Hi guys. First let me explain a little of my history with the Vios. In 2013 I started attending autocross events with my automatic Yaris sedan. I had some basic engine, suspension, and brakes modifications with little racing experience...so I was slow. I always asked questions and adjusted my driving until I was within tenths of the fast guys at the local region. Then one year at nationals there was a K20 civic completely dominating the class, and thats when I decided to build the car for track racing. First it was the 2ZRFE engine swap from a corolla, It was awesome and I ran with that engine for 6 months and won almost every local autox in SMF....until my automatic transmission started limiting the car's potential. This is where the 2zrVios story kicks into high gear, with a manual transmission swap/build...
Before you ask why I painted the case orange, take a look at my car. I'm a big fan of using traditional Toyota livery witch is a set of 3 colors; Yellow, Orange, and Red.
Ask anyone out there that has done a 2zr swap in their Yaris what they noticed first, and they will all tell you "torque". The 2zrfe makes 25ftlbs more than the original 1nzfe in stock form, so the outcome in our 2300lb car is always LOTS of one-tire wheel spin. Now lets discuss what makes the ARtrackbox special. There are two modifications to this proven Toyota C50 that make it a completely different animal than any virgin C50 out there....it has the Cusco Type-RS Limited Slip Differential (unboxing here ) wrapped with a Scion sourced 4.3 Final Drive gear. What that means is, I get full use of every gear in the transmission instead of just first through fourth on a road course. In addition to better acceleration, I also get a full locking differential that will not "unload" like a torsion if I lift a wheel in a turn.
I'm not going to do a full tear-down and assembly write up here, because there are already a few time lapsed videos on YouTube. What I will go over here is what those videos did not cover, taking measurements, inspection, and setting differential bearing preload. Bearings are easy, either they rotate smoothly and quietly or not.
Now lets start with synchronizers, since everyone likes to blame these guys for shifting issues. All of the specifications I retrieved from the Toyota Yaris C50 service manual.
In the above picture I'm measuring synchro to gear gap, this measurement tells you how much the synchro has worn. You should also verify the teeth on the synchros are still pointy and not rounded, then press the synchro onto the gear cone firmly and try to turn them separately. The synchro should lock onto the gear when you press them together.
Next, thrust clearance.
Thrust clearance tells you how much each gear has worn and is allowed to moved axially. If any gear can move too much when the shift collar forces the synchro against it, the gear may not slow down or engage at all.
Next, differential bearing preload.
In this image you can see the differential bearing shim, case washer, and new bearing race. The case washer has no markings and gets installed under the bell housing side differential bearing race. The adjusting shim however is on the case side and has two identical letter markings to signify its thickness. The procedure requires us to install the differential and torque the case bolts to 22ftlbs, install your special tool then using an in/lb torque wrench measure how much force it takes to turn the differential. If you need to change the shim just remove the case, set it on a soft surface, and tap on the shim until the shim and bearing race fall out. Replace the shim with the next size, then repeat the process until your preload measurement is within spec.
Once your preload is set, you can assemble the transmission completely, but before you seal the end case verify you can shift through all gears and that there is no abnormal noise. If you installed a clutch type LSD don't forget to do the break-in procedure listed below, do figure eights in a parking lot for a half hour then change the fluid.
I installed an OEM corolla flywheel and clutch because my 2zr will remain N/A for all of next year, and even with the custom long tube header I'm still within the torque rating of the stock pressure plate. The next time I have to service the transmission or clutch I may upgrade to the lightweight flywheel though, they have been proven to free up some power.
My hopes are to focus more on NASA HPDE, Redline Time Attack, and TRD cup to find the ragged edge with this build and show what it can do. The Yaris is a great platform, its light, it accepts many engine or transmission swaps, and it has great aftermarket support. Check out the start-up and test drive video below, then get out there and slay some tires! -Tom
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