Brakes: 850: Whistling / buzzing noise

[volvo2]

Whistling / buzzing noise at speed and after driving some distance – Volvo 850 1994, 200k miles

I’ve been getting a buzzing sound, but only after driving for at least 40 miles and only when traveling above 20 mph or so. I think it is coming from the left rear wheel. It comes more when turning right and fades when turning left. I’ve also noticed that hub is getting warmer than it should. I found today that, due to rust, the pads were not retracting properly. I sorted that out but still have the problem, ie the sound and the heat. Wheel seems t rotate freely and I can’t feel an movement.

Could this be a wheel bearing on the way out?

[Dippydog]

It's certainly exhibiting the signs of a wheel bearing being worn.When you turn right the weight transfer puts more pressure on the left hand side wheels and so the noise gets louder and obviously when turning left the pressure on the left wheels is reduced thereby lessening the noise.Others more knowledgeable than me may be able to comment/advise further.

[jack taylor]

I second Dippydog.

[volvo again]

Have to agree, wheel bearing.
Relatively easy to replace...I think it's the same as v70 models but you need to check first.

https://www.pelicanparts.com/techart...eplacement.htm

[DaveNP]

From my experience in the V70 the wheel bearings can get quite noisy before you'll detect movement by pushing and pulling on the wheel, the trick I learned from the forum is to jack the wheel up and spin it while lightly touching the suspension spring, the slight roughness in the bearing will make the spring vibrate.

[volvo2]

Many thanks for the replies and especially the link to the guidance on bearing replacement - looks fairly straightforward. I will replace the bearing and report back on the outcome.

I did also wonder if it could be the handbrake some how delaminating and rubbing but the heat seems too extreme for that, and as I mentioned before, the wheel rotates freely when rotated by hand.

I did also try pressing and releasing the foot brake just in case the calliper was sticking in some way (I replaced this calliper with genuine Volvo about 50k miles ago). That seemed OK but I do wonder if that might be going on while on the road. Hopefully not and it is the bearing causing the problem.

[volvo2]

Over the weekend I replaced my left-hand rear wheel bearing, as well as the rear brake pads and brake shoes (for the handbrake).

I hope this new bearing has solved the problem. Have driven 60 miles so far without the heating or the sound.

By the way, in case anyone else is replacing a rear bearing - on pre-1995 cars, like mine, they have a 20mm nut (to hold the bearing on the stub-axle, while post 1995 a 22mm nut. The Volvo guidance says the 20mm nuts (which include an integral locked device) should NOT be refitted. Unlike the 22mm nuts, which can be refitted.