Drivetrain

In a nutshell, the drivetrain is responsible for making sure the power gets from the engine to your wheels. And yes, it is more complex than that, but like your engine, the drivetrain consists of many components that endure a lot of wear and tear especially if you are making more power that surpasses the factory limits. The main ingredients in your drivetrain include the transmission, the driveshaft that connects the transmission to the rear differential, and of course the axles. Although we don't carry internals such as your gear sets of synchros for your transmission, we carry the parts that wear out and make sure that you are taking advantage of every ounce of power your engine produces, such as the clutch. 

When you start performing modifications that increase boost, horsepower, and torque, you will overpower the holding capacity of your OEM clutch, you will overheat the clutch disc and you will experience clutch slippage. The aftermarket relieves this issue with clutch kits that have heavy-duty pressure plates that are combined with one or more discs made of ceramic materials that have a higher heat tolerance and better holding power. 

The clutch and flywheel function almost like your brakes. The flywheel acts as a disc and the pressure plate will push the clutch disc against the flywheel for a proper disengagement to allow for smooth shifts. If the surface of your flywheel is worn, you will need to replace your flywheel or get it resurfaced, otherwise, this will also cause clutch slippage. 

Regarding your driveshaft, this connects your transmission to your rear differential, and generally, your factory driveshaft is just fine. However, let's discuss why driveshafts twist, break, and how this can lead to destroyed rear differentials. If you are out there recklessly doing AWD launches, especially on heavy aftermarket wheels that have larger tires with a thin sidewall, there is little to no room for the tires to absorb the drivetrain shock. The shock will stay between the transmission and the rear differential, with the driveshaft being the weakest link. If you are making more than 500+ horsepower, you are also at risk of destroying your driveshaft when launching. At the dragstrip, what is the most common ingredient on each fast car? That would be drag slicks. Not only are they a soft compound for grip, but they have a fat sidewall that allows the car to squat when they launch off the line. When you see those slow-motion videos of real drag cars, you will see how the rear tires wrinkle. This is because they are absorbing the drivetrain shock. This is also why you will see really fast STI or Evo models at the drag strip with a smaller wheel setup that will have tall drag slicks and that is to absorb the drivetrain shock and provide a proper squat when launching. Another option to avoid destroying the driveshaft is upgrading to a carbon fiber driveshaft. Carbon Fiber will twist as you launch, and the twisting, and the lightness of the carbon fiber absorbs the shock to transfer the power to the wheels. 

Before the power gets to the wheels, it has to go through the axles first, and if you're making big power, you've got the clutch that can handle the power, you've got the driveshaft that can handle the power, the axles are left to hold the line. Before hard energy gets traveled to the wheels, those axles are responsible for that transfer in power, that rotational mass, and the physics of spinning those wheels to move a 3000+lb object. For vehicles that make good power, breaking axles can be a common problem if you are at the drag strip, or in a driving situation that requires launching. We have Chromoly options brought to you by the Driveshaft Shop that will sustain both the energy and the power. 

 

COOL, BUT I JUST WANT MY CAR TO SHIFT SMOOTHER. 

We can certainly help with that. The factory shifter bushings whether in the shifter linkage or if it's the rear shifter bushing, are made using soft rubber materials. Worn shifter bushings can cause excessive side-to-side, as well as vertical movement. The worn rear shifter bushing can lead to increased movement and vibration. We carry several urethane examples that are longer-lasting and will increase the overall shifter feel. We also have short shifter kits that include bushings to reduce your throw, all while improving the overall shifter feel. 

Now that we have a pretty good roadmap of the drivetrain, let's take a deeper dive into the main drivetrain components and find the right part for your race car, rally car, weekend show car, or daily driver. 

 

CLUTCHES: As mentioned above, clutches are one of the most highly purchased drivetrain components that need to be replaced in your vehicle and the shelf life depends on your power levels and your driving style. The more horsepower and boost you are making, you need a stronger clutch that includes a heavy-duty pressure plate that clamps down on one or multiple discs depending on your power levels. And in this section, you will also find all of the related clutch components to replace if the rest of your clutch parts are in good working order. 

