc brake conversion. I had a set of 15x7 RPF1's and the rear caliper did not clear the wheel drum taper, so I used these longer studs and 10mm spacers to make it fit. ARP does not make a kit specifically for the Yaris so I had to do a bit of research to find the right size Knurl, luckily all I needed to do was measure and compare on ARP's website. The Lexus IS300 wheel stud kit was a direct match, they come in packs of 5, so you need to order 4 packs even though the Yaris hubs are 4x100. You can order these HERE.

Installation is relatively simple but you will need a wheel stud installer and open-ended lug-nuts. Once the brakes are removed, the original front studs can be hammered out and the new studs installed from the forward side of the hub. However, the rear hubs will need to be removed due to insufficient clearance of the backplate. During instalation be sure to apply some synthetic grease to the threads, this will ease in installation and protect the stud from any corrosion in the future. You can get the grease HERE, and the installer HERE.

The final piece of this fail-proof upgrade is a proper lug-nut. I've been around cars and racing a long time, and I've seen people use a lot of different lug-nuts. So please listen when I say to avoid the aluminum nuts. Yes they are lighter, but they also expand at a different rate of the stud and strip after several on-off cycles. Remember to apply some grease to the stud, use a steel lug-nut, and torque to spec. I really like the Gorilla forged lug-nuts, they are heavy duty, have a knurled end for easy installation, and are open-ended. You can purchase the forged lugs HERE.

Maintenance is easy, all you need to do is clean the threads, inspect for wear, and apply new grease. I've had this set-up on my car for 3 years now, and I've never had any issues. I rotate the tires after every race and at lunchtime during track events. Hundreds of on-off cycles and 4 different wheel set-ups, you could safely say I've tested them thoroughly.