System and method for controlling loads on a dual mass flywheel attached to an engine based on engine speed

1. A system comprising:

an engine speed module that determines an engine speed when a clutch is engaged with a dual mass flywheel; and

a downshift indicator module that generates a downshift indicator signal when the engine speed is less than a first speed, the downshift indicator signal indicating when to downshift a manual transmission, wherein the first speed is based on a predetermined relationship between the engine speed and oscillation of the dual mass flywheel.

2. The system of claim 1 , wherein the first speed is greater than a resonant speed of the engine that causes the dual mass flywheel to oscillate at a resonant frequency.

3. The system of claim 1 , wherein, when the clutch is disengaged from the dual mass flywheel, the engine speed module estimates the engine speed at a future time when the clutch is reengaged.

4. The system of claim 3 , wherein the engine speed module estimates the engine speed based on a selected gear of the manual transmission and vehicle speed.

5. The system of claim 4 , further comprising a selected gear module that determines the selected gear based on a measured position of a gear selector.

6. The system of claim 5 , further comprising a Hall effect sensor that generates a selector position signal indicating the measured position of the gear selector.

7. The system of claim 1 , further comprising an engine control module that stops the engine when the engine speed is less than a second speed.

8. The system of claim 7 , wherein the second speed is less than the first speed.

9. The system of claim 7 , wherein the second speed is greater than a resonant speed of the engine that causes the dual mass flywheel to oscillate at a resonant frequency.

10. The system of claim 1 , further comprising a shift indicator that in response to the downshift indicator signal, delivers at least one of a visual message, an audible message, and a tactile message indicating when to downshift the manual transmission.

11. A method comprising:

determining an engine speed when a clutch is engaged with a dual mass flywheel; and

generating a downshift indicator signal when the engine speed is less than a first speed, the downshift indicator signal indicating when to downshift a manual transmission, wherein the first speed is based on a predetermined relationship between the engine speed and oscillation of the dual mass flywheel.

12. The method of claim 11 , wherein the first speed is greater than a resonant speed of the engine that causes the dual mass flywheel to oscillate at a resonant frequency.

13. The method of claim 11 , further comprising, when the clutch is disengaged from the dual mass flywheel, estimating the engine speed at a future time when the clutch is reengaged.

14. The method of claim 13 , further comprising estimating the engine speed based on a selected gear of the manual transmission and vehicle speed.

15. The method of claim 14 , further comprising determining the selected gear based on a measured position of a gear selector.

16. The method of claim 15 , further comprising generating a lector position signal using a Hall effect sensor, the selector position signal indicating the measured position of the gear selector.

17. The method of claim 11 , further comprising stopping the engine when the engine speed is less than a second speed.

18. The method of claim 17 , wherein the second speed is less than the first speed.

19. The method of claim 17 , wherein the second speed is greater than a resonant speed of the engine that causes the dual mass flywheel to oscillate at a resonant frequency.

20. The method of claim 11 , further comprising, in response to the downshift indicator signal, using a shift indicator to deliver at least one of a visual message, an audible message, and a tactile message indicating when to downshift the manual transmission.