Tech Tip: Volvo Rattle Noise From Dual Mass Flywheel
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Tech Tip: Volvo Rattle Noise From Dual Mass Flywheel

If a rattle noise is heard on a vehicle with a manual transmission, attention should be paid to the Dual Mass Flywheel (DMF). In the case of customer complaints, follow the steps listed in this Tech Tip.

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If a rattle noise is heard on a vehicle with a manual transmission, attention should be paid to the Dual Mass Flywheel (DMF).

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SERVICE:
In the case of customer complaints, follow the steps below.

A. Measure the DMF Radial Free-Play:

The DMF should be mounted on the crankshaft during the measurement. (For the measurement you will need a torque wrench.)

1. Impose a torque of 6 Nm (4.4 lbf.-ft.) on one of the bolts that holds the clutch and DMF together.

• The secondary side of the DMF will now turn in the same direction as the applied torque.

2. Draw a line over both the primary and secondary side of the DMF.

3. Now impose a 6 Nm (4.4 lbf.-ft.) torque in the opposite direction than before.

• The secondary side of the DMF will now turn in the same direction as the applied torque.

4. Draw a line on the primary sides of the DMF in alignment with the line that you previously drew on the secondary side of the DMF.

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5. Measure the distance between the two lines on the primary side of the DMF.

6. If the distance is below 35 mm (1-3/8”), the radial play of the DMF is OK.

B. Measure the DMF Axial Free-Play:

The DMF should be demounted from the crankshaft and placed on an even surface during the measurement. (For the measurement you need a dial indicator.)

1. Use a dial indicator and place it as shown in Fig. 1. The DMF should be in equal ­balance when the dial indicator is put in place.

Fig. 1

2. Apply a force of approximately 100 N (approx. 10 kg mass or 22.5 lbf.) on pin (A) at the opposite side of the dial indicator.

3. Read the distance of the axial free-play on the dial indicator.

4. Now turn the DMF one-third of a revolution and do the whole procedure from the beginning (from point 1) and apply the force on pin B.

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5. Repeat the procedure for pin C.

6. If the largest distance from the three cases is below 2 mm (0.078”), the axial play of the DMF is OK.

Replace the DMF if radial or axial free-play are ­outside specification, or if the noise is still present.

Courtesy of Mitchell 1.

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