If you're not familiar with the WPC process, I'll describe it based on what I've learned from their website:
WPC treatment is not a coating that can wear off, the process results in a micro-dimple surface that reduces friction and strengthens the product. They "fire" an extremely small media at parts extremely fast, to compact the surface at a microscopic level. These dimples then serve as oil reservoirs that hold oil in place when the equipment is not in use. This process is similar to shot peening, but instead of using beads, the media resembles a fine powder. This results in a surface treatment that increases strength through thermal discharge, sealing up minor surface cracks and tool marks from machining...without a resulting dimension change. The surface becomes condensed with improved density, and this overcomes the issue of brittleness associated with "hardened" parts.
One of the things I was really surprised by was the packaging, individually sealed and branded parts bags! Now I had seen some pictures of this packaging on the internet before, but only for a new set of treated gears. I had no idea they gave every product this special treatment, however, it's completely necessary to protect the gears after treatment from corrosion since they're now bare metal. Make sure you package your gears well when you send them to WPC because they send the finished product back to you within the same materials.
Once you open the packaging, the first thing you'll notice is superior cleanliness. WPC does mention that you need to thoroughly clean the components yourself to remove any possibility of leftover media. After cleaning the parts you also need to apply a layer of lubricant so that no surface corrosion can form. This is really no different than handling untreated parts, any bare metal part will corrode if left unprotected.
I did a lot of research on what commonly fails in the C60 6-speed transmission before finishing up the Cusco LSD install. The last thing I wanted was to put a new differential and bearings in this box, then have to worry about launching or adding power and having a failure. After posting my first few C60 videos the comments started rolling in, and they all had a similar context. Google, YouTube, Facebook....they all yielded the answers I was looking for; 3rd and 4th gear. Most people break third gear in drag racing situations, apparently wheel-hop causes these kinds of breakages. I measured all of the gears in my WPC prep video and found that the third and fourth gears were thinner than all of the other gears. The 5th gear set was 15mm whereas 3rd and 4th were 13mm, so I skipped treating 5th since 1st and 2nd are also 15mm yet never have an issue.
When I was searching the far corners of the internet for every possible C60 failure, I came across a few images of broken output shafts. All of these instances again involved drag racing. I believe the issue is due to the physical size of the pinion teeth since the C60 has the most aggressive final drive ratio of all the C-transmissions. The easiest way to distinguish a 3.9FD from a 4.5 is to simply look at the teeth, the tooth profile in the above image may look identical but did you notice the 4.5 on the right has the bearing race removed? The 3.9 shafts have 8mm of tooth vs the 4.5 shafts only having 5mm(refer back to the first image also).
I chose to only have the known weaknesses of my transmission treated since I'm not wealthy, but you can have all of your components done. To get the 3rd and 4th gearset, and output shaft serviced, with shipping, tax, and insurance it cost me $182. To me, that was a steal for all of the benefits you will gain. WPC advised me beforehand that it would be "about" $500 for all of the gears, both shafts, and the ring gear. Keep in mind though that shipping will be more due to the increased weight.
I don't know anyone personally that has had any gears treated by WPC, nor do I know anyone that has broken a C transmission. Like I mentioned, I wanted to feel at ease that I've done everything possible to ensure this gearbox survives abuse. I was also excited to see the WPC results myself and run my own test. Overall I am extremely happy with the whole experience, customer service, attention to detail, and an awesome end product. Huge thanks to Izumi Ogawa for streamlining the process. You can see my video below:
The DR-Type coilovers from BC Racing use digressive valving, this means they rely on high flow pistons and preloaded shim stacks in order to get high, low speed damping forces(~2 in/sec). The pistons flow enough oil that the shims control the valving profile, and at high shaft speeds oil flow through the piston is not restricted. This provides decent force ramp up from about 20 in/s and higher, but less than linear and progressive valves. "Cornering" happens at ~2 in/sec so the digressive shock will have better feel and control in most road racing applications. Refer to the comparison below:
With the technical points out of the way, lets talk about my experience with these on the Toyota Yaris. When you order a set of Yaris DR-Type coilovers from BC Racing you can get the standard 5K front/ 3K rear spring rates, custom BC rates, or the SWIFT spring upgrade with custom spring rates. The INSTALL for this suspension upgrade is straight-forward and only requires basic set-up for most. We tested the standard spring rates first to see how they perform, then made changes. Check out the DR damper dyno graph below:
On The Street...
On the street these spring rates were perfect. We started with the dampers right in the middle at 16 clicks, but the ride was very harsh. I turned them down to 10 clicks and the ride quality was nearly identical to my previous Tokico damper feel. If you want coilovers just to slam your car and maybe attend an occasional autocross, the BR-Type and standard rates may be more suitable for you
At autocross these rates were not so great. The 5K front was fine, but the 3K rear had us completely maxed out on the dampers to get some rotation. We went to a 5K rear swift spring to try a square setup, and the car starts rotating perfectly around 5 clicks front/16 clicks rear. Then we tried adding a UR BRACE to the rear of the car to be sure we weren't losing spring performance due to chassis flex. There was just a bit more rotation after the brace so we decided to stay with the square 5K spring set-up.
At the track this square setup felt amazeballs, but I turned all of the dampers down to 5 clicks to be sure the car stayed nice and predictable. Even at this low setting the car did great and you could still get some rotation with a little flick of the wheel. I have no doubt a more talented or fearless driver could crank up the damping and toss the car around this course faster than I did.
Why Swift Springs?
