Anyone that has ever owned a vehicle with a manual transmission has probably had to have the clutch replaced at some point. Depending on the vehicle, it will come equipped from the factory with a single mass flywheel (SMF) or dual mass flywheel (DMF). You will find that most of our beloved European cars came stock with a dual mass flywheel and for good reason. Below I will go through the concept, and why you would want to convert from one to the other.
A dual mass flywheel is basically two flywheels with springs in the middle to act as a dampener. The two flywheel halves are able to move independently of each other within a limited range. The springs help absorb engine vibration which reduces wear on the transmission and the rest of the drivetrain. The benefits of a dual mass flywheel are smooth operation and dampening of noise, vibration, and harshness (NVH).
A single mass flywheel provides a direct contact between the engine and clutch assembly. Some clutch pressure plates contain springs to help dampen vibrations, but in general, an SMF cannot dampen engine vibration as well as a DMF. They tend to be much cheaper than a dual mass flywheel to replace, and because they are made of one piece they can also be resurfaced if within factory specifications. The construction of a single piece of metal gives it a greater heat capacity to prevent it from warping. It also allows the engine to rev quicker. This is ideal for track cars.
As you may have gathered, the main downside in a DMF is cost, since the assembly is more complicated and must be replaced as a complete unit. This is because, unlike single mass conventional clutch and flywheel assemblies, you cannot resurface a dual mass flywheel when you do a clutch job.
Converting from a dual mass flywheel to a single mass flywheel can be done on most vehicles if a kit is available. eEuroparts has a number of clutch conversion kits available from Valeo, an OE supplier to many luxury European car companies. If you want to convert your car from a dual mass to a conventional single mass flywheel clutch, and we don’t have a kit for you, let us know and we can help you source a high quality kit.
The kits consist of a flywheel, clutch disc, and pressure plate. Most drivers will convert based on cost factors, while performance enthusiasts will convert to a single mass flywheel since it can handle increased engine torque and it gives direct feedback to the driver.
To Switch or Not To Switch
The time has come and your vehicle is in the shop for a clutch replacement. The mechanic says your dual mass flywheel needs replacement. First of all it is recommended to replace the flywheel whenever replacing the clutch. Resurfacing a clutch can still leave hot spots on the flywheel that translates to jutter and vibration. This is even more important on vehicles with a dual mass flywheel because they can fail and separate if overloaded which will damage the clutch.
Keeping with a dual mass flywheel will keep the feel and drivability of the vehicle just as you’re used to. This is a great set up for driving on the street as it helps aid the driver’s comfort. When changing over to a single mass flywheel expect to experience a different feel of the clutch when engaging, increased shifts to keep the vehicle in motion in the low rpm range, and possibly gear rattle from the transmission.