When I break very hard and down shift at the same time I feel a vibration when I'm letting the clutch out. It only happens when I break very hard. Any ideas on what would cause this?<p>Thanks,<br>Mark (98.5 2.8 QMS)

Assuming you are not using the gears as a brake, you are nonetheless performing two tasks at once, and it may be that your touch on the clutch suffers from the distraction of braking. Have someone else with skills you trust try the same maneuver.<br>