Vibration - again

[Childnurse]

OK, here we go again.

I posted a query a while ago about a vibration that sets up in our Traveller as soon as it gets above 45mph. It was suggested then that it might be the wheels and/or the prop shaft.

Since then, and heeding that advice, we have had a full set of new tyres and the wheels have been balanced. We have also had the prop shaft sorted out and new UJ's put in at both ends. Took the car out again today and the problem is still there.

Any idea's? My son (whose car this actually is) is supposed to be driving it 155 miles to the Midlands tomorrow.

In desperation....

[philthehill]

When you say you sorted the prop shaft - what did you do or have done to it other than changing the UJs?

[RobThomas]

Empty rear dampers?

[firedrake1942]

Have you checked engine steady tie and mounts and gearbox steady cable. male sure all bolts holding bell housing to engine rear are in place.

Possibly wheel bearings ? If they go you should see melted grease on the wheels, at least at the front.

[Childnurse]

Thank you for the suggestions so far. It's not easy to come to a diagnosis down a broadband connection, so I am very grateful.

OK, I'm going to initially put to one side the engine steady and the gearbox steady cable. As the vibration is coming from the back of the car I will concentrate on the dampers and the wheel bearings. Then I'll work forward.

I'll let you know what I find. (Wonder where you can get wheel bearings on a Sunday..... ).

[Childnurse]

When you say you sorted the prop shaft - what did you do or have done to it other than changing the UJs?

We thought it might have become bent, but apparently it's as straight as a die - I don't know how hey test for this sort of thing, but it seems it''s in balance. We did have new UJ's fitted though, as the old ones were shot.

[Childnurse]

So here's the latest.

I suppose we should have thought of this sooner, but this morning we put the back of the car on axle stands and ran it up to an equivalent of 45mph in 4th gear. Just before it reached 40 the vibration became apparent (no road noise or other sounds or rattles). When we looked under the car the prop shaft was clearly running a few ml out of true, but the problem appears to be not the shaft, but the pinion going into the differential, which is clearly out of whack. How hard would you have to hit the pinion (or more likely the flange) to knock it out of true?

Whichever way you look at this, it is probably an expensive repair.

That said, and looking on the bright side, we have changed the oil in the dampers, put new U-bolts and bump stops on the rear axle, checked the wheel bearings and everything else suggested in your replies (for which many thanks!), so it's not all bad.

Any thoughts about the pinion would be welcome. though.

[biomed32uk]

Interesting, I can't imagine how you would bend that, unless the car has been jacked up on it.

If the bearing has collapsed I am sure it would sound awful, I reckon the best bet is to acquire a decent 2nd hand diff, I think club spares has some complete axles so that may be a way to go.

Good luck in getting it sorted.

[philthehill]

The rear flange of the propshaft has a register which fits inside the diff flange.
If the propshaft rear flange register has been fitted into the diff flange there should be no difference in concentricity between the two.
Whilst the flange may look to be out of concentricity you can only measure the out of concentricity accurately by having a fixed datum point against the diff flange and turning the diff flange and properly measuring the run out.
Do the same for the propshaft tube as close to the rear U/J as possible and see what the run out is for the propshaft.
Please post on here your findings.

I would suggest that having completed the above & having marked the propshaft and diff flange adjacent to one another you disconnect the propshaft rear flange from the diff flange - check the tightness (140 lb ft) of the diff pinion nut (it may be loose) - it the nut is tight refit the propshaft turning it by 180 degrees and see how it goes.

[pde2000]

I've just replaced the diff in my series II, so I have a nearly new 4.22 diff available. The job of swapping diffs is not so hard, just requiring new gaskets for the diff and halfshafts. My prop is now spinning off centre at the back too, and something i need to remedy immediately before it wears out the pinion bearing in the 5.375 diff. I live near you it seems, and would appreciate the details of the garage you used for the prop, and if you want to use my 4.22..

Otherwise it could be that your diff is fine and the garage that replaced the UJ's didn't get them centered properly. If the diff is broken it should be fairly obvious.

[mowogg]

has the car been in a front end collision before? I believe for the force of pushing the engine back in a crash can create the damage you are describing?

[StillGotMy1stCar]

How hard would you have to hit the pinion (or more likely the flange) to knock it out of true?

Anything is possible, I have seen a pinion shaft shear off on a Discovery by wheel spinning in the snow. When traction is gained the shock can be fatal.
Take Philthehills advise, also check for play in the pinion bearing and that the UJ circlips haven’t come adrift.
Regards John.

[Monty-4]

As others have said I think your'll have a much easier time replacing the whole diff. Standard ones are cheap, if it's noisy throw some Molyslip in.

[Childnurse]

Crikey. A wealth of information -thank you one and all.

I don't have much time right now but I will try and post a video of the rotating prop shaft if I can (anyone know how I go about doing that, by the way?).

Time is pressing, especially as we are trying to move house at the moment too, but I will certainly get back under the car and see what I can do. I have to admit that a replacement diff may be the way to go. Thank you, also, PDE2000. I used western Propshafts in Benfleet Essex: http://www.iessex.co.uk/profile/766487/ ... ropshafts/ (and thank you or your offer). Once I've had a closer look at the diff - thanks for the info Philthehill - I'll be in touch).

So a lot to do, but I will update asap.

Thanks again.

[Childnurse]

Great news!

The vibration has disappeared! A new differential (Thank you pde2000) was fitted this morning and the car taken out for a drive this afternoon. Tentatively taken above 45mph the vibration ceased to appear, so the speed was increased to around 55 and the car purred along as though it was on ice. As a result my son will now drive it to the Midlands tomorrow confident in the knowledge that his fillings (if he had any) would still be in place when he gets there.

Thank you one and all for your advice and suggestions. It will be great for the car to be out of the garage with wind in it's radiator grill!

We've looked at the old diff and it looks as though at some point the car has almost certainly been jacked up on the differential pinion. Good grief.

[biomed32uk]

Glad its sorted out, quite why you would jack it there I don't know, unless it slipped off. Inexperience by someone I suppose.