 

SINGLE DISC CLUTCHES: These are highly versatile. Typically when you think of high-horsepower cars making 500+ WHP, you would think that they need a 2 or 3-disc clutch kit. And that is true depending on the clutch manufacturer, however, there are single-disc clutch kits that are capable of supporting 400, 500, and 600 horsepower levels for your Subaru WRX or STI. This is accomplished with a pressure plate with a higher clamping load that is combined with the main ingredient which is the clutch disc design. These clutch discs will have thick friction pads that can disengage the flywheel during high-performance driving conditions. Note that the single-disc clutch kits that are made to support higher horsepower levels might not be the most comfortable clutches to drive in terms of engagement. Aside from these high-horsepower single-disc examples, remember that we have OEM-like clutch kits that support OEM power levels, and we carry several upon several examples that are perfect for those of you making between 300-450 WHP that are very streetable with OEM-like driving manners. 

 

MULTI-DISC CLUTCH KITS: Multi-disc clutch kits have been designed to really support big horsepower levels. You have a Mitsubishi Evo 8 with a forward-facing turbo kit, forged guts, and a moon tune that is waiting in line at the drag strip with an STI with a rotated turbo kit, forged guts, also with a moon tune. More than likely both cars will have a multi-disc clutch kit to support 800+ HP levels. Compared to a single-disc kit, multi-disc clutch kits are separated by floater plates and are available in 2, and sometimes more clutch discs. The purpose of multiple discs is to greatly increase the clamping power to sustain high levels of torque. Multi-disc clutch kits take a little use to while driving, but usually are more streetable when compared to a really aggressive single-disc clutch kit with 4 or 6 friction pads where you really can't slip these clutches, and make for a painful driving experience if you get stuck in traffic. Multi-disc clutch kits will usually include their own flywheel designed with a specific weight to maintain a good balance. We carry a great selection by some of the most familiar brands in the clutch industry that include the likes of ACT, Exedy, as well as South Bend, and XClutch. 

 

FLYWHEELS: Without a good flywheel your clutch cannot work properly. In Layman's terms, your flywheel is like a brake disc and your clutch disc is like a brake pad. What would cause your brakes not to work? There are a few instances so let's discuss scenarios that would relate to a function of a flywheel. Brake fade happens when your pads get so hot that it glazes over the disc preventing friction. And the other reason is that your brake pad is simply gone and can't stop the car. Same function as a flywheel. Your flywheel can either be glazed with clutch disc debris preventing a proper clutch engagement, or your flywheel could simply be worn. Depending on how worn your flywheel is, you could get it resurfaced at a good machine shop, or you can just get a replacement. We have many options. We have OEM-like flywheels that have the same weight and rotational mass. These will be the most comfortable to drive in as the heavy flywheel absorbs a lot of the clutch shock, and it is easier to slip the disc when driving for everyday purposes. Lightweight flywheels add more horsepower and torque. This is achieved because the lighter the flywheel, the less rotational mass at the crankshaft. This will allow the engine to rev faster which will free more power. Depending on what lightweight flywheel you choose, sometimes a tune is required because otherwise, your ECU won't recognize the extra power output, and you could be hitting more boost and need the right timing and fuel tables to compensate, or you need to readjust the boost. Also, note that lightweight flywheels will create more clutch chatter noises which is normal when compared to a flywheel with OEM-like weight. 

 

CLUTCH REPLACEMENT PARTS: If you're guilty of trying to do an AWD burnout but you smoked your clutch instead, you're in the right spot. In this section, you're going to find all of the right clutch components that you can purchase separately if the rest of your clutch components are in good working order. You can find clutch discs, flywheel bolts, clutch forks, and that retainer ring on the Exedy clutch that likes to pop off every time your input shaft makes contact. You can also find major components such as a pressure plate and throw-out bearing. This is also a great way to help you save money so that you don't have to purchase an entirely new clutch kit. 

 

CLUTCH LINES: The examples we carry all feature braided stainless construction. Why is this important? Because the OEM clutch line can expand over time, potentially creating little air pockets that can cause premature wear, while affecting your overall clutch efficiency. And if they break then you will have no function of your clutch whatsoever. Braided stainless clutch lines do not expand under pressure, giving you a direct response from the pedal to the slave cylinder. This promotes a better clutch response, with better clutch wear and efficiency, and the installation is fairly simple for the available makes and models. 

