Rhythmic sound when driving

[giusepppe]

As soon as I start driving, I get a rhythmic sound coming from under the car, I have checked all four wheels for damage, or a nail in the tyre, any ideas what it could be. thanks in advance for any ideas.

 

[markjay]

Try to see if the frequency is related to engine speed or to wheel speed. Also, from which side is the sound coming?

 

[jdrrco]

Could it be a Gloria Estefan cd?

I'll get my coat...

 

[StMarks]

Wheel bearing, distorted or binding brake, a driveshaft or propshaft out of true,, so may possibilities..

 

[ChrisHGTV]

One thing that's easy to check is if your tyres have gone 50p piece shaped. You can run your hand on the inside edge and can feel it. Ive had that before and it sounds almost like a wheel bearing. The older Eagle F1 tyres were quite prone - i can't remember the specific reason now but something to do with how the suspension loads the tyre. (Not related to incorrect adjustment)

 

[SpikyMikey]

Could it be a Gloria Estefan cd?

I'll get my coat...

.....Rhythm is gonna get ya.....

 

[SpikyMikey]

One thing that's easy to check is if your tyres have gone 50p piece shaped. You can run your hand on the inside edge and can feel it. Ive had that before and it sounds almost like a wheel bearing. The older Eagle F1 tyres were quite prone - i can't remember the specific reason now but something to do with how the suspension loads the tyre. (Not related to incorrect adjustment)

The Eagles on my S204 do this if it's been sitting unused for a while. A few miles running makes them round again.

 

[markjay]

The Eagles on my S204 do this if it's been sitting unused for a while. A few miles running makes them round again.

Ah, that's called the Hotel California syndrome.....

(Just keeping with the music theme of this thread )

 

[TTManUK]

put the car into neutral whilst it is rolling, see if the noise stops - try to separate prop shaft rotation noises from axle based rotation

 

[Bellow]

The nature of the sound would help. Short and sharp, slow and low, etc?

 

[ChrisHGTV]

The Eagles on my S204 do this if it's been sitting unused for a while. A few miles running makes them round again.

Ah interesting - what ive experienced is actual wear. You can feel like a saw tooth profile as well, with a good few cm between teeth as it were. The Alfa used to be really prone on the rears, im not sure if its anything to do with the rear wheel steer.

 

[Stratman]

put the car into neutral whilst it is rolling, see if the noise stops - try to separate prop shaft rotation noises from axle based rotation

The propshaft will still rotate while rolling in neutral

 

[markjay]

The propshaft will still rotate while rolling in neutral

Not on my Alfetta it didn't - the transmission was in the rear sharing housing with the diff

 

[ALFAitalia]

Not on my Alfetta it didn't - the transmission was in the rear sharing housing with the diff

Erm?....no. As a fellow ALFA man you have not thought that through!.....not only will it still be turning in neutral, it will be spinning way faster than the S Class one would be........You would have to roll along in neutral and switch the engine off to stop driveshaft rotation.

 

[Bellow]

.not only will it still be turning in neutral, it will be spinning way faster than the S Class one would be........

Nope, it would be at idle speed.
And during normal driving, if the S-Class has overdriven upper ratios (probable) then its propshaft rotates faster than the Alfetta's.

 

[ALFAitalia]

The Alfetta one rotates at crank speed!

 

[Bellow]

The Alfetta one rotates at crank speed!

Yeah, I know. And in neutral, foot off the gas, it would be rotating at idle speed.
Propshafts rotate faster than cranks when behind a gearbox with overdrive upper ratios. Which is why on US trucks with long single-piece propshafts they dyno test in third gear to prevent 'tossing the shaft'.

 

[giusepppe]

Thanks for all your replies and suggestions, I have had all four wheels off, one at a time, to see if there as any damage to the wheels, or discs, tightened one of the front bearing nears side, which was loose, then drove the cars onto railway sleepers, front and rear, only thing i noticed was oil leaking from around the auto box, could not see exactly where because did not take the plastic shields off, the sound is related to the speed of the car, the sound gets faster as you speed up, so think it might be related to the prop shaft, will have have another look, this time with the plastic shields off, it does sound like something is loose and flapping of the underside, will definitely try running with it in neutral.

 

[Gnasher141]

Tyres - I had exactly the same thing with Bridgestone tyres on a Impreza I had - changed wheels and tyres - noise gone

 

[giusepppe]

I have michelins all round, fitted after wheels were refurbished last year, having tracking done on Thursday as slight ware on near side, apart from that, they looked okay