Annoying droning noise from the brakes

For classic Porsche 911 content

Moderators: hot66, impmad2000, Barry, Viv_Surby, Derek, Mike Usiskin

Peter Roberts
Married to the DDK
Posts: 299
Joined: Wed Sep 08, 2004 1:23 pm
Location: South Wales

Annoying droning noise from the brakes

Post by Peter Roberts »

My long stored 911T has ben back on the road for a few months after a very long lay up. It has developed a nasty noise after a few miles from cold which i believe is coming from one of the discs. Pads are all good and it is not a scraping noise but a low pitched drone accompanied by a vibration that can be felt through the steering wheel. It varies from being just audible to being loud enough to be heard by people outside the car. It is not there all the time and if i just touch the brake pedal it stops only to retrn after a few hundred yards. Rocking the streerind wheel from side to side and a fast roundabout will induce the noise and a shart left turn reduces it. The brakes do not squeal when applied normally so i do not put it down to pad material.
I have stripped out all the padsto ensure they are loose in the calipers and have applied copperslip. Checked the pistons are not sticking and checked for free wheel rotation after applying the brakes so pistons do release.. Front wheel bearings are set correctly with no excess play.
I have tried free wheeling in and out of gear but it is definitely coming from the brakes.
Any Suggetions please?
356SC
911T
Wide bodied 3.2 Carrera Targa ( cashing in pension now sold)
928GTS (now sold)
Carrera C4S ( now sold)
Carrera 4 with Techart ( now sold)
944 race carfor track days ( Now sold )
1978 Mini Clubman Estate restoration complete
User avatar
MikeB
Put a fork in me, I'm done!
Posts: 1904
Joined: Thu Aug 07, 2008 11:13 pm
Location: N. Ireland

Re: Annoying droning noise from the brakes

Post by MikeB »

Could it be a wheel bearing? Jack the front up and give the wheel a spin to see if the bearing roars and check for any wobble
Cheers

Mike

RS Rep 3.0 on Webers
Nine One One
Put a fork in me, I'm done!
Posts: 1619
Joined: Fri Mar 01, 2013 11:45 am
Location: Kernow - good old Cornwall

Re: Annoying droning noise from the brakes

Post by Nine One One »

Agree it may well be wheel bearings, don’t forget when the weight of the car is on them, they are under load, more so with the car jacked up, and trying them then. If it has been laid up for a long time, its worth taking them apart and regressing them?

https://www.youtube.com/watch?v=7Kq1W-s-ivQ
Peter Roberts
Married to the DDK
Posts: 299
Joined: Wed Sep 08, 2004 1:23 pm
Location: South Wales

Re: Annoying droning noise from the brakes

Post by Peter Roberts »

I have checked the wheel bearings ( i have had the wheels off enough times trying to sort this out) and there is no play. i am familiaar with wheel bearing noises which are more of a rumble than a droning noise. I am also aware that when you load up the bearings under cornering it exagerates the rumble but this is not the same type of sound. Its more like something is dragging on the brakes but i have exhausted all the checks i can do with the pads and pistons. Also it was not there before i laid the car up but is there now so a wheel bearing would have shown up previously. However like all mysterious noises if i cannot find any other reason the bearings will come out for checking as i want to put the car up for sale.
Thanks for your feedback
356SC
911T
Wide bodied 3.2 Carrera Targa ( cashing in pension now sold)
928GTS (now sold)
Carrera C4S ( now sold)
Carrera 4 with Techart ( now sold)
944 race carfor track days ( Now sold )
1978 Mini Clubman Estate restoration complete
Strictly
DDK slapper chatter
Posts: 432
Joined: Mon Jan 07, 2008 4:08 pm
Location: Newquay, Cornwall

Re: Annoying droning noise from the brakes

Post by Strictly »

Check your brake disc for run out (warpage), that would give a vibration or "judder". Better to measure, but your might be able to eyeball it by spinning the disc while focusing on a fixed reference point, such as disc to caliper
911hillclimber
Nurse, I think I need some assistance
Posts: 18858
Joined: Mon Mar 10, 2008 6:26 pm
Location: West Midlands

Re: Annoying droning noise from the brakes

Post by 911hillclimber »

Front or back or difficult to say?

Fronts, nothing there really, you have done it all but you say the steering carries this vibration, so warped disc is a good idea.
Backing stone guard touching onto the disc?

There is not a lot left assuming the bearings are good.
I might be tempted to try the wheel bearing set loose, say 0.5mm play at the tyre and see if that changes anything. I have run my 73T with more than that for a year and no noises.

