A proper McLaren transaxle upgrade addresses far more than just the clutch. The 7-speed Graziano-sourced dual-clutch transaxle, often referred to as the SSG (Seamless Shift Gearbox), is one of the few components that ties together nearly the entire modern McLaren story.
It is there in the everyday Sports and Super Series cars, in the hybrid-hypercar P1, in the road-legal Senna, and in the ultra-exclusive likes of the Speedtail and Sabre. McLaren even leans on a version of it in the track-only GTR specials that sit above their road-going siblings, and it shows up just as readily in the handful of ultra-limited runs the brand has produced along the way.
Whatever the badge, it is a compact, well-engineered unit that integrates the gearbox and differential into a single housing, but like any factory component, it was designed around the factory power figures of whichever model it is bolted into.
Once an engine is putting down meaningfully more torque than McLaren originally calibrated for, the transaxle becomes the next link in the chain that needs attention, not just the engine itself. A real transaxle upgrade is not a single part, it is a full system covering the clutch, differential, electronics, axles, and supporting hardware all working together.
Why the Stock Transaxle Reaches Its Limit
Before getting into what a McLaren dual-clutch gearbox upgrade actually involves, it helps to understand why the factory unit runs out of headroom in the first place.
The factory clutch packs and differential inside the Graziano unit are sized with a specific torque ceiling in mind. As power increases, whether through ECU tuning, supporting hardware, or a full engine build , that ceiling gets closer with every gain.
The most common symptom is clutch slip: the packs simply cannot hold the additional torque cleanly, which shows up as inconsistent power delivery, excess heat, and accelerated wear over time.
The factory differential has its own limits too. It is tuned for predictable, comfortable street manners rather than aggressive lockup, so a high-power car can end up putting more torque to one wheel than the other under hard acceleration or through a corner, rather than distributing it evenly to the tarmac.
Dodson Motorsport Clutch Upgrades
To address the clutch side of that equation, we use Dodson Motorsport clutch upgrades. Dodson has built a strong reputation in dual-clutch transmission upgrades across multiple high-performance platforms, and their clutch packs are built with friction material and clamping characteristics designed to handle substantially more torque than the factory units before slip becomes an issue.
For a tuned McLaren, that translates directly into more consistent, repeatable power delivery, the engine's added output actually reaches the wheels instead of being absorbed by clutch slip and heat.
Drexler Differentials
On the differential side, we pair that clutch upgrade with a Drexler differential as the core of our McLaren differential upgrade. Drexler is well known in motorsport circles for plate-type limited-slip differentials that offer more aggressive, predictable lockup characteristics than a factory open or mild-LSD setup.
In practice, that means better traction out of corners and under hard launches, with torque distributed more evenly between the rear wheels rather than allowing the inside wheel to spin freely under load.
For a car that is already making more power than stock, that improved traction is often what actually turns the added horsepower into faster, more consistent acceleration rather than wheelspin.
TCU and CCU Tuning for the McLaren Transaxle
New clutch and differential hardware only delivers its full benefit if the electronics controlling them are recalibrated to match.
The TCU governs shift logic and timing, while the CCU manages how the clutch engages and disengages, and both are tuned at the factory around the stock clutch's exact engagement characteristics.
Drop in a Dodson clutch with a different bite point and clamping behavior without adjusting that calibration, and the result is a transaxle that is mechanically capable of more but does not actually shift or engage the way the new hardware allows.
We treat TCU and CCU calibration as a required part of any transaxle build, not an optional add-on, so the upgraded clutch and differential behave the way they are designed to from the first shift.
We have covered the broader case for TCU and CCU tuning in more depth in an earlier post , if you want to dig further into how those control units work.
300M Rear Axle Set
Once the clutch and differential can hold and distribute more torque, that torque has to get to the wheels through the rear axles, and the factory axles are sized around the same stock power ceiling as everything else in the transaxle.
As part of our build program, we use a 300M rear axle set in place of the factory units. 300M is an aerospace and motorsport-grade alloy steel prized for its exceptional strength-to-weight ratio and fatigue resistance, which is why it shows up in landing gear and high-load racing components where repeated, high-torque cycling would fatigue a standard steel axle over time.
On a tuned McLaren, that translates to axles that can reliably carry the additional torque the clutch and differential are now capable of putting down, without becoming the next weak point in the drivetrain.
Our In-House Billet Covers and Shift Forks
Upgrading the clutch, differential, and axles addresses torque capacity and traction, but sustained hard use, repeated launches, aggressive shifting, extended track sessions, puts stress on parts of the transaxle that are easy to overlook. That is why we engineered our own supporting components specifically for this application.
Our 6061-AL billet differential cover and 6061-AL billet gearbox cover replace the factory cast covers with parts designed for rigidity and heat management rather than cost and weight alone.
Billet aluminum holds its shape under load far more consistently than a cast cover, which matters as clamping forces and fluid temperatures climb with an upgraded clutch and differential in the mix.
Better heat dissipation also means more stable fluid temperatures during back-to-back hard runs, which protects everything else inside the housing.
The shift forks are a smaller component that rarely gets attention until it fails. Increased clamping force from an upgraded clutch, combined with repeated aggressive or launch-control shifting, puts more stress on the forks than McLaren ever designed the factory parts to handle.
Our shift forks are machined from 4041 steel alloy specifically to hold up to that increased load without flexing or wearing prematurely, because a shift fork that wears out of spec leads to notchy, inconsistent gear engagement no matter how well the rest of the transaxle has been built.
Why It Has to Be Treated as a System
None of these upgrades work in isolation. A stronger clutch pack without a matching differential just moves the weak point to the rear wheels. A differential capable of handling more torque without axles built to match just moves that weak point further down the drivetrain.
And mechanical upgrades without a matching TCU and CCU calibration leave performance on the table that the hardware is already capable of delivering.
We have designed, engineered, and tested each of these components, clutch, differential, electronics, axles, and covers, specifically to work together, so that a transaxle upgrade actually holds up to the power level it is built to support rather than introducing a new bottleneck somewhere else in the drivetrain.
Build the Transaxle Around Your Power Goals
If your build is approaching the limits of what a stock transaxle can reliably handle, our team can walk you through which combination of these upgrades makes sense for your specific power goals and how you actually drive the car.
This transaxle program is also built directly into our complete powertrain builds, you can see the full component breakdown as part of our McLaren Performance Packages .