Vibration at speed, every few seconds....

[jgra1]

chaps, I have this with my current xantia and have had it before, noticeably with a heavy comfy and slightly missed 605

It isn't a constant vibration at a certain speed, more of a 'wave' of vibration that builds and dies every few seconds, noticeable at 70-80 ish...

I have 3 new tyres, all balanced allegedly.. car has exclusive alloys..

I can only imagine that all wheels, driveshafts etc have a perfect 'resonance' with each other, at certain speeds ...

It doesnt worry me but spoils a nice ride, every so slightly... anyone else had this happen?

John

[AndersDK]

I'm just wondering ...
What about the 4.th wheel ?
If that wheel is missing, I'd say your car would be prone to do all kinds of vibrations during drive ...
Have you checked if the wheel is still there - lately ... ?

Yeah - well

Never heard the wheels could do inter-resonance, but each wheel and its suspension can do so with bad shockers - or spheres.
Remember that a roadwheel have both a static and a dynamic balancing to be done :
the static is the wellknown hopping at a certain speed
the dynamic is the sidewards balancing causing annoying wobble in steering wheel.
Both types can be caused by a duck egg on the tyre.
- and they can do it to your description as many parts are involved each having their own preferred resonance frequency.

[jgra1]

thanks Anders will check the 4th wheel is there in a second

the 5th wheel was vibrating so i took it off, who needs steering anyway

[srx600]

I had a similiar problem with a ZX which was caused by flat spots on the tyres. New tyres solved the problem. (as to why they had flat spots I have no idea)

[jgra1]

thanks srx...

3 of the tyres are brand new.. will take a good look at 4th..

[Peter.N.]

I would say that you have two tyres on the same axle slightly out of balance and they are going in and out of phase with each other as their relative position changes i.e. when cornering, as the outside wheel is rotating faster than the inside..

[C.J.]

I had a similiar problem with a ZX which was caused by flat spots on the tyres. New tyres solved the problem. (as to why they had flat spots I have no idea)

I've had that recently on my Fabia. My symptoms were different though.
Diagnosed by the main stealer when I took it in to investigate under warranty, what I thought was a duff wheel bearing with constant whining noise
As you said, new tyres solved the problem.
Bit of a pig though, as the old ones still had a fair bit of meat left on them.

I thought 'flat spotting' only happened in F1 too, due to excessive skidding?

[lolingram]

jgra1

Post subject: Vibration at speed, every few seconds....

chaps, I have this with my current xantia and have had it before, noticeably with a heavy comfy and slightly missed 605. It isn't a constant vibration at a certain speed, more of a 'wave' of vibration that builds and dies every few seconds, noticeable at 70-80 ish...

I have 3 new tyres, all balanced allegedly.. car has exclusive alloys..

I can only imagine that all wheels, driveshafts etc have a perfect 'resonance' with each other, at certain speeds.

It doesnt worry me but spoils a nice ride, every so slightly... anyone else had this happen?

Apart from tyres, I would bet on driveshaft inner universal(s)... had identical symptoms with my Xant hback VSX. Sometimes it would disappear for ages, only to re-appear on very large radius downhill bends on the autoroute... Eventually gets worse of course.

[xantia_v6]

I have 3 new tyres, all balanced allegedly.. car has exclusive alloys..

Assuming that your exclusive alloys have no centre hole, I have found that many tyre shops cannot balance them correctly. The problem is that their adaptor does not centre the wheel correctly, so they balance the wheel mounted eccentrically on their machine, which is then out of balance when centred on the hub.

With one mobile tyre fitter, who insisted that he had balanced the wheel correctly, I made him remove the wheel from his adapter, rotate it though 180 degrees and recheck the balance, and it was well out.

There hare however some balancing adapters that do seem to centre the wheel properly, you just need to find one.

[Downunder]

I have had this vibration in my series I Xantia ever since I have owned it. It occurs under heavy acceleration. It has existed throughout many tyre changes so I don't believe it has anything to do with tyres. I thought it may have something to do with a drive shaft out of balance, so I changed the left hand side. No effect. So I put up with it. As it occurs under hard acceleration only, it is not a problem as I don't do that very often because it causes high fuel consumption. Problem solved - well sort of. I just keep wondering.....

[AndersDK]

... it may have something to do with a drive shaft out of balance, so I changed the left hand side. No effect ...

According to Murphys law, its always the opposite side that fails when you diagnose one sides wheel, CV joint, bearing, tyre, tie-rod etc ...

[howzat]

Assuming your tyres are all correctly balanced, the vibrations described can be caused by tyres which are slightly "out of round" or have varying sidewall stiffness. As tyres have slightly different sizes due to wear or different maufacturers, they run at slightly different speeds. The result is that the forces produced by the a/m defects move in and out of phase producing the varying vibration. Try jacking each wheel and rotating it against a fixed point to check for "runout".

[jgra1]

thanks all


John

[Duracell]

I think Xantia_V6 is correct - If you have exclusive alloys then your problem is almost certainly a balance problem - your symptoms are identical to the problems I had with my exlusive every time I had tyres changed. I got so fed up with it that I bought aftermarket alloys. My wife has just had the same problem with her C5 - it took 2 returns to have the balancing redone before they got it right. I cant understand why Citroen continued to make centerless alloys

Good Luck

[Johnno]

I'm interested to know what the outcome of this topic is - tyres or driveshaft? I noticed the same rythmic 'build and fade away' vibration driving the C5 along the Autoroute from Saumur recently. Those smooth French motorways sure do give you a chance to find all those wheezes, bangs and rattles.

I didn't notice it on the way down with only myself and the missus, but returning with three people plus luggage it somwhat spoiled an otherwise faultless trip. My first nervous thought was the dreaded DMF but a driveshaft seems equally likely - and cheaper!

jgra1 - any outcome?