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[damon80]

Hi Folks,

I've been away for a while, so sorry about that :-(

I've mentioned before on here about some noises/vibrations coming from my Miggy.  Long story short, last time around, some of the suggestions were...:

Exhaust (at the time, my exhaust was on its way out.  It's since been replaced, and the noise is still there).

Wheel balancing (had all wheels balanced, and noise is still there...)

Suspension/Bushes (just had it MOT'd, and it flew through.  A mate of mine is an MOT tester (but he's a strict bugger lol) - he let me have a ganger underneath, and he showed me how new all the bushes and shockers are.

Prop Shaft (why I was underneath, I had a bit of a rummage with the prop, but there didn't seem like there was any undue play in it)

Diff (again, why I was underneath, had a good look around the diff area, and there was no sign of leakage whatsoever).

But still, the grumbling noise is there :-(  I'll have another do at describing it...

Round town, and up to 50/55mph - no noise.
On motorway - foot down accelerating - no noise.
On motorway - foot on accelerator, at (ahem, officer lol) 70mph - no noise.
On motorway - foot off accelerator above 60mph - grumbling noise.
On motorway - foot off accelerator above 60mph, with the clutch pedal fully down - grumbling noise.

The last point leads me to believe that it ain't the prop or its associated bearings.

Other than than that, I is stumped :-(

Any adivce/suggestions would be appreaiated :-)

[p j morgan]

sounds like it could be your thrust bearing on your clutch? try it with your engine ticking over .press your clutch peddle down and listen for a whineing noise,!

[gstylebaby]

Can you tell which side it is coming from and does it start off at a certain level and slow down as you are slowing down (if that makes sense). Also is it more like a whining noise ?

[damon80]

sounds like it could be your thrust bearing on your clutch? try it with your engine ticking over .press your clutch peddle down and listen for a whineing noise,!

There is a bit of a whine from the clutch release/thrust bearing when in neutral, but only when the clutch pedal is released.  Noise goes when I press the clutch pedal.  It's not really noticable, and it's a totally different noise than the noise I can hear from the back end when on the move...

[damon80]

Can you tell which side it is coming from and does it start off at a certain level and slow down as you are slowing down (if that makes sense). Also is it more like a whining noise ?

Nope, definately not a whining noise, it's a grumbling noise.  And yes, the noise "slows down" as the car slows down.  Below 60mph, it stops making the noise.

It's really got me stumped has this, and is really bugging me now    It's almost ruining my enjoyment of the car 

Any help/advice would be appreciated as always folks 

[Marks DTM Calib]

Has it got any oil in the diff (BOA90LS as its ex-plod)

[damon80]

Has it got any oil in the diff (BOA90LS as its ex-plod)

Not checked the diff oil level - but no sign of any leaks?

How do I go about checking the level? 

[Ken L]

If the noise is comming from the rear it would seem likely to me that it is the dif, some play in the internals that is being taken up whilst under pressure from accelerating, and not noticible at slow speeds, if it is, changing to oil wont make any difference, and it will likely cause no other problems, just anoying, another diff?

[Andy H]

My 1994 V6 had me convinced that the rear wheel bearings were shot when the two inner rear brake pads rusted/seized in the brake calipers.

Because they hadn't moved for ages the inner faces of the rear discs were rusted and pitted. The pads were barely in contact with the discs but if you changed direction slightly while driving on a quiet road surface it did sound as though something expensive was about to go wrong.

In normal driving the rear discs don't really work hard enough to keep the discs clean. I tried freeing up the pads (which helped) but the problem didn't really go away until the MOT tester used his size 12 boot on the brake pedal while it was on the roller brake tester 

[damon80]

My 1994 V6 had me convinced that the rear wheel bearings were shot when the two inner rear brake pads rusted/seized in the brake calipers.

Because they hadn't moved for ages the inner faces of the rear discs were rusted and pitted. The pads were barely in contact with the discs but if you changed direction slightly while driving on a quiet road surface it did sound as though something expensive was about to go wrong.

In normal driving the rear discs don't really work hard enough to keep the discs clean. I tried freeing up the pads (which helped) but the problem didn't really go away until the MOT tester used his size 12 boot on the brake pedal while it was on the roller brake tester 

Don't think it's that Andy, as rear brake discs have no marks on em whatsoever...  And plus you can still hear the noise when braking (well, until it goes below 60mph, which is when the noise stops anyway)

[damon80]

If the noise is comming from the rear it would seem likely to me that it is the dif, some play in the internals that is being taken up whilst under pressure from accelerating, and not noticible at slow speeds, if it is, changing to oil wont make any difference, and it will likely cause no other problems, just anoying, another diff?

I was hoping this wouldn't be the case! 

Got bob and no hope of locating a fresh LSD for my Mig I take it?

So just a case of putting up with it then?  (Unless anybody else has any ideas??)

[Andy H]

My 1994 V6 had me convinced that the rear wheel bearings were shot when the two inner rear brake pads rusted/seized in the brake calipers.

Because they hadn't moved for ages the inner faces of the rear discs were rusted and pitted. The pads were barely in contact with the discs but if you changed direction slightly while driving on a quiet road surface it did sound as though something expensive was about to go wrong.

In normal driving the rear discs don't really work hard enough to keep the discs clean. I tried freeing up the pads (which helped) but the problem didn't really go away until the MOT tester used his size 12 boot on the brake pedal while it was on the roller brake tester 

Don't think it's that Andy, as rear brake discs have no marks on em whatsoever...  And plus you can still hear the noise when braking (well, until it goes below 60mph, which is when the noise stops anyway)

OK
Another idea...
My old Range Rover has a prop shaft about 5 feet long. When the splines got worn it was fine on the motorway while I had my foot on the throttle, because the slack in the splines was taken up, but the moment I lifted off I was convinced that the gearbox was about to fall out.

Not saying it isn't the diff but... the centre CV joint could be behaving like the worn splines on my Range Rover. Because of the way a CV joint works if the balls or the grooves become damaged the free play comes and goes as the damaged balls move around so a quick waggle test isn't always conclusive. It really needs to be exercised over the full range of movement it is subjected to in use to see if there is any slack or roughness.