Part time vibration

[Import95]

First post to the forum and looking for some help! I imported a Stag to Sweden 2 years ago (my second Stag),, one of about 30 in the country. It has developed a vibration but only when it has done a run of more than 30-40 klms. It vibrates at low speed and then disappears, so I can drive through it. Spoken to a couple of people in Stockholm who have no idea! It is away for the winter now ( you think you have snow in the UK?) but I would like to get it sorted for the late spring, any help much appreciated, Paul in Stockholm

[stustag]

imported post

Hi Paul

Welcome.

These are the parts I would check

• Viscous coupling with engine OFF grab the fan and spin it, if it does not stop turning in about 1/4 -1/2 turn then it may be shot. Check for rocking as well to see if the bearing is gone.
• If not the above check all UJ's prop and half shafts for play, look carefully where the UJ fits into the yoke for signs of wear in the yoke itself.
• If the vibration is through the steering check the wheel balance,tyre pressure, Ball joints and wheel bearings.
• Check the engine mounting rubbers and gearbox mounting rubbers.

That is all I can think of right now hope this helps.

Stuart

[Import95]

imported post

Thanks Stuart, when the snow goes below a metre I'll check the fan and the uj's, pretty sure that it isnt the ball joints etc.

Hapy New Year
Paul

[KOY 23]

imported post

Welcome.
How old are the tyres?
John

[Import95]

imported post

Hi John

Not sure to be honest, The Stag is tucked away for the winter (not at my place), but I would guess 4-5 years, the vibration only happens at low speed and disappears when the car has cooled down again. The tyres are in good nick. Thanks for your help, Paul

[twitchiwobble]

imported post

Hi Paul

Your vibration symptoms seem quite specific.

It is NOT likely to be U/J's on the transmission, because the vibration would progressivelyincrease with engine revolutions and it would not be possible to "drive throught it"

Viscous Coupling is also unlikely, because if the coupling was vibrating enough for you to be aware of, then there would bound to be metal-to metal friction contact within the coupling (and that would be hideously noisy!)

I must say that tyres seem favourite. Really, a four-wheel balance would be my first thought.

I do not know if bad engine mounts would give "drive-through" vibration symptoms?

I wish you well in your investigations!

[peterrc]

imported post

Hi Paul, tyres sound favourite but another thing to consider is oil pressure. The oil would be thick to start with but thin after 20km by 'driving through it' you are increasing the revs and pressure.
If it is oil pressure you should be able to replicate it in the garage without going out in the cold.
Peter

[dasadrew]

imported post

On some of my cars I have a tyre vibration but this is due to flats on the tyres overnight. It actually goes away when the tyres warm up.

However, staying on the tyre/suspension area, the shock absorber oil does get warm when you drive, would cause a decrease in damping if they're knackered and the oil gets warm and thin, would set itself back to "zero" when everything cools down. It would also exhibit a resonance which would be pronounced at certain speeds.

It is, unfortunately, not so easy to diagnose (in spite of what the tyre dealers tell you, an external leak is really the end of the shock absorber and internal leaking past seals can occur LONG before any external leak occurs). The only correct way to detect it is to put the car on a vibration platform - in Germany, the German "RAC" have these. Maybe Sweden has a similar arrangement?

Shock absorbers normally start deteriorating after 30,000 miles or less, but are rarely replaced because they don't leak externally.

Drew

[Import95]

imported post

Hi to all who have replied and all on the forum, it is great to be part of such a fantastic club with such helpful and friendly members. I have now received a number of very credible explanations to my vibtation prolem and I am sure it will be solved in the spring ready for a new season.

Thanks everyone and a Happy New Year to all Stag owners and admirers:
Paul

[SGN]

imported post

Hi Paul

Have you tried switching the engine off and putting it in neutral when the vibration starts,(providing it is safe to do so)that would eliminate the viscous fan,when my fan failed I was shocked at the effect it had on the car,the car felt that it was losing power every time it started to seize,(I thought it was the auto gearbox slipping at the time), and the vibration was quite alarming.
It used to start to seize/vibrate after around 10 miles of driving.

Cheers
Steve

[Import95]

imported post

Thanks Steve I will give that a go.
All the best Paul

[RogerP]

imported post

SGN wrote:

Hi Paul

Have you tried switching the engine off and putting it in neutral when the vibration starts,(providing it is safe to do so)that would eliminate the viscous fan,when my fan failed I was shocked at the effect it had on the car,the car felt that it was losing power every time it started to seize,(I thought it was the auto gearbox slipping at the time), and the vibration was quite alarming.
It used to start to seize/vibrate after around 10 miles of driving.

Cheers
Steve

Careful you don't activate the steering lock.

Rogerp

[SGN]

imported post

RogerP wrote:

SGN wrote:

Hi Paul

Have you tried switching the engine off and putting it in neutral when the vibration starts,(providing it is safe to do so)that would eliminate the viscous fan,when my fan failed I was shocked at the effect it had on the car,the car felt that it was losing power every time it started to seize,(I thought it was the auto gearbox slipping at the time), and the vibration was quite alarming.
It used to start to seize/vibrate after around 10 miles of driving.

Cheers
Steve

Careful you don't activate the steering lock.

Rogerp

He would forget about the vibration - briefly

[RogerP]

imported post

SGN wrote:

RogerP wrote:

SGN wrote:

Hi Paul

Have you tried switching the engine off and putting it in neutral when the vibration starts,(providing it is safe to do so)that would eliminate the viscous fan,when my fan failed I was shocked at the effect it had on the car,the car felt that it was losing power every time it started to seize,(I thought it was the auto gearbox slipping at the time), and the vibration was quite alarming.
It used to start to seize/vibrate after around 10 miles of driving.

Cheers
Steve

Careful you don't activate the steering lock.

Rogerp

He would forget about the vibration - briefly

Cor could you imagine the panic look :shock:

[Phil]

imported post

An old school friend did this once in his fathers brand new xj6 his mate tried to open the glovebox but it was locked. Took key out handed to passenger then click of the steering lock next thing upside-down in ditch. Luckily no one hurt but I'm glad I didn't have to explain to parents

Phil