rotational knocking sound from front

[Zedster]

We haven't used our V70 for a while. I drove it the other day for the first time in around 4 weeks and immediately heard a rotational knocking sound which appeared to come from the front.

The knocking frequency increased with vehicle speed. It occurs whether driving or applying the brakes and it also occurs if I knock the car into nuetral and coast (it's an automatic).

It sounds like the knock is occuring once per rotation of the wheels like there is something stuck on the tyre.

I have jacked the car up and rotated each front wheel by hand and can't feel anything. I have inspected the surface of the wheel for nails etc and there is nothing present on either side. I have also looked at the discs and nothing seams trapped in the brakes (again turning by hand does not reveal any sound).

I am a little confues how to work out what the cause is beyond this. Has anyone come across this before? or has anyone got any ideas.

What I find most confusing is it has just started.

[simboc2004]

Possibly a stone in/on one of the brake callipers? I have had that before. Reverse for a bit and see if it stops.

[Kev0607]

Originally Posted by Zedster

We haven't used our V70 for a while. I drove it the other day for the first time in around 4 weeks and immediately heard a rotational knocking sound which appeared to come from the front.

The knocking frequency increased with vehicle speed. It occurs whether driving or applying the brakes and it also occurs if I knock the car into nuetral and coast (it's an automatic).

It sounds like the knock is occuring once per rotation of the wheels like there is something stuck on the tyre.

I have jacked the car up and rotated each front wheel by hand and can't feel anything. I have inspected the surface of the wheel for nails etc and there is nothing present on either side. I have also looked at the discs and nothing seams trapped in the brakes (again turning by hand does not reveal any sound).

I am a little confues how to work out what the cause is beyond this. Has anyone come across this before? or has anyone got any ideas.

What I find most confusing is it has just started.

Have you got a jet wash? Give the wheels a blast. That should dislodge any dirt that may have stuck to the discs/brake parts whilst the car has been parked. Once dry, bring it for a good spin gently applying the brakes frequently. If there's anything stuck, that should dislodge it.

[Tatsfield]

Originally Posted by simboc2004

Possibly a stone in/on one of the brake callipers? I have had that before. Reverse for a bit and see if it stops.

I also had that on one of the front discs. The noise was on one side lock and appeared on slow cornering and was loud. It was a tiny wedge shaped piece of stone wedged between the disc and the caliper and while reversing wouldn't shift it, looking at the back of the disc from under the car enabled the stone to be flicked out with a screwdriver. Suddenly all was quiet again!