Citroen

[Libo]

Hello i have a citroen c4 1.6 hdi (diesel) 2012. In the 4th gear, starting from 2000 and lasting to 3000 RPM, from 90 to 120 kmph, the car is starting to vibrate from the whole body. It is a firm, regular and relatively high pitch vibration but seems more like a longitudinal vibration

[ml11ML]

Does it go away if you press the clutch? My c5 also has a vibration that appears and gets worse from about 100kmh (60mph) onwards in any gear but disappears almost entirely (maybe something else AND a very slightly bent wheel?) when the clutch is pressed. I checked the driveshafts, front suspension arms and in general everything suspension related for any movement and all is firm. I have also suspected the dmf to have gone bad as I run mine 40HP higher than stock but it doesn't rattle at idle like I'm told it should if it goes bad.

On mine the whole body vibrates as well as the steering wheel. I would think it was a badly balanced wheel but it goes away with pressing the clutch! Never figured it out, I just drive at 100kmh.

[GiveMeABreak]

Very possibly wheel balancing - which you will notice with vibration through the steering wheel and even the seat. I'd get the balancing and tracking checked first.

It does need looking at or you'll start to get issues elsewhere.

[Gibbo2286]

Not only balancing a close inspection of the tyre condition for lumps/bulges. A tyre company doing balancing will do that automatically.

[white exec]

Yes - check the tyres for roundness and 'running true'.
Some tyres can become oval, and no amount of balancing will make them travel without vibration.
Some vibrations can also get damped out by the shock absorbers at most speeds, but not at every speed, which is where a vibartion can be speed-related.

To check for roundness, just lift one wheel at a time clear of the ground, and rotate it by hand with a reference point (any object) sat a few mm away from it, and watch the gap.

[Gibbo2286]

Back when I was trading I bought aa Austin A60 in Cardiff auction, out on the M4 it was almost undriveable everything shook at more than about fifteen mph.
Checking the tyre back home I found they were all junk, every one had sidewall splits that had been patched on the inside with 'gaiters' cut out of the sidewalls of other tyres.
A new set of tyres turned what was a horrible shed into a fine car.