The rear brakes have the addition of the handbrake and the CV joints etc, but try the fronts first?
73T 911 Coupe, road/hillclimber 3.2L
Lola t 492 / 3.2 hillclimb racer
Boxster 987 Gen II 2.9
Bruce M
Me and DDK sitting in a tree! KISSING
Posts: 2746
Joined: Fri Aug 27, 2004 1:07 pm

Re: Annoying droning noise from the brakes

Post by Bruce M »

Are the tyres shot or flat spotted after the long term storage?
Peter Roberts
Married to the DDK
Posts: 299
Joined: Wed Sep 08, 2004 1:23 pm
Location: South Wales

Re: Annoying droning noise from the brakes

Post by Peter Roberts »

New tyres fitted after the lay up due to thier age
356SC
911T
Wide bodied 3.2 Carrera Targa ( cashing in pension now sold)
928GTS (now sold)
Carrera C4S ( now sold)
Carrera 4 with Techart ( now sold)
944 race carfor track days ( Now sold )
1978 Mini Clubman Estate restoration complete
gridgway
Nurse, I think I need some assistance
Posts: 5715
Joined: Tue Sep 02, 2008 10:59 pm

Re: Annoying droning noise from the brakes

Post by gridgway »

Have you bled the brakes? Can't for the life of me think it could be related, but the fluid might be past its sell by date after a long lay up.
Peter Roberts
Married to the DDK
Posts: 299
Joined: Wed Sep 08, 2004 1:23 pm
Location: South Wales

Re: Annoying droning noise from the brakes

Post by Peter Roberts »

I have bled the brakes several times whilst trying to resolve thsi proplem so brake fluid is as good as changed. One of the characteristics is that it does not happen for the first several miles from cold but none of the brakes are binding. I have a lift so have put the car up in the air after a run whilst still hot and wheels are free
356SC
911T
Wide bodied 3.2 Carrera Targa ( cashing in pension now sold)
928GTS (now sold)
Carrera C4S ( now sold)
Carrera 4 with Techart ( now sold)
944 race carfor track days ( Now sold )
1978 Mini Clubman Estate restoration complete
911hillclimber
Nurse, I think I need some assistance
Posts: 18858
Joined: Mon Mar 10, 2008 6:26 pm
Location: West Midlands

Re: Annoying droning noise from the brakes

Post by 911hillclimber »

But are the discs true?
73T 911 Coupe, road/hillclimber 3.2L
Lola t 492 / 3.2 hillclimb racer
Boxster 987 Gen II 2.9
Strictly
DDK slapper chatter
Posts: 432
Joined: Mon Jan 07, 2008 4:08 pm
Location: Newquay, Cornwall

Re: Annoying droning noise from the brakes

Post by Strictly »

It could also be the brake shims maybe, or maybe the orientation of the pistons. I'm a bit rusty, but im thinking the pistons had a specific angle for orientation. You can solve the problem for sure. Here is what I would do, swap your calipers from left to right. If you can move the noise from one side of the car to the other, ditch the "noisy" caliper and fit a new one. If you cannot move the noise, then you can rule out the caliper with pads in it. Try again with the disk etc. Sure all messy work, but if you want to solve it, and it is really not obvious the only way is to "mess around" with the "variables" until the culprit shows its face.
gridgway
Nurse, I think I need some assistance
Posts: 5715
Joined: Tue Sep 02, 2008 10:59 pm

Re: Annoying droning noise from the brakes

Post by gridgway »

An alternative but on the same theme, borrow a pair of calipers to try. Change one at a time.
Looking for things that have changed since before storage, the tyres have changed. So borrow a pair of front wheels and try them (no idea what the problem might be there, just that it's something that changed). Obviously if it made the noise on the old tyres, then don't bother.
Maybe do the same with the dampers?
911hillclimber
Nurse, I think I need some assistance
Posts: 18858
Joined: Mon Mar 10, 2008 6:26 pm
Location: West Midlands

Re: Annoying droning noise from the brakes

Post by 911hillclimber »

Dampers is an interesting thought.
Groaning as opposed to squeals etc does sound like a damper moving reluctantly and a part prone to sticking etc over time when not used.
You can't swop the callipers over readily I think, the bleed nipple would be inverted and make bleeding tricky?

The pad shims are located in angled recesses and the Pistons need to be orientated to suit.
All in the Haynes book.
73T 911 Coupe, road/hillclimber 3.2L
Lola t 492 / 3.2 hillclimb racer
Boxster 987 Gen II 2.9
Peter Roberts
Married to the DDK
Posts: 299
Joined: Wed Sep 08, 2004 1:23 pm
Location: South Wales

Re: Annoying droning noise from the brakes

Post by Peter Roberts »

Interesting comments. The droan is constant but if i just touch the brake pedal lightly it stops only to return after a very short time. I think this rules out dampers
Most intersting is the issue of shims. I have not got any fitted> In fact there were none fitted before i did the brakes and replaced the pads.
The pads have been in and out several times over the last few weks whilst i have been trying to sort this out. The back of the pads have something stuck to them that is a pretty soft material as the piston has made a slight indentation into it. The pads, being new are quite a tight fit into the gao and dont know if i can get the pistons back far enough to get a shim in. I have got copperslip on the back of the pads but will check if shims should be fitted.
This is the best suggestion yet so will order up a set to try.
356SC
911T
Wide bodied 3.2 Carrera Targa ( cashing in pension now sold)
928GTS (now sold)
Carrera C4S ( now sold)
Carrera 4 with Techart ( now sold)
944 race carfor track days ( Now sold )
1978 Mini Clubman Estate restoration complete
Post Reply