 

 

AXLES AND DRIVESHAFTS: The driveshaft and your axles will propel your wheels. The factory units in some of our favorite sport compacts such as the WRX, STI, or Evo are pretty strong in stock form and can sustain moderate upgrades. However, if you continuously launch your car at the drag strip, or off the line at your local autocross or rally event, or if you are making substantial amounts of horsepower, something will give eventually. For example, if you have an STI and you have aftermarket 18-inch wheels on street tires with a thin sidewall, and you try to launch hard off the line. The tires will be the softest point to absorb the drivetrain shock, and won't have much room to absorb the power. If you have stiff suspension, the shock will backfire back through the axles and driveshaft, and things will twist. Because of these reasons, we carry much stronger options. We have 1-piece driveshafts made from carbon fiber or aluminum. The carbon fiber units are preferred to sustain launches as they will twist during a launch thus, absorbing the shock. Aluminum units are ideal for those of you who are making big power and can endure continuous high-performance driving conditions. And if you have an upgraded driveshaft, your factory axles will be the next units to address. Even on high-horsepower drag builds, owners will typically have spare units to replace because broken axles are common with launching. If you are making a good amount of power, make sure you upgrade those axles. 

 

DRIVE AXLES: Here, you will find replacement axles and axle parts from Subaru OEM, to upgraded units from the famous Driveshaft Shop. We have seen those wild YouTube videos of twin-turbo Lamborghinis trapping 200+ in half-mile events and they have one thing in common, Driveshaft Shop axles. The Driveshaft Shop axles are made using the strongest of materials to sustain high levels of horsepower and torque to survive launches on all surfaces whether they be a prepped drag strip, gravel at the rally event, or concrete at your local autocross event. If you are making big horsepower levels, these are something that you need to consider as snapping an axle during acceleration will certainly test your driving skills. Be safe, and be reliable with a quality replacement. 

 

DRIVESHAFTS AND DRIVELINES: One-piece replacements are available and brought to you by Driveshaft Shop, PST, and there are components available by Torque Solution. The one-piece driveshafts are premium-balanced and have been designed to sustain high levels of horsepower in conditions where you need to launch your vehicle. Your factory driveshaft will typically twist at the rear differential side, and the OEM unit can only handle so much torque and driveshaft shop. If you are building a high-powered street car or a purpose-built race car, drag car, or rally car, an upgraded driveshaft is a common and mandatory upgrade to remain reliable, and they will also improve the overall reliability of your transmission as they will take the brunt of your drivetrain shock. 

 

 

DIFFERENTIALS: There is a lot of sorcery and mathematics behind the explanation of differentials. However, they are designed to maximize the traction and torque transfer to your rear wheels. Traditionally, a rear limited-slip differential can be known for having both rear wheels spin at the same time when leaving the line. Back in school if you had that one buddy that tried to do a burnout in his V6 mustang and only one tire spun creating that one-tire-fire, it did not have an LSD. But beyond that, there are 1.5-way differentials and 2-way differentials. 1.5-way units engage both wheels during acceleration while partially on deceleration, while 2-way units will engage while accelerating and decelerating. Both units will increase traction and acceleration and are common among those who are competitive in autocross. 1.5-way units will lock one wheel during a high-speed corner during deceleration which will also transfer the torque to the same wheel making the car easier to carry speed on the corner with smooth acceleration as you exit. 2-way units keep the rear wheels engaged the entire time through high-speed cornering, and will help you blast out of the apex. Aside from differentials, you will find covers here as well. All of the components are brought to you by the most established brands in the industry to make for an excellent upgrade that will lower those lap times at your local track while adding more driving excitement for spirited canyon runs. 

 

LIMITED SLIP DIFFERENTIALS: You can choose from 1.5-way to 2-way limited slip differentials to suit your driving style and your driving needs. We carry several examples from the likes of Tomei, as well as Cusco, both examples are strong units that are more robust when compared to the OEM units. The 1.5-way examples engage both wheels during acceleration while partially on deceleration, while 2-way units will engage while accelerating and decelerating. Both examples will increase the traction and the acceleration that will make a noticeable difference while competing in your weekend track day, drift, or autocross event. 

 

DIFFERENTIAL COVERS: Aside from being aesthetically pleasing, these do have an important purpose. The differential cover examples that we offer are brought to you by some of the most established brands in the automotive aftermarket that include Cusco and Greddy. These differential covers are slightly larger to have a higher fluid capacity, and they have been designed with cooling fins, both features will increase the overall cooling efficiency of your rear differential while prolonging the differential life and performance. These covers will also have extra provisions for you to add a differential oil cooler for those with a purpose-built race car or drift car and need to keep the rear differential oil temps under control. 

 

LSD OIL, ADDITIVES, AND ACCESSORIES: We have limited-slip differential oils in a variety of viscosities to allow you to choose the proper weight. And we also have friction modifiers to provide your rear differential with extra protection. Additionally, Mooresport offers DCCS rebuild kits for STI owners that need to refresh their LSD. All fluids and items are brought to you by companies that are well-established and know exactly what it takes to properly service your rear differential. 

