Vibration when letting off clutch 2004 Mustang 3.9 5 spd

 Ford Mustang

Hi! So I have an 04 mustang. When I bought it, it had a vibration when engaging the clutch from a stop, downshifting, and upshifting. So, I figured the flywheel had hot spots in it. So I replaced the clutch and flywheel with new OEM parts. The only thing I didn’t replace was the pilot bearing, because I didn’t have the tool, and it looked, felt fine and smooth when I turned it with my finger. Also, there is no noise I would think is the pilot bearing.

Anyways, I replaced the clutch kit, and flywheel, and I’m still getting the vibration when engaging (letting off of) the clutch, in first and reverse from stop and while up and downshifting. It’s not as bad when the car is moving as it is when you’re pulling out from a stop. I am going to check my u-joints and motor and transmission mounts today, and check pilot bearing fork to see that it’s seated right and looks ok. Any ideas? This kept me up all night trying to go over it in my head. Thanks in advance for your help!

Vibration when letting off clutch

A vibration from hot spots on the flywheel is quite common. This can be a result of hot rodding or using the clutch aggressively. If you paid to have the flywheel replaced, one might want to ask to see the old one to make sure it was actually replaced. If you replaced it yourself, then you already know it actually was replaced.

So now what?

Now we may want to consider that the clutch assembly is not the cause of the vibration. There is a chance that an engine misfire is present. The misfire may be more pronounced when the engine is under a load. This would explain why it is more noticeable when taking off from a stop. It may be worth hooking up a scan tool with active data streaming to check for the misfire. Ford generally will not set a code until the misfire present consistently.