Found in the Lotus Elise and Exige with 2ZZ and 1ZZ engines as well as Toyota Corolla, Celica, MR2-S and Matrix, the Toyota C-series transmission is known to be a solid performer and is available in many different variations, even with factory limited slip differential in some rare cases. It does have its weak points but we have the solutions.
At stock power levels the C transmissions are pretty durable, even used in drag racing or road racing applications. With some added power though the gears become a weak point. In road race applications, exceeding 250whp pushes the stock 3rd and 4th gear to and past their limit. UPGRADE both to solve this issue. The final drive gears can also be a weak point, but more commonly in FWD applications where wheel hop shock loads the gearbox. Upgrade to urethane engine/transmission mounts to minimize wheel hop. There is no stock-ratio upgrade for the final drive, though we do carry stronger 4.8 and 5.0 final drives which are well suited to road course racing.
Street style clutches transmit the least shock load and vibration. They are the best choice for gear durability regardless of whether you’re driving on the street, drag, or road racing. You only need a puck style clutch if you’re melting street discs.
For turbo street applications the C transmissions tend to hold up fairly well at 300whp, but fail very frequently at 400+ whp. The MWR E153 transmission upgrade is the right solution for high horsepower applications, especially in street driven cars.
The 6-speed (C60, C63, C66) transmissions have 3 support bearings per shaft so they have very few bearing problems. The 5-speed variants have only 2 support bearings on the input shaft and 2 on the output shaft; it’s not uncommon to get some noise (most noticeable cruising in 5th gear) and even a failure of the #2 output shaft bearing. Relatively rare in the MR2-S, but much more common in the Corolla/Matrix/Vibe. If caught early you can simply replace the bearing. Let it fail and the gearbox self destructs and can even lock up. Many people choose to simply upgrade to a 6-speed transmission as a solution for a noisy 5-speed. More gears, better durability. MWR carries a full line of 6-speed transmissions to bolt in to most of the cars we specialize in.
Popping out of gear
Not a common problem but it does happen, especially in 6th gear. The problem is related to the synchros but is rarely just a bad synchro; usually the repair will require replacement of (example for C60 4.5 6-spd):
The stock synchros do ok but do wear out over time. Heavy puck type clutch discs accelerate this wear. The best upgrade available is HERE. If your synchros are badly damaged, grinding badly, you may also need replacement gears, hub rings and shift forks.
If you have a 2000-02 transmission then you have the older style 3rd and 4th gear synchros. During a rebuild you can upgrade to the 03+ style synchros which are a bit better in durability and performance. You also need to upgrade to the 03+ 3rd and 4th gears as well as the later hub ring. For a C60/C64 (C series transmissions that come with the 4.5 final drive, found in Celica GTS and Elise/Exige) you’d need: