Drive Shaft Noise - Intermediate Bearing?

[rg]

Folks,

And here's the next snag... !

There's a a "zubb-zubb-zubb-zubb" noise audible from the driver's side drive shaft area. It's only feint at the moment and louder at certain speeds, such as 30mph in 3rd/4th. The wheel bearing is almost new on this side, and I'm familiar with wheel bearing noise, having tolerated it for a while last year.

There's not the classic "clack-clack-clack" of a worn CV joint on certain locks, so I'm wondering if this is the intermediate bearing.

Are they known to fail at 180K, and are they a pain to replace? I've had a bit of a read-up, but I'm still unclear.

r

[noz]

Hi Rob,

Is the frequency of the noise related to road speed or engine speed?

noz

[Peter.N.]

I had a centre bearing fail completely without making a sound - well not one I could hear anyway. If its at road speed as Noz asks, have you tried the usual wheel bearing test of transfering the load from one side to the other? Could still be the wheel bearing

Peter

[rg]

Hello chaps,

The noise is most certainly "road speed", and not as heavy as a wheel bearing. It's more a "tap" than a "rumble". As I mentioned above, I had to replace the bearing on that side recently, and was familiar with the frequency, and characteristic change in noise with steered direction.

Are there any useful ways of checking play with the shaft on the car? Is there normally any discernible play?



r

[xmexclusive]

Hi Rg

If the centre bearing is well worn then it allows the shaft to oscillate about its centre line.
That generates rapidly changing out of balance loads.
The effect is most noticeable on heavy acceleration with the steering set straight.
Front of the vehicle can then hunt (repeated rapid lateral oscillations).
Hunting is a railway engineering term where a vehicle bounces back and forth between the rails instead of running true.

John

This post has been edited by xmexclusive on October 03, 2012 08:32 am

[rg]

John,

Many thanks. It's not causing any hunting under power, just noise at the moment.

I have a railway interest and preservation movement background, and used to endure high-speed "hunting" of bogies on elderly BR Mk1 stock on the Derby-Birmingham line!

I suspect that I'll need to let the noise get a bit worse to allow a full diagnosis.

r

[citroenxm]

QUOTE (xmexclusive @ October 03, 2012 08:31 am) 

Hi Rg

If the centre bearing is well worn then it allows the shaft to oscillate about its centre line.
That generates rapidly changing out of balance loads.
The effect is most noticeable on heavy acceleration with the steering set straight.
Front of the vehicle can then hunt (repeated rapid lateral oscillations).
Hunting is a railway engineering term where a vehicle bounces back and forth between the rails instead of running true.

John

Had this on my V6 12v SEi, she had a rather violent sideways motion under accelleration, I put it orginally to bent drive shafts (discovered on a Xantia previously) however after investigation the intermediate bearing was non exsitant!!

Theres enough "slack" for the shaft to move in the event of the bearing missing etc.

After a replacment shaft was fitted smoothness was restored.

The bearing in the meantime during disintigration made no noises... It just disapreared..

[techmanagain]

With respect - you appear to have had work done on the front wheel/hub assemblies recently; have you considered something simple, like a badly fitted brake pad or even something so simple as a piece of grit lodged in there?
No point in looking for a complicated solution if you have not checked the easy ones first.

[rg]

Thanks for the suggestion! I'm all for simple fixes and a lack of over-reaction.

I will, indeed, take a look to see if anything is chafing, but the frequency of the noise makes it sound more like something on the actual shaft, rather than the slightly faster frequency of a disc or wheel.

r

[noz]

Rob,

Can you jack up the car, one side at a time. Chock the back wheels. Release the parking brake. Start the engine. Engage 5th gear. Let out the clutch slowly. The wheel should spin at a rate high enough for you to search for the source of the noise. You could try raising the revs slightly until the noise can be heard at its clearest.

Be aware that when you try this, the wheel which is off the ground will be going at a speed equivalent to twice the speedometer reading. Do not go above half the rated speed of the tyre when read on the speedo. It is likely you will not need to go anywhere near that speed to hear your noise.

If the noise appears to be coming from a location near either wheel, try removing the wheel itself and repeating the above procedure.