When you order a set of coilovers from BC Racing, you will have the choice of; Standard spring rates, Custom BC spring rates, or the Swift spring upgrade. Now I can imagine you are curious like me as to what the difference is between the BC and Swift springs, so I'll drop in a description from the Swift website below:
...So you see, It's about getting the absolute best performance out of your suspension. The Swift springs are extremely light, holding them in comparison to the BC springs will make you wonder how they hold the weight of the car. The evenly spaced coils and linear spring design results in more predictability and control through transitions, unlike the increasing rate of a progressive spring. If you're like me and do an excessive amount of research and planning, you will always have the thought in your head that your leaving time on the course because of that "one last thing". For me it was not having Swift springs or corner balancing, but now we're finally there. For the front you need the 8", 60mm ID. The rear is a 6", 60mm ID.
Do you really need to corner balance?
The answer to this question is based on how you use your vehicle. If your're never going to do any type of racing, then odds are you dont need it. But if youre racing like me and want to ensure the suspension is operation at its absolute best, to squeeze every tenth out of your tires requires a properly balanced car. A drivers weight ballast is placed in the car with the race tires on and fluids at their normal levels, then the spring perches are adjusted to achieve an optimum 50/50 cross weight balance. Suspension geometry, ride heights, and rake are all verified at the same time. Once this procedure is complete, a wheel alignment is performed, resulting in a 100% optimized suspension. I was able to notice the difference right away after the corner balancing, a smoother ride and easier slide recovery being the main benefits.
The main take-away here is that you should consider the intended use and future plans for your vehicle before deciding on a suspension system. I thought I never really "needed" coilovers until I started doing WEIGHT REDUCTION and changing the cars balance, but I'll tell you you...that was a miscalculation. The ability to fine tune the suspension has been one of the most beneficial upgrades to this car, and I'm still impressed to this day. BC Racing Coilovers AND Swift springs....highly recommended. Then when you're ready to get serious, get that corner balancing done.
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)
Thanks to the sales team at Frank Subaru, I was able to test drive the NEW Subaru Ascent today, and it was awesome! The completely new 2.4L turbo engine and re-mapped CVT work together seemlessly to provide suprisingly fast acceleration, and the suspension feels tight and nimble. If you can imagine for a second, the current Subaru Outback and a WRX were mashed into one vehicle with a 3rd row of seats....Yeah its that good. Read more about this from my post on Wheelwell.
I've been told several times by people that suspension braces "just add weight", but almost every time I install one there is some kind of a noticeable change. I don't have many braces, just what I feel are the three essentials: strut tower, front lower, and a rear lower. I also have a 4 point Autopower roll bar, and it's worth mentioning that this acts as a very large brace as well. So let's discuss the things I feel are the purposes of a brace and whether or not this UR brace meets that criteria.
1 - Reinforcing An Actual Weakness
As enthusiasts, we must strive to remain focused and not be tempted into buying every single shiny part we can. The ultimate goal should be to connect suspension pick-up points across large openings like an engine bay or trunk, and always triangulate when possible. Unfortunately for those of us modifying a Yaris, there are limited options. The strut bar is a given because of the engine bay void, and then there is a not so obvious area under the rear of the car. The rear lower brace not only reinforces the recesses of the rear axle beam primary bushings, but it also ties these points together on each side of the car. From the factory Toyota had placed two stamped steel braces here, so we know without a doubt it needs to be supported. Can you imagine the forces being applied to these bushings when cornering over 1G?! Exactly, get this one.
2 - Upgraded Hardware Included
The benefits of adding a brace that transfers suspension loads probably wouldn't last very long if it attaches using Grade 2 fasteners. A good rule of thumb is to meet or exceed the original fastener hardness, and that's exactly what UR does. The original Toyota fasteners are the recessed, mark-less 4T bolts. The 4T's are the lowest on the chart for strength classification but the UR lower brace comes with a set of stainless 18.8 fasteners. That's quite the upgrade, just be sure to put some grease on the threads before installation and torque to 20ftlbs.
3 - Construction And Fitment
Now of course when you purchase a part designed to keep chassis flex to a minimum, you shouldn't be able to bend it with your bare hands. I've seen some no-name strut tower braces that are so flimsy they bend when being leaned on, that's ridiculous. Gladly that's not how UR operates. When I did the 6-speed swap I had my engine supported by a chain that was looped around the strut bar, for 5 weeks! The rear lower bar seems to be just as strong, the welds seem to have made full penetration and the paintwork is exceptional. The fitment is great as well, I'm sure the elongated mounting holes help with that aspect.
4 - Ground Clearance
One of the biggest downfalls of installing under-braces is smashing them on speed bumps. I've ridden in peoples cars that are pretty low, and when going over those Texas-sized speed bumps you feel your teeth chatter from the impact. Not only is this super unpleasant, the next time he had his car on the lift for service all of the braces were smashed up pretty bad. The openings where the bolts are were bent over and covering parts of the bolt and some of the threads in the chassis were pulled back. Good luck removing that.
If you look at the picture above you'll notice that is not the case with the UR rear lower brace. It wraps around the rear of the fuel tank only about 1 inch lower. One could even argue this can provide an amount of protection to the fuel tank, especially since it's composite. I've driven this car over many speed bumps without a single scrape, I've had the car on a Uhaul trailer as well without issue.
I honestly don't have one negative thing to say about Ultra Racing or this brace. I've seen some videos on YouTube mentioning the weld quality or how the elongated holes are a sign of weakness. If a product does what it's intended to, doesnt fail prematurely, looks great, and has a lifetime warranty...how can anyone say its sub-par just based on the price? Exactly.
Again, it's hard for me to provide feedback on a noticeable change in performance because I have a roll bar. However, I'm sure someone without one will feel a increase in chassis rigidity after installing this brace like I did with the roll bar. Check out the install video below!