If you search the web for any type of Honda gear sets you're garranteed to get plenty of results right away, but for us Toyota owners its always been tough. We've always had to rely on the guys that have done hybrid builds on the forums or the super knowledgeable guys over at Monkeywrench Racing. I have built a couple performance Toyota transaxles for myself, but most of my experience comes from Subarus. I've probably built around 50 transmissions in my time as a technician, and I also keep up with Paul Cangialosi on Youtube (GearBoxVideo). This guy has a ton of manual transmission experience and knowledge, and even has wrote a book on the topic! So I'll be sharing everything I've learned from Paul, my fellow Toyota racers, and my own personal experience here to help others decide on a path for their Toyota transaxle build.
1) Final Drive Gear
A Toyota Final Drive Gear consists of 1) the output shaft and 2) the differential ring gear. The final drive gear is essentially the gear ratio between your output-shaft and your wheels, and this ratio is largely responsible for your acceleration and top speed. Most Toyota cars have a 3.9:1FD and that equates to roughly a 145mph mechanical top speed, but in reality thats not attainable due to the speed limiter or low power output. Toyota decides on a ratio that is a perfect mix of fuel economy and acceleration, performance usually being the least of their priorities. So if you swap the 3.9FD for a 4.3, you get an instant acceleration boost and your top speed drops to about 125mph. Your cruising RPM will also increase and the MPG will drop, because now you are spinning the output shaft 4.3 times for every 1 turn of the differential. The higher the number, the quicker your acceleration. Very important.
2) Limited Slip Differential
This right here is the game changer, the one piece that belongs in every racing gearbox. You can have the most expensive build out there with carbon synchros and Kazz gears, but if you dont have an LSD youre going to spin one tire constantly and lose time. A clutch-type limited-slip-differential has a small clutch pack on the end of each axle stub, a cam and wedge blocks in the center, and some preload springs. The springs hold the clutches at a specific preload but still allows some slipage, and when you accelerate the cam forces the wedge blocks against the clutches and locks the wheels together. My personal recommendation is the Cusco Type-RS, I had one for a whole year of autocross and track duty without any issues or noise. I had forgotten how much of a necesity the LSD was untill I did the C60 swap with a open differential. Get the LSD at all costs, or you will regret it.
3) Gear Ratios
In a manual gearbox, gear ratios fill the gap between starting from a stop and doing 70mph on a highway. You cant start off in 5th or 6th gear or you will destroy the clutch from slipping it for so long, likewise you cant go any faster than 35mph in 1st gear or the engine will explode. In most Toyota transaxles the 2-3-4 gear ratios are similar, with variences in 1st and 5th(or 6th) gears based on the accompanied final drive. Lets take a look at the most common boxes below.
C50 5-speed (Yaris, xA, xB-Gen1, xD)
There are 3 versions of the C50 in US circulation that I know about:
1) The Yaris has a 33mm output shaft, all brass synchros, 3.7 final drive, and a 23 spline differential.
2) The 04-07 Scion xB has a 33mm output shaft, all brass synchros, 4.3 final drive, and a 23 spline differential.
3) The Scion xD has a 40mm output shaft, mostly brass synchros with 3rd being a bi-metal, 3.7 final drive, and a 20 spline differential.
The Scion xB 4.3 FD can be put into the Yaris box with the Cusco LSD, but I've found in this application the highway cruising RPM is rather high. The best option is to use the C59 .725 5th gear with this combination. If you don't drive it on the street, then disregard this step.
The C50-59 have what seem to be "the problem bearings" between 4th and 5th gear, and Ive seen several of these explode and cause gear damage. In every case its the bearing on the output shaft that fails, and I'm going to assume its due to a combination of the open-cage design and the thrust characteristics of helical cut gears. Conrad style bearings are not rated to handle a ton of axial load, so when you are launching or doing burnouts the output shaft bearing is getting hammered from all those forces. If your gearbox starts becoming noisy while driving, don't put off the repair or you'll need a whole new transmission instead of just bearings. You can tell these bearings by their open cage design, they are very different from the superior sealed style C60 bearings.
C56 5-speed (Celica GT, MR2 Spyder)
This C56 seems like the best 5-speed option for sure, you pretty much get a close ratio box with a great final drive from the start. The only thing you need to do to this one is drop in the Cusco Type-RS LSD, set the preload, drop in the good C60 bearings, and seal it up using the bell-housing to suit your application. And like with the C50, if you drive this on the highway a lot get the C59 5th gear to bring down the RPM a bit.
C59 5-speed (Corolla, Matrix)
The C59 is another very common gearbox, probably the most widely used in the Toyota lineup. There are also several versions of this transaxle in circulation:
1) The 95'-02' Corolla with a 3.7 FD
2) The 03'-08' Corolla/Matrix with a 3.9 FD
3) The 09'-13' Corolla with a 4.3 FD
These transmissions have the worst ratios, and probably for fuel economy reasons. There is also a speculation that the C59 is the strongest of the group, but its likely those claims arent backed by a real motorsport comparison and are just based on the number of units that fail. To make this gearbox shine you would need the latest 4.3 FD, the Cusco LSD, and swap in the C56 4th gear.
C60 6-speed (All 2ZZ-GE cars + Lotus)
The C60 represents the pinnacle of Toyota transaxle design. It has the bigger 40mm output shaft bearing, the sealed 4th, 5th and 6th bearings, bi-metal and coated 3rd gear synchro, a 4.5 FD and 6 perfectly spaced gear ratios. You cant quite grasp how amazing this gearbox is until you drive it, this thing has a way of making a 140hp car feel fast. There are a ton of aftermarked parts for this box as well; from carbon synchros to a full fledged dog-box! The only thing this gearbox needs is the Cusco LSD, and you can run with the K-swap guys.
I hope this guide helps you plan your ideal gearbox, I've started to produce assembly method videos as well! You can always check out my Youtube channel where I've uploaded a ton of race footage showing how some of these builds perform on the street, autocross, and road course.
Here is where I'll list a bunch of the parts I know about for these transmissions, starting with the 5-speed:
1) Mfactory 4.7, 4.9, 5.1 FD (AE92)($600)
2) KAZZ 4.6 FD($1400)
3) KAZZ close ratio gearset($3100)
1) InoKinetic Carbon-lined synchros($350)
2) Jubu Racing 5.0 FD (330ftlb rating)($1900)
3) Jubu Racing/SSC Gear stronger 3-4 gear-set (265ftlb rating)($1200)
4) KAZZ 4.8FD($1300)
5) KAZZ close ratio gear-set($3400)
6) Quaife dog-gear set($6000)
6) Quaife Sequential transmission ($8000)