Farina Motorsports, MKIV Volkswagen dual-mass to single-mass conversion overview

The Basics
Authors: Matthew Farina, Adrian Farina
All 4 cylinder MKIV's were fitted from the factory with dual-mass flywheels. Dual-mass flywheels differ from single-mass flywheels in that they are comprised of two rotating masses as apposed to one. The two rotating masses are coupled with a sprung hub thereby allowing them to rotate relative to each other to a small degree. The primary purpose of this design is to reduce drivetrain noise (typically referred to as chatter) and vibration while cushioning the drivetrain from shock. Because of this dual-mass flywheels typically provide very smooth and low-effort launches. Dual-mass flywheels are suitable for the every-day driver, but they are not performance oriented. The alternative is a single-mass conversion. This entails replacing the original dual-mass flywheel and clutch assembly with a solid single-mass flywheel and new clutch assembly (pressure plate and disc). The pressure plate and disc are replaced because they will not fit the new single-mass flywheel. Also since we have replaced the dual-mass flywheel, which did the job of dampening the drivetrain, the original rigid (non sprung) clutch disc is replaced with a sprung hub unit. This does reduce driveline noise and vibration to a small degree, but it's primary purpose is to protect the drivetrain from shock. There are many advantages to a single-mass conversion: • Increases engine response • Less drivetrain loss • Sportier feel • Better acceleration • Reduced weight • Increased clutch diameter (225mm to 228mm) • Can be resurfaced However there can also be disadvantages: • Increased driveline noise • Increased driveline vibration • Increased effort required when launching Although the above may dissuade some from the conversion, most people find that the advantages far outweigh the disadvantages. While you may want to run out and buy the lightest flywheel you can find there are some drawbacks to watch out for. The most important is that the lighter a flywheel is the less inertia it can hold. This becomes a problem when launching the car from a standstill. The heavy dual-mass flywheel held more inertia and actually assisted in launching the car. With a lighter flywheel you will have to slip the clutch more to get the car moving. While this is not a huge issue with a moderately light flywheel it can become one with an extremely lightweigh unit. I'm not saying you shouldn't buy a 5lb flywheel, just be aware of the drawbacks. There are no reliability issues inherent in this conversion provided you buy quality parts.
The Parts
The single-mass conversion for MKIV 4 cylinders is commonly referred to as a VR6/G60 swap, because you replace the stock flywheel with a 228mm G60 Corrado flywheel and the stock clutch assembly with a 228mm VR6 clutch.
Flywheels
Several companies offer flywheels for this conversion: Eurospec: • Billet steel construction • 14 pounds • Most inexpensive Autotech: • Billet steel construction • 11.8 pounds Autotech: • Aluminum construction • 8.3 pounds Fidanza: • Aluminum construction • 6.5 pounds OEM G60: • Steel construction • 21.6 pounds There are also other brands available and all will differ in weight, material, cost and build quality. Do some research and decide which is best for you. Two factors to consider before purchase are cost and weight. We have already discussed weight earlier, but if cost is your biggest concern Eurospec's billet steel G60 flywheel is a great choice. With great quality and low cost it's hard to beat. The oem flywheel from a Corrado G60 can be used, but the Eurospec flywheels are usually cheaper, and the G60 flywheel is almost as heavy as the stock dual-mass unit.
Clutches
Any 228mm 12 valve VR6 clutch kit will work. Your decision between using an OEM kit or upgraded aftermarket kit should depend on how much power you are planning to make and your budget. The stock VR6 clutch is capable of handling significant power levels over a stock 1.8t, but they are not indestructable, and many people prefer the stiffer pedal feel of upgraded clutch kits.
Bolts
New flywheel and pressure plate bolts are required for this conversion. These are the OEM part numbers for the necessary bolts: Pressure Plate bolts: N10101001 (6 required) Flywheel bolts: N90206103 (6 required)