Why is the X SHIFT sequential gearbox the best choice for the Toyota GR Yaris/Corolla?

Sequential gearboxes for GR motorsport divison

The GR motorsport division cars are becoming a phenomenon and highly popular sports cars, which is something we wanted to be a part of. But why is the X SHIFT sequential gearbox the obvious and perfect choice for your GR Yaris and GR Corolla race car? Why should you choose our gearbox over the competition?

In this technical article, you'll learn all the essential information, and we'll also clear up some half-truths and myths spread by other manufacturers that you may have come across.

A COMPLETELY NEW GEARBOX CONCEPT

The GR Yaris project was built from the ground up as a completely new project without compromise. The new three-shaft concept allowed the design of up to a seven-speed sequential gearbox while maintaining compact dimensions and high torque capacity. The state-of-the-art shifting system features precise shifting precision and the dual-locking system allows fast shifts without any clearances on the gear lever. All of this separates us from our competitors, who often use older gearbox concepts that are merely modified to fit GR Yaris/Corolla cars.

CAST GEARBOX CASINGS

Die-cast casings have been a standard with us for over 10 years, and in that time the casting process and the material chosen have been carefully fine-tuned. All casted casings are X-rayed at to avoid hidden defects. Before production of the cast versions, the test pieces underwent a strength analysis to check the deformation of the casting in the most stressed areas of the gearbox and the associated transfer case. The casing achieves a tensile strength of up to 365 MPa, which can be proven by tensile test reports. For the performance of the GR Yaris/Corolla three-cylinder engines, this is more than sufficient strength.

Die-cast casings are common in the world of racing gearboxes and are used by many of the world's leading manufacturers. They indicate that the packaging is properly designed and prove that gearbox production is in higher volumes. Larger billet casings are typically used only in prototype production or for smaller parts (such as the rear case cover on our GR Yaris gearbox) or generally in small batch production.

You can read more about this topic in our separate article HERE. Our cast packages are used in race cars with torque exceeding 1200 Nm (e.g. Mitsubishi EVO drag specials) and to date, there has been no problem with the strength or cracking of our cast packages.

Compatibility of clutch kits

WIDE COMPATIBILITY OF CLUTCH KITS

All racing clutches currently on the market fit our gearbox. Both the OEM dual-mass clutch and a variety of single-mass racing clutches in single, twin, and triple plate configurations can be used. The design of the gearbox was done in conjunction with leading Japanese clutch manufacturer Ogura, whose twin-lobe clutch retains its compact dimensions and features spring-loaded torsional damping, making it one of the best and strongest clutch versions on the market today.

Examples of compatible clutches:

• Ogura clutches – 559DB (twin plate, 240 mm)
• Xtreme – stage 1 (single plate, 240 mm), stage 2 (twin plate, 240 mm), stage 3 (twin plate, 184 mm)
• ATS Japan – single, twin and triple plate options in configuration metal/carbon
• ItalianRP – single plate
• Exedy Single sports UF-EVO – single plate
• Pumaspeed Cometition Clutch – single plate
• NPC Performance clutches – single plate

CLUTCH BEARINGS

The clutch can be operated by a classic OEM hydraulic "push" bearing, its position is identical to that of the original gearbox. As a possible upgrade, we offer the possibility of fitting the gearbox with a racing bearing from the "CP 6859" family from the manufacturer AP RACING, for which the mounting is already prepared in every gearbox version. For these cases, there is also a "connection channel" inside the bellhousing section, into which the hoses from the racing bearing can be connected, while the outlet from this bridge is located outside the gearbox and the supply hose from the clutch cylinder + bleeder valve can be conveniently connected here. Of course, this "channel" can also be used to connect the clutch hose to the OEM bearing.

