Feel Vibration at + 2k RPM though seat of pants!

[spartacus]

Took an early 4.2 out for a test drive yesterday, drives like a peach, solid at all speeds I was brave enough to try, just one problem, vibration/resonance at just over 2000 rpm which goes as the revs increase. This resonance is noticeable through the drivers seat. I have done a search on older postings, some say its caused by the older AP clutch, others say its common with early 4.2s.

What i want to know is, if it’s a case of "they all do that sir" then no problem, I can live with it. If it’s a case of the early AP clutch about to fail then that’s a different matter? I personally suspect its just a drive train vibration caused by the engine design, see talk of unbalanced crank possibly be cause of so many broken clutch fingers.

Would be interested to hear any further opinions?

[mark.rowe]

I had a similar sounding problem on mine after i'd changed the exhausts.
Turned out to be the drivers side cat vibrating against the chassis.
Could be something as simple as that if lucky
It was vibrating between 2-2.5k then it went away.

[DuncanM]

spartacus said:

Took an early 4.2 out for a test drive yesterday, drives like a peach, solid at all speeds I was brave enough to try, just one problem, vibration/resonance at just over 2000 rpm which goes as the revs increase. This resonance is noticeable through the drivers seat. I have done a search on older postings, some say its caused by the older AP clutch, others say its common with early 4.2s. What i want to know is, if it’s a case of "they all do that sir" then no problem, I can live with it. If it’s a case of the early AP clutch about to fail then that’s a different matter? I personally suspect its just a drive train vibration caused by the engine design, see talk of unbalanced crank possibly be cause of so many broken clutch fingers. Would be interested to hear any further opinions?

From my experience you can get rid of a lot of this by tuning the throttle pots as best you can and then resetting the adaptive maps (simpleish work).

Otherwise I'd certainly agree that they all do that .

Duncan

[jon h]

I've had a '97 4.2 for a week now. I get the same vibration you describe, so I HOPE "they all do that!"

Jon H

[Extra 300 Driver]

Mine does, since it refitted the cats.

Strange, the girlfriend always wants to take the Cerbera now!

[spartacus]

Thanks guys, you have all out my mind at rest. Will post details when I get her home. Nice Cooper Green Cerb!