Suspension: 70: vibration is driving me nuts

[brens-s80]

hi,

I'am having an unusual problem with my 1997 S70 2.5. I can feel a light vibration from about 40mph up to 70 , but after that it becomes more pronounced and feel like the engine is dancing around the engine bay.

its not to be confused with wheel balance as the steering wheel does not vibrate at all and does not pull either left or right. I have had the tyres balanced and tracing done as well to no effect .

to date i have found that the top engine mount along with the front engine mount and the transmission mounts all needed replacing due to wear and tear,while replacing these has reduced the vibrations they have not eliminated it.

I have also checked the front wishbone bushes and there is slight movement in the front one on the passenger side and none in the rest. I've also checked the antiroll bar bushes as well and they are fine.

any one got any idea's ????

tia

brendan

[Blue 8]

The car hasn't been left standing for a while has it ? tyre flat spot? but my first guess would be that it could be a worn front damper/shock.

[capt jack]

Start by checking out your rear wheels and tyres. Vibration that varies with speed is usually a wheel-balance problem, and if not obvious through the steering can be caused by the rear.

Swap the wheels back to front, then drive the car.

If the vibration is then felt through the steering you'll know where the problem is.

How worn are your rear tyres? If they're well gone they may be beyond re-balancing and need replacing. Worn tyres can go out of shape. Pirelli P6000 tyres are known for this. Flat spots due to under-use as mentioned could easily cause these symptoms. Also, check the pressures!

Do a more general check of the rear suspension - rock the wheels fore and aft and top to toe, and look for any blebs, scuffs and other untoward wear on the rear tyres.

Had this with my old 240 estate, and it turned out to be a blister in the wall of a well-worn (but legal) rear tyre. That it was on the inside wall made it double-difficult to spot!

Cheers

Jack

PS; How do you know this happens above 40? Last time I was in your part of the world the traffic never seemed to get mcuh above 14mph, let alone 40, and 70 was a mere distant dream! J.

[JonYorks]

Could rear wheels be out of balance?
Fronts would be felt through steering wheel and rears through the whole car.

[brens-s80]

hi all,

thanks for your inputs however the wheels have been swapped front to rear and as i said all 4 have been balanced and the tracking has been done and the tyres are new and the car hasn't been left standing as its my daily drive.

tyre pressures are spot on as are the wheel bearings

ah capt jack trust me there are stretches were we go above 40 !!!! as anyone who's driven with me will attest to :-D

keep them idea's acoming


brendan

[JonYorks]

Could be the worn wishbone bush you mention, unless you've sorted that.
Driveshaft bent somehow? or just out of balance due to excessive rust etc.
Not sure about all models but yours will have a bearing carrier on one driveshaft which could be loose or have knackered bearing.

Also, I remember reading once about cars with abs will eventually put flat areas on the tyres, some can become like 50 pence pieces!

[Blue 8]

have you had your shocks checked?

[dmkelly]

I had something like this and it turned out to be the steering rack. The ends were worn, however we couldn't prove it until the rack was removed and replaced. We tried everything else first but nothing. Drove me mad for 18 months.

Hope this helps.

DK

[RSF]

Loose door panels and interior panels can cause bad vibration.
I have bad vibration when pulling off,as if I am over gearing,judder's when I let the clutch out slow too (no shake from my steering at all).
Grab your engine by the manifold and the oil cap and rock it,see if your engine rock's,if to much another mount could be suspect.
I'm suspecting rear engine mount on mine and will be getting it done as well as a poly top mount bush (get one of them too and give it a try)I hear they sort vibration out but also cause them if you get a stiff one.

Are your anti roll bar drop link's ok?

[v70cd]

Hi. How long ago was the balancing done? When the tyres were fitted? The balancing is correct at first then as the tread wears, the original weights fitted to the wheel will become slightly 'incorrect' according to the remaining tread on the tyre - especially on front wheeled drive Volvos. But if it was a recent balance/track then it would start to bug me too !! Hopefully it's something simple...and cheap.