Introduction

The Nissan Skyline R33 GT-R holds a special place in automotive history as one of the most capable all-wheel-drive performance cars of its era. Its legendary RB26DETT engine and ATTESA E-TS Pro drivetrain were ahead of their time, delivering remarkable grip and acceleration straight from the factory. However, as owners push power beyond the 400 to 500 wheel-horsepower mark, the stock transmission and drivetrain components begin to show their limits. Clutch slip, gear whine, bearing failures, and even snapped axles become real concerns. Upgrading the drivetrain isn't just about chasing bigger numbers—it's about building a car that can reliably put that power to the ground lap after lap, launch after launch.

In this comprehensive guide, we will break down every major drivetrain component on the R33 GT-R, explain why stock parts fail, and detail the best upgrade pathways. Whether you are building a street monster, a track-day weapon, or a drag-strip contender, these upgrades will ensure your R33 handles the power without breaking.

Understanding the R33 GT-R Drivetrain Architecture

Before selecting parts, it is important to understand how the R33 GT-R's drivetrain works. The RB26DETT engine is longitudinally mounted and drives all four wheels through a five-speed manual transmission (later models used a six-speed Getrag, but the R33 retained the earlier five-speed). Power flows from the transmission into a transfer case, which splits torque between the front and rear axles via a central differential. The rear wheels are driven by a solid axle differential (R200), while the front uses a similar unit mounted in a front subframe.

The stock transmission, known as the FS5R30A, is a robust unit but was designed for around 280 PS from the factory. Clutch packs, synchros, and gear sets become marginal once torque exceeds 500 Nm. The transfer case, while well-engineered, can suffer from chain stretch and bearing wear under sustained high-power use. The driveshaft and axles are another weak point, especially on cars with sticky tires and hard launches.

Understanding these stress points allows you to prioritize upgrades based on your specific power goals and driving style. A car that sees mostly street driving may only need a clutch and differential upgrades, while a dedicated race car will require a complete overhaul of every component. For further background on the original R33 GT-R specifications, refer to Nissan's official heritage page.

Transmission Upgrades

The five-speed manual gearbox is often the first component to cry for mercy when power levels rise. Upgrading the transmission involves more than just swapping the clutch; you must address the gear set, synchros, shift mechanism, and cooling to achieve long-term reliability.

Aftermarket Clutch Kits

Stock clutches are designed for smooth engagement and daily drivability. At power levels above 400 hp, the pressure plate cannot clamp the disc sufficiently, leading to slip. Upgrading to a multi-plate clutch (twin or triple disc) provides much higher torque capacity while still allowing reasonable pedal feel. Organic discs are best for street cars because they offer smoother engagement and longer life, while ceramic or metallic discs are suited for track use where rapid engagement and high heat tolerance are needed. Brands like OS Giken, Exedy, and South Bend Clutch offer proven kits for the R33 GT-R. A lightweight flywheel can also be added to reduce rotational inertia and improve throttle response.

Reinforced Gear Sets

The stock FS5R30A gear set is strong but not indestructible. At 600+ hp, gear teeth can crack or spall under high torque. Upgraded gearsets, often made from EN36 or 300M steel, are available from manufacturers like PPG, Dogbox, and Albins. These sets can handle over 800 hp without failure. Some owners opt for a straight-cut dog engagement gearbox (often called a "dog box") for the ultimate in strength and shift speed, though these are noisy and less street-friendly. For most high-performance builds, a billet gear set matched with a reinforced shift fork and upgraded synchros strikes the best balance.

Short Shifter and Linkage Upgrades

Improving shift feel does not directly increase power handling, but better engagement reduces missed shifts and transmission stress. A short shifter reduces throw length and improves precision. Combined with brass or polyurethane shifter bushings, the shift feel becomes much more direct. For cars with ultra-high power, a sequential shifter conversion is an option, though expensive. Many tuners recommend the C's short shifter or the NISMO short throw kit as reliable upgrades.

Transmission Cooling

Heat is the enemy of transmission longevity. As torque loads increase, so does internal heat from gear meshing and friction. Installing a dedicated transmission oil cooler with a thermostat, along with a larger capacity sump or an oil pump and spray bar for the gear set, can dramatically reduce operating temperatures. A simple radiator-style cooler plumbed into the transmission drain and fill ports is common. For extreme builds, an active cooling system with a fan is recommended.

Upgraded Shift Forks and Synchros

Shift forks can bend under aggressive use, causing missed shifts. Billet steel forks are a direct upgrade that resists flex. Brass or carbon synchros provide better wear resistance and faster engagement. These are typically installed during a gear set upgrade, as the transmission must be removed and disassembled. It is cost-effective to do all internal upgrades at once.

Differential Upgrades

The R33 GT-R uses a combination of a front and rear differential. The rear unit is an R200, and the front is an R180. Both can benefit from upgrades to improve traction and handling.

Limited Slip Differential (LSD) Types

Stock R33 GT-R diffs use a viscous coupling or a mechanical LSD depending on the year. These units are adequate for stock power but can become inconsistent under high load. Upgrading to a clutch-type LSD (such as from NISMO or OS Giken) provides more predictable lockup and better power distribution. For rear applications, a 1.5-way or 2-way LSD is common; 1.5-way offers good traction under acceleration with moderate deceleration characteristics, while 2-way provides maximum lock under both acceleration and braking, best for track use. For the front diff, a smaller LSD unit is available from Kaaz or Cusco. Note that front LSDs can affect steering feel and understeer characteristics.