 

 

DRIVETRAIN MOUNTS AND BUSHINGS: If your transmission mount is worn, or if your failure-prone OEM pitch stop finally broke, and if any of your engine mounts are on the way out, this will cause excessive drivetrain movement, especially under load as the engine produces torque. The main purpose of your mounts and bushings is to keep both your engine and drivetrain secured and locked down so that all of the energy gets to the wheels where it belongs. Otherwise, you will only make your problem worse if you don't address the issue promptly. the good news is that we have several fine examples of quality replacements made using long-lasting urethane materials. These will prevent excessive movement and knocking noises while improving the overall engine and drivetrain feel, feedback, and performance. 

 

PITCH STOP MOUNTS: The pitch stop connects from the top of the transmission on most Subaru models, to a support mounted to the firewall. This helps support the transmission and prevents movement when the engine is under load. Under load and during acceleration the engine naturally will want to raise as torque is applied. The pitch stop mount prevents this movement so that the energy will effectively travel through the drivetrain and to the wheels. The problem is that OEM pitch stop mounts are prone to breaking, as they can only handle so much stress. We carry a massive selection of quality replacements that combine robust steel construction, and many examples will also include durable urethane bushings. These examples will provide excellent support to the transmission with robust craftsmanship that you can rely on. 

 

ENGINE MOUNTS: Your engine mounts are items that wear over time, and will only get worse as you perform modifications that increase the power and torque as more power creates more movement. You want to make sure all of your engine mounts and all of your drivetrain mounts are in good condition so that you can transfer that power and energy to the wheels, rather than getting lost on weak mounts. Depending on what kind of power you are making, or if you have a track-dedicated race car, we have different variations of engine mounts to suit your needs. There are a variety of engine mounts that have urethane construction, and they will come in different stiffness levels. The stiffer the mount, the stronger the support to make sure that energy gets to the wheels while keeping engine movement down to a minimum. Now the stiffer the engine mount, the more noise, vibration, and harshness you will experience (NVH). So if you have a high tolerance for race car noises you will be fine with a stiff engine mount. And for those with race cars, there are solid mount options made of billet aluminum that will offer the best support, but with all of the noises in the cabin of your vehicle. However, if you drive a WRX, Evo, or MazdaSpeed 3 with bolt-ons, and just want a decent replacement mount you will be happy with an engine mount with a 90 durometer urethane rating. We have several pages worth of engine mounts to suit your power levels and driving styles. 

 

SUBFRAME BUSHINGS: Your subframe has multiple mounting points to the chassis, as well as mounting provisions for the differential as well as other suspension components. This means also means that your subframe either front or rear will experience a lot of weight and a lot of movement. We carry a great selection of subframe bushings, as well as subframe inserts to secure your subframe and prevent excessive movement and excessive noise. The examples we carry feature long-lasting urethane construction which will be your best option for those of you with street cars and who want something more comfortable. And we have solid options for those of you with vehicles making substantial amounts of power and torque, or for those with track-dedicated race cars. All of the examples that we carry are also brought to you by the most familiar brands in the industry to meet or exceed OEM build quality. 

 

TRANSMISSION AND DIFFERENTIAL BUSHINGS: Just like everything else in your drivetrain, your transmission and differential will experience excessive amounts of movement, torque, and energy. Your engine transfers the power to the drivetrain that has the job of sending that energy to your differential to spin the wheels. If any of your bushings wear out or fail, the power, the energy, and the torque will cause excessive noise and movement in that bushing location. But like all OEM bushings, these will become soft and weak over time and need to be replaced. And stronger bushings that support your transmission and your rear differential mean that the power and energy stay with the wheels where it belongs rather than causing a drum solo in your vehicle while driving down the road. You can choose from several options that include transmission cross-member bushings, driveshaft carrier bushings, differential bushings, differential cross-member bushings, differential lockdowns, differential to subframe bushings, and everything else in between. That being said, it is clear that the differential needs a lot of support as it is a heavy metal pumpkin that would otherwise cause quite a racket without proper bushings. All of the options we carry are brought to you by the establishments you're familiar with such as COBB Tuning, Cusco, Beatrush, Kartboy, and PERRIN just to name a few. Keep the power to the ground, and make sure all of your bushings are up to date and up to spec. 

