Bang, Clatter but nothing obvious

[Barreti]

Excuse my ignorance Taz Turbo. But wouldn't we get stuff either in the diff oil or stuck to the magnetic drain plug on the diff if it was this then?

[NiceCupOfTea]

Chatting to Nick (ncs) the other night he had a similar bang on his Griff a while back - I think he said it was a pulley bolt shearing which led to something expensive. Somebody had something similar with a Chim recently ISTR.

[Steve_D]

NiceCupOfTea said:

Chatting to Nick (ncs) the other night he had a similar bang on his Griff a while back - I think he said it was a pulley bolt shearing which led to something expensive. Somebody had something similar with a Chim recently ISTR.

Pully bolt would perhaps bang then clatter as it passed under the car but would not produce noise for the rest of the trip.

Prop shaft UJ gets my vote. The vibration was it out of balance as the needle bearing broke up. The scuff marks are it running out of true.
I know you have checked but I would check again particularly as you say there is some play. A good joint will have no play you can discern by hand.
Try both twisting the joint and push/pull in each plane of the joint.

Steve

[taz turbo]

Barreti said:

Excuse my ignorance Taz Turbo. But wouldn't we get stuff either in the diff oil or stuck to the magnetic drain plug on the diff if it was this then?

Exactly the same symptoms as you experienced, again on a 4.3BV, drained the Diff. oil all looked good with nothing nasty in the oil.

Found a concerning amount of movement on the input flange (millimetres not hundredths) , replaced the Diff and all was good again.

Good luck.

Chris.

[Simon says]

Trouble is if the pinion front bearing as failed on the GKN then the shed material from the bearing will stay in the nose of the diff (you cant drain that area) so when you drain the diff you will be lucky to remove any swarf if any basically the drain plug is not in the lowest part of the diff on the GKN but of course this wont be Barreti's problem we hope

[Cerberus90]

Barreti said:

Oh yes. I forgot.

The other check I did on the drive shafts was to pull/push in and out - and there is movement but no grinding or odd noises.
And I tried to push them up/down but they are nice and tight.

Currently the car is on stands so the wheels are hanging. In case it makes any difference.

Next step - diff oil and road test I think, but I'll happily check for anything anyone suggests.

You know when you start to wonder if you really did hear something ?

No, I certainly did. And you could hear it very obviously when I went under the bridge coming home.

Could it have been from another car???


Stone or small piece of metal or something flicked up off the road and bounced round the arches, or underneath and off the exhaust??

[Barreti]

An update chaps, though sadly still no resolution.

I couldn't find anything wrong after inspecting/pulling/pushing/turning everything I could see or get my hands to under the car.

So with the back wheels off and the car on axle stands I started it up. In both neutral and throughout the gear range. I drove it through every gear, to approx 3000rpm and an indicated 40mph in 5th gear. And did this test a couple of times with the engine off between the 'runs'

There was nothing. Not a squeak - other than from my bum! Being sat 3ft in the air in my garage with an indicated 40mph is a bit cheek clenching!
In fact it sounded better than ever because I've probably refitted the exhaust better.

I've now road tested it and the noise was evident before we even got off the drive.

So here is what we found

The noise is only there under load but it is obvious as soon as I start to move.
It disappears when freewheeling both with the clutch depressed and the car in gear or with the car in neutral.
The noise is NOT evident when the car is travelling in reverse at up to approx 10-15mph
The noise DOES NOT change if the car is driven around left or right corners.
The noise has a definite rhythmn.
It isn't a metallic rattle as I said earlier, it is a thump thump.
It sounds a bit like a chug chug as if the exhaust is blowing. BUT ITS NOT THE EXHAUST.

It sounds like an old steam road roller driving down the road!

I think it might be the rear propshaft UJ
Does this sound like a fair guess?

[Simon says]

Could be prop related Ian but don't dismiss those CV joints yet this used to be a common failing on Granada both MK2/3 outer joints (the same) thump, thump ,thump under power or load,CV's normally the culprit and no amount of pulling or pushing them will show up the problem i.e faulty flawed ball bearings or ball tracks it just happens you could try reversing the drive-shafts this often cured the Granada problem when customer was on a budget you will not recreate the problem with the car in the air either

[GAjon]

Have you checked for any tyre deformation? They can sound like a failing CV joint.

[Barreti]

Definitely not a tyre. Not this much noise. And it disappears as soon as you drop out of drive. But thanks for the suggestion.

Simon, how do I know where to start with the CV joints then?

[carsy]

I am with simon on this one. Its easier to check cv's than diff so start with cv's. I think you are going to have to take each drive shaft off and inspect them properly. Its going to be cv or diff , heres hoping its a cv.

[DarkMatter]

As you said you detected a little play in one of the prop-shaft UJs I'd suspect that before the CV joint, not too difficult to remove the prop after removing the exhaust and rear a/r bar (if you have one).

As the prop rotates at a different speed to the drive shafts the frequency of the thump thump should give you a clue as to whether it is prop or drive shaft related.

[Simon says]

Agree with the last 2 posts Ian, I think you may have to have a strip down may of been covered already but are you sure the prop is not banging on the exhaust through there being excess movement in a prop UJ ? I am still with the failing CV joint though if they are swapped round to run in the opposite direction the problem normally never reoccurs

[Ribol]

Like the others I would have said prop/half shafts but if the prop UJ was this bad surely it would have lateral movement and it would have been spotted when you checked it?

If it was a half shaft then with the level of noise you describe it would very much be coming from one side, which you haven't mentioned?

So, just to be different, has anyone suggested an engine mounting gone causing something to touch (prop?) where it didn't use to?

[V8 GRF]

Wheel bearing on the way out but only showing symptoms under load?

[PoleDriver]

To investigate:-
Jack car up.
Put into gear.
Get someone to hold one back wheel while you try and turn the other.
Look for any play from wheel to diff to propshaft to gearbox.
Do the same for the other side.
If this doesn't reveal any play try rocking the wheels with your hand at top and bottom then again at left and right. This should reveal any wheel bearing problems.

HTH

[rev-erend]

As the exhaust etc is off - you might as well check the front pinion nut is tight .. as this is know to loosen with a collapseable crush bearing.

Use a pen or chalk to mark the prop / axle then undo the 4 prop bolts.

Move the prop to one side, and check the large pinion bolt is tight. Someone might need to press the foot brake while doing this ..

Remember to align the prop with the chalk marks afterwards.

It's only 4 bolts so does not take long and eliminates a common problem on the Griff.

p.s. I think what your mate in the Chim actually said was - is your handbrake on .. because you could not keep up with the superior car

[Brummmie]

Mine made a racket under load when i snapped teeth off the C W..



I only found the teeth in the casing when i stripped it.
Does it sound rhythmic and increase with speed?

[rev-erend]

Snapping teeth like that is often caused by the pinion nut being loose.

[Brummmie]

rev-erend said:

Snapping teeth like that is often caused by the pinion nut being loose.

Everything was tight, it took a hoooge bar to do it up to compress the crush washer. this was 2 years of abuse maybe?

I have a half inch bigger CW in there now..

so far so good.