Intermittent - 'unsurfaced road' type sensation Mk6

[firewalker]

Going to be hard to explain but -
Mk6 LWB RWD has on the last couple of runs suddenly sounded/felt 'wrong' and the best description I can offer is it feels and sounds like I've just driven onto an unsurfaced piece of road (like where theres usually a cautionary red triangle sign to say the surfacing roadwork isn't finished so go slow).
The road surface however has not been noticeably unusual, happening on a familiar route along different parts of the A1 which was flowing normally in quiet conditions.

The first time I carried on steadily trying to make sense of it, then it seemed to ease off. My passenger didn't notice anything.

The second time (return journey) was more noticeable I pulled over thinking it may have been a flat tyre, could see nothing wrong and when I pulled away managed to drive about 70 miles without anything seeming wrong. This time my passenger agreed that it had sounded concerning, suggesting the same 'unsurfaced' road type of sensation.

So just wondering if anyone has experienced the same symptoms and been able to get to the bottom of it?
Or can anyone guess at some places to take a look at?

[loot]

Can you replicate it somewhere/anywhere else? That would be my first thought, also while it is happening (carefully) try the following.

Normal driving.
Clutch down coasting.
Under a gear.
Over a gear.
In neutral.
Gently pull the handbrake up and down with button in.
Steer left and back, right and back.
Those conditions may present a different sound/feel.
And might narrow it down.

If only that stretch of the A1 then maybe it's a sink hole waiting to happen?

[firewalker]

Can you replicate it somewhere/anywhere else? That would be my first thought, also while it is happening (carefully) try the following.

Normal driving.
Clutch down coasting.
Under a gear.
Over a gear.
In neutral.
Gently pull the handbrake up and down with button in.
Steer left and back, right and back.
Those conditions may present a different sound/feel.
And might narrow it down.

If only that stretch of the A1 then maybe it's a sink hole waiting to happen?

Lets not rule out sinkholes then
It was on totally different stretches mate, opposite directions even.

In the short time it presented itself I did try:
Normal driving
Clutch down coasting
with no noticable effect. I wondered about the clutch slipping but have had that before on an earlier Transit and it did not seem familiar and I would have expected it to worsen in the 70+ miles that followed.

I'll take it for a spin tomorrow to try your other suggestions, though as it is so intermittent not sure how to replicate it.

[Altransit]

I've had something similar in the past, and it turned out to be a misshapen tyre, that used to show up at a particular road speed on long straight stretches of road, never any other time.

It took a while to diagnose, as I didn't have a clue what it was, but to test the theory, you can try swapping tyres front to back, and see if the sensation changes at all

[firewalker]

I've had something similar in the past, and it turned out to be a misshapen tyre, that used to show up at a particular road speed on long straight stretches of road, never any other time.

It took a while to diagnose, as I didn't have a clue what it was, but to test the theory, you can try swapping tyres front to back, and see if the sensation changes at all

Aha, thanks - new tyres on a few months ago but still never had the problem until last weekend.
How was it 'misshapen'?
Is it something that can be identified while stationary?

[amlav]

Maybe it is worth looking at the drive shaft bearing . It has some rubber between bearing and the bracket and rubber can perish and dislodge making the drive shaft to vibrate (sometimes intermitently grabing or just turning in the bracket ).

[firewalker]

Thanks for all the suggestions so far.
I took it along to a tyre centre who advised that the tyres were fine.
They rebalanced a wheel and pointed out that a worn front wheel bearing might be the problem, there was noticeable play there so a new bearing will be fitted in a couple of days time.
I though I noticed the abrasive noise once or twice for a short second or two on the journey back but it was gone as soon as it came.

Hopefully that's it but I'm struggling to see how the noise initially came on then went after a short time - twice on different road stretches with no braking, turning, gear changing etc.
If the bearing was on the way out wouldn't it be a more persistent and constant 'drone' gradually getting louder?

[ned]

My first thought was a wheel bearing, I have had them grumble on and off to start with before they constantly grumble.

[twin wheel camper]

My first thought was a wheel bearing, I have had them grumble on and off to start with before they constantly grumble.

Sounds like a women starts groaning and just keeps getting worse until you replace
The wheel bearing does sound like a likely culprit I’ve had them before go quiet only to suddenly start again out of the blue
Anyway it needs changing even if it doesn’t cure the problem so that would be my first port of call.

[ned]

My first thought was a wheel bearing, I have had them grumble on and off to start with before they constantly grumble.

Sounds like a women starts groaning and just keeps getting worse until you replace
The wheel bearing does sound like a likely culprit I’ve had them before go quiet only to suddenly start again out of the blue
Anyway it needs changing even if it doesn’t cure the problem so that would be my first port of call.

I worry when the er indoors doesn't groan as I know I'm in trouble for something

[firewalker]

My first thought was a wheel bearing, I have had them grumble on and off to start with before they constantly grumble.

I've had girlfriends like that but not wheel bearings. Reassuring that it could be the correct diagnosis though, thanks

[andz327]

Yeah like Ned suggested it sounds like a wheelbearing, does the noise change slightly on bends or even goes away until your straight again then probably a wheel bearing but with it being RWD it could be propshaft related

[firewalker]

Yeah like Ned suggested it sounds like a wheelbearing, does the noise change slightly on bends or even goes away until your straight again then probably a wheel bearing but with it being RWD it could be propshaft related

It didn't stick around long enough to get a feel for what was triggering it, but the roads were relatively straight.
A dodgey wheel bearing has been replaced today, a tyre centre checked the tyres and wheel balancing are ok and diff oil level checked ok

Propshaft bearing not checked, it was more of a scraping noise and the more I think about it the more I think wheel bearing, what threw me was it being intermittent.

[andz327]

Is it sorted ??

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[firewalker]

Is it sorted ??

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Yes - did the same run last weekend, all fine.
New wheel bearing on drivers side front and tracking sorted.
The lesson then is that dodgey wheel bearings aren't necessarily identified by a constant increasing noise, they can grumble on and off!