Technical Grinding noise rear left wheel - brake issue?

[capers626]

Hi all,

I've been having an issue with an intermittent grinding noise coming (only) from the rear left wheel of my 1993 Fiat Uno, which varies according to speed of rotation. This occurs when driving along but not all the time and feels like a drag effect without applying the brakes. I thought it was due to a worn out wheel bearing. However, this has been replaced and the same noise remains.

According to the mechanic who fitted the bearing, the brake cylinder is not leaking (on either side) and the existing shoes and drums are in serviceable condition. Pressing the brake pedal does not change the noise and the brakes are stopping the car as normal.

Is it possible that the nearside cylinder has partially seized without any sign of leakage or weeping behind the protective rubber boots?

Or could the noise be caused by something else such as a build up of rust on the drum?

Cheers,
Andy

 

[ZaphodB]

If you have access to a jack , you could lift that corner and test rotation yourself (with and without brakes applied)

If a mechanic who's got the wherewithall to replace a wheel bearing successfully, can't find out the source, I'd take it to another mechanic.......

Noise from a drum brake wheel is very simple, it's either the bearing or an element of the braking system...

(I was going to suggest it was possibly an ABS sensor kicking in on that corner , but it doesn't have ABS)

Is it a metallic grinding noise ?... if not could be the tyre touching the body perhaps, broken spring, but again I'd guess a mechanic capable of replacing a wheel bearing might notice something obvious like that.

 

[capers626]

If you have access to a jack , you could lift that corner and test rotation yourself (with and without brakes applied)

If a mechanic who's got the wherewithall to replace a wheel bearing successfully, can't find out the source, I'd take it to another mechanic.......

Noise from a drum brake wheel is very simple, it's either the bearing or an element of the braking system...

(I was going to suggest it was possibly an ABS sensor kicking in on that corner , but it doesn't have ABS)

Is it a metallic grinding noise ?... if not could be the tyre touching the body perhaps, broken spring, but again I'd guess a mechanic capable of replacing a wheel bearing might notice something obvious like that.

Hi ZaphodB,

Thanks for your input. Yes, on the face of it there are a limited number of brake related causes for the noise though it is intermittent. If, for example, it is down to a build up of rust you'd of thought the mechanic would have erred on the side of prepping the drum before reassembly...

I wouldn't say it's a metallic grinding noise though I could be wrong - it just sounds like something is stuck in the wrong position. According to what he said, everything is moving freely in terms of the action of the cylinder in tandem with the springs and shoes, which have little wear. He's going to take another look next week. Till then, I'm not going to risk driving the car.

Cheers,
Andy

 

[bugsymike]

It can be any number of things, the dust shield catching the brake drum,a brake shoe return spring rubbing, the hand brake balance bar between the shoes catching the hub, it could even be a bit of gravel caught in a front brake disc back plate as noises quite often are not where you may think they are coming from or a front brake pad worn down unevenly just touching metal to metal.
If you were to go for a drive , when noise occurs try very lightly touching the foot brake to see if it affects the noise, the same thing with the handbrake, not enough to slow vehicle, just enough to affect the brake mechanism.
The other thing you could try is seeing if going around a left or right hand bend affects it.
Many years ago I had a top of the range Peugeot 604 saloon with an occasional annoying rattle, just before selling it I found a spare caliper retaining clip lodged in the rear suspension from when a previous owner had work done.

 

[capers626]

It can be any number of things, the dust shield catching the brake drum,a brake shoe return spring rubbing, the hand brake balance bar between the shoes catching the hub, it could even be a bit of gravel caught in a front brake disc back plate as noises quite often are not where you may think they are coming from or a front brake pad worn down unevenly just touching metal to metal.
If you were to go for a drive , when noise occurs try very lightly touching the foot brake to see if it affects the noise, the same thing with the handbrake, not enough to slow vehicle, just enough to affect the brake mechanism.
The other thing you could try is seeing if going around a left or right hand bend affects it.
Many years ago I had a top of the range Peugeot 604 saloon with an occasional annoying rattle, just before selling it I found a spare caliper retaining clip lodged in the rear suspension from when a previous owner had work done.

Hi Bugsymike,

All useful suggestions though as I mentioned in my original post pressing the brake pedal does not change the grinding noise. I agree it is difficult to tell exactly where the noise is located but do think it is coming from the rear. Further investigation needed, ideally the mechanic will hear it from a test drive.

Cheers,
Andy

 

[bugsymike]

Hi Bugsymike,

All useful suggestions though as I mentioned in my original post pressing the brake pedal does not change the grinding noise. I agree it is difficult to tell exactly where the noise is located but do think it is coming from the rear. Further investigation needed, ideally the mechanic will hear it from a test drive.

Cheers,
Andy

Yes I did read that, but none the less sometimes those suggestions can make a change in the symptoms and help diagnosis.
Noises can be hard to locate, I always listened to what my customers said as they may not know the technical side, but as they drive the vehicle all the time, they have more knowledge in when it happens, sometimes a mechanic on his own may not even pick up the sound until the owner sat with him suddenly says "there it is".
Even recently on an old Skoda 4x4 of mine I heard a noise and it happened coincidentally as I pulled on the hand brake it failed, I put it down to a broken cable rubbing something, in the end when jacked up there were two faults, a rear self adjusting handbrake caliper accounting for the sudden extra handbrake travel and a propshaft rubber donut reinforcing band that had broken away from it's metalastic bush and touched the car chassis as you slowed down giving the rubbing noise, both oddly happening at that same time.

 

[capers626]

Yes I did read that, but none the less sometimes those suggestions can make a change in the symptoms and help diagnosis.
Noises can be hard to locate, I always listened to what my customers said as they may not know the technical side, but as they drive the vehicle all the time, they have more knowledge in when it happens, sometimes a mechanic on his own may not even pick up the sound until the owner sat with him suddenly says "there it is".
Even recently on an old Skoda 4x4 of mine I heard a noise and it happened coincidentally as I pulled on the hand brake it failed, I put it down to a broken cable rubbing something, in the end when jacked up there were two faults, a rear self adjusting handbrake caliper accounting for the sudden extra handbrake travel and a propshaft rubber donut reinforcing band that had broken away from it's metalastic bush and touched the car chassis as you slowed down giving the rubbing noise, both oddly happening at that same time.

Yes, ideally the test drive will take place with the mechanic and me in the car as the last time the noise was present he couldn't hear anything from outside and then it stopped all by itself! As the grinding is intermittent but regular (in the sense that it keeps cropping up randomly), I don't think a stone is likely to be causing the issue but stranger things have happened...