Lightened Flywheel Motronic BMW E28 E30 E34 325i 520i Z1 M20 Engine steel light

The original screws can be reused.

Basically, with our Epytec flywheels, the original clutch including pressure plate can continue to be used. Alternatively, sports or performance clutches can also be used, provided they correspond in shape, diameter, and toothing to the original clutch.

Please clarify with the respective clutch manufacturer before purchasing whether the clutch is identical to the series clutch. If this is the case, it fits 100% with our flywheels.

In many cases, we can also directly offer the suitable components. This means that, depending on the application, we can recommend and deliver a suitable clutch disc as well as a corresponding pressure plate that are optimally matched to our flywheels. Just get in touch with us — we are happy to advise you and put together a suitable solution.

Important Note on the Use of Single-Mass Flywheels

Many vehicles are equipped with a dual-mass flywheel as standard, which actively dampens engine vibrations. If a single-mass flywheel is used instead in combination with a standard clutch, unwanted side effects may occur, as the standard clutch is not designed for this lack of damping.

This can lead to the following problems:

• Jerking and vibrations, especially at idle or low speeds

• Unsteady starting behavior

• Increased stress on the clutch and transmission

• Accelerated wear of the clutch disc

• Partial noise formation, e.g. transmission rattle

Therefore, for the use of a single-mass flywheel, we generally recommend a clutch disc that is matched to it with reinforced torsion springs and a suitable pressure plate. Only in this way can the missing damping of the standard dual-mass flywheel be sensibly replaced and a smooth and durable operation be ensured.

The flywheel is made of 16MnCr (Chromium Molybdenum) steel, therefore it has a density of 7.76 in kg/dm³

No, we can only sell the flywheels as a complete set.

Yes – if the starter is still the old one, we recommend replacing it directly when converting to a single-mass flywheel (SMF).

The SMF slightly changes the vibration and starting behavior. As a result, the starter may be mechanically more stressed during starting than before. A fresh starter ensures reliable starting processes and significantly reduces the risk of wear, noise, or starting problems.

Moreover, the starter is already easily accessible during the flywheel change – the additional effort is usually small, but the benefit is great.

In short: If the starter has not been replaced yet, it is best to proactively replace it during the SMF conversion.

Yes – a new clutch should be broken in. We recommend a break-in period of several hundred kilometers after installation, typically around 500 km (for some setups, even up to 1,000 km). During this time, the clutch lining optimally adapts to the flywheel and pressure plate, manufacturing and handling residues are "removed," and a clean contact pattern is formed. This ensures optimal functionality and durability later on.

Important: If the clutch is overloaded or "abused" during the first kilometers, the lining can overheat and get damaged (e.g., glazing/warping). Such damages are generally not covered by warranty because they result from improper use.

How to properly break in your new clutch

• Start gently and moderate loads: During the first kilometers, avoid full-throttle starts or hard launches.

• Shift up early / shift down late: Keep RPMs and loads low, especially in lower gear ranges.

• Do not let it slip: Especially on hills, do not "hold" with the clutch, but start with the handbrake instead.

• No additional load: During the first 500 km, avoid towing trailers/caravans and strong continuous loads as much as possible.

Is "clutch judder" normal at the beginning?

Yes, after a clutch replacement, occasional judder or a slightly different pedal/start feel may occur in the first kilometers. This usually settles during the break-in period.

However, if the judder remains noticeable even after about 1,000 km, you should have it checked in a workshop – it could be due to an installation or adjustment issue (release system, flywheel, alignment, etc.).

Our Epytec flywheels do not have a stamped TDC marking and generally no additional ignition markings either. This is intentionally designed because, depending on the engine/gearbox combination, housing/pointer, sensors, and peripherals used, different markings or references are required. Instead of a universal marking, we use – as with the original – the mechanical reference via the pin on the back (corresponding to the principle of the series flywheel).

How do I correctly transfer the TDC marking?

If you need a visible TDC marking for your settings (e.g., for timing), proceed as follows:

1. Turn the original flywheel to TDC before disassembly (set the engine exactly to TDC).

2. In this position, check the TDC position on the original at the pointer/marking window.

3. Transfer TDC marking to the new flywheel:
   Mount/align the new flywheel in the same position (via the pin as in the original) and mark the TDC position accordingly on the new flywheel.

This way, you have a TDC marking that fits exactly to your engine/setup.

Basically, you can assume that our Epytec flywheels have a friction coefficient at least at the level of an original cast flywheel. In practice, it is often even slightly better due to the higher alloyed steel used, as the material offers a very stable friction surface.

However, it's important to note that the "actually usable" friction coefficient in the vehicle is not determined solely by the flywheel but always by the overall system – primarily, this includes:

• the material of the clutch disc/friction linings (organic, sintered, performance blends)

• the condition and surface of the friction surfaces (clean, grease-free, correctly installed)

• the proper break-in of the clutch to ensure an even contact pattern

The lining material, in particular, has the greatest influence here. If you use a sport or sinter clutch, the friction behavior can differ significantly from a standard clutch. Therefore, you should inquire about the exact friction coefficient or the specifications of the friction disc from the manufacturer of the clutch/friction disc.

Our flywheels are delivered with the specified unbalance (i.e., not "neutral" to zero).

This is how we set the unbalance precisely: We first balance the flywheel to 0. Then, we attach a test mass at the designated location, which exactly corresponds to the desired unbalance, and balance the flywheel with this test mass again to 0. Once the test mass is removed, the exact specified unbalance remains in the flywheel.