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Discussion Starter · #1 ·
My recently acquired project is a 2004 MK1 MG ZS120+

At speeds above 40mph a drone starts which gets far worse at Motorway speeds.

To my ears it appears to come from the O/S/R wheel area.

I've been visiting Rover and MG sites for over ten years now and cannot recall ever reading of an instance of noisy wheel bearings on the MG ZS.

This is the car showing 45600 miles which the VOSA MoT history supports~



I'm fairly certain that it is the rear offside wheel bearing but I would not bet much money on that. At 70mph the noise fills the whole car so could be any one or more of the four bearings.

So, if anyone having experience with prematurely worn wheel bearings on these cars can provide details of the problem, particularly which wheel(s) were affected that will be appreciated.

I plan to get my wife who has younger and better ears than I to sit in the middle back seats and try to pinpoint where the noise is coming from. Until then it's all guesswork.
 

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YELLOW PERIL
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Not a sticky o/s/r calliper, I had sticky sliders that did the pads and disk in.

Seems quite a common fault.

After a run, feel the wheels and see if the rears feel hot.
 

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It's a big fan
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A drone around 50 mph caused by the rear tyres is quite common but it normally goes away if you speed up a bit.

Move the rear wheels to the front to see if it is the wheels/tyres or the hubs.
 

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I plan to get my wife who has younger and better ears than I to sit in the middle back seats and try to pinpoint where the noise is coming from.
Put a couple of duvets (bedding) in the back so the sound isn't bouncing around - it will make her job a lot easier!
 

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Discussion Starter · #6 ·
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At speeds above 40mph a drone starts which gets far worse at Motorway speeds.

To my ears it appears to come from the O/S/R wheel area.

I'm fairly certain that it is the rear offside wheel bearing but I would not bet much money on that. At 70mph the noise fills the whole car so could be any one or more of the four bearings.
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I love a happy ending. I was right about it being the offside rear bearing but, I would not have bet much on it. Depending on circumstances when driving around, I got the impression it could be any one of the four wheel bearings.

Anyway, X-Posted from other threads this outcome :~

A reasonably happy ending :~

This is the car with a suspect noisy rear wheel bearing. "Hum in the Bum" as some describe it in the trade.

Tackled the Offside Caliper this afternoon and the Caliper Piston was badly corroded just like the Nearside one I replaced ~ see earlier pictures. Again it works but the exposed part of the Caliper Piston looks really badly corroded. Do not like to see that and soon after Easter Holidays, I'll get a remanufactured replacement.

The two 14mm Caliper Carrier Bolts were very tight but, with careful power applied both were undone without any issues. I had sprayed them liberally with some Penetrating Fluid which may have helped. With the carrier removed, the disc was also removed revealing the Hub-Bearing Assembly. I turned it a few times but could not detect any real roughness but, I've known others to 'feel' smoother. Anyway, using a sharpened Bolster Chisel, I soon had the Hub's dust cover removed after a few taps with the Club Hammer on the Chisel. Then undone the Axle Nut with my 32 mm Socket. This revealed a mass of what looks to my eyes like COPPER BASED GREASE. Most unsuitable grease for wheel bearing use! I took a picture showing the stuff. What do others think? :~



The Stub Axle showed some patches of light surface corrosion.:~



A few minutes with some 180 grade wet and dry soon had that looking respectable. I fitted the used Hub-Bearing Assembly I got from a scrap yard Rover 400 ~ a Diesel Version which had the rear discs like the MG ZS. I used a new 32mm Axle Nut and tightened it to 133 ft.lbs. Then peened the staked Nut into the Stub Axle groove.

Used some fresh Castrol LM grease to load the replacement bearing and then cleaned up and refitted the Disc, Pads and Caliper. Checked the Brake operation both foot and hand before fitting the Road Wheel and even the handbrake operation had improved.

Now the final test. Took it for a blast down the local bypass at Motorway speeds ... nice and silent wheel bearing.

Sorted.

It says 'on the tin' of the Castrol LM Grease it's ideal for wheel bearings. So, a question. Who would pack a bearing with Copper Based Grease except by some mistake? Whatever, that old bearing was very noisy at speed.
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