Need to Replace a Dual Mass Flywheel?
Some passenger and 4WD vehicles will have a single mass flywheel (also known as a SMF) and others a dual mass flywheel (also known as a DMF).
What is the Difference between a DMF and SMF?
The dual mass flywheel was designed to help smooth out the torque produced by petrol and diesel engines, by increasing the kinetic energy stored on the input shaft side of the gearbox and provide easier gear changes.
The dampening springs are usually in the clutch plate so when the clutch was replaced with the new clutch kit there was no need previously to be concerned. Now with the new dual mass design the dampening springs are in the flywheel.
Unfortunately for those who drive a vehicle with a DMF they are noted for their a high failure rates and are much more expensive to replace than a standard flywheel and clutch.
When we say more expensive, they are generally in the range of ‘double the cost’ of a standard flywheel replacement, making your clutch and flywheel replacement a much more expensive repair than it otherwise would be.
The images to the left show the visible difference between the dual mass and single mass flywheel.
DMF - no springs are visible on the clutch plate (they are built into the flywheel)
SMF - you can see the springs built into the clutch plate. Also evident is the difference in the flywheel (to the left at the back)
Replacing the Flywheel
Even if the wear on the flywheel is minor it must be replaced, you will not get another clutch life out of the dual mass flywheel, and they cannot be machined without removing the secondary component from the primary mass.
No clutch manufacturer will guarantee their kit without machining the flywheel, and given that, you must replace it.
Even if you think the flywheel looks great, think again, when the pressure plate is bolted to the flywheel, it clamps or squeezes the clutch plate up against the face on the flywheel. This causes the flywheel to distort and bow, and eventually this bow becomes permanent.
If you have a DMF that does needs replacing , you may be able to use a solid single mass flywheel from Exedy instead of having to pay for the extra expense of a DMF.
Replacing a dual mass flywheel with a single mass flywheel is a very cost effective decision to make, especially if you plan on keeping your vehicle for long period of time.
It will mean that the next clutch replacement, should you need one, will be so much cheaper, and you will have the option to machine the SMF, offering further cost savings not available with DMF installations. When the original change is made you may feel a slight difference in gear changes.
The Exedy clutch finder will explain which flywheel can be used with each replacement clutch kit in either a standard replacement kit, as well as sports and performance options, depending on your vehicle type.