Rubbing noise

[ninjag]

I've got a strange rubbing noise coming from what seems like my front o/s wheel and can't figure it out. It's can get quite loud at times and it's not a constant noise so don't think it's a wheel bearing, but it's a rhythmic one so I'm more inclined to think pad related.

One of the caliper slide pins in the front o/s was sticking due to light corrosion in the hole, so I've buffed it up, cleaned and lubed so it all moves freely now. I did the same for all the other corners. Brembo discs and pads all round, tons of pad left and barely any lip on the discs. There's nothing catching the discs etc.

Front calipers never get hot, just a little warm. Rear calipers get warmer but I think that's down to the torque vectoring system.

After jacking up and inspecting everything looks fine. When spinning the wheel you can slightly hear it but can't spin it fast enough to really get it going. But all the other corners make a similar noise, but again difficult to tell as I can't rotate them fast enough.

Could it just be the pad material making this noise or could the sticking slide pin have caused damage to the front o/s disc or pad? The discs doesn't seem warped, but I never checked the pad to see it was still perfectly flat or if the sticking slide pin could have caused uneven wear on it somehow?


Cheers

 

[ninjag]

Forgot to add, when wet it doesn't seem to make the noise, same for when I get hose the wheels and drive off, takes about 5 mins before returning.

 

[spartacus 68]

It’s quite difficult to determine wheel bearing with wheel still on unless the bearing is absolutely shot and there’s lateral movement. You can strip off caliper and disc until you’re down to the hub, and then rotate by hand. With bearings on the way out, find the best road you can with decent surface and drive at 50mph - you will hear constant drone If bearing is worn. It will get louder as bearing gets worse.

On calipers, again if slide pins were potential culprit, then don’t forget potential issue with aluminium oxide corrosion than swells the rubber dust cap boot on the piston and causes sticking. I rebuilt the calipers all round after I had one sticking caliper. Autodoc sell rebuild kits. I used Budweg parts, including overhaul of rears, removing electro-mechanical handbrake. Use red grease to lightly lube before rebuilding piston in the bore with new square brake seals, of course cleaning off all corrosion on the caliper first with wire wheel.

 

[rum4mo]

Is there not a drive shaft support bearing in there somewhere, I know that my 2011 S4 used to make a very slight rubbing noise for a mile of so but nowadays it possibly makes it all the time, though you need to try hard to hear it.

The brakes get cleaned up every other year and I'm sure that the floating guides remain free between "clean ups", I've tried applying the brakes to hear if that changes or kills that slight rubbing noise, but it doesn't.

I'd put it down to happening once every wheel revolution, so that is why I'm thinking that it is related to the drive shaft (intermediate) support bearing.

 

[ninjag]

Is it the grooved ball earing you are referring to in this diagram (item 11)? It does sound like once every revolution with mine as well. However, the noise goes away when I jet wash the wheels?

 

[rum4mo]

I've never actually looked into this very deeply, I just stick with worrying about it, slightly!

If it disappears when you wash the wheels, it does sound more like a braking issue with that wheel.

Edit:- I have yet to change to Summer wheels and tyres, I'll check that everything is moves freely when I do that and post my findings.

Another Edit:- maybe even the dust cover for the wheel bearing assembly that is located on the inner side of the hub bearing - if there is one, and maybe the same for my car!

 

[ninjag]

Ah, I have All Seasons on (regrettably) and the mechanic at work thinks it could be the tyres, but the noise just doesn't sound right to be tyres.

But you've got me thinking, I've been poking around heat shields underneath around the suspension to secure them up and stop the rattling due to rusted bolts. There's a heat shield on the driver's side between the suspension arms and the engine and it was a pain to squeeze back in. I wonder if it's rubbing against something and when I spray water in there it would probably cover the shield as well.

I'll need to get it up on the lift again.

 

[rum4mo]

There is, I seem to remember a shaped shield that fits in there, but it gets pinned into place does it not, so as long as the dowel pins(?) are still there and securing it, it should not be that that is touching the exposed shaft.

I did swop wheels/tyres over and every thing on the front brakes of my S4 are still free to move.

All-seasons or Winter tyres causing that noise - I don't buy that reasoning, okay some All-season or Winter tyres can cause a bit of moaning/droning under heavy braking or almost bearing whine, but so far, on both my previous 2000 VW Passat 4Motion and my wife's current 2015 VW Polo, the whining/droning noises first noticed when the Winter tyres were on both cars, continued when I swopped to Summer tyres - and both times it was front wheel bearings.

I was just adding that bit in though your problem does not sound like it has anything to do with front bearings - hopefully.

 

[ninjag]

When I was last under doing the other heat shields, that one next to the steering column was able to bang against something so I bent it back a little. I never checked further forward though, but when I think about it I don't think it can be the problem because I would expect that to be a constant rubbing noise, but the noise is cyclical.

I've just had it MOT'd today with a full clean bill of health, no advisories etc, so hopefully nothing safety related! lol I'm at 80k miles now and whilst it's only been 20k since the last DSG fluid change, it was the first time it was done so I'm going to do it again now. I'll have a closer look whilst it's up on the lift.

 

[ninjag]

The noise has gone away, so I'm going to assume it was the front sticking slide pin must have reshaped the pad and it's now flattened itself. Or something like that lol

 

[Simon]

I can't recall what car it was but I had a droning noise once so i took it to my usual mechanic (who was very good) because i was convinced it was a worn wheel bearing. he handed it back to me and told me it was the tyres. I assumed he just didn't want to do the work so got in an **** with him, the noise didn't get any better or worse so I just put up with it. fast forward a few months and I replaced the now worn out tyres, drove away from the fitting place and the drone was gone...

I did call him and make my apologies

 

[ninjag]

Yeah my All Season tyres do have a lot more road noise than the Eagle 5's from before, but this was a rubbing noise and coincided with the rotation of the wheel so I was 100% sure it was brake related. Either way, I'm glad it's gone! On to another DSG fluid change and the engine oil whilst I'm at it as soon as the parts arrive.

 

[ninjag]

The noise came back not long after the last post and stayed despite checking all four corners thoroughly. I finally tried not using the EPB when parked up and the noise disappeared when driving afterwards, so I tried this for a few days and no noise I then parked up yesterday and applied the EPB then later on drove off and immediately the noise is back.

So, now that I know the EPB is causing it, I need to work out what exactly is happening. There are no warning lights etc and it works as expected. I was wondering if the EPB wasn't retracting properly under normal operation, but if that were the case then not using the handbrake at all wouldn't have made any difference as it would still be stuck in the wrong position and I suspect a flashing red handbrake light would come on.

Could the EPB be clamping too hard and causing the pads to stick in place? This could explain why braking doesn't cause the noise to go away, but then surely the force from regular braking would also cause the pads to stick in place (for when not using the EPB)? The only other thing I can think of is the EPB is somehow interfering with the piston that isn't happening during normal braking.