 

TRANSMISSION MOUNTS: Now regarding Subarus, the transmission mount features a steel body but with rubber that absorbs the energy and road vibration. These will wear over time and mileage and luckily we carry many fine examples. You can choose from OEM units to replacements with long-lasting urethane bushings which will be your best option. The options with urethane bushings are much stronger with minimal cabin noise and vibration. And then there are solid units for those of you with track-dedicated race cars and these will produce the most vibration and noise, but are certainly ideal for those with substantial amounts of power. Additionally, transmission mounts will help promote and maintain a smooth shifting operation to improve the overall drivability on the street or on the track. 

 

 

SHIFTERS AND BUSHINGS:  The components available in this section are some of the most popular drivetrain upgrades as the shifter ultimately connects the driver to the transmission. The bushings in the shifter will become weak over time and mileage and will create excessive shifter slop. And from the factory, you may think that the shifter throw is too long, and we have short shifter kits to relieve that issue. New bushings will provide a tighter and more precision shifter feeling and when combined with a short shifter, renews your overall driving experience. All of the components in this section are relatively affordable and are simple to install to make for a great weekend project. 

 

SHIFTER BUSHINGS: Available for many makes and models, but especially available for our specialty which is Subarus. The factory bushings are made using soft rubber materials that will become weak and your shifter will develop more shifter slop and excessive play. You can solve this issue with a new set of shifter bushings to eliminate the side-to-side movement, and you can get the rear shifter bushing to further eliminate any excessive shift play. We also carry several new shifter bushing options for other makes and models other than Subaru that include but are not limited to the Ford Focus ST/RS models, the Mitsubishi Evo models, as well as Nissan and Hyundai models with a manual transmission. Several great companies offer options from the likes of Kartboy, Boomba Racing, COBB Tuning, PERRIN, Torque Solution, and Faction Fab among others. Many great options to allow you to renew that crisp and precision shifter feeling. 

 

SHORT THROW SHIFTERS: Another popular drivetrain modification designed to shorten the factory shifter throw in your vehicle. We carry several different options in several different design variations for several different makes and models. We have units that can reduce the throw in the Subaru WRX by 30%, and we have examples from COBB Tuning that can shorten the shifter throw while shortening the shifter height. We have adjustable options You can choose from a variety of short shifter levers, shifter plates, and shifter stops, and there are shifter assemblies available that will provide you with a shorter throw to improve the overall driving experience on the street while lowering the lap times at your weekend track event. 

 

SHIFTER AND BUSHING COMBOS: This is the best way to improve the shifting feel and dynamic of your vehicle. You get new bushings to eliminate any shifter slop, and you get the short shifter to reduce the shifter throws. This is a great way to renew and improve the overall shifting function which greatly improves the driving experience for the street or the track, and the installation is fairly simple. Companies that include the likes of Kartboy, COBB Tuning, and Torque Solution. This is also one of the more rewarding drivetrain modifications that provide crisp and precision shifts with little effort that will help lower those lap times at the track while dealing with daily traffic a little easier. If you have a spare weekend with some simple tools, this will make a great project that is very rewarding to improve the driving dynamics of your vehicle. 

 

 

DRIVETRAIN PACKAGE DEALS: What an excellent way to improve the driving experience of your Subaru by completely overhauling and improving the shifting function of your Subaru. Now the majority of the kits in this section focus on improving the shifting mechanism by removing any excessive shifter play while shortening the shifter throw, but there are also packages that include new engine and transmission mounts to support and secure your engine and drivetrain. COBB Tuning has staged drivetrain packages that include the main ingredients to restore and renew your shifter feel. These will include new shifter bushings, rear shifter bushing, and a short throw shifter with a new reverse lockout. And many of the COBB kits will include a new shift knob to complete the package. As these cars get older with more mileage the OEM bushings will become weak which creates a sloppy shift feeling, it can be difficult to find certain gears while driving, and it will only get worse if not addressed. These kits will include all of the necessary bushings to eliminate excessive shifter play and are combined with a quality short shifter that will help lower lap times at your weekend track event, or will make everyday driving much more enjoyable. 

 

So many high-performance options to choose from. But more importantly, your engine and drivetrain need to be secured. It is all about getting the power and the energy to the ground. If your engine mounts are weak you will have excessive engine lifting or movement under load. This will also cause excessive transmission movement. If your transmission is experiencing excessive movement due to weak mounts, this means your driveshaft could rotate out of balance. All of the bushings in the front and rear subframes, your rear differential mount bushings - all of these components must be in good working condition to have a solid driving vehicle. We have all of the options to further upgrade and enhance your drivetrain. And we have all of the right clutch choices to handle current and future upgrades. All of the components are built for a track-dedicated race car or rally car that can be used in your daily driver, weekend show car, or even your overlander.