Gear Ratios

Changing final drive ratios can optimize acceleration for specific tracks or drag racing. A shorter final drive (higher numerically, e.g., 4.111:1 instead of 3.545:1) improves acceleration at the cost of top speed. Many drag racers use 4.4:1 or even 4.6:1 gears. For road courses, a taller ratio may be better to keep the engine in the power band. Keep in mind that changing ratios may require a speedometer recalibration. Ring and pinion sets from companies like Weir Performance or Nissan Motorsports are available.

Differential Bushings and Cradle Bushings

Soft rubber bushings allow the differential to move under load, causing wheel hop and imprecise handling. Upgrading to solid aluminum or polyurethane bushings locks the diff in place and reduces lost motion. This is a relatively cheap and effective upgrade. Also consider subframe and cradle bushings for the rear; these further reduce drivetrain slop.

Differential Cooling

Like the transmission, differentials generate heat. Adding a diff cooler with a small pump and heat exchanger can extend the life of LSD clutches and gears. For street cars, a larger finned aluminum cover (such as the NISMO finned cover) can help dissipate heat without a full cooler setup.

Driveshaft Upgrades

The driveshaft on the R33 GT-R is a steel two-piece unit with a center bearing. At high power, the stock shaft can twist, vibrate, or even snap. Substituting a one-piece aluminum or carbon fiber driveshaft reduces rotational mass and eliminates the center bearing failure point. Furthermore, these shafts are balanced for high RPM operation. A one-piece aluminum shaft from The Driveshaft Shop or DSS is a common upgrade that frees up roughly 5-7 lbs of rotating weight, improving throttle response. Carbon fiber shafts are even lighter and stronger but come at a premium. Whichever material you choose, ensure that the shaft is built specifically for the R33 GT-R to maintain proper length and yoke angles.

Transfer Case Upgrades

The transfer case on the R33 GT-R channels power to the front wheels using a chain drive. Under high torque, the chain can stretch and skip teeth, causing wear. The transfer case output bearings also fatigue over time.

Heavy-Duty Chain and Gears

Replacing the stock chain with a heavy-duty Morse or Hy-Vo chain reduces stretch and improves reliability. Some aftermarket suppliers offer billet sprockets and an upgraded chain tensioner. These upgrades should be done when the transfer case is rebuilt.

Bracing and Mounts

Installing a transfer case brace (similar to a rear diff brace) reinforces the casing and prevents flex under load. Solid or polyurethane transfer case mounts also help maintain alignment of the driveline angles, reducing vibration and wear on the input shaft.

Transfer Case Cooling and Fluid

Using a high-quality synthetic gear oil (75W-90 or 75W-140) designed for limited slip differentials can improve transfer case durability. Some owners also add a small oil cooler for the transfer case, though this is less common than transmission cooling. However, if you are running high-power and extended track sessions, it is a worthwhile addition.

Axles, Hubs, and CV Joints

Axles on the R33 GT-R are another weak point when upgrading to sticky tires and high torque. The rear axles (especially on earlier models) can snap during hard launches. Upgraded chromoly axles from Drive Shaft Shop, GTR Heritage, or York Automotive replace the stock units and are rated to 800+ hp. Some owners also upgrade to stronger CV joints (constant velocity joints) or switch to an aftermarket tripod-style joint for better articulation and strength. On the front, the axles are less stressed but can still benefit from upgraded CV shafts if you are running large front tires or a high-power AWD system. Hubs and wheel studs should also be upgraded to ARP studs to prevent wheel separation under heavy cornering loads.

Mounts and Bushings Throughout the Drivetrain

Replacing all rubber drivetrain mounts with polyurethane or solid mounts reduces flex and improves power delivery. This includes engine mounts, transmission mount, differential bushings, subframe bushings, and even the torque mount (for the RB26). While solid mounts can transmit more noise and vibration, they dramatically sharpen throttle response and reduce wheel hop. For a street car, polyurethane offers a good compromise.

Drivetrain Tuning and ECU Considerations

Upgrading the drivetrain is not just about hardware. Tuning the ECU to manage boost, throttle response, and launch control can reduce shock loading on drivetrain components. Many aftermarket ECUs (like Haltech, Link, or AEM) allow you to set boost-by-gear, torque limiting in first gear, and flat-foot shifting. Proper tuning can save your transmission from unnecessary stress while still making impressive power. Additionally, installing a clutch switch or a neutral safety switch prevents accidental starts in gear. For more detailed tuning information, check out EcuTek's Nissan Skyline support page.

Building a Complete Drivetrain Package

When planning your upgrade path, consider a phased approach. For a 400-500 hp street build, a good clutch, upgraded differential bushings, and a solid shifter may be sufficient. For 500-700 hp, you should add a reinforced gearset, upgraded axles, and a driveshaft. For 700 hp and above, a full dog box, heavy-duty transfer case, and complete bushing replacement are necessary. A total drivetrain rebuild can cost thousands, but it is cheaper than replacing a shattered transmission or differential on the side of the road. Many reputable shops like GTR Heritage specialize in R32-R34 drivetrain upgrades and can provide a complete package tailored to your goals.

Conclusion

The R33 GT-R remains one of the most capable platforms for building a high-horsepower all-wheel-drive monster, but its stock drivetrain was designed for the 1990s, not modern power levels. By systematically upgrading the clutch, gears, differentials, driveshaft, transfer case, axles, and mounts, you can build a car that not only makes big power but also delivers it reliably to all four wheels. Whether you are hitting the drag strip, attacking a road course, or just enjoying spirited drives, a properly upgraded drivetrain will transform the driving experience. Do your research, choose quality parts, and consider working with a specialist who understands these cars. The result is a Skyline that performs as good as it looks—and that is what GT-R ownership is all about.

For further reading, the Skyline Owners Club forums have extensive user experiences with specific drivetrain upgrades, and RHDJapan stocks many of the parts discussed here. Good luck with your build.