When searching for noises I usually use a long, thin piece of wood (like a bit of dowelling for example) or a piece of threaded rod or other long thin piece of metal. By placing one end on the (non-rotating) item, usually the bearing housing or such-like and the other end on the flap just to the front of your ear and pressing hard so that the sound passes into your skull, it acts as a stethoscope. As a technique, its surprisingly accurate and has served me well.

cheers

noz

[sdelasal]

Rob - you said "but the frequency of the noise makes it sound more like something on the actual shaft, rather than the slightly faster frequency of a disc or wheel" ... - actually, the wheel will be rotating at the same rotational speed (e.g. rev/min) as the drive shaft... Steve

This post has been edited by sdelasal on October 07, 2012 11:06 am

[kenhall1202]

Precessional motion of a worn out mid shaft bearing within the housing could happen at a different frequency to the shaft / wheel rotation frequency.

Ken

[rg]

Apologies, folks - I've just picked this one up as the email notification is not working.

Thanks for all your replies. More investigation, I think.

Noz., there may be a duplicate thread from me running on this topic. You are welcome to combine them/delete the newest one

r

[rg]

Bearing replaced, but noise persists. Drat.

The wheel bearing seems fine, utterly silent and with a little bit of healthy resistance when spun. And the noise, although affected by lock, is not as heavy as with a wheel bearing.

The caliper is quite worn on the pin, and I'm wondering if this is "hunting" and causing the noise. It has quite a lot of lateral play, and the stiffness of the parking brake cable may cause the hunting characteristics to differ with change of lock as it puts pressure on the caliper.

Any thoughts, chaps?

Any would I be best to replace pin and caliper, or is the wear usually just in one component?


r

P.S. - Just run car with parking brake partially applied, and noise persists. So this probably denies my theory.

Has anyone else had a new wheel bearing (supplied by AEP Glasgow) fail?

This post has been edited by rg on February 27, 2013 11:40 am

[noz]

Hi Rob,

I know of three possible causes of premature failure in front wheel bearings:

Sticking master Brake Cylinder
The RH Drive 2.5TD XM has the master cylinder in the scuttle area below the windscreen. This area is subject to everything the weather and road can throw at it. The return spring in the cylinder is not strong enough to overcome the additional friction of the corroding joints in the pedal mechanism. Thus, the brakes are kept slightly "on" when they should be off. The ports in the piston inside the cylinder are so located that the port for the front drivers brake caliper is exposed first which makes this one prone to being kept on. This makes the brake pads drag on the disk and causes the pads, caliper, disk and hub to heat up and run hot. This eventually goes for the grease and dries the bearing out eventually causing it to fail. Air bubbles in the brake line can also cause this to occur because the expanding air bubble keeps the brake on when it should be off.

Removing a Brake Disk
When the brake disk gets to the point of replacement the first thing you have to do is get the old one off. However, if it has not been off for a very long time then it will be stuck to the hub flange. In addition, the hole at the back of the disk through which the hub flange passes has plenty of clearance when new. After the disk has rusted considerably the hole closes up until it is smaller than the hub flange diameter preventing the removal of the disk. The natural thing to do is to hit the disk with a hammer to free it. However, each hammer blow is transmitted through the balls in the hub bearing causing the bearing races to become indented. The indentations in the race eventually wear the ball bearings causing premature failure of the whole bearing.

Replacing the Bottom Ball Joint
Of my 3 2.5td XMs I've replaced all 6 Bottom Ball Joints. Maybe I have just been unlucky. Maybe they are undersized for the forces they are required to transmit. In any case, getting the old ones out is an absolute B%^&*$. The threads on the mild steel ball joints seize into the threads on the cast iron hub assembly. The only way I've found to get them out is to heat them. The only problem is that it cooks the grease in the bearing and causes the bearing to fail prematurely.

Out of my 3 2.5TD XMs I've replaced 5 out of the 6 Wheel Bearings. Again, am I unlucky or are the wheel bearings undesized for the load they must carry?

I take it that none of the plastic inner wheel arch liners are rubbing on the driveshafts or on the outer edge of the tyre? Does the note of the noise change when you turn a corner? Did you try my stethescope method above to try to track down the source of the noise?

Hope that gives you food for thought.

cheers

noz