Deep Rumbles :eek:

[NoLongerTVRless]

I still can't stop grinning about my bitchin' new toy, but now I've had it a week, I am noticing more bits and pieces.

One is I can hear/feel a deep rumble coming from the rear (I think) which comes in around 70 and louder by 80. Much more noticable with hood on, but can still feel if not hear it hood down.

Is my rear diff about to explode into a thoudsand pieces, or should I relax as 'they all sound like that'?

The rumble does sound like a wheel (constant with speed) and not a transmission (variable) noise.

Any ideas guys?

[Stig]

Sounds like a wheel bearing. Listen closely as you corner, if it goes away then it's almost a cert.

If it disappears round a left hander then it's the left, right for right.

[NoLongerTVRless]

Ooh hope so - wheel bearing s/be much cheaper than the paranoid scenarios my brain was compiling!

Only trouble is, not many decent 80mph corners locally, and vibration not present at lower speeds. Will try around the bypass tonight and hope for a traffic free bend.

[Colin BlueS2]

I have a simlar noise from the rear of mine, only present at motorway speeds and haven't noticed it coming and going around corners.

Didn't think about the wheel bearing but I'll get it up on stands and give them a wiggle this week.

Could it be something as simple as low oil level in the diff? I'll be checking that too.

Colin

[NoLongerTVRless]

I shall watch this space!

If low oil level in the diff gives vibrations that resonate through the cabin (and your chest!), I feel this is more likely.

I know all wheel bearings are different, but I've had many a wheel bearing go on me over the years, and this rumble doesn't feel like one.

I reckon you're right Colin, and will get my axle stands out.

[craigy]

Pretty sure it's more likely to be propshaft U/J's if it is that pronounced. However mine does the same under hard acceleration in forth/fifth at about 70mph, although not too pronounced. My convertible Triumph GT6 did exactly the same, and and had already been fully restored, so I consider it to be normal! (imsurethatswhatyouwantedtohear)

[Psychobert]

Had a similar problem 6 months ago and it turned out to be the prop shaft. One way to tell is to see if the noise and vibration is only there when the engine is under load, (as opposed to coasting with the completely foot off the power). If its transmission related then I think you will not notice it when you lift off the loud pedal. Wheel bearings will tend to be constant and will get worse or better depending on the loading on the wheel

[Yellabelly]

Psychobert said:

Had a similar problem 6 months ago and it turned out to be the prop shaft. One way to tell is to see if the noise and vibration is only there when the engine is under load, (as opposed to coasting with the completely foot off the power). If its transmission related then I think you will not notice it when you lift off the loud pedal. Wheel bearings will tend to be constant and will get worse or better depending on the loading on the wheel

I tend to agree with psychobert, if it was wheel bearings you would hear them driving round in circles at low speed in a local carpark, the fact that you are getting a low resonance would suggest propshaft U/J or possibly diff bearing. Ford Granada w/shop manual tends to suggest same.
Good Luck

[NoLongerTVRless]

Thanks peeps

I took it out of gear and coasted in neutral, and still the rumbles remained!

[Psychobert]

Reasonably sure you've not got transmission problems in that case. just aswell, wasn't a cheap job due to the amount of labout required to drop everything off to get to the prop shaft.

[NoLongerTVRless]

Phew, thanks m8 - It doesn't sound like an 'I should be worried' noise, more of a 'better get that looked at sometime' noise, but s'pose I had still better check tho' just in case!

[gavinjfowler]

Try checking UJs on propshaft. This is all in Bible. When mine were on the way out I had very a very similar rumble. The speed at which it starts will gradually lower as they ger looser and looser! Not too expensive to fix though.

[S3 Kieran]

(formerly TVRless)

Thanks Gavin - I must get hold of the gospel according to Steve!

[Colin BlueS2]

As the S is currently on stands awaiting delivery of new dampers I had a good old poke around underneath at the propshaft UJ's and driveshafts tonight. I couldn't see or feel any play in either of these so stumped as to the source of the noise currently. I will have a look at the diff oil level and the gearbox oil level whilst the car is off the road this week. The silencer has a coating of oil on it which explains the smell of warm oil after a long run!! So I'm hoping that it's just a low oil level that is causing the rumble.

Colin