That large, flat disc, otherwise known as the flywheel, does more for the engine than you can imagine. The disc doesn't only make a great friction surface for the clutch. It can also smooth out the engine's power strokes. Aside from this balancing act, it also helps get the engine get started and helps keep the engine steady and unscathed even with high-speed vibrations from the crankshaft. This spinning drum isn't just about gear shifting or making the clutch work by transferring mechanical energy from the engine to the clutch plate. It does so much more for the engine and deals with a great amount of stress.
Symptoms of a broken flywheel
Though crafted for a special engine mission and important clutch work, this metal disc also has its vulnerabilities. The disc may crack, the teeth of its ring gear may wear out, or the spinning drum may get contaminated with oil. You'll know that this part has gone bad if you ever experience any of these:
Gear slipping. When the clutch slips more frequently, this may cause undue stress on the spinning drum, as it overheats, weakens, distorts, and cracks the disc. When contaminated with water, grease, or oil, gear slipping might cause damage on the spinning drum. You'll know there's slippage when the pedal feels soft or almost spongy and engagement is delayed after the release.
Clutch drag. This is often brought about by a faulty pilot bearing or bushing in the flywheel or crankshaft. When you shift gears, you might notice some slight grinding. Eventually, this may lead to difficulties starting the vehicle as you shift to first gear. When you change gears, the clutch may stay closer to the engine RPM, as the clutch isn't able to release fully.
Pulsing brake pedal. Exposed to heating and cooling cycles, it's quite normal for the rotating metal disc to be warped a bit. But when you notice a pulsing brake pedal that only gets worse in time, usually experienced with rising and falling engine RPM, then warpage on the disc might be bad.
Clutch chatter. The clutch may fail to engage smoothly and instead skip on the metal disc, which acts as a friction plate or surface. This may be caused by a number of problems in the clutch assembly, but those related to the spinning drum may be the result of damaged dowel pins and grooves in the metal disc.
If you feel or hear some rattling as you step on the clutch or release and experience some difficulties during first engagement or when shifting gears, you may want to check the clutch assembly and the flywheel that serves as the clutch's friction surface. A closer look at the rotating metal disc can reveal cracks, dents, and other signs of damage.
Replacing an old, busted flywheel
When searching for a replacement to the worn-out metal disc, here are some factors that you have to consider:
Size. Know the size of the disc that will fit into your vehicle's engine and clutch assembly. Use the make, type, and year of your vehicle as a guide or just compare the old one to the replacement you'll buy.
Material. Pick the right material for the type of vehicle you're driving. The disc may be made of aluminum, a lightweight material that can provide more horsepower, especially to race vehicles. It may also be crafted out of steel, which is heavier but can generate more torque, which is best for off-road or utility vehicles.
Type. Choose between a single and dual mass system. The single mass design is fit for most vehicles. The only downside here is that this system tends to create more vibrations to the drivetrain. As a result, driving with this flywheel can feel a bit rough. The dual mass design, on the other hand, creates less vibration and puts less stress on the transmission and the drivetrain. The main advantage of using this system is smooth driving. However, this isn't the best option for a modified engine.