Knocking sound from left front when coasting

Adam · Post by **Adam** » Mon Jun 05, 17 4:50 pm

Got this strange knocking sound coming from the left front wheel area when coasting to a halt. Only does it at walking speed, and only once thoroughly warmed up. Roadspeed related, seems to equate to each wheel revolution. Stops when the car stops.

I would have said it sounds like a warped brake disc knocking a sticky brake piston back into the caliper, except that it makes no difference to the sound when I brake. It knocks whether the car is in gear or not, but it goes away as soon as I touch the gas, which makes me think drivetrain.

Nothing to do with my new front wheels, since it did it with the old wheels. Wheel bearings are fine - no play in them. Spun the wheels when jacked up - slight brake drag, but not hitting anything. I will check the torque converter bolts and UJs, but it does seem to emanate from the front left wheel area. Definitely not rear end.

Any ideas chaps?
TIA

Dart Vader · Post by **Dart Vader** » Mon Jun 05, 17 5:22 pm

Has the dust cover over the spindle nut come off and is now rattling around in the wheel. Mines done that and the Rallye wheel trim cap cover the dust cap so it just rattles around in there

Maybe when you speed up the centrifugal forces stops it moving

Adam · Post by **Adam** » Mon Jun 05, 17 9:25 pm

No Justin. Swapped wheels just last week. Nice try though

octanejunkie · Post by **octanejunkie** » Mon Jun 05, 17 9:58 pm

Loose bolt somewhere...?

I'm currently trying to track down noises too. Very irritating..

Dave999 · Post by **Dave999** » Tue Jun 06, 17 9:27 am

do you have rubber or urethane lower control arm bushes?

is there clearance between the disk brake slider bracket and the disk

dave

Blue · Post by **Blue** » Tue Jun 06, 17 10:18 am

Torque convertor bolts or a cracked flexplate would be my first thoughts.

Adam · Post by **Adam** » Tue Jun 06, 17 11:20 am

Dave - yes urethane bushings, and I did replace that caliper a couple of years ago. Trying to think whether the knocking sound was there before or not.

Thanks for the ideas chaps.

greeny · Post by **greeny** » Wed Jun 07, 17 11:39 pm

Had a similar noise on my daily driver today. Racking my brain as to what it could be. It turned it was incorrectly torqued wheel bolts . Just a thought chief. Hope you find a quick fix thats is easy to do and is cheap . Be safe. Greeny

Dave999 · Post by **Dave999** » Thu Jun 08, 17 10:57 am

[quote="Adam"]Dave - yes urethane bushings, and I did replace that caliper a couple of years ago. Trying to think whether the knocking sound was there before or not.

Thanks for the ideas chaps.[/quote

could be lower control arm clacking back and forth, the torsion bar fits into the adjuster and keeps it all in place but the pin end of the arm is no longer "pinned" when you use a urethane sleeve in the old rubber mount outer shell, the faster you go the less likely it is to happen

does it do it going backwards or going backwards and then hitting the brakes?

Dave

Adam · Post by **Adam** » Thu Jun 08, 17 12:40 pm

Thanks Dave, much appreciated. I'll check out some of your suggestions at the weekend.

Urethane bushings were installed 20 years ago, and the noise has only started recently, but I guess they may have worn and allowed some movement. Just passed a very thorough MOT, so I would have thought they would have picked up any movement.

I'll try it going backwards. It only seems to do it when it's hot in traffic on the motorway, so might be tricky

Don't think it can be torque converter bolts, because it never knocks when stationary with the engine running, whether in gear or not. Only when rolling slowly.

I'm convinced it's brake related. I shall check all clearances at the weekend, e.g. rotor to dust shield, caliper etc.

Adam · Post by **Adam** » Thu Jun 08, 17 12:42 pm

greeny wrote:Had a similar noise on my daily driver today. Racking my brain as to what it could be. It turned it was incorrectly torqued wheel bolts . Just a thought chief. Hope you find a quick fix thats is easy to do and is cheap . Be safe. Greeny

Thanks for this, but I've had the wheels off and on a few times recently, and I'm sure I torqued them all correctly.

Blue · Post by **Blue** » Thu Jun 08, 17 12:43 pm

Because you have just changed the front wheels double check that although the nuts are tight it is actually firmly clamping the wheel and not just the nut's bottoming out. Any part of your rallye wheel trims not quite tight?

Adam · Post by **Adam** » Thu Jun 08, 17 12:49 pm

Blue wrote:Because you have just changed the front wheels double check that although the nuts are tight it is actually firmly clamping the wheel and not just the nut's bottoming out. Any part of your rallye wheel trims not quite tight?

Thanks Blue, good suggestions, but it was making the noise with the old wheels too. The noise definitely synchronises with each wheel revolution though.