Strong dogrings

HIGH DURABILITY AND STRENGTH OF INTERNAL COMPONENTS

Based on proven design methods for the strongest sequential gearboxes on the market - Subaru +PLUS and Mitsubishi EVO SHD, we were able to develop similarly strong gears for the Toyota GR Yaris/Corolla. Using KISSsoft software and years of design experience, gears with optimized tooth geometry were calculated to withstand up to 1400Nm of engine torque, far beyond the contemporary maximum power output of the three-cylinder G16E engines! The optimized geometry allowed the width of the gears (and also the weight) to be reduced to allow the use of strong dog ring system, which are usually the weakest and most stressed components of the gearbox. Compared to our competitors, we have much more massive dog rings with undercut dogs, while their lifetime is at least twice as long, and they can last several racing seasons if the ignition disconnection is set correctly, as proven by customer reviews not only from the ongoing GR Yaris Cup competitions, but also from other customer’s racing applications around the world. Combined with strong forks and a strong shifting barrel, this is a very robust gearbox suitable for any application: Rally, circuit, sprint, hillclimb and street/roll racing.

THE PRESENCE OF AN OIL PUMP

The oil pump fitted in the basic configuration is an additional benefit for increased reliability and extends the life of “sliding” components such as bearings, inner bushings, forks and more. It also ensures that the oil is continuously circulated to the outermost parts of the gearbox (e.g. the gearshift parts), which are not optimally lubricated in gearboxes without an oil pump. It also allows the oil cooler to be inserted into the oil circuit, which is important for maintaining the oil temperature on optimal level, e.g. during endurance racing.

UPGRADING ANOTHER PART OF THE DRIVETRAIN

In addition, the gearbox allows the oil circuit to be extended to lubricate a very exposed part of the drivetrain - the front transfer case. This transfer case has a separate oil fill from the factory, which has proven to be inadequate in demanding races and often results in exceeding optimum oil temperatures and insufficient lubrication of the hypoid gear, which by design has increased lubrication requirements. Our unique system allows this case to be linked to the gearbox and the oil pump ensures that the oil is constantly circulating in both units. In addition, we also offer the unique XSHIFT SHD hypoid gear with reinforced tooths, which dramatically increases reliability as it is designed for much higher performance. Combined with the common transfer case lubrication, this is a significant upgrade to the transfer case and is further proof that we are constantly innovating and developing products and accessories for the gearboxes our customers purchase from us.

PLUG & PLAY INSTALLATION

The gearbox is almost tailor made for the car and is a complete replacement with an absolute minimum of OEM parts. The gearbox fits exactly over the engine mounting holes and is in the same position as the original box (it is even narrower on the left side). The driveshafts are completely identical to the OEM position, as the gearbox has the same driveshaft and differential output spacing. Competitors based on older gearbox concepts often have a few mm different axial distance between the drive shaft and the differential output, which can cause higher stress on the axle-shaft’s joints and also poorer handling.

RACE & STREET PACKAGES

In addition to plug & play gearbox mounting, we offer many combinations of other accessories. The racing set includes only the racing lever and the base with the option of shifting with solid shift rod. The street set, on the other hand, includes shifting bowden and base that fits OEM tunnel points and is the best solution to keep the interior as original as possible with minimal modifications. You can also choose from two types of levers - a sportier aluminum design or a stylish carbon design. Both can be combined, or fitted separately with the excellent pneumatic paddle shift system that we worked with MME to develop, a leader in this technology. With the option of fitting it to an OEM steering wheel, this is a high-level system that is hard to find from other manufacturers. Of course, the LED indicator with automatic brightness dimming and the universal wiring for the programmable ECU are also on offer.

CUSTOMER SUPPORT and FUTURE

Our goal is always the most satisfied customer, whom we always try to meet as much as possible. We can offer you maximum technical support and experience gained from active testing, development and various competitions in which we actively involved. We also have our own service facilities where we carry out preventive maintenance as well as complete overhauls and reassembly. During each year we also appear at various events and exhibitions where we can be found. You can find all the latest information on our website.

And if you have any doubts, technical or otherwise, please do not hesitate to contact us by phone or email. It is also possible to make an appointment to personally visit our R&D and production facilities and discuss all the possibilities we are able to offer you. We have many new products in the pipeline for the future on other cars (not only) of Japanese production and we are also expanding our administrative and production facilities to meet the increasing demands and needs of our loyal and new customers.  

X Shift Gearboxes Team