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Drivetrain Modification

Enabling your Drivetrain to handle your “tuned” engine


Opening the carbon fiber hood of your ride, you gaze at all those engine mods you made, like the HKS fuel rail, the SARD fuel pressure regulator, the TODA cams and adjustable cam gears, the RC fuel injectors, and all the go-fast engine goodies that just goes on and on. However, come to think of it, can your engine’s drivetrain handle the additional power from all those mods? In most cases, we tend to concentrate all our efforts towards the engine alone and forget the other systems that must also be upgraded. Keep in mind that with newfound engine power comes a more aggressive driving attitude as well as hard launches and higher rpm’s. Now with that kind of abuse, something could get damaged and might give in without you knowing it, like your transmission, or differential. So before you start picking up shattered pieces of your drivetrain on the track or on the street, let’s look at some of the components that could use some upgrading.

High Performance Clutch

The Clutch

Simply put, the clutch acts as the connection point between the engine and the transmission and serves as the main source of power distribution. Now if you subject your stock clutch with high-torque loads and high-rev launches from your “tuned” engine, sooner or later the friction material on the plate, which is there to help the clutch grab the spinning flywheel will get so hot and just glaze over that it will now be unable to latch onto the flywheel, resulting to clutch slippage and lost power. As a solution, there are various aftermarket clutch companies to choose from like Exedy, HKS, and Centerforce, just to name a few that offer performance clutches that are able to withstand high temperatures ranging from a stage one 500-degree street clutch all the way to the stage three 1,200-degree competition clutch depending on your needs. Now before you get any crazy ideas like running a racing clutch in a streetcar, better keep reading. Because as cool as it may sound, the fact is that racing clutches need to be really hot in order for it to engage properly, and the temperatures typically generated by a street car isn’t that high enough, so it would be useless running a racing clutch on the street. Aside from that, due to the stronger clamping force, there is an increased pedal effort, due to the stiffer springs installed on the pressure plate and the disc. Moreover, they do not have as much friction material as compared to street clutches in order to save weight, making everyday start and stop driving a no-no, as they will wear out quickly. Some people can tolerate clutch chatter, heavy pedal effort, higher cost, and extreme modification. But why tolerate unnecessary issues when you do not have to. So choose the right clutch with better friction material than stock that is fit for track use, and yet still remain suitable for everyday driving. Some people can tolerate clutch chatter, or noise, or heavy pedal effort, or shorter clutch life, or higher cost, or extreme modifications tolerate unnecessary

Limited Slip Differential

The Differential and the L.S.D.

Located within the transaxle, the differential allows the rotational speed of your ride’s inner and outer drive axles to differ as needed to go around corners. However, when it is subjected to hard acceleration, only one wheel starts to spin, and there will be no torque delivered to the non-spinning axle, hence the single tire mark you got on the road during your last burnout. Now if you want to maximize your power-to-pavement effectiveness, your diff will need a limited slip differential (LSD). Depending on the make, a limited slip differential can either be composed of small multi-plate clutches, planetary gears, or the viscous type that is made up of fluids, but is said to be less efficient than the former two. The LSD is able to transmit torque in a roughly 50-50 split between the two driving axles. So that when you execute your burnout this time, your car will now leave behind two trails of burnt rubber, and if your car has to go around a corner the clutch plates or the gears disengage for a while so that the axles can turn independently with one another.

LSD Lingo

1-way LSD – The LSD comes into use once the throttle is stepped on.

1.5- way LSD – The LSD comes into use once the throttle is stepped on and when the
car is braking there is a slight LSD effect.

2-way LSD – The LSD comes into use whether the car is accelerating or braking.

Sometimes you will hear these terms used in the business of L.S.D. trading and the racing d

Short throw Shifter

Shorty the Shifter

While it does not have anything to do directly with your Drivetrain, a short-shift kit can definitely improve your transmission’s performance by reducing the amount of arm movement required to make lightning-quick shifts, as well as the time it takes to throw the shift lever between gears. Now this is a simple bolt-on affair utilizing basic tools that almost anyone can do, that won’t cost you an arm and a leg. Short-shift kits are able to minimize the gear throw by changing the mounting points of the levers as compared to a stock lever, so that a smaller movement of the lever is achieved to change gears. A word of advice to the newbies; you have to punch the pedal faster to match the new speed of your hands rowing through the gears.

Lightened Flywheel

To Lighten or not to Lighten?

It is a racer’s mantra to make everything light on his car. However, when speaking about lightened flywheels, there is a bit of hesitation. So let us analyze the process and effect. When one is to subject a rotating mass like a flywheel into a weight reduction, the result would be that it would spin faster, and therefore make the engine feel more responsive. Sounds right, but only to a certain extent. Now why is that? You see, a flywheel stores inertia, which keeps the engine spinning whenever the clutch is disengaged, so that it does not fall too far out of its power band between shifts. However, if one were to put an over lightened flywheel it will not keep up with the engine revs, and you will struggle to get back into the power band every time you up shift. Most tuners make use of this trick in tandem with a lightened crankshaft that have both been balanced, and flitted with a counterweight to maximize the potential of the engine. However if you do decide to install a lightened flywheel do take into consideration that it will NOT give you any more power, so top speed, will remain unchanged. Although it WILL allow more power to reach the wheels under accelerating conditions because less energy is wasted accelerating the engines rotating parts.

FWD Drag Axles

Front Wheel Drive Axles

Now I have seen a fair share of snapped and broken axles as a result of too much shock loads imposed by a much stronger motor than what they used to drive before. Therefore, since it plays an important role into putting power to the pavement, it would be best to check on the condition of your axles, along with the CV joints paying close attention to the trunnion bearings for wear if you plan to strengthen your motor. Now some tuners try to adapt a much beefier axle by using a larger one from a bigger engine of the same make, and if they do not have the same number of splines or a difference in bolt patterns, they just have it, custom machined in order to make everything fit together. However, if you really want he real deal, then there is always the Driveshaft Shop in the States. Using only aircraft-grade chromoly it can’t get any harder than that and their tripod joints for the CV are three times larger in diameter than the factory ones. The shop can custom fabricate a very strong axle, depending on your cars power output, whereby their level one axle is good for up to 225 hp, all the way up to their level 5 axle that is capable of withstanding 600-